summaryrefslogtreecommitdiff
path: root/doc/html/thread/synchronization.html
blob: a90bc1d378d2a47c1d7e05fdddb71ca5dc4606d0 (plain) 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
6244
6245
6246
6247
6248
6249
6250
6251
6252
6253
6254
6255
6256
6257
6258
6259
6260
6261
6262
6263
6264
6265
6266
6267
6268
6269
6270
6271
6272
6273
6274
6275
6276
6277
6278
6279
6280
6281
6282
6283
6284
6285
6286
6287
6288
6289
6290
6291
6292
6293
6294
6295
6296
6297
6298
6299
6300
6301
6302
6303
6304
6305
6306
6307
6308
6309
6310
6311
6312
6313
6314
6315
6316
6317
6318
6319
6320
6321
6322
6323
6324
6325
6326
6327
6328
6329
6330
6331
6332
6333
6334
6335
6336
6337
6338
6339
6340
6341
6342
6343
6344
6345
6346
6347
6348
6349
6350
6351
6352
6353
6354
6355
6356
6357
6358
6359
6360
6361
6362
6363
6364
6365
6366
6367
6368
6369
6370
6371
6372
6373
6374
6375
6376
6377
6378
6379
6380
6381
6382
6383
6384
6385
6386
6387
6388
6389
6390
6391
6392
6393
6394
6395
6396
6397
6398
6399
6400
6401
6402
6403
6404
6405
6406
6407
6408
6409
6410
6411
6412
6413
6414
6415
6416
6417
6418
6419
6420
6421
6422
6423
6424
6425
6426
6427
6428
6429
6430
6431
6432
6433
6434
6435
6436
6437
6438
6439
6440
6441
6442
6443
6444
6445
6446
6447
6448
6449
6450
6451
6452
6453
6454
6455
6456
6457
6458
6459
6460
6461
6462
6463
6464
6465
6466
6467
6468
6469
6470
6471
6472
6473
6474
6475
6476
6477
6478
6479
6480
6481
6482
6483
6484
6485
6486
6487
6488
6489
6490
6491
6492
6493
6494
6495
6496
6497
6498
6499
6500
6501
6502
6503
6504
6505
6506
6507
6508
6509
6510
6511
6512
6513
6514
6515
6516
6517
6518
6519
6520
6521
6522
6523
6524
6525
6526
6527
6528
6529
6530
6531
6532
6533
6534
6535
6536
6537
6538
6539
6540
6541
6542
6543
6544
6545
6546
6547
6548
6549
6550
6551
6552
6553
6554
6555
6556
6557
6558
6559
6560
6561
6562
6563
6564
6565
6566
6567
6568
6569
6570
6571
6572
6573
6574
6575
6576
6577
6578
6579
6580
6581
6582
6583
6584
6585
6586
6587
6588
6589
6590
6591
6592
6593
6594
6595
6596
6597
6598
6599
6600
6601
6602
6603
6604
6605
6606
6607
6608
6609
6610
6611
6612
6613
6614
6615
6616
6617
6618
6619
6620
6621
6622
6623
6624
6625
6626
6627
6628
6629
6630
6631
6632
6633
6634
6635
6636
6637
6638
6639
6640
6641
6642
6643
6644
6645
6646
6647
6648
6649
6650
6651
6652
6653
6654
6655
6656
6657
6658
6659
6660
6661
6662
6663
6664
6665
6666
6667
6668
6669
6670
6671
6672
6673
6674
6675
6676
6677
6678
6679
6680
6681
6682
6683
6684
6685
6686
6687
6688
6689
6690
6691
6692
6693
6694
6695
6696
6697
6698
6699
6700
6701
6702
6703
6704
6705
6706
6707
6708
6709
6710
6711
6712
6713
6714
6715
6716
6717
6718
6719
6720
6721
6722
6723
6724
6725
6726
6727
6728
6729
6730
6731
6732
6733
6734
6735
6736
6737
6738
6739
6740
6741
6742
6743
6744
6745
6746
6747
6748
6749
6750
6751
6752
6753
6754
6755
6756
6757
6758
6759
6760
6761
6762
6763
6764
6765
6766
6767
6768
6769
6770
6771
6772
6773
6774
6775
6776
6777
6778
6779
6780
6781
6782
6783
6784
6785
6786
6787
6788
6789
6790
6791
6792
6793
6794
6795
6796
6797
6798
6799
6800
6801
6802
6803
6804
6805
6806
6807
6808
6809
6810
6811
6812
6813
6814
6815
6816
6817
6818
6819
6820
6821
6822
6823
6824
6825
6826
6827
6828
6829
6830
6831
6832
6833
6834
6835
6836
6837
6838
6839
6840
6841
6842
6843
6844
6845
6846
6847
6848
6849
6850
6851
6852
6853
6854
6855
6856
6857
6858
6859
6860
6861
6862
6863
6864
6865
6866
6867
6868
6869
6870
6871
6872
6873
6874
6875
6876
6877
6878
6879
6880
6881
6882
6883
6884
6885
6886
6887
6888
6889
6890
6891
6892
6893
6894
6895
6896
6897
6898
6899
6900
6901
6902
6903
6904
6905
6906
6907
6908
6909
6910
6911
6912
6913
6914
6915
6916
6917
6918
6919
6920
6921
6922
6923
6924
6925
6926
6927
6928
6929
6930
6931
6932
6933
6934
6935
6936
6937
6938
6939
6940
6941
6942
6943
6944
6945
6946
6947
6948
6949
6950
6951
6952
6953
6954
6955
6956
6957
6958
6959
6960
6961
6962
6963
6964
6965
6966
6967
6968
6969
6970
6971
6972
6973
6974
6975
6976
6977
6978
6979
6980
6981
6982
6983
6984
6985
6986
6987
6988
6989
6990
6991
6992
6993
6994
6995
6996
6997
6998
6999
7000
7001
7002
7003
7004
7005
7006
7007
7008
7009
7010
7011
7012
7013
7014
7015
7016
7017
7018
7019
7020
7021
7022
7023
7024
7025
7026
7027
7028
7029
7030
7031
7032
7033
7034
7035
7036
7037
7038
7039
7040
7041
7042
7043
7044
7045
7046
7047
7048
7049
7050
7051
7052
7053
7054
7055
7056
7057
7058
7059
7060
7061
7062
7063
7064
7065
7066
7067
7068
7069
7070
7071
7072
7073
7074
7075
7076
7077
7078
7079
7080
7081
7082
7083
7084
7085
7086
7087
7088
7089
7090
7091
7092
7093
7094
7095
7096
7097
7098
7099
7100
7101
7102
7103
7104
7105
7106
7107
7108
7109
7110
7111
7112
7113
7114
7115
7116
7117
7118
7119
7120
7121
7122
7123
7124
7125
7126
7127
7128
7129
7130
7131
7132
7133
7134
7135
7136
7137
7138
7139
7140
7141
7142
7143
7144
7145
7146
7147
7148
7149
7150
7151
7152
7153
7154
7155
7156
7157
7158
7159
7160
7161
7162
7163
7164
7165
7166
7167
7168
7169
7170
7171
7172
7173
7174
7175
7176
7177
7178
7179
7180
7181
7182
7183
7184
7185
7186
7187
7188
7189
7190
7191
7192
7193
7194
7195
7196
7197
7198
7199
7200
7201
7202
7203
7204
7205
7206
7207
7208
7209
7210
7211
7212
7213
7214
7215
7216
7217
7218
7219
7220
7221
7222
7223
7224
7225
7226
7227
7228
7229
7230
7231
7232
7233
7234
7235
7236
7237
7238
7239
7240
7241
7242
7243
7244
7245
7246
7247
7248
7249
7250
7251
7252
7253
7254
7255
7256
7257
7258
7259
7260
7261
7262
7263
7264
7265
7266
7267
7268
7269
7270
7271
7272
7273
7274
7275
7276
7277
7278
7279
7280
7281
7282
7283
7284
7285
7286
7287
7288
7289
7290
7291
7292
7293
7294
7295
7296
7297
7298
7299
7300
7301
7302
7303
7304
7305
7306
7307
7308
7309
7310
7311
7312
7313
7314
7315
7316
7317
7318
7319
7320
7321
7322
7323
7324
7325
7326
7327
7328
7329
7330
7331
7332
7333
7334
7335
7336
7337
7338
7339
7340
7341
7342
7343
7344
7345
7346
7347
7348
7349
7350
7351
7352
7353
7354
7355
7356
7357
7358
7359
7360
7361
7362
7363
7364
7365
7366
7367
7368
7369
7370
7371
7372
7373
7374
7375
7376
7377
7378
7379
7380
7381
7382
7383
7384
7385
7386
7387
7388
7389
7390
7391
7392
7393
7394
7395
7396
7397
7398
7399
7400
7401
7402
7403
7404
7405
7406
7407
7408
7409
7410
7411
7412
7413
7414
7415
7416
7417
7418
7419
7420
7421
7422
7423
7424
7425
7426
7427
7428
7429
7430
7431
7432
7433
7434
7435
7436
7437
7438
7439
7440
7441
7442
7443
7444
7445
7446
7447
7448
7449
7450
7451
7452
7453
7454
7455
7456
7457
7458
7459
7460
7461
7462
7463
7464
7465
7466
7467
7468
7469
7470
7471
7472
7473
7474
7475
7476
7477
7478
7479
7480
7481
7482
7483
7484
7485
7486
7487
7488
7489
7490
7491
7492
7493
7494
7495
7496
7497
7498
7499
7500
7501
7502
7503
7504
7505
7506
7507
7508
7509
7510
7511
7512
7513
7514
7515
7516
7517
7518
7519
7520
7521
7522
7523
7524
7525
7526
7527
7528
7529
7530
7531
7532
7533
7534
7535
7536
7537
7538
7539
7540
7541
7542
7543
7544
7545
7546
7547
7548
7549
7550
7551
7552
7553
7554
7555
7556
7557
7558
7559
7560
7561
7562
7563
7564
7565
7566
7567
7568
7569
7570
7571
7572
7573
7574
7575
7576
7577
7578
7579
7580
7581
7582
7583
7584
7585
7586
7587
7588
7589
7590
7591
7592
7593
7594
7595
7596
7597
7598
7599
7600
7601
7602
7603
7604
7605
7606
7607
7608
7609
7610
7611
7612
7613
7614
7615
7616
7617
7618
7619
7620
7621
7622
7623
7624
7625
7626
7627
7628
7629
7630
7631
7632
7633
7634
7635
7636
7637
7638
7639
7640
7641
7642
7643
7644
7645
7646
7647
7648
7649
7650
7651
7652
7653
7654
7655
7656
7657
7658
7659
7660
7661
7662
7663
7664
7665
7666
7667
7668
7669
7670
7671
7672
7673
7674
7675
7676
7677
7678
7679
7680
7681
7682
7683
7684
7685
7686
7687
7688
7689
7690
7691
7692
7693
7694
7695
7696
7697
7698
7699
7700
7701
7702
7703
7704
7705
7706
7707
7708
7709
7710
7711
7712
7713
7714
7715
7716
7717
7718
7719
7720
7721
7722
7723
7724
7725
7726
7727
7728
7729
7730
7731
7732
7733
7734
7735
7736
7737
7738
7739
7740
7741
7742
7743
7744
7745
7746
7747
7748
7749
7750
7751
7752
7753
7754
7755
7756
7757
7758
7759
7760
7761
7762
7763
7764
7765
7766
7767
7768
7769
7770
7771
7772
7773
7774
7775
7776
7777
7778
7779
7780
7781
7782
7783
7784
7785
7786
7787
7788
7789
7790
7791
7792
7793
7794
7795
7796
7797
7798
7799
7800
7801
7802
7803
7804
7805
7806
7807
7808
7809
7810
7811
7812
7813
7814
7815
7816
7817
7818
7819
7820
7821
7822
7823
7824
7825
7826
7827
7828
7829
7830
7831
7832
7833
7834
7835
7836
7837
7838
7839
7840
7841
7842
7843
7844
7845
7846
7847
7848
7849
7850
7851
7852
7853
7854
7855
7856
7857
7858
7859
7860
7861
7862
7863
7864
7865
7866
7867
7868
7869
7870
7871
7872
7873
7874
7875
7876
7877
7878
7879
7880
7881
7882
7883
7884
7885
7886
7887
7888
7889
7890
7891
7892
7893
7894
7895
7896
7897
7898
7899
7900
7901
7902
7903
7904
7905
7906
7907
7908
7909
7910
7911
7912
7913
7914
7915
7916
7917
7918
7919
7920
7921
7922
7923
7924
7925
7926
7927
7928
7929
7930
7931
7932
7933
7934
7935
7936
7937
7938
7939
7940
7941
7942
7943
7944
7945
7946
7947
7948
7949
7950
7951
7952
7953
7954
7955
7956
7957
7958
7959
7960
7961
7962
7963
7964
7965
7966
7967
7968
7969
7970
7971
7972
7973
7974
7975
7976
7977
7978
7979
7980
7981
7982
7983
7984
7985
7986
7987
7988
7989
7990
7991
7992
7993
7994
7995
7996
7997
7998
7999
8000
8001
8002
8003
8004
8005
8006
8007
8008
8009
8010
8011
8012
8013
8014
8015
8016
8017
8018
8019
8020
8021
8022
8023
8024
8025
8026
8027
8028
8029
8030
8031
8032
8033
8034
8035
8036
8037
8038
8039
8040
8041
8042
8043
8044
8045
8046
8047
8048
8049
8050
8051
8052
8053
8054
8055
8056
8057
8058
8059
8060
8061
8062
8063
8064
8065
8066
8067
8068
8069
8070
8071
8072
8073
8074
8075
8076
8077
8078
8079
8080
8081
8082
8083
8084
8085
8086
8087
8088
8089
8090
8091
8092
8093
8094
8095
8096
8097
8098
8099
8100
8101
8102
8103
8104
8105
8106
8107
8108
8109
8110
8111
8112
8113
8114
8115
8116
8117
8118
8119
8120
8121
8122
8123
8124
8125
8126
8127
8128
8129
8130
8131
8132
8133
8134
8135
8136
8137
8138
8139
8140
8141
8142
8143
8144
8145
8146
8147
8148
8149
8150
8151
8152
8153
8154
8155
8156
8157
8158
8159
8160
8161
8162
8163
8164
8165
8166
8167
8168
8169
8170
8171
8172
8173
8174
8175
8176
8177
8178
8179
8180
8181
8182
8183
8184
8185
8186
8187
8188
8189
8190
8191
8192
8193
8194
8195
8196
8197
8198
8199
8200
8201
8202
8203
8204
8205
8206
8207
8208
8209
8210
8211
8212
8213
8214
8215
8216
8217
8218
8219
8220
8221
8222
8223
8224
8225
8226
8227
8228
8229
8230
8231
8232
8233
8234
8235
8236
8237
8238
8239
8240
8241
8242
8243
8244
8245
8246
8247
8248
8249
8250
8251
8252
8253
8254
8255
8256
8257
8258
8259
8260
8261
8262
8263
8264
8265
8266
8267
8268
8269
8270
8271
8272
8273
8274
8275
8276
8277
8278
8279
8280
8281
8282
8283
8284
8285
8286
8287
8288
8289
8290
8291
8292
8293
8294
8295
8296
8297
8298
8299
8300
8301
8302
8303
8304
8305
8306
8307
8308
8309
8310
8311
8312
8313
8314
8315
8316
8317
8318
8319
8320
8321
8322
8323
8324
8325
8326
8327
8328
8329
8330
8331
8332
8333
8334
8335
8336
8337
8338
8339
8340
8341
8342
8343
8344
8345
8346
8347
8348
8349
8350
8351
8352
8353
8354
8355
8356
8357
8358
8359
8360
8361
8362
8363
8364
8365
8366
8367
8368
8369
8370
8371
8372
8373
8374
8375
8376
8377
8378
8379
8380
8381
8382
8383
8384
8385
8386
8387
8388
8389
8390
8391
8392
8393
8394
8395
8396
8397
8398
8399
8400
8401
8402
8403
8404
8405
8406
8407
8408
8409
8410
8411
8412
8413
8414
8415
8416
8417
8418
8419
8420
8421
8422
8423
8424
8425
8426
8427
8428
8429
8430
8431
8432
8433
8434
8435
8436
8437
8438
8439
8440
8441
8442
8443
8444
8445
8446
8447
8448
8449
8450
8451
8452
8453
8454
8455
8456
8457
8458
8459
8460
8461
8462
8463
8464
8465
8466
8467
8468
8469
8470
8471
8472
8473
8474
8475
8476
8477
8478
8479
8480
8481
8482
8483
8484
8485
8486
8487
8488
8489
8490
8491
8492
8493
8494
8495
8496
8497
8498
8499
8500
8501
8502
8503
8504
8505
8506
8507
8508
8509
8510
8511
8512
8513
8514
8515
8516
8517
8518
8519
8520
8521
8522
8523
8524
8525
8526
8527
8528
8529
8530
8531
8532
8533
8534
8535
8536
8537
8538
8539
8540
8541
8542
8543
8544
8545
8546
8547
8548
8549
8550
8551
8552
8553
8554
8555
8556
8557
8558
8559
8560
8561
8562
8563
8564
8565
8566
8567
8568
8569
8570
8571
8572
8573
8574
8575
8576
8577
8578
8579
8580
8581
8582
8583
8584
8585
8586
8587
8588
8589
8590
8591
8592
8593
8594
8595
8596
8597
8598
8599
8600
8601
8602
8603
8604
8605
8606
8607
8608
8609
8610
8611
8612
8613
8614
8615
8616
8617
8618
8619
8620
8621
8622
8623
8624
8625
8626
8627
8628
8629
8630
8631
8632
8633
8634
8635
8636
8637
8638
8639
8640
8641
8642
8643
8644
8645
8646
8647
8648
8649
8650
8651
8652
8653
8654
8655
8656
8657
8658
8659
8660
8661
8662
8663
8664
8665
8666
8667
8668
8669
8670
8671
8672
8673
8674
8675
8676
8677
8678
8679
8680
8681
8682
8683
8684
8685
8686
8687
8688
8689
8690
8691
8692
8693
8694
8695
8696
8697
8698
8699
8700
8701
8702
8703
8704
8705
8706
8707
8708
8709
8710
8711
8712
8713
8714
8715
8716
8717
8718
8719
8720
8721
8722
8723
8724
8725
8726
8727
8728
8729
8730
8731
8732
8733
8734
8735
8736
8737
8738
8739
8740
8741
8742
8743
8744
8745
8746
8747
8748
8749
8750
8751
8752
8753
8754
8755
8756
8757
8758
8759
8760
8761
8762
8763
8764
8765
8766
8767
8768
8769
8770
8771
8772
8773
8774
8775
8776
8777
8778
8779
8780
8781
8782
8783
8784
8785
8786
8787
8788
8789
8790
8791
8792
8793
8794
8795
8796
8797
8798
8799
8800
8801
8802
8803
8804
8805
8806
8807
8808
8809
8810
8811
8812
8813
8814
8815
8816
8817
8818
8819
8820
8821
8822
8823
8824
8825
8826
8827
8828
8829
8830
8831
8832
8833
8834
8835
8836
8837
8838
8839
8840
8841
8842
8843
8844
8845
8846
8847
8848
8849
8850
8851
8852
8853
8854
8855
8856
8857
8858
8859
8860
8861
8862
8863
8864
8865
8866
8867
8868
8869
8870
8871
8872
8873
8874
8875
8876
8877
8878
8879
8880
8881
8882
8883
8884
8885
8886
8887
8888
8889
8890
8891
8892
8893
8894
8895
8896
8897
8898
8899
8900
8901
8902
8903
8904
8905
8906
8907
8908
8909
8910
8911
8912
8913
8914
8915
8916
8917
8918
8919
8920
8921
8922
8923
8924
8925
8926
8927
8928
8929
8930
8931
8932
8933
8934
8935
8936
8937
8938
8939
8940
8941
8942
8943
8944
8945
8946
8947
8948
8949
8950
8951
8952
8953
8954
8955
8956
8957
8958
8959
8960
8961
8962
8963
8964
8965
8966
8967
8968
8969
8970
8971
8972
8973
8974
8975
8976
8977
8978
8979
8980
8981
8982
8983
8984
8985
8986
8987
8988
8989
8990
8991
8992
8993
8994
8995
8996
8997
8998
8999
9000
9001
9002
9003
9004
9005
9006
9007
9008
9009
9010
9011
9012
9013
9014
9015
9016
9017
9018
9019
9020
9021
9022
9023
9024
9025
9026
9027
9028
9029
9030
9031
9032
9033
9034
9035
9036
9037
9038
9039
9040
9041
9042
9043
9044
9045
9046
9047
9048
9049
9050
9051
9052
9053
9054
9055
9056
9057
9058
9059
9060
9061
9062
9063
9064
9065
9066
9067
9068
9069
9070
9071
9072
9073
9074
9075
9076
9077
9078
9079
9080
9081
9082
9083
9084
9085
9086
9087
9088
9089
9090
9091
9092
9093
9094
9095
9096
9097
9098
9099
9100
9101
9102
9103
9104
9105
9106
9107
9108
9109
9110
9111
9112
9113
9114
9115
9116
9117
9118
9119
9120
9121
9122
9123
9124
9125
9126
9127
9128
9129
9130
9131
9132
9133
9134
9135
9136
9137
9138
9139
9140
9141
9142
9143
9144
9145
9146
9147
9148
9149
9150
9151
9152
9153
9154
9155
9156
9157
9158
9159
9160
9161
9162
9163
9164
9165
9166
9167
9168
9169
9170
9171
9172
9173
9174
9175
9176
9177
9178
9179
9180
9181
9182
9183
9184
9185
9186
9187
9188
9189
9190
9191
9192
9193
9194
9195
9196
9197
9198
9199
9200
9201
9202
9203
9204
9205
9206
9207
9208
9209
9210
9211
9212
9213
9214
9215
9216
9217
9218
9219
9220
9221
9222
9223
9224
9225
9226
9227
9228
9229
9230
9231
9232
9233
9234
9235
9236
9237
9238
9239
9240
9241
9242
9243
9244
9245
9246
9247
9248
9249
9250
9251
9252
9253
9254
9255
9256
9257
9258
9259
9260
9261
9262
9263
9264
9265
9266
9267
9268
9269
9270
9271
9272
9273
9274
9275
9276
9277
9278
9279
9280
9281
9282
9283
9284
9285
9286
9287
9288
9289
9290
9291
9292
9293
9294
9295
9296
9297
9298
9299
9300
9301
9302
9303
9304
9305
9306
9307
9308
9309
9310
9311
9312
9313
9314
9315
9316
9317
9318
9319
9320
9321
9322
9323
9324
9325
9326
9327
9328
9329
9330
9331
9332
9333
9334
9335
9336
9337
9338
9339
9340
9341
9342
9343
9344
9345
9346
9347
9348
9349
9350
9351
9352
9353
9354
9355
9356
9357
9358
9359
9360
9361
9362
9363
9364
9365
9366
9367
9368
9369
9370
9371
9372
9373
9374
9375
9376
9377
9378
9379
9380
9381
9382
9383
9384
9385
9386
9387
9388
9389
9390
9391
9392
9393
9394
9395
9396
9397
9398
9399
9400
9401
9402
9403
9404
9405
9406
9407
9408
9409
9410
9411
9412
9413
9414
9415
9416
9417
9418
9419
9420
9421
9422
9423
9424
9425
9426
9427
9428
9429
9430
9431
9432
9433
9434
9435
9436
9437
9438
9439
9440
9441
9442
9443
9444
9445
9446
9447
9448
9449
9450
9451
9452
9453
9454
9455
9456
9457
9458
9459
9460
9461
9462
9463
9464
9465
9466
9467
9468
9469
9470
9471
9472
9473
9474
9475
9476
9477
9478
9479
9480
9481
9482
9483
9484
9485
9486
9487
9488
9489
9490
9491
9492
9493
9494
9495
9496
9497
9498
9499
9500
9501
9502
9503
9504
9505
9506
9507
9508
9509
9510
9511
9512
9513
9514
9515
9516
9517
9518
9519
9520
9521
9522
9523
9524
9525
9526
9527
9528
9529
9530
9531
9532
9533
9534
9535
9536
9537
9538
9539
9540
9541
9542
9543
9544
9545
9546
9547
9548
9549
9550
9551
9552
9553
9554
9555
9556
9557
9558
9559
9560
9561
9562
9563
9564
9565
9566
9567
9568
9569
9570
9571
9572
9573
9574
9575
9576
9577
9578
9579
9580
9581
9582
9583
9584
9585
9586
9587
9588
9589
9590
9591
9592
9593
9594
9595
9596
9597
9598
9599
9600
9601
9602
9603
9604
9605
9606
9607
9608
9609
9610
9611
9612
9613
9614
9615
9616
9617
9618
9619
9620
9621
9622
9623
9624
9625
9626
9627
9628
9629
9630
9631
9632
9633
9634
9635
9636
9637
9638
9639
9640
9641
9642
9643
9644
9645
9646
9647
9648
9649
9650
9651
9652
9653
9654
9655
9656
9657
9658
9659
9660
9661
9662
9663
9664
9665
9666
9667
9668
9669
9670
9671
9672
9673
9674
9675
9676
9677
9678
9679
9680
9681
9682
9683
9684
9685
9686
9687
9688
9689
9690
9691
9692
9693
9694
9695
9696
9697
9698
9699
9700
9701
9702
9703
9704
9705
9706
9707
9708
9709
9710
9711
9712
9713
9714
9715
9716
9717
9718
9719
9720
9721
9722
9723
9724
9725
9726
9727
9728
9729
9730
9731
9732
9733
9734
9735
9736
9737
9738
9739
9740
9741
9742
9743
9744
9745
9746
9747
9748
9749
9750
9751
9752
9753
9754
9755
9756
9757
9758
9759
9760
9761
9762
9763
9764
9765
9766
9767
9768
9769
9770
9771
9772
9773
9774
9775
9776
9777
9778
9779
9780
9781
9782
9783
9784
9785
9786
9787
9788
9789
9790
9791
9792
9793
9794
9795
9796
9797
9798
9799
9800
9801
9802
9803
9804
9805
9806
9807
9808
9809
9810
9811
9812
9813
9814
9815
9816
9817
9818
9819
9820
9821
9822
9823
9824
9825
9826
9827
9828
9829
9830
9831
9832
9833
9834
9835
9836
9837
9838
9839
9840
9841
9842
9843
9844
9845
9846
9847
9848
9849
9850
9851
9852
9853
9854
9855
9856
9857
9858
9859
9860
9861
9862
9863
9864
9865
9866
9867
9868
9869
9870
9871
9872
9873
9874
9875
9876
9877
9878
9879
9880
9881
9882
9883
9884
9885
9886
9887
9888
9889
9890
9891
9892
9893
9894
9895
9896
9897
9898
9899
9900
9901
9902
9903
9904
9905
9906
9907
9908
9909
9910
9911
9912
9913
9914
9915
9916
9917
9918
9919
9920
9921
9922
9923
9924
9925
9926
9927
9928
9929
9930
9931
9932
9933
9934
9935
9936
9937
9938
9939
9940
9941
9942
9943
9944
9945
9946
9947
9948
9949
9950
9951
9952
9953
9954
9955
9956
9957
9958
9959
9960
9961
9962
9963
9964
9965
9966
9967
9968
9969
9970
9971
9972
9973
9974
9975
9976
9977
9978
9979
9980
9981
9982
9983
9984
9985
9986
9987
9988
9989
9990
9991
9992
9993
9994
9995
9996
9997
9998
9999
10000
10001
10002
10003
10004
10005
10006
10007
10008
10009
10010
10011
10012
10013
10014
10015
10016
10017
10018
10019
10020
10021
10022
10023
10024
10025
10026
10027
10028
10029
10030
10031
10032
10033
10034
10035
10036
10037
10038
10039
10040
10041
10042
10043
10044
10045
10046
10047
10048
10049
10050
10051
10052
10053
10054
10055
10056
10057
10058
10059
10060
10061
10062
10063
10064
10065
10066
10067
10068
10069
10070
10071
10072
10073
10074
10075
10076
10077
10078
10079
10080
10081
10082
10083
10084
10085
10086
10087
10088
10089
10090
10091
10092
10093
10094
10095
10096
10097
10098
10099
10100
10101
10102
10103
10104
10105
10106
10107
10108
10109
10110
10111
10112
10113
10114
10115
10116
10117
10118
10119
10120
10121
10122
10123
10124
10125
10126
10127
10128
10129
10130
10131
10132
10133
10134
10135
10136
10137
10138
10139
10140
10141
10142
10143
10144
10145
10146
10147
10148
10149
10150
10151
10152
10153
10154
10155
10156
10157
10158
10159
10160
10161
10162
10163
10164
10165
10166
10167
10168
10169
10170
10171
10172
10173
10174
10175
10176
10177
10178
10179
10180
10181
10182
10183
10184
10185
10186
10187
10188
10189
10190
10191
10192
10193
10194
10195
10196
10197
10198
10199
10200
10201
10202
10203
10204
10205
10206
10207
10208
10209
10210
10211
10212
10213
10214
10215
10216
10217
10218
10219
10220
10221
10222
10223
10224
10225
10226
10227
10228
10229
10230
10231
10232
10233
10234
10235
10236
10237
10238
10239
10240
10241
10242
10243
10244
10245
10246
10247
10248
10249
10250
10251
10252
10253
10254
10255
10256
10257
10258
10259
10260
10261
10262
10263
10264
10265
10266
10267
10268
10269
10270
10271
10272
10273
10274
10275
10276
10277
10278
10279
10280
10281
10282
10283
10284
10285
10286
10287
10288
10289
10290
10291
10292
10293
10294
10295
10296
10297
10298
10299
10300
10301
10302
10303
10304
10305
10306
10307
10308
10309
10310
10311
10312
10313
10314
10315
10316
10317
10318
10319
10320
10321
10322
10323
10324
10325
10326
10327
10328
10329
10330
10331
10332
10333
10334
10335
10336
10337
10338
10339
10340
10341
10342
10343
10344
10345
10346
10347
10348
10349
10350
10351
10352
10353
10354
10355
10356
10357
10358
10359
10360
10361
10362
10363
10364
10365
10366
10367
10368
10369
10370
10371
10372
10373
10374
10375
10376
10377
10378
10379
10380
10381
10382
10383
10384
10385
10386
10387
10388
10389
10390
10391
10392
10393
10394
10395
10396
10397
10398
10399
10400
10401
10402
10403
10404
10405
10406
10407
10408
10409
10410
10411
10412
10413
10414
10415
10416
10417
10418
10419
10420
10421
10422
10423
10424
10425
10426
10427
10428
10429
10430
10431
10432
10433
10434
10435
10436
10437
10438
10439
10440
10441
10442
10443
10444
10445
10446
10447
10448
10449
10450
10451
10452
10453
10454
10455
10456
10457
10458
10459
10460
10461
10462
10463
10464
10465
10466
10467
10468
10469
10470
10471
10472
10473
10474
10475
10476
10477
10478
10479
10480
10481
10482
10483
10484
10485
10486
10487
10488
10489
10490
10491
10492
10493
10494
10495
10496
10497
10498
10499
10500
10501
10502
10503
10504
10505
10506
10507
10508
10509
10510
10511
10512
10513
10514
10515
10516
10517
10518
10519
10520
10521
10522
10523
10524
10525
10526
10527
10528
10529
10530
10531
10532
10533
10534
10535
10536
10537
10538
10539
10540
10541
10542
10543
10544
10545
10546
10547
10548
10549
10550
10551
10552
10553
10554
10555
10556
10557
10558
10559
10560
10561
10562
10563
10564
10565
10566
10567
10568
10569
10570
10571
10572
10573
10574
10575
10576
10577
10578
10579
10580
10581
10582
10583
10584
10585
10586
10587
10588
10589
10590
10591
10592
10593
10594
10595
10596
10597
10598
10599
10600
10601
10602
10603
10604
10605
10606
10607
10608
10609
10610
10611
10612
10613
10614
10615
10616
10617
10618
10619
10620
10621
10622
10623
10624
10625
10626
10627
10628
10629
10630
10631
10632
10633
10634
10635
10636
10637
10638
10639
10640
10641
10642
10643
10644
10645
10646
10647
10648
10649
10650
10651
10652
10653
10654
10655
10656
10657
10658
10659
10660
10661
10662
10663
10664
10665
10666
10667
10668
10669
10670
10671
10672
10673
10674
10675
10676
10677
10678
10679
10680
10681
10682
10683
10684
10685
10686
10687
10688
10689
10690
10691
10692
10693
10694
10695
10696
10697
10698
10699
10700
10701
10702
10703
10704
10705
10706
10707
10708
10709
10710
10711
10712
10713
10714
10715
10716
10717
10718
10719
10720
10721
10722
10723
10724
10725
10726
10727
10728
10729
10730
10731
10732
10733
10734
10735
10736
10737
10738
10739
10740
10741
10742
10743
10744
10745
10746
10747
10748
10749
10750
10751
10752
10753
10754
10755
10756
10757
10758
10759
10760
10761
10762
10763
10764
10765
10766
10767
10768
10769
10770
10771
10772
10773
10774
10775
10776
10777
10778
10779
10780
10781
10782
10783
10784
10785
10786
10787
10788
10789
10790
10791
10792
10793
10794
10795
10796
10797
10798
10799
10800
10801
10802
10803
10804
10805
10806
10807
10808
10809
10810
10811
10812
10813
10814
10815
10816
10817
10818
10819
10820
10821
10822
10823
10824
10825
10826
10827
10828
10829
10830
10831
10832
10833
10834
10835
10836
10837
10838
10839
10840
10841
10842
10843
10844
10845
10846
10847
10848
10849
10850
10851
10852
10853
10854
10855
10856
10857
10858
10859
10860
10861
10862
10863
10864
10865
10866
10867
10868
10869
10870
10871
10872
10873
10874
10875
10876
10877
10878
10879
10880
10881
10882
10883
10884
10885
10886
10887
10888
10889
10890
10891
10892
10893
10894
10895
10896
10897
10898
10899
10900
10901
10902
10903
10904
10905
10906
10907
10908
10909
10910
10911
10912
10913
10914
10915
10916
10917
10918
10919
10920
10921
10922
10923
10924
10925
10926
10927
10928
10929
10930
10931
10932
10933
10934
10935
10936
10937
10938
10939
10940
10941
10942
10943
10944
10945
10946
10947
10948
10949
10950
10951
10952
10953
10954
10955
10956
10957
10958
10959
10960
10961
10962
10963
10964
10965
10966
10967
10968
10969
10970
10971
10972
10973
10974
10975
10976
10977
10978
10979
10980
10981
10982
10983
10984
10985
10986
10987
10988
10989
10990
10991
10992
10993
10994
10995
10996
10997
10998
10999
11000
11001
11002
11003
11004
11005
11006
11007
11008
11009
11010
11011
11012
11013
11014
11015
11016
11017
11018
11019
11020
11021
11022
11023
11024
11025
11026
11027
11028
11029
11030
11031
11032
11033
11034
11035
11036
11037
11038
11039
11040
11041
11042
11043
11044
11045
11046
11047
11048
11049
11050
11051
11052
11053
11054
11055
11056
11057
11058
11059
11060
11061
11062
11063
11064
11065
11066
11067
11068
11069
11070
11071
11072
11073
11074
11075
11076
11077
11078
11079
11080
11081
11082
11083
11084
11085
11086
11087
11088
11089
11090
11091
11092
11093
11094
11095
11096
11097
11098
11099
11100
11101
11102
11103
11104
11105
11106
11107
11108
11109
11110
11111
11112
11113
11114
11115
11116
11117
11118
11119
11120
11121
11122
11123
11124
11125
11126
11127
11128
11129
11130
11131
11132
11133
11134
11135
11136
11137
11138
11139
11140
11141
11142
11143
11144
11145
11146
11147
11148
11149
11150
11151
11152
11153
11154
11155
11156
11157
11158
11159
11160
11161
11162
11163
11164
11165
11166
11167
11168
11169
11170
11171
11172
11173
11174
11175
11176
11177
11178
11179
11180
11181
11182
11183
11184
11185
11186
11187
11188
11189
11190
11191
11192
11193
11194
11195
11196
11197
11198
11199
11200
11201
11202
11203
11204
11205
11206
11207
11208
11209
11210
11211
11212
11213
11214
11215
11216
11217
11218
11219
11220
11221
11222
11223
11224
11225
11226
11227
11228
11229
11230
11231
11232
11233
11234
11235
11236
11237
11238
11239
11240
11241
11242
11243
11244
11245
11246
11247
11248
11249
11250
11251
11252
11253
11254
11255
11256
11257
11258
11259
11260
11261
11262
11263
11264
11265
11266
11267
11268
11269
11270
11271
11272
11273
11274
11275
11276
11277
11278
11279
11280
11281
11282
11283
11284
11285
11286
11287
11288
11289
11290
11291
11292
11293
11294
11295
11296
11297
11298
11299
11300
11301
11302
11303
11304
11305
11306
11307
11308
11309
11310
11311
11312
11313
11314
11315
11316
11317
11318
11319
11320
11321
11322
11323
11324
11325
11326
11327
11328
11329
11330
11331
11332
11333
11334
11335
11336
11337
11338
11339
11340
11341
11342
11343
11344
11345
11346
11347
11348
11349
11350
11351
11352
11353
11354
11355
11356
11357
11358
11359
11360
11361
11362
11363
11364
11365
11366
11367
11368
11369
11370
11371
11372
11373
11374
11375
11376
11377
11378
11379
11380
11381
11382
11383
11384
11385
11386
11387
11388
11389
11390
11391
11392
11393
11394
11395
11396
11397
11398
11399
11400
11401
11402
11403
11404
11405
11406
11407
11408
11409
11410
11411
11412
11413
11414
11415
11416
11417
11418
11419
11420
11421
11422
11423
11424
11425
11426
11427
11428
11429
11430
11431
11432
11433
11434
11435
11436
11437
11438
11439
11440
11441
11442
11443
11444
11445
11446
11447
11448
11449
11450
11451
11452
11453
11454
11455
11456
11457
11458
11459
11460
11461
11462
11463
11464
11465
11466
11467
11468
11469
11470
11471
11472
11473
11474
11475
11476
11477
11478
11479
11480
11481
11482
11483
11484
11485
11486
11487
11488
11489
11490
11491
11492
11493
11494
11495
11496
11497
11498
11499
11500
11501
11502
11503
11504
11505
11506
11507
11508
11509
11510
11511
11512
11513
11514
11515
11516
11517
11518
11519
11520
11521
11522
11523
11524
11525
11526
11527
11528
11529
11530
11531
11532
11533
11534
11535
11536
11537
11538
11539
11540
11541
11542
11543
11544
11545
11546
11547
11548
11549
11550
11551
11552
11553
11554
11555
11556
11557
11558
11559
11560
11561
11562
11563
11564
11565
11566
11567
11568
11569
11570
11571
11572
11573
11574
11575
11576
11577
11578
11579
11580
11581
11582
11583
11584
11585
11586
11587
11588
11589
11590
11591
11592
11593
11594
11595
11596
11597
11598
11599
11600
11601
11602
11603
11604
11605
11606
11607
11608
11609
11610
11611
11612
11613
11614
11615
11616
11617
11618
11619
11620
11621
11622
11623
11624
11625
11626
11627
11628
11629
11630
11631
11632
11633
11634
11635
11636
11637
11638
11639
11640
11641
11642
11643
11644
11645
11646
11647
11648
11649
11650
11651
11652
11653
11654
11655
11656
11657
11658
11659
11660
11661
11662
11663
11664
11665
11666
11667
11668
11669
11670
11671
11672
11673
11674
11675
11676
11677
11678
11679
11680
11681
11682
11683
11684
11685
11686
11687
11688
11689
11690
11691
11692
11693
11694
11695
11696
11697
11698
11699
11700
11701
11702
11703
11704
11705
11706
11707
11708
11709
11710
11711
11712
11713
11714
11715
11716
11717
11718
11719
11720
11721
11722
11723
11724
11725
11726
11727
11728
11729
11730
11731
11732
11733
11734
11735
11736
11737
11738
11739
11740
11741
11742
11743
11744
11745
11746
11747
11748
11749
11750
11751
11752
11753
11754
11755
11756
11757
11758
11759
11760
11761
11762
11763
11764
11765
11766
11767
11768
11769
11770
11771
11772
11773
11774
11775
11776
11777
11778
11779
11780
11781
11782
11783
11784
11785
11786
11787
11788
11789
11790
11791
11792
11793
11794
11795
11796
11797
11798
11799
11800
11801
11802
11803
11804
11805
11806
11807
11808
11809
11810
11811
11812
11813
11814
11815
11816
11817
11818
11819
11820
11821
11822
11823
11824
11825
11826
11827
11828
11829
11830
11831
11832
11833
11834
11835
11836
11837
11838
11839
11840
11841
11842
11843
11844
11845
11846
11847
11848
11849
11850
11851
11852
11853
11854
11855
11856
11857
11858
11859
11860
11861
11862
11863
11864
11865
11866
11867
11868
11869
11870
11871
11872
11873
11874
11875
11876
11877
11878
11879
11880
11881
11882
11883
11884
11885
11886
11887
11888
11889
11890
11891
11892
11893
11894
11895
11896
11897
11898
11899
11900
11901
11902
11903
11904
11905
11906
11907
11908
11909
11910
11911
11912
11913
11914
11915
11916
11917
11918
11919
11920
11921
11922
11923
11924
11925
11926
11927
11928
11929
11930
11931
11932
11933
11934
11935
11936
11937
11938
11939
11940
11941
11942
11943
11944
11945
11946
11947
11948
11949
11950
11951
11952
11953
11954
11955
11956
11957
11958
11959
11960
11961
11962
11963
11964
11965
11966
11967
11968
11969
11970
11971
11972
11973
11974
11975
11976
11977
11978
11979
11980
11981
11982
11983
11984
11985
11986
11987
11988
11989
11990
11991
11992
11993
11994
11995
11996
11997
11998
11999
12000
12001
12002
12003
12004
12005
12006
12007
12008
12009
12010
12011
12012
12013
12014
12015
12016
12017
12018
12019
12020
12021
12022
12023
12024
12025
12026
12027
12028
12029
12030
12031
12032
12033
12034
12035
12036
12037
12038
12039
12040
12041
12042
12043
12044
12045
12046
12047
12048
12049
12050
12051
12052
12053
12054
12055
12056
12057
12058
12059
12060
12061
12062
12063
12064
12065
12066
12067
12068
12069
12070
12071
12072
12073
12074
12075
12076
12077
12078
12079
12080
12081
12082
12083
12084
12085
12086
12087
12088
12089
12090
12091
12092
12093
12094
12095
12096
12097
12098
12099
12100
12101
12102
12103
12104
12105
12106
12107
12108
12109
12110
12111
12112
12113
12114
12115
12116
12117
12118
12119
12120
12121
12122
12123
12124
12125
12126
12127
12128
12129
12130
12131
12132
12133
12134
12135
12136
12137
12138
12139
12140
12141
12142
12143
12144
12145
12146
12147
12148
12149
12150
12151
12152
12153
12154
12155
12156
12157
12158
12159
12160
12161
12162
12163
12164
12165
12166
12167
12168
12169
12170
12171
12172
12173
12174
12175
12176
12177
12178
12179
12180
12181
12182
12183
12184
12185
12186
12187
12188
12189
12190
12191
12192
12193
12194
12195
12196
12197
12198
12199
12200
12201
12202
12203
12204
12205
12206
12207
12208
12209
12210
12211
12212
12213
12214
12215
12216
12217
12218
12219
12220
12221
12222
12223
12224
12225
12226
12227
12228
12229
12230
12231
12232
12233
12234
12235
12236
12237
12238
12239
12240
12241
12242
12243
12244
12245
12246
12247
12248
12249
12250
12251
12252
12253
12254
12255
12256
12257
12258
12259
12260
12261
12262
12263
12264
12265
12266
12267
12268
12269
12270
12271
12272
12273
12274
12275
12276
12277
12278
12279
12280
12281
12282
12283
12284
12285
12286
12287
12288
12289
12290
12291
12292
12293
12294
12295
12296
12297
12298
12299
12300
12301
12302
12303
12304
12305
12306
12307
12308
12309
12310
12311
12312
12313
12314
12315
12316
12317
12318
12319
12320
12321
12322
12323
12324
12325
12326
12327
12328
12329
12330
12331
12332
12333
12334
12335
12336
12337
12338
12339
12340
12341
12342
12343
12344
12345
12346
12347
12348
12349
12350
12351
12352
12353
12354
12355
12356
12357
12358
12359
12360
12361
12362
12363
12364
12365
12366
12367
12368
12369
12370
12371
12372
12373
12374
12375
12376
12377
12378
12379
12380
12381
12382
12383
12384
12385
12386
12387
12388
12389
12390
12391
12392
12393
12394
12395
12396
12397
12398
12399
12400
12401
12402
12403
12404
12405
12406
12407
12408
12409
12410
12411
12412
12413
12414
12415
12416
12417
12418
12419
12420
12421
12422
12423
12424
12425
12426
12427
12428
12429
12430
12431
12432
12433
12434
12435
12436
12437
12438
12439
12440
12441
12442
12443
12444
12445
12446
12447
12448
12449
12450
12451
12452
12453
12454
12455
12456
12457
12458
12459
12460
12461
12462
12463
12464
12465
12466
12467
12468
12469
12470
12471
12472
12473
12474
12475
12476
12477
12478
12479
12480
12481
12482
12483
12484
12485
12486
12487
12488
12489
12490
12491
12492
12493
12494
12495
12496
12497
12498
12499
12500
12501
12502
12503
12504
12505
12506
12507
12508
12509
12510
12511
12512
12513
12514
12515
12516
12517
12518
12519
12520
12521
12522
12523
12524
12525
12526
12527
12528
12529
12530
12531
12532
12533
12534
12535
12536
12537
12538
12539
12540
12541
12542
12543
12544
12545
12546
12547
12548
12549
12550
12551
12552
12553
12554
12555
12556
12557
12558
12559
12560
12561
12562
12563
12564
12565
12566
12567
12568
12569
12570
12571
12572
12573
12574
12575
12576
12577
12578
12579
12580
12581
12582
12583
12584
12585
12586
12587
12588
12589
12590
12591
12592
12593
12594
12595
12596
12597
12598
12599
12600
12601
12602
12603
12604
12605
12606
12607
12608
12609
12610
12611
12612
12613
12614
12615
12616
12617
12618
12619
12620
12621
12622
12623
12624
12625
12626
12627
12628
12629
12630
12631
12632
12633
12634
12635
12636
12637
12638
12639
12640
12641
12642
12643
12644
12645
12646
12647
12648
12649
12650
12651
12652
12653
12654
12655
12656
12657
12658
12659
12660
12661
12662
12663
12664
12665
12666
12667
12668
12669
12670
12671
12672
12673
12674
12675
12676
12677
12678
12679
12680
12681
12682
12683
12684
12685
12686
12687
12688
12689
12690
12691
12692
12693
12694
12695
12696
12697
12698
12699
12700
12701
12702
12703
12704
12705
12706
12707
12708
12709
12710
12711
12712
12713
12714
12715
12716
12717
12718
12719
12720
12721
12722
12723
12724
12725
12726
12727
12728
12729
12730
12731
12732
12733
12734
12735
12736
12737
12738
12739
12740
12741
12742
12743
12744
12745
12746
12747
12748
12749
12750
12751
12752
12753
12754
12755
12756
12757
12758
12759
12760
12761
12762
12763
12764
12765
12766
12767
12768
12769
12770
12771
12772
12773
12774
12775
12776
12777
12778
12779
12780
12781
12782
12783
12784
12785
12786
12787
12788
12789
12790
12791
12792
12793
12794
12795
12796
12797
12798
12799
12800
12801
12802
12803
12804
12805
12806
12807
12808
12809
12810
12811
12812
12813
12814
12815
12816
12817
12818
12819
12820
12821
12822
12823
12824
12825
12826
12827
12828
12829
12830
12831
12832
12833
12834
12835
12836
12837
12838
12839
12840
12841
12842
12843
12844
12845
12846
12847
12848
12849
12850
12851
12852
12853
12854
12855
12856
12857
12858
12859
12860
12861
12862
12863
12864
12865
12866
12867
12868
12869
12870
12871
12872
12873
12874
12875
12876
12877
12878
12879
12880
12881
12882
12883
12884
12885
12886
12887
12888
12889
12890
12891
12892
12893
12894
12895
12896
12897
12898
12899
12900
12901
12902
12903
12904
12905
12906
12907
12908
12909
12910
12911
12912
12913
12914
12915
12916
12917
12918
12919
12920
12921
12922
12923
12924
12925
12926
12927
12928
12929
12930
12931
12932
12933
12934
12935
12936
12937
12938
12939
12940
12941
12942
12943
12944
12945
12946
12947
12948
12949
12950
12951
12952
12953
12954
12955
12956
12957
12958
12959
12960
12961
12962
12963
12964
12965
12966
12967
12968
12969
12970
12971
12972
12973
12974
12975
12976
12977
12978
12979
12980
12981
12982
12983
12984
12985
12986
12987
12988
12989
12990
12991
12992
12993
12994
12995
12996
12997
12998
12999
13000
13001
13002
13003
13004
13005
13006
13007
13008
13009
13010
13011
13012
13013
13014
13015
13016
13017
13018
13019
13020
13021
13022
13023
13024
13025
13026
13027
13028
13029
13030
13031
13032
13033
13034
13035
13036
13037
13038
13039
13040
13041
13042
13043
13044
13045
13046
13047
13048
13049
13050
13051
13052
13053
13054
13055
13056
13057
13058
13059
13060
13061
13062
13063
13064
13065
13066
13067
13068
13069
13070
13071
13072
13073
13074
13075
13076
13077
13078
13079
13080
13081
13082
13083
13084
13085
13086
13087
13088
13089
13090
13091
13092
13093
13094
13095
13096
13097
13098
13099
13100
13101
13102
13103
13104
13105
13106
13107
13108
13109
13110
13111
13112
13113
13114
13115
13116
13117
13118
13119
13120
13121
13122
13123
13124
13125
13126
13127
13128
13129
13130
13131
13132
13133
13134
13135
13136
13137
13138
13139
13140
13141
13142
13143
13144
13145
13146
13147
13148
13149
13150
13151
13152
13153
13154
13155
13156
13157
13158
13159
13160
13161
13162
13163
13164
13165
13166
13167
13168
13169
13170
13171
13172
13173
13174
13175
13176
13177
13178
13179
13180
13181
13182
13183
13184
13185
13186
13187
13188
13189
13190
13191
13192
13193
13194
13195
13196
13197
13198
13199
13200
13201
13202
13203
13204
13205
13206
13207
13208
13209
13210
13211
13212
13213
13214
13215
13216
13217
13218
13219
13220
13221
13222
13223
13224
13225
13226
13227
13228
13229
13230
13231
13232
13233
13234
13235
13236
13237
13238
13239
13240
13241
13242
13243
13244
13245
13246
13247
13248
13249
13250
13251
13252
13253
13254
13255
13256
13257
13258
13259
13260
13261
13262
13263
13264
13265
13266
13267
13268
13269
13270
13271
13272
13273
13274
13275
13276
13277
13278
13279
13280
13281
13282
13283
13284
13285
13286
13287
13288
13289
13290
13291
13292
13293
13294
13295
13296
13297
13298
13299
13300
13301
13302
13303
13304
13305
13306
13307
13308
13309
13310
13311
13312
13313
13314
13315
13316
13317
13318
13319
13320
13321
13322
13323
13324
13325
13326
13327
13328
13329
13330
13331
13332
13333
13334
13335
13336
13337
13338
13339
13340
13341
13342
13343
13344
13345
13346
13347
13348
13349
13350
13351
13352
13353
13354
13355
13356
13357
13358
13359
13360
13361
13362
13363
13364
13365
13366
13367
13368
13369
13370
13371
13372
13373
13374
13375
13376
13377
13378
13379
13380
13381
13382
13383
13384
13385
13386
13387
13388
13389
13390
13391
13392
13393
13394
13395
13396
13397
13398
13399
13400
13401
13402
13403
13404
13405
13406
13407
13408
13409
13410
13411
13412
13413
13414
13415
13416
13417
13418
13419
13420
13421
13422
13423
13424
13425
13426
13427
13428
13429
13430
13431
13432
13433
13434
13435
13436
13437
13438
13439
13440
13441
13442
13443
13444
13445
13446
13447
13448
13449
13450
13451
13452
13453
13454
13455
13456
13457
13458
13459
13460
13461
13462
13463
13464
13465
13466
13467
13468
13469
13470
13471
13472
13473
13474
13475
13476
13477
13478
13479
13480
13481
13482
13483
13484
13485
13486
13487
13488
13489
13490
13491
13492
13493
13494
13495
13496
13497
13498
13499
13500
13501
13502
13503
13504
13505
13506
13507
13508
13509
13510
13511
13512
13513
13514
13515
13516
13517
13518
13519
13520
13521
13522
13523
13524
13525
13526
13527
13528
13529
13530
13531
13532
13533
13534
13535
13536
13537
13538
13539
13540
13541
13542
13543
13544
13545
13546
13547
13548
13549
13550
13551
13552
13553
13554
13555
13556
13557
13558
13559
13560
13561
13562
13563
13564
13565
13566
13567
13568
13569
13570
13571
13572
13573
13574
13575
13576
13577
13578
13579
13580
13581
13582
13583
13584
13585
13586
13587
13588
13589
13590
13591
13592
13593
13594
13595
13596
13597
13598
13599
13600
13601
13602
13603
13604
13605
13606
13607
13608
13609
13610
13611
13612
13613
13614
13615
13616
13617
13618
13619
13620
13621
13622
13623
13624
13625
13626
13627
13628
13629
13630
13631
13632
13633
13634
13635
13636
13637
13638
13639
13640
13641
13642
13643
13644
13645
13646
13647
13648
13649
13650
13651
13652
13653
13654
13655
13656
13657
13658
13659
13660
13661
13662
13663
13664
13665
13666
13667
13668
13669
13670
13671
13672
13673
13674
13675
13676
13677
13678
13679
13680
13681
13682
13683
13684
13685
13686
13687
13688
13689
13690
13691
13692
13693
13694
13695
13696
13697
13698
13699
13700
13701
13702
13703
13704
13705
13706
13707
13708
13709
13710
13711
13712
13713
13714
13715
13716
13717
13718
13719
13720
13721
13722
13723
13724
13725
13726
13727
13728
13729
13730
13731
13732
13733
13734
13735
13736
13737
13738
13739
13740
13741
13742
13743
13744
13745
13746
13747
13748
13749
13750
13751
13752
13753
13754
13755
13756
13757
13758
13759
13760
13761
13762
13763
13764
13765
13766
13767
13768
13769
13770
13771
13772
13773
13774
13775
13776
13777
13778
13779
13780
13781
13782
13783
13784
13785
13786
13787
13788
13789
13790
13791
13792
13793
13794
13795
13796
13797
13798
13799
13800
13801
13802
13803
13804
13805
13806
13807
13808
13809
13810
13811
13812
13813
13814
13815
13816
13817
13818
13819
13820
13821
13822
13823
13824
13825
13826
13827
13828
13829
13830
13831
13832
13833
13834
13835
13836
13837
13838
13839
13840
13841
13842
13843
13844
13845
13846
13847
13848
13849
13850
13851
13852
13853
13854
13855
13856
13857
13858
13859
13860
13861
13862
13863
13864
13865
13866
13867
13868
13869
13870
13871
13872
13873
13874
13875
13876
13877
13878
13879
13880
13881
13882
13883
13884
13885
13886
13887
13888
13889
13890
13891
13892
13893
13894
13895
13896
13897
13898
13899
13900
13901
13902
13903
13904
13905
13906
13907
13908
13909
13910
13911
13912
13913
13914
13915
13916
13917
13918
13919
13920
13921
13922
13923
13924
13925
13926
13927
13928
13929
13930
13931
13932
13933
13934
13935
13936
13937
13938
13939
13940
13941
13942
13943
13944
13945
13946
13947
13948
13949
13950
13951
13952
13953
13954
13955
13956
13957
13958
13959
13960
13961
13962
13963
13964
13965
13966
13967
13968
13969
13970
13971
13972
13973
13974
13975
13976
13977
13978
13979
13980
13981
13982
13983
13984
13985
13986
13987
13988
13989
13990
13991
13992
13993
13994
13995
13996
13997
13998
13999
14000
14001
14002
14003
14004
14005
14006
14007
14008
14009
14010
14011
14012
14013
14014
14015
14016
14017
14018
14019
14020
14021
14022
14023
14024
14025
14026
14027
14028
14029
14030
14031
14032
14033
14034
14035
14036
14037
14038
14039
14040
14041
14042
14043
14044
14045
14046
14047
14048
14049
14050
14051
14052
14053
14054
14055
14056
14057
14058
14059
14060
14061
14062
14063
14064
14065
14066
14067
14068
14069
14070
14071
14072
14073
14074
14075
14076
14077
14078
14079
14080
14081
14082
14083
14084
14085
14086
14087
14088
14089
14090
14091
14092
14093
14094
14095
14096
14097
14098
14099
14100
14101
14102
14103
14104
14105
14106
14107
14108
14109
14110
14111
14112
14113
14114
14115
14116
14117
14118
14119
14120
14121
14122
14123
14124
14125
14126
14127
14128
14129
14130
14131
14132
14133
14134
14135
14136
14137
14138
14139
14140
14141
14142
14143
14144
14145
14146
14147
14148
14149
14150
14151
14152
14153
14154
14155
14156
14157
14158
14159
14160
14161
14162
14163
14164
14165
14166
14167
14168
14169
14170
14171
14172
14173
14174
14175
14176
14177
14178
14179
14180
14181
14182
14183
14184
14185
14186
14187
14188
14189
14190
14191
14192
14193
14194
14195
14196
14197
14198
14199
14200
14201
14202
14203
14204
14205
14206
14207
14208
14209
14210
14211
14212
14213
14214
14215
14216
14217
14218
14219
14220
14221
14222
14223
14224
14225
14226
14227
14228
14229
14230
14231
14232
14233
14234
14235
14236
14237
14238
14239
14240
14241
14242
14243
14244
14245
14246
14247
14248
14249
14250
14251
14252
14253
14254
14255
14256
14257
14258
14259
14260
14261
14262
14263
14264
14265
14266
14267
14268
14269
14270
14271
14272
14273
14274
14275
14276
14277
14278
14279
14280
14281
14282
14283
14284
14285
14286
14287
14288
14289
14290
14291
14292
14293
14294
14295
14296
14297
14298
14299
14300
14301
14302
14303
14304
14305
14306
14307
14308
14309
14310
14311
14312
14313
14314
14315
14316
14317
14318
14319
14320
14321
14322
14323
14324
14325
14326
14327
14328
14329
14330
14331
14332
14333
14334
14335
14336
14337
14338
14339
14340
14341
14342
14343
14344
14345
14346
14347
14348
14349
14350
14351
14352
14353
14354
14355
14356
14357
14358
14359
14360
14361
14362
14363
14364
14365
14366
14367
14368
14369
14370
14371
14372
14373
14374
14375
14376
14377
14378
14379
14380
14381
14382
14383
14384
14385
14386
14387
14388
14389
14390
14391
14392
14393
14394
14395
14396
14397
14398
14399
14400
14401
14402
14403
14404
14405
14406
14407
14408
14409
14410
14411
14412
14413
14414
14415
14416
14417
14418
14419
14420
14421
14422
14423
14424
14425
14426
14427
14428
14429
14430
14431
14432
14433
14434
14435
14436
14437
14438
14439
14440
14441
14442
14443
14444
14445
14446
14447
14448
14449
14450
14451
14452
14453
14454
14455
14456
14457
14458
14459
14460
14461
14462
14463
14464
14465
14466
14467
14468
14469
14470
14471
14472
14473
14474
14475
14476
14477
14478
14479
14480
14481
14482
14483
14484
14485
14486
14487
14488
14489
14490
14491
14492
14493
14494
14495
14496
14497
14498
14499
14500
14501
14502
14503
14504
14505
14506
14507
14508
14509
14510
14511
14512
14513
14514
14515
14516
14517
14518
14519
14520
14521
14522
14523
14524
14525
14526
14527
14528
14529
14530
14531
14532
14533
14534
14535
14536
14537
14538
14539
14540
14541
14542
14543
14544
14545
14546
14547
14548
14549
14550
14551
14552
14553
14554
14555
14556
14557
14558
14559
14560
14561
14562
14563
14564
14565
14566
14567
14568
14569
14570
14571
14572
14573
14574
14575
14576
14577
14578
14579
14580
14581
14582
14583
14584
14585
14586
14587
14588
14589
14590
14591
14592
14593
14594
14595
14596
14597
14598
14599
14600
14601
14602
14603
14604
14605
14606
14607
14608
14609
14610
14611
14612
14613
14614
14615
14616
14617
14618
14619
14620
14621
14622
14623
14624
14625
14626
14627
14628
14629
14630
14631
14632
14633
14634
14635
14636
14637
14638
14639
14640
14641
14642
14643
14644
14645
14646
14647
14648
14649
14650
14651
14652
14653
14654
14655
14656
14657
14658
14659
14660
14661
14662
14663
14664
14665
14666
14667
14668
14669
14670
14671
14672
14673
14674
14675
14676
14677
14678
14679
14680
14681
14682
14683
14684
14685
14686
14687
14688
14689
14690
14691
14692
14693
14694
14695
14696
14697
14698
14699
14700
14701
14702
14703
14704
14705
14706
14707
14708
14709
14710
14711
14712
14713
14714
14715
14716
14717
14718
14719
14720
14721
14722
14723
14724
14725
14726
14727
14728
14729
14730
14731
14732
14733
14734
14735
14736
14737
14738
14739
14740
14741
14742
14743
14744
14745
14746
14747
14748
14749
14750
14751
14752
14753
14754
14755
14756
14757
14758
14759
14760
14761
14762
14763
14764
14765
14766
14767
14768
14769
14770
14771
14772
14773
14774
14775
14776
14777
14778
14779
14780
14781
14782
14783
14784
14785
14786
14787
14788
14789
14790
14791
14792
14793
14794
14795
14796
14797
14798
14799
14800
14801
14802
14803
14804
14805
14806
14807
14808
14809
14810
14811
14812
14813
14814
14815
14816
14817
14818
14819
14820
14821
14822
14823
14824
14825
14826
14827
14828
14829
14830
14831
14832
14833
14834
14835
14836
14837
14838
14839
14840
14841
14842
14843
14844
14845
14846
14847
14848
14849
14850
14851
14852
14853
14854
14855
14856
14857
14858
14859
14860
14861
14862
14863
14864
14865
14866
14867
14868
14869
14870
14871
14872
14873
14874
14875
14876
14877
14878
14879
14880
14881
14882
14883
14884
14885
14886
14887
14888
14889
14890
14891
14892
14893
14894
14895
14896
14897
14898
14899
14900
14901
14902
14903
14904
14905
14906
14907
14908
14909
14910
14911
14912
14913
14914
14915
14916
14917
14918
14919
14920
14921
14922
14923
14924
14925
14926
14927
14928
14929
14930
14931
14932
14933
14934
14935
14936
14937
14938
14939
14940
14941
14942
14943
14944
14945
14946
14947
14948
14949
14950
14951
14952
14953
14954
14955
14956
14957
14958
14959
14960
14961
14962
14963
14964
14965
14966
14967
14968
14969
14970
14971
14972
14973
14974
14975
14976
14977
14978
14979
14980
14981
14982
14983
14984
14985
14986
14987
14988
14989
14990
14991
14992
14993
14994
14995
14996
14997
14998
14999
15000
15001
15002
15003
15004
15005
15006
15007
15008
15009
15010
15011
15012
15013
15014
15015
15016
15017
15018
15019
15020
15021
15022
15023
15024
15025
15026
15027
15028
15029
15030
15031
15032
15033
15034
15035
15036
15037
15038
15039
15040
15041
15042
15043
15044
15045
15046
15047
15048
15049
15050
15051
15052
15053
15054
15055
15056
15057
15058
15059
15060
15061
15062
15063
15064
15065
15066
15067
15068
15069
15070
15071
15072
15073
15074
15075
15076
15077
15078
15079
15080
15081
15082
15083
15084
15085
15086
15087
15088
15089
15090
15091
15092
15093
15094
15095
15096
15097
15098
15099
15100
15101
15102
15103
15104
15105
15106
15107
15108
15109
15110
15111
15112
15113
15114
15115
15116
15117
15118
15119
15120
15121
15122
15123
15124
15125
15126
15127
15128
15129
15130
15131
15132
15133
15134
15135
15136
15137
15138
15139
15140
15141
15142
15143
15144
15145
15146
15147
15148
15149
15150
15151
15152
15153
15154
15155
15156
15157
15158
15159
15160
15161
15162
15163
15164
15165
15166
15167
15168
15169
15170
15171
15172
15173
15174
15175
15176
15177
15178
15179
15180
15181
15182
15183
15184
15185
15186
15187
15188
15189
15190
15191
15192
15193
15194
15195
15196
15197
15198
15199
15200
15201
15202
15203
15204
15205
15206
15207
15208
15209
15210
15211
15212
15213
15214
15215
15216
15217
15218
15219
15220
15221
15222
15223
15224
15225
15226
15227
15228
15229
15230
15231
15232
15233
15234
15235
15236
15237
15238
15239
15240
15241
15242
15243
15244
15245
15246
15247
15248
15249
15250
15251
15252
15253
15254
15255
15256
15257
15258
15259
15260
15261
15262
15263
15264
15265
15266
15267
15268
15269
15270
15271
15272
15273
15274
15275
15276
15277
15278
15279
15280
15281
15282
15283
15284
15285
15286
15287
15288
15289
15290
15291
15292
15293
15294
15295
15296
15297
15298
15299
15300
15301
15302
15303
15304
15305
15306
15307
15308
15309
15310
15311
15312
15313
15314
15315
15316
15317
15318
15319
15320
15321
15322
15323
15324
15325
15326
15327
15328
15329
15330
15331
15332
15333
15334
15335
15336
15337
15338
15339
15340
15341
15342
15343
15344
15345
15346
15347
15348
15349
15350
15351
15352
15353
15354
15355
15356
15357
15358
15359
15360
15361
15362
15363
15364
15365
15366
15367
15368
15369
15370
15371
15372
15373
15374
15375
15376
15377
15378
15379
15380
15381
15382
15383
15384
15385
15386
15387
15388
15389
15390
15391
15392
15393
15394
15395
15396
15397
15398
15399
15400
15401
15402
15403
15404
15405
15406
15407
15408
15409
15410
15411
15412
15413
15414
15415
15416
15417
15418
15419
15420
15421
15422
15423
15424
15425
15426
15427
15428
15429
15430
15431
15432
15433
15434
15435
15436
15437
15438
15439
15440
15441
15442
15443
15444
15445
15446
15447
15448
15449
15450
15451
15452
15453
15454
15455
15456
15457
15458
15459
15460
15461
15462
15463
15464
15465
15466
15467
15468
15469
15470
15471
15472
15473
15474
15475
15476
15477
15478
15479
15480
15481
15482
15483
15484
15485
15486
15487
15488
15489
15490
15491
15492
15493
15494
15495
15496
15497
15498
15499
15500
15501
15502
15503
15504
15505
15506
15507
15508
15509
15510
15511
15512
15513
15514
15515
15516
15517
15518
15519
15520
15521
15522
15523
15524
15525
15526
15527
15528
15529
15530
15531
15532
15533
15534
15535
15536
15537
15538
15539
15540
15541
15542
15543
15544
15545
15546
15547
15548
15549
15550
15551
15552
15553
15554
15555
15556
15557
15558
15559
15560
15561
15562
15563
15564
15565
15566
15567
15568
15569
15570
15571
15572
15573
15574
15575
15576
15577
15578
15579
15580
15581
15582
15583
15584
15585
15586
15587
15588
15589
15590
15591
15592
15593
15594
15595
15596
15597
15598
15599
15600
15601
15602
15603
15604
15605
15606
15607
15608
15609
15610
15611
15612
15613
15614
15615
15616
15617
15618
15619
15620
15621
15622
15623
15624
15625
15626
15627
15628
15629
15630
15631
15632
15633
15634
15635
15636
15637
15638
15639
15640
15641
15642
15643
15644
15645
15646
15647
15648
15649
15650
15651
15652
15653
15654
15655
15656
15657
15658
15659
15660
15661
15662
15663
15664
15665
15666
15667
15668
15669
15670
15671
15672
15673
15674
15675
15676
15677
15678
15679
15680
15681
15682
15683
15684
15685
15686
15687
15688
15689
15690
15691
15692
15693
15694
15695
15696
15697
15698
15699
15700
15701
15702
15703
15704
15705
15706
15707
15708
15709
15710
15711
15712
15713
15714
15715
15716
15717
15718
15719
15720
15721
15722
15723
15724
15725
15726
15727
15728
15729
15730
15731
15732
15733
15734
15735
15736
15737
15738
15739
15740
15741
15742
15743
15744
15745
15746
15747
15748
15749
15750
15751
15752
15753
15754
15755
15756
15757
15758
15759
15760
15761
15762
15763
15764
15765
15766
15767
15768
15769
15770
15771
15772
15773
15774
15775
15776
15777
15778
15779
15780
15781
15782
15783
15784
15785
15786
15787
15788
15789
15790
15791
15792
15793
15794
15795
15796
15797
15798
15799
15800
15801
15802
15803
15804
15805
15806
15807
15808
15809
15810
15811
15812
15813
15814
15815
15816
15817
15818
15819
15820
15821
15822
15823
15824
15825
15826
15827
15828
15829
15830
15831
15832
15833
15834
15835
15836
15837
15838
15839
15840
15841
15842
15843
15844
15845
15846
15847
15848
15849
15850
15851
15852
15853
15854
15855
15856
15857
15858
15859
15860
15861
15862
15863
15864
15865
15866
15867
15868
15869
15870
15871
15872
15873
15874
15875
15876
15877
15878
15879
15880
15881
15882
15883
15884
15885
15886
15887
15888
15889
15890
15891
15892
15893
15894
15895
15896
15897
15898
15899
15900
15901
15902
15903
15904
15905
15906
15907
15908
15909
15910
15911
15912
15913
15914
15915
15916
15917
15918
15919
15920
15921
15922
15923
15924
15925
15926
15927
15928
15929
15930
15931
15932
15933
15934
15935
15936
15937
15938
15939
15940
15941
15942
15943
15944
15945
15946
15947
15948
15949
15950
15951
15952
15953
15954
15955
15956
15957
15958
15959
15960
15961
15962
15963
15964
15965
15966
15967
15968
15969
15970
15971
15972
15973
15974
15975
15976
15977
15978
15979
15980
15981
15982

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>Synchronization</title>
<link rel="stylesheet" href="../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
<link rel="home" href="../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset">
<link rel="up" href="../thread.html" title="Chapter&#160;38.&#160;Thread 4.7.2">
<link rel="prev" href="ScopedThreads.html" title="Scoped Threads">
<link rel="next" href="thread_local_storage.html" title="Thread Local Storage">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../boost.png"></td>
<td align="center"><a href="../../../index.html">Home</a></td>
<td align="center"><a href="../../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="ScopedThreads.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../thread.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="thread_local_storage.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="thread.synchronization"></a><a class="link" href="synchronization.html" title="Synchronization">Synchronization</a>
</h2></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.tutorial">Tutorial</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts">Mutex Concepts</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_option">Lock Options</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_guard">Lock Guard</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.with_lock_guard">With Lock Guard</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_concepts">Lock Concepts</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks">Lock Types</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks">Other Lock Types
      - EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_functions">Lock functions</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_factories">Lock Factories
      - EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types">Mutex Types</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref">Condition Variables</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.once">One-time Initialization</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.barriers">Barriers -- EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches">Latches -- EXPERIMENTAL</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors">Executors and Schedulers
      -- EXPERIMENTAL</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures">Futures</a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.tutorial"></a><a class="link" href="synchronization.html#thread.synchronization.tutorial" title="Tutorial">Tutorial</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.tutorial.internal_locking">Internal
        Locking</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes">External
        Locking -- <code class="computeroutput"><span class="identifier">strict_lock</span></code> and
        <code class="computeroutput"><span class="identifier">externally_locked</span></code> classes</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.tutorial.with">Executing Around
        a Function</a></span></dt>
</dl></div>
<p>
        <a href="http://web.archive.org/web/20140531071228/http://home.roadrunner.com/~hinnant/mutexes/locking.html" target="_top">Handling
        mutexes in C++</a> is an excellent tutorial. You need just replace std
        and ting by boost.
      </p>
<p>
        <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2406.html" target="_top">Mutex,
        Lock, Condition Variable Rationale</a> adds rationale for the design
        decisions made for mutexes, locks and condition variables.
      </p>
<p>
        In addition to the C++11 standard locks, Boost.Thread provides other locks
        and some utilities that help the user to make their code thread-safe.
      </p>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.tutorial.internal_locking"></a><a class="link" href="synchronization.html#thread.synchronization.tutorial.internal_locking" title="Internal Locking">Internal
        Locking</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.tutorial.internal_locking.concurrent_threads_of_execution">Concurrent
          threads of execution</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.tutorial.internal_locking.internal_locking">Internal
          locking</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.tutorial.internal_locking.internal_and_external_locking">Internal
          and external locking</a></span></dt>
</dl></div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
            This tutorial is an adaptation of chapter Concurrency of the Object-Oriented
            Programming in the BETA Programming Language and of the paper of Andrei
            Alexandrescu "Multithreading and the C++ Type System" to the
            Boost library.
          </p></td></tr>
</table></div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.tutorial.internal_locking.concurrent_threads_of_execution"></a><a class="link" href="synchronization.html#thread.synchronization.tutorial.internal_locking.concurrent_threads_of_execution" title="Concurrent threads of execution">Concurrent
          threads of execution</a>
</h5></div></div></div>
<p>
            Consider, for example, modeling a bank account class that supports simultaneous
            deposits and withdrawals from multiple locations (arguably the "Hello,
            World" of multithreaded programming).
          </p>
<p>
            From here a component is a model of the <code class="computeroutput"><span class="identifier">Callable</span></code>
            concept.
          </p>
<p>
            I C++11 (Boost) concurrent execution of a component is obtained by means
            of the <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">thread</span></code>(<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code>):
          </p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span> <span class="identifier">thread1</span><span class="special">(</span><span class="identifier">S</span><span class="special">);</span>
</pre>
<p>
            where <code class="computeroutput"><span class="identifier">S</span></code> is a model of
            <code class="computeroutput"><span class="identifier">Callable</span></code>. The meaning
            of this expression is that execution of <code class="computeroutput"><span class="identifier">S</span><span class="special">()</span></code> will take place concurrently with the
            current thread of execution executing the expression.
          </p>
<p>
            The following example includes a bank account of a person (Joe) and two
            components, one corresponding to a bank agent depositing money in Joe's
            account, and one representing Joe. Joe will only be withdrawing money
            from the account:
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">BankAccount</span><span class="special">;</span>

<span class="identifier">BankAccount</span> <span class="identifier">JoesAccount</span><span class="special">;</span>

<span class="keyword">void</span> <span class="identifier">bankAgent</span><span class="special">()</span>
<span class="special">{</span>
    <span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span><span class="number">10</span><span class="special">;</span> <span class="identifier">i</span><span class="special">&gt;</span><span class="number">0</span><span class="special">;</span> <span class="special">--</span><span class="identifier">i</span><span class="special">)</span> <span class="special">{</span>
        <span class="comment">//...</span>
        <span class="identifier">JoesAccount</span><span class="special">.</span><span class="identifier">Deposit</span><span class="special">(</span><span class="number">500</span><span class="special">);</span>
        <span class="comment">//...</span>
    <span class="special">}</span>
<span class="special">}</span>

<span class="keyword">void</span> <span class="identifier">Joe</span><span class="special">()</span> <span class="special">{</span>
    <span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span><span class="number">10</span><span class="special">;</span> <span class="identifier">i</span><span class="special">&gt;</span><span class="number">0</span><span class="special">;</span> <span class="special">--</span><span class="identifier">i</span><span class="special">)</span> <span class="special">{</span>
        <span class="comment">//...</span>
        <span class="keyword">int</span> <span class="identifier">myPocket</span> <span class="special">=</span> <span class="identifier">JoesAccount</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="number">100</span><span class="special">);</span>
        <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="identifier">myPocket</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
        <span class="comment">//...</span>
    <span class="special">}</span>
<span class="special">}</span>

<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> <span class="special">{</span>
    <span class="comment">//...</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span> <span class="identifier">thread1</span><span class="special">(</span><span class="identifier">bankAgent</span><span class="special">);</span> <span class="comment">// start concurrent execution of bankAgent</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span> <span class="identifier">thread2</span><span class="special">(</span><span class="identifier">Joe</span><span class="special">);</span> <span class="comment">// start concurrent execution of Joe</span>
    <span class="identifier">thread1</span><span class="special">.</span><span class="identifier">join</span><span class="special">();</span>
    <span class="identifier">thread2</span><span class="special">.</span><span class="identifier">join</span><span class="special">();</span>
    <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
            From time to time, the <code class="computeroutput"><span class="identifier">bankAgent</span></code>
            will deposit $500 in <code class="computeroutput"><span class="identifier">JoesAccount</span></code>.
            <code class="computeroutput"><span class="identifier">Joe</span></code> will similarly withdraw
            $100 from his account. These sentences describe that the <code class="computeroutput"><span class="identifier">bankAgent</span></code> and <code class="computeroutput"><span class="identifier">Joe</span></code>
            are executed concurrently.
          </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.tutorial.internal_locking.internal_locking"></a><a class="link" href="synchronization.html#thread.synchronization.tutorial.internal_locking.internal_locking" title="Internal locking">Internal
          locking</a>
</h5></div></div></div>
<p>
            The above example works well as long as the components <code class="computeroutput"><span class="identifier">bankAgent</span></code> and <code class="computeroutput"><span class="identifier">Joe</span></code>
            doesn't access <code class="computeroutput"><span class="identifier">JoesAccount</span></code>
            at the same time. There is, however, no guarantee that this will not
            happen. We may use a mutex to guarantee exclusive access to each bank.
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">BankAccount</span> <span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span> <span class="identifier">mtx_</span><span class="special">;</span>
    <span class="keyword">int</span> <span class="identifier">balance_</span><span class="special">;</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">void</span> <span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">mtx_</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span>
        <span class="identifier">balance_</span> <span class="special">+=</span> <span class="identifier">amount</span><span class="special">;</span>
        <span class="identifier">mtx_</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">();</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">mtx_</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span>
        <span class="identifier">balance_</span> <span class="special">-=</span> <span class="identifier">amount</span><span class="special">;</span>
        <span class="identifier">mtx_</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">();</span>
    <span class="special">}</span>
    <span class="keyword">int</span> <span class="identifier">GetBalance</span><span class="special">()</span> <span class="special">{</span>
        <span class="identifier">mtx_</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span>
        <span class="keyword">int</span> <span class="identifier">b</span> <span class="special">=</span> <span class="identifier">balance_</span><span class="special">;</span>
        <span class="identifier">mtx_</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">();</span>
        <span class="keyword">return</span> <span class="identifier">b</span><span class="special">;</span>
    <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
            Execution of the <code class="computeroutput"><span class="identifier">Deposit</span></code>
            and <code class="computeroutput"><span class="identifier">Withdraw</span></code> operations
            will no longer be able to make simultaneous access to balance.
          </p>
<p>
            A mutex is a simple and basic mechanism for obtaining synchronization.
            In the above example it is relatively easy to be convinced that the synchronization
            works correctly (in the absence of exception). In a system with several
            concurrent objects and several shared objects, it may be difficult to
            describe synchronization by means of mutexes. Programs that make heavy
            use of mutexes may be difficult to read and write. Instead, we shall
            introduce a number of generic classes for handling more complicated forms
            of synchronization and communication.
          </p>
<p>
            With the RAII idiom we can simplify a lot this using the scoped locks.
            In the code below, guard's constructor locks the passed-in object <code class="computeroutput"><span class="identifier">mtx_</span></code>, and guard's destructor unlocks
            <code class="computeroutput"><span class="identifier">mtx_</span></code>.
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">BankAccount</span> <span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span> <span class="identifier">mtx_</span><span class="special">;</span> <span class="comment">// explicit mutex declaration </span>
    <span class="keyword">int</span> <span class="identifier">balance_</span><span class="special">;</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">void</span> <span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">mtx_</span><span class="special">);</span>
        <span class="identifier">balance_</span> <span class="special">+=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">mtx_</span><span class="special">);</span>
        <span class="identifier">balance_</span> <span class="special">-=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">int</span> <span class="identifier">GetBalance</span><span class="special">()</span> <span class="special">{</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">mtx_</span><span class="special">);</span>
        <span class="keyword">return</span> <span class="identifier">balance_</span><span class="special">;</span>
    <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
            The object-level locking idiom doesn't cover the entire richness of a
            threading model. For example, the model above is quite deadlock-prone
            when you try to coordinate multi-object transactions. Nonetheless, object-level
            locking is useful in many cases, and in combination with other mechanisms
            can provide a satisfactory solution to many threaded access problems
            in object-oriented programs.
          </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.tutorial.internal_locking.internal_and_external_locking"></a><a class="link" href="synchronization.html#thread.synchronization.tutorial.internal_locking.internal_and_external_locking" title="Internal and external locking">Internal
          and external locking</a>
</h5></div></div></div>
<p>
            The BankAccount class above uses internal locking. Basically, a class
            that uses internal locking guarantees that any concurrent calls to its
            public member functions don't corrupt an instance of that class. This
            is typically ensured by having each public member function acquire a
            lock on the object upon entry. This way, for any given object of that
            class, there can be only one member function call active at any moment,
            so the operations are nicely serialized.
          </p>
<p>
            This approach is reasonably easy to implement and has an attractive simplicity.
            Unfortunately, "simple" might sometimes morph into "simplistic."
          </p>
<p>
            Internal locking is insufficient for many real-world synchronization
            tasks. Imagine that you want to implement an ATM withdrawal transaction
            with the BankAccount class. The requirements are simple. The ATM transaction
            consists of two withdrawals-one for the actual money and one for the
            $2 commission. The two withdrawals must appear in strict sequence; that
            is, no other transaction can exist between them.
          </p>
<p>
            The obvious implementation is erratic:
          </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">ATMWithdrawal</span><span class="special">(</span><span class="identifier">BankAccount</span><span class="special">&amp;</span> <span class="identifier">acct</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">sum</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">acct</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="identifier">sum</span><span class="special">);</span>
    <span class="comment">// preemption possible</span>
    <span class="identifier">acct</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="number">2</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
            The problem is that between the two calls above, another thread can perform
            another operation on the account, thus breaking the second design requirement.
          </p>
<p>
            In an attempt to solve this problem, let's lock the account from the
            outside during the two operations:
          </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">ATMWithdrawal</span><span class="special">(</span><span class="identifier">BankAccount</span><span class="special">&amp;</span> <span class="identifier">acct</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">sum</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">acct</span><span class="special">.</span><span class="identifier">mtx_</span><span class="special">);</span> <span class="number">1</span>
    <span class="identifier">acct</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="identifier">sum</span><span class="special">);</span>
    <span class="identifier">acct</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="number">2</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
            Notice that the code above doesn't compile, the <code class="computeroutput"><span class="identifier">mtx_</span></code>
            field is private. We have two possibilities:
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
                make <code class="computeroutput"><span class="identifier">mtx_</span></code> public
                which seems odd
              </li>
<li class="listitem">
                make the <code class="computeroutput"><span class="identifier">BankAccount</span></code>
                lockable by adding the lock/unlock functions
              </li>
</ul></div>
<p>
            We can add these functions explicitly
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">BankAccount</span> <span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span> <span class="identifier">mtx_</span><span class="special">;</span>
    <span class="keyword">int</span> <span class="identifier">balance_</span><span class="special">;</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">void</span> <span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">mtx_</span><span class="special">);</span>
        <span class="identifier">balance_</span> <span class="special">+=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">mtx_</span><span class="special">);</span>
        <span class="identifier">balance_</span> <span class="special">-=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">()</span> <span class="special">{</span>
        <span class="identifier">mtx_</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">()</span> <span class="special">{</span>
        <span class="identifier">mtx_</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">();</span>
    <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
            or inheriting from a class which add these lockable functions.
          </p>
<p>
            The <code class="computeroutput"><span class="identifier">basic_lockable_adapter</span></code>
            class helps to define the <code class="computeroutput"><span class="identifier">BankAccount</span></code>
            class as
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">BankAccount</span>
<span class="special">:</span> <span class="keyword">public</span> <span class="identifier">basic_lockable_adapter</span><span class="special">&lt;</span><span class="identifier">mutex</span><span class="special">&gt;</span>
<span class="special">{</span>
    <span class="keyword">int</span> <span class="identifier">balance_</span><span class="special">;</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">void</span> <span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(*</span><span class="keyword">this</span><span class="special">);</span>
        <span class="identifier">balance_</span> <span class="special">+=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(*</span><span class="keyword">this</span><span class="special">);</span>
        <span class="identifier">balance_</span> <span class="special">-=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">int</span> <span class="identifier">GetBalance</span><span class="special">()</span> <span class="special">{</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(*</span><span class="keyword">this</span><span class="special">);</span>
        <span class="keyword">return</span> <span class="identifier">balance_</span><span class="special">;</span>
    <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
            and the code that doesn't compiles becomes
          </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">ATMWithdrawal</span><span class="special">(</span><span class="identifier">BankAccount</span><span class="special">&amp;</span> <span class="identifier">acct</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">sum</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">acct</span><span class="special">);</span>
    <span class="identifier">acct</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="identifier">sum</span><span class="special">);</span>
    <span class="identifier">acct</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="number">2</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
            Notice that now acct is being locked by Withdraw after it has already
            been locked by guard. When running such code, one of two things happens.
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
                Your mutex implementation might support the so-called recursive mutex
                semantics. This means that the same thread can lock the same mutex
                several times successfully. In this case, the implementation works
                but has a performance overhead due to unnecessary locking. (The locking/unlocking
                sequence in the two Withdraw calls is not needed but performed anyway-and
                that costs time.)
              </li>
<li class="listitem">
                Your mutex implementation might not support recursive locking, which
                means that as soon as you try to acquire it the second time, it blocks-so
                the ATMWithdrawal function enters the dreaded deadlock.
              </li>
</ul></div>
<p>
            As <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span></code> is not recursive, we need to
            use its recursive version <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">recursive_mutex</span></code>.
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">BankAccount</span>
<span class="special">:</span> <span class="keyword">public</span> <span class="identifier">basic_lockable_adapter</span><span class="special">&lt;</span><span class="identifier">recursive_mutex</span><span class="special">&gt;</span>
<span class="special">{</span>

    <span class="comment">// ...</span>
<span class="special">};</span>
</pre>
<p>
            The caller-ensured locking approach is more flexible and the most efficient,
            but very dangerous. In an implementation using caller-ensured locking,
            BankAccount still holds a mutex, but its member functions don't manipulate
            it at all. Deposit and Withdraw are not thread-safe anymore. Instead,
            the client code is responsible for locking BankAccount properly.
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">BankAccount</span>
    <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">basic_lockable_adapter</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">:</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="special">{</span>
    <span class="keyword">int</span> <span class="identifier">balance_</span><span class="special">;</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">void</span> <span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">balance_</span> <span class="special">+=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">balance_</span> <span class="special">-=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
            Obviously, the caller-ensured locking approach has a safety problem.
            BankAccount's implementation code is finite, and easy to reach and maintain,
            but there's an unbounded amount of client code that manipulates BankAccount
            objects. In designing applications, it's important to differentiate between
            requirements imposed on bounded code and unbounded code. If your class
            makes undue requirements on unbounded code, that's usually a sign that
            encapsulation is out the window.
          </p>
<p>
            To conclude, if in designing a multi-threaded class you settle on internal
            locking, you expose yourself to inefficiency or deadlocks. On the other
            hand, if you rely on caller-provided locking, you make your class error-prone
            and difficult to use. Finally, external locking completely avoids the
            issue by leaving it all to the client code.
          </p>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes"></a><a class="link" href="synchronization.html#thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes" title="External Locking -- strict_lock and externally_locked classes">External
        Locking -- <code class="computeroutput"><span class="identifier">strict_lock</span></code> and
        <code class="computeroutput"><span class="identifier">externally_locked</span></code> classes</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes.locks_as_permits">Locks
          as permits</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes.improving_external_locking">Improving
          External Locking</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes.allowing_other_strict_locks">Allowing
          other strict locks</a></span></dt>
</dl></div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
            This tutorial is an adaptation of the paper by Andrei Alexandrescu "Multithreading
            and the C++ Type System" to the Boost library.
          </p></td></tr>
</table></div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes.locks_as_permits"></a><a class="link" href="synchronization.html#thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes.locks_as_permits" title="Locks as permits">Locks
          as permits</a>
</h5></div></div></div>
<p>
            So what to do? Ideally, the BankAccount class should do the following:
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
                Support both locking models (internal and external).
              </li>
<li class="listitem">
                Be efficient; that is, use no unnecessary locking.
              </li>
<li class="listitem">
                Be safe; that is, BankAccount objects cannot be manipulated without
                appropriate locking.
              </li>
</ul></div>
<p>
            Let's make a worthwhile observation: Whenever you lock a BankAccount,
            you do so by using a <code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code> object. Turning this statement around,
            wherever there's a <code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code>, there's also a locked <code class="computeroutput"><span class="identifier">BankAccount</span></code> somewhere. Thus, you can
            think of-and use-a <code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code> object as a permit. Owning a <code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code>
            gives you rights to do certain things. The <code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code> object should not be copied or aliased
            (it's not a transmissible permit).
          </p>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
                As long as a permit is still alive, the <code class="computeroutput"><span class="identifier">BankAccount</span></code>
                object stays locked.
              </li>
<li class="listitem">
                When the <code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code> is destroyed, the <code class="computeroutput"><span class="identifier">BankAccount</span></code>'s mutex is released.
              </li>
</ol></div>
<p>
            The net effect is that at any point in your code, having access to a
            <code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code>
            object guarantees that a <code class="computeroutput"><span class="identifier">BankAccount</span></code>
            is locked. (You don't know exactly which <code class="computeroutput"><span class="identifier">BankAccount</span></code>
            is locked, however-an issue that we'll address soon.)
          </p>
<p>
            For now, let's make a couple of enhancements to the <code class="computeroutput"><span class="identifier">lock_guard</span></code>
            class template defined in Boost.Thread. We'll call the enhanced version
            <code class="computeroutput"><span class="identifier">strict_lock</span></code>. Essentially,
            a <code class="computeroutput"><span class="identifier">strict_lock</span></code>'s role
            is only to live on the stack as an automatic variable. <code class="computeroutput"><span class="identifier">strict_lock</span></code> must adhere to a non-copy
            and non-alias policy. <code class="computeroutput"><span class="identifier">strict_lock</span></code>
            disables copying by making the copy constructor and the assignment operator
            private.
          </p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">strict_lock</span>  <span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span> <span class="identifier">Lockable</span> <span class="identifier">lockable_type</span><span class="special">;</span>


    <span class="keyword">explicit</span> <span class="identifier">strict_lock</span><span class="special">(</span><span class="identifier">lockable_type</span><span class="special">&amp;</span> <span class="identifier">obj</span><span class="special">)</span> <span class="special">:</span> <span class="identifier">obj_</span><span class="special">(</span><span class="identifier">obj</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">obj</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span> <span class="comment">// locks on construction</span>
    <span class="special">}</span>
    <span class="identifier">strict_lock</span><span class="special">()</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">strict_lock</span><span class="special">(</span><span class="identifier">strict_lock</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">strict_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">strict_lock</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="special">~</span><span class="identifier">strict_lock</span><span class="special">()</span> <span class="special">{</span> <span class="identifier">obj_</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">();</span> <span class="special">}</span> <span class="comment">//  unlocks on destruction </span>

    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">mutex_type</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">l</span><span class="special">)</span> <span class="keyword">const</span> <span class="keyword">noexcept</span> <span class="comment">// strict lockers specific function </span>
    <span class="special">{</span>
      <span class="keyword">return</span> <span class="identifier">l</span> <span class="special">==</span> <span class="special">&amp;</span><span class="identifier">obj_</span><span class="special">;</span>
    <span class="special">}</span>
<span class="keyword">private</span><span class="special">:</span>
    <span class="identifier">lockable_type</span><span class="special">&amp;</span> <span class="identifier">obj_</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
            Silence can be sometimes louder than words-what's forbidden to do with
            a <code class="computeroutput"><span class="identifier">strict_lock</span></code> is as important
            as what you can do. Let's see what you can and what you cannot do with
            a <code class="computeroutput"><span class="identifier">strict_lock</span></code> instantiation:
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
                You can create a <code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code> only starting from a valid T
                object. Notice that there is no other way you can create a <code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code>.
              </li></ul></div>
<pre class="programlisting"><span class="identifier">BankAccount</span> <span class="identifier">myAccount</span><span class="special">(</span><span class="string">"John Doe"</span><span class="special">,</span> <span class="string">"123-45-6789"</span><span class="special">);</span>
<span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span> <span class="identifier">myLock</span><span class="special">(</span><span class="identifier">myAccount</span><span class="special">);</span> <span class="comment">// ok</span>
</pre>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
                You cannot copy <code class="computeroutput"><span class="identifier">strict_lock</span></code>s
                to one another. In particular, you cannot pass <code class="computeroutput"><span class="identifier">strict_lock</span></code>s
                by value to functions or have them returned by functions:
              </li></ul></div>
<pre class="programlisting"><span class="keyword">extern</span> <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span> <span class="identifier">Foo</span><span class="special">();</span> <span class="comment">// compile-time error</span>
<span class="keyword">extern</span> <span class="keyword">void</span> <span class="identifier">Bar</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;);</span> <span class="comment">// compile-time error</span>
</pre>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
                However, you still can pass <code class="computeroutput"><span class="identifier">strict_lock</span></code>s
                by reference to and from functions:
              </li></ul></div>
<pre class="programlisting"><span class="comment">// ok, Foo returns a reference to strict_lock&lt;BankAccount&gt;</span>
<span class="keyword">extern</span> <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;&amp;</span> <span class="identifier">Foo</span><span class="special">();</span>
<span class="comment">// ok, Bar takes a reference to strict_lock&lt;BankAccount&gt;</span>
<span class="keyword">extern</span> <span class="keyword">void</span> <span class="identifier">Bar</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;&amp;);</span>
</pre>
<p>
            All these rules were put in place with one purpose-enforcing that owning
            a <code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code>
            is a reasonably strong guarantee that
          </p>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
                you locked a T object, and
              </li>
<li class="listitem">
                that object will be unlocked at a later point.
              </li>
</ol></div>
<p>
            Now that we have such a strict <code class="computeroutput"><span class="identifier">strict_lock</span></code>,
            how do we harness its power in defining a safe, flexible interface for
            BankAccount? The idea is as follows:
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
                Each of BankAccount's interface functions (in our case, Deposit and
                Withdraw) comes in two overloaded variants.
              </li>
<li class="listitem">
                One version keeps the same signature as before, and the other takes
                an additional argument of type <code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code>. The first version is internally
                locked; the second one requires external locking. External locking
                is enforced at compile time by requiring client code to create a
                <code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code>
                object.
              </li>
<li class="listitem">
                BankAccount avoids code bloating by having the internal locked functions
                forward to the external locked functions, which do the actual job.
              </li>
</ul></div>
<p>
            A little code is worth 1,000 words, a (hacked into) saying goes, so here's
            the new BankAccount class:
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">BankAccount</span>
<span class="special">:</span> <span class="keyword">public</span> <span class="identifier">basic_lockable_adapter</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span>
<span class="special">{</span>
    <span class="keyword">int</span> <span class="identifier">balance_</span><span class="special">;</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">void</span> <span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">,</span> <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;&amp;)</span> <span class="special">{</span>
        <span class="comment">// Externally locked</span>
        <span class="identifier">balance_</span> <span class="special">+=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(*</span><span class="keyword">this</span><span class="special">);</span> <span class="comment">// Internally locked</span>
        <span class="identifier">Deposit</span><span class="special">(</span><span class="identifier">amount</span><span class="special">,</span> <span class="identifier">guard</span><span class="special">);</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">,</span> <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;&amp;)</span> <span class="special">{</span>
        <span class="comment">// Externally locked</span>
        <span class="identifier">balance_</span> <span class="special">-=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(*</span><span class="keyword">this</span><span class="special">);</span> <span class="comment">// Internally locked</span>
        <span class="identifier">Withdraw</span><span class="special">(</span><span class="identifier">amount</span><span class="special">,</span> <span class="identifier">guard</span><span class="special">);</span>
    <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
            Now, if you want the benefit of internal locking, you simply call <code class="computeroutput"><span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span><span class="special">)</span></code> and
            <code class="computeroutput"><span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span><span class="special">)</span></code>.
            If you want to use external locking, you lock the object by constructing
            a <code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code>
            and then you call <code class="computeroutput"><span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span><span class="special">,</span>
            <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;&amp;)</span></code>
            and <code class="computeroutput"><span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span><span class="special">,</span> <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;&amp;)</span></code>.
            For example, here's the <code class="computeroutput"><span class="identifier">ATMWithdrawal</span></code>
            function implemented correctly:
          </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">ATMWithdrawal</span><span class="special">(</span><span class="identifier">BankAccount</span><span class="special">&amp;</span> <span class="identifier">acct</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">sum</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">acct</span><span class="special">);</span>
    <span class="identifier">acct</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="identifier">sum</span><span class="special">,</span> <span class="identifier">guard</span><span class="special">);</span>
    <span class="identifier">acct</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="number">2</span><span class="special">,</span> <span class="identifier">guard</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
            This function has the best of both worlds-it's reasonably safe and efficient
            at the same time.
          </p>
<p>
            It's worth noting that <code class="computeroutput"><span class="identifier">strict_lock</span></code>
            being a template gives extra safety compared to a straight polymorphic
            approach. In such a design, BankAccount would derive from a Lockable
            interface. <code class="computeroutput"><span class="identifier">strict_lock</span></code>
            would manipulate Lockable references so there's no need for templates.
            This approach is sound; however, it provides fewer compile-time guarantees.
            Having a <code class="computeroutput"><span class="identifier">strict_lock</span></code>
            object would only tell that some object derived from Lockable is currently
            locked. In the templated approach, having a <code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code> gives a stronger guarantee-it's a
            <code class="computeroutput"><span class="identifier">BankAccount</span></code> that stays
            locked.
          </p>
<p>
            There's a weasel word in there-I mentioned that ATMWithdrawal is reasonably
            safe. It's not really safe because there's no enforcement that the <code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span></code>
            object locks the appropriate BankAccount object. The type system only
            ensures that some BankAccount object is locked. For example, consider
            the following phony implementation of ATMWithdrawal:
          </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">ATMWithdrawal</span><span class="special">(</span><span class="identifier">BankAccount</span><span class="special">&amp;</span> <span class="identifier">acct</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">sum</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">BankAccount</span> <span class="identifier">fakeAcct</span><span class="special">(</span><span class="string">"John Doe"</span><span class="special">,</span> <span class="string">"123-45-6789"</span><span class="special">);</span>
    <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">fakeAcct</span><span class="special">);</span>
    <span class="identifier">acct</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="identifier">sum</span><span class="special">,</span> <span class="identifier">guard</span><span class="special">);</span>
    <span class="identifier">acct</span><span class="special">.</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="number">2</span><span class="special">,</span> <span class="identifier">guard</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
            This code compiles warning-free but obviously doesn't do the right thing-it
            locks one account and uses another.
          </p>
<p>
            It's important to understand what can be enforced within the realm of
            the C++ type system and what needs to be enforced at runtime. The mechanism
            we've put in place so far ensures that some BankAccount object is locked
            during the call to <code class="computeroutput"><span class="identifier">BankAccount</span><span class="special">::</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span><span class="special">,</span>
            <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;&amp;)</span></code>.
            We must enforce at runtime exactly what object is locked.
          </p>
<p>
            If our scheme still needs runtime checks, how is it useful? An unwary
            or malicious programmer can easily lock the wrong object and manipulate
            any BankAccount without actually locking it.
          </p>
<p>
            First, let's get the malice issue out of the way. C is a language that
            requires a lot of attention and discipline from the programmer. C++ made
            some progress by asking a little less of those, while still fundamentally
            trusting the programmer. These languages are not concerned with malice
            (as Java is, for example). After all, you can break any C/C++ design
            simply by using casts "appropriately" (if appropriately is
            an, er, appropriate word in this context).
          </p>
<p>
            The scheme is useful because the likelihood of a programmer forgetting
            about any locking whatsoever is much greater than the likelihood of a
            programmer who does remember about locking, but locks the wrong object.
          </p>
<p>
            Using <code class="computeroutput"><span class="identifier">strict_lock</span></code> permits
            compile-time checking of the most common source of errors, and runtime
            checking of the less frequent problem.
          </p>
<p>
            Let's see how to enforce that the appropriate BankAccount object is locked.
            First, we need to add a member function to the <code class="computeroutput"><span class="identifier">strict_lock</span></code>
            class template. The <code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">*)</span></code>
            function returns a reference to the locked object.
          </p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="keyword">class</span> <span class="identifier">strict_lock</span> <span class="special">{</span>
    <span class="special">...</span> <span class="identifier">as</span> <span class="identifier">before</span> <span class="special">...</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">*</span> <span class="identifier">mtx</span><span class="special">)</span> <span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">mtx</span><span class="special">==&amp;</span><span class="identifier">obj_</span><span class="special">;</span> <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
            Second, BankAccount needs to use this function compare the locked object
            against this:
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">BankAccount</span> <span class="special">{</span>
<span class="special">:</span> <span class="keyword">public</span> <span class="identifier">basic_lockable_adapter</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span>
    <span class="keyword">int</span> <span class="identifier">balance_</span><span class="special">;</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">void</span> <span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">,</span> <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">&gt;&amp;</span> <span class="identifier">guard</span><span class="special">)</span> <span class="special">{</span>
        <span class="comment">// Externally locked</span>
        <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">guard</span><span class="special">.</span><span class="identifier">owns_lock</span><span class="special">(*</span><span class="keyword">this</span><span class="special">))</span>
            <span class="keyword">throw</span> <span class="string">"Locking Error: Wrong Object Locked"</span><span class="special">;</span>
        <span class="identifier">balance_</span> <span class="special">+=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
<span class="comment">// ...</span>
<span class="special">};</span>
</pre>
<p>
            The overhead incurred by the test above is much lower than locking a
            recursive mutex for the second time.
          </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes.improving_external_locking"></a><a class="link" href="synchronization.html#thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes.improving_external_locking" title="Improving External Locking">Improving
          External Locking</a>
</h5></div></div></div>
<p>
            Now let's assume that BankAccount doesn't use its own locking at all,
            and has only a thread-neutral implementation:
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">BankAccount</span> <span class="special">{</span>
    <span class="keyword">int</span> <span class="identifier">balance_</span><span class="special">;</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">void</span> <span class="identifier">Deposit</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">balance_</span> <span class="special">+=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">Withdraw</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">balance_</span> <span class="special">-=</span> <span class="identifier">amount</span><span class="special">;</span>
    <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
            Now you can use BankAccount in single-threaded and multi-threaded applications
            alike, but you need to provide your own synchronization in the latter
            case.
          </p>
<p>
            Say we have an AccountManager class that holds and manipulates a BankAccount
            object:
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">AccountManager</span>
<span class="special">:</span> <span class="keyword">public</span> <span class="identifier">basic_lockable_adapter</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span>
<span class="special">{</span>
    <span class="identifier">BankAccount</span> <span class="identifier">checkingAcct_</span><span class="special">;</span>
    <span class="identifier">BankAccount</span> <span class="identifier">savingsAcct_</span><span class="special">;</span>
    <span class="special">...</span>
<span class="special">};</span>
</pre>
<p>
            Let's also assume that, by design, AccountManager must stay locked while
            accessing its BankAccount members. The question is, how can we express
            this design constraint using the C++ type system? How can we state "You
            have access to this BankAccount object only after locking its parent
            AccountManager object"?
          </p>
<p>
            The solution is to use a little bridge template <code class="computeroutput"><span class="identifier">externally_locked</span></code>
            that controls access to a BankAccount.
          </p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span>  <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">externally_locked</span> <span class="special">{</span>
    <span class="identifier">BOOST_CONCEPT_ASSERT</span><span class="special">((</span><span class="identifier">LockableConcept</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;));</span>

<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">obj</span><span class="special">,</span> <span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">lockable</span><span class="special">)</span>
        <span class="special">:</span> <span class="identifier">obj_</span><span class="special">(</span><span class="identifier">obj</span><span class="special">)</span>
        <span class="special">,</span> <span class="identifier">lockable_</span><span class="special">(</span><span class="identifier">lockable</span><span class="special">)</span>
    <span class="special">{}</span>

    <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">lockable</span><span class="special">)</span>
        <span class="special">:</span> <span class="identifier">obj_</span><span class="special">()</span>
        <span class="special">,</span> <span class="identifier">lockable_</span><span class="special">(</span><span class="identifier">lockable</span><span class="special">)</span>
    <span class="special">{}</span>

    <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">)</span> <span class="special">{</span>

<span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED</span>
        <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">lock</span><span class="special">.</span><span class="identifier">owns_lock</span><span class="special">(&amp;</span><span class="identifier">lockable_</span><span class="special">))</span> <span class="keyword">throw</span> <span class="identifier">lock_error</span><span class="special">();</span> <span class="comment">//run time check throw if not locks the same</span>
<span class="preprocessor">#endif</span>
        <span class="keyword">return</span> <span class="identifier">obj_</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="keyword">void</span> <span class="identifier">set</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">obj</span><span class="special">,</span> <span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">lockable</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">obj_</span> <span class="special">=</span> <span class="identifier">obj</span><span class="special">;</span>
        <span class="identifier">lockable_</span><span class="special">=</span><span class="identifier">lockable</span><span class="special">;</span>
    <span class="special">}</span>
<span class="keyword">private</span><span class="special">:</span>
    <span class="identifier">T</span> <span class="identifier">obj_</span><span class="special">;</span>
    <span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">lockable_</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
            <code class="computeroutput"><span class="identifier">externally_locked</span></code> cloaks
            an object of type T, and actually provides full access to that object
            through the get and set member functions, provided you pass a reference
            to a <code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">Owner</span><span class="special">&gt;</span></code>
            object.
          </p>
<p>
            Instead of making <code class="computeroutput"><span class="identifier">checkingAcct_</span></code>
            and <code class="computeroutput"><span class="identifier">savingsAcct_</span></code> of type
            <code class="computeroutput"><span class="identifier">BankAccount</span></code>, <code class="computeroutput"><span class="identifier">AccountManager</span></code> holds objects of type
            <code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">,</span>
            <span class="identifier">AccountManager</span><span class="special">&gt;</span></code>:
          </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">AccountManager</span>
    <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">basic_lockable_adapter</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span> <span class="identifier">basic_lockable_adapter</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">lockable_base_type</span><span class="special">;</span>
    <span class="identifier">AccountManager</span><span class="special">()</span>
        <span class="special">:</span> <span class="identifier">checkingAcct_</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
        <span class="special">,</span> <span class="identifier">savingsAcct_</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span>
    <span class="special">{}</span>
    <span class="keyword">inline</span> <span class="keyword">void</span> <span class="identifier">Checking2Savings</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">);</span>
    <span class="keyword">inline</span> <span class="keyword">void</span> <span class="identifier">AMoreComplicatedChecking2Savings</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">);</span>
<span class="keyword">private</span><span class="special">:</span>

    <span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">,</span> <span class="identifier">AccountManager</span><span class="special">&gt;</span> <span class="identifier">checkingAcct_</span><span class="special">;</span>
    <span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">BankAccount</span><span class="special">,</span> <span class="identifier">AccountManager</span><span class="special">&gt;</span> <span class="identifier">savingsAcct_</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
            The pattern is the same as before - to access the BankAccount object
            cloaked by <code class="computeroutput"><span class="identifier">checkingAcct_</span></code>,
            you need to call <code class="computeroutput"><span class="identifier">get</span></code>.
            To call <code class="computeroutput"><span class="identifier">get</span></code>, you need
            to pass it a <code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">AccountManager</span><span class="special">&gt;</span></code>. The one thing you have to take care
            of is to not hold pointers or references you obtained by calling <code class="computeroutput"><span class="identifier">get</span></code>. If you do that, make sure that
            you don't use them after the strict_lock has been destroyed. That is,
            if you alias the cloaked objects, you're back from "the compiler
            takes care of that" mode to "you must pay attention" mode.
          </p>
<p>
            Typically, you use <code class="computeroutput"><span class="identifier">externally_locked</span></code>
            as shown below. Suppose you want to execute an atomic transfer from your
            checking account to your savings account:
          </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">AccountManager</span><span class="special">::</span><span class="identifier">Checking2Savings</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">AccountManager</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(*</span><span class="keyword">this</span><span class="special">);</span>
    <span class="identifier">checkingAcct_</span><span class="special">.</span><span class="identifier">get</span><span class="special">(</span><span class="identifier">guard</span><span class="special">).</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="identifier">amount</span><span class="special">);</span>
    <span class="identifier">savingsAcct_</span><span class="special">.</span><span class="identifier">get</span><span class="special">(</span><span class="identifier">guard</span><span class="special">).</span><span class="identifier">Deposit</span><span class="special">(</span><span class="identifier">amount</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
            We achieved two important goals. First, the declaration of <code class="computeroutput"><span class="identifier">checkingAcct_</span></code> and <code class="computeroutput"><span class="identifier">savingsAcct_</span></code>
            makes it clear to the code reader that that variable is protected by
            a lock on an AccountManager. Second, the design makes it impossible to
            manipulate the two accounts without actually locking a BankAccount.
            <code class="computeroutput"><span class="identifier">externally_locked</span></code> is
            what could be called active documentation.
          </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes.allowing_other_strict_locks"></a><a class="link" href="synchronization.html#thread.synchronization.tutorial.external_locking_____strict_lock__and__externally_locked__classes.allowing_other_strict_locks" title="Allowing other strict locks">Allowing
          other strict locks</a>
</h5></div></div></div>
<p>
            Now imagine that the AccountManager function needs to take a <code class="computeroutput"><span class="identifier">unique_lock</span></code> in order to reduce the
            critical regions. And at some time it needs to access to the <code class="computeroutput"><span class="identifier">checkingAcct_</span></code>. As <code class="computeroutput"><span class="identifier">unique_lock</span></code>
            is not a strict lock the following code doesn't compile:
          </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">AccountManager</span><span class="special">::</span><span class="identifier">AMoreComplicatedChecking2Savings</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">AccountManager</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(*</span><span class="keyword">this</span><span class="special">,</span> <span class="identifier">defer_lock</span><span class="special">);</span>
    <span class="keyword">if</span> <span class="special">(</span><span class="identifier">some_condition</span><span class="special">())</span> <span class="special">{</span>
        <span class="identifier">guard</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span>
    <span class="special">}</span>
    <span class="identifier">checkingAcct_</span><span class="special">.</span><span class="identifier">get</span><span class="special">(</span><span class="identifier">guard</span><span class="special">).</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="identifier">amount</span><span class="special">);</span> <span class="comment">// COMPILE ERROR</span>
    <span class="identifier">savingsAcct_</span><span class="special">.</span><span class="identifier">get</span><span class="special">(</span><span class="identifier">guard</span><span class="special">).</span><span class="identifier">Deposit</span><span class="special">(</span><span class="identifier">amount</span><span class="special">);</span>  <span class="comment">// COMPILE ERROR</span>
    <span class="identifier">do_something_else</span><span class="special">();</span>
<span class="special">}</span>
</pre>
<p>
            We need a way to transfer the ownership from the <code class="computeroutput"><span class="identifier">unique_lock</span></code>
            to a <code class="computeroutput"><span class="identifier">strict_lock</span></code> during
            the time we are working with <code class="computeroutput"><span class="identifier">savingsAcct_</span></code>
            and then restore the ownership on <code class="computeroutput"><span class="identifier">unique_lock</span></code>.
          </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">AccountManager</span><span class="special">::</span><span class="identifier">AMoreComplicatedChecking2Savings</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">AccountManager</span><span class="special">&gt;</span> <span class="identifier">guard1</span><span class="special">(*</span><span class="keyword">this</span><span class="special">,</span> <span class="identifier">defer_lock</span><span class="special">);</span>
    <span class="keyword">if</span> <span class="special">(</span><span class="identifier">some_condition</span><span class="special">())</span> <span class="special">{</span>
        <span class="identifier">guard1</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span>
    <span class="special">}</span>
    <span class="special">{</span>
        <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">AccountManager</span><span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">guard1</span><span class="special">);</span>
        <span class="identifier">checkingAcct_</span><span class="special">.</span><span class="identifier">get</span><span class="special">(</span><span class="identifier">guard</span><span class="special">).</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="identifier">amount</span><span class="special">);</span>
        <span class="identifier">savingsAcct_</span><span class="special">.</span><span class="identifier">get</span><span class="special">(</span><span class="identifier">guard</span><span class="special">).</span><span class="identifier">Deposit</span><span class="special">(</span><span class="identifier">amount</span><span class="special">);</span>
    <span class="special">}</span>
    <span class="identifier">guard1</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">();</span>
<span class="special">}</span>
</pre>
<p>
            In order to make this code compilable we need to store either a Lockable
            or a <code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span></code>
            reference depending on the constructor. We also need to store which kind
            of reference we have stored, and in the destructor call either to the
            Lockable <code class="computeroutput"><span class="identifier">unlock</span></code> or restore
            the ownership.
          </p>
<p>
            This seems too complicated to me. Another possibility is to define a
            nested strict lock class. The drawback is that instead of having only
            one strict lock we have two and we need either to duplicate every function
            taking a <code class="computeroutput"><span class="identifier">strict_lock</span></code>
            or make these function templates. The problem with template functions
            is that we don't profit anymore of the C++ type system. We must add some
            static metafunction that checks that the Locker parameter is a strict
            lock. The problem is that we can not really check this or can we?. The
            <code class="computeroutput"><span class="identifier">is_strict_lock</span></code> metafunction
            must be specialized by the strict lock developer. We need to believe
            it "sur parole". The advantage is that now we can manage with
            more than two strict locks without changing our code. This is really
            nice.
          </p>
<p>
            Now we need to state that both classes are <code class="computeroutput"><span class="identifier">strict_lock</span></code>s.
          </p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Locker</span><span class="special">&gt;</span>
<span class="keyword">struct</span> <span class="identifier">is_strict_lock</span> <span class="special">:</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">false_</span> <span class="special">{};</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="keyword">struct</span> <span class="identifier">is_strict_lock</span><span class="special">&lt;</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">:</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">true_</span> <span class="special">{}</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Locker</span><span class="special">&gt;</span>
<span class="keyword">struct</span> <span class="identifier">is_strict_lock</span><span class="special">&lt;</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Locker</span><span class="special">&gt;</span> <span class="special">&gt;</span> <span class="special">:</span> <span class="identifier">mpl</span><span class="special">::</span><span class="identifier">true_</span> <span class="special">{}</span>
</pre>
<p>
            Well let me show what this <code class="computeroutput"><span class="identifier">nested_strict_lock</span></code>
            class looks like and the impacts on the <code class="computeroutput"><span class="identifier">externally_locked</span></code>
            class and the <code class="computeroutput"><span class="identifier">AccountManager</span><span class="special">::</span><span class="identifier">AMoreComplicatedFunction</span></code>
            function.
          </p>
<p>
            First <code class="computeroutput"><span class="identifier">nested_strict_lock</span></code>
            class will store on a temporary lock the <code class="computeroutput"><span class="identifier">Locker</span></code>,
            and transfer the lock ownership on the constructor. On destruction it
            will restore the ownership. Note the use of <code class="computeroutput"><span class="identifier">lock_traits</span></code>
            and that the <code class="computeroutput"><span class="identifier">Locker</span></code> needs
            to have a reference to the mutex otherwise an exception is thrown.
          </p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Locker</span> <span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">nested_strict_lock</span>
    <span class="special">{</span>
      <span class="identifier">BOOST_CONCEPT_ASSERT</span><span class="special">((</span><span class="identifier">MovableLockerConcept</span><span class="special">&lt;</span><span class="identifier">Locker</span><span class="special">&gt;));</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">lockable_type</span><span class="special">&lt;</span><span class="identifier">Locker</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">lockable_type</span><span class="special">;</span>
    <span class="keyword">typedef</span> <span class="keyword">typename</span> <span class="identifier">syntactic_lock_traits</span><span class="special">&lt;</span><span class="identifier">lockable_type</span><span class="special">&gt;::</span><span class="identifier">lock_error</span> <span class="identifier">lock_error</span><span class="special">;</span>

    <span class="identifier">nested_strict_lock</span><span class="special">(</span><span class="identifier">Locker</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">)</span>
        <span class="special">:</span> <span class="identifier">lock_</span><span class="special">(</span><span class="identifier">lock</span><span class="special">)</span>  <span class="comment">// Store reference to locker</span>
        <span class="special">,</span> <span class="identifier">tmp_lock_</span><span class="special">(</span><span class="identifier">lock</span><span class="special">.</span><span class="identifier">move</span><span class="special">())</span> <span class="comment">// Move ownership to temporary locker </span>
    <span class="special">{</span>
        <span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED</span>
        <span class="keyword">if</span> <span class="special">(</span><span class="identifier">tmp_lock_</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">()==</span><span class="number">0</span><span class="special">)</span> <span class="special">{</span>
            <span class="identifier">lock_</span><span class="special">=</span><span class="identifier">tmp_lock_</span><span class="special">.</span><span class="identifier">move</span><span class="special">();</span> <span class="comment">// Rollback for coherency purposes </span>
            <span class="keyword">throw</span> <span class="identifier">lock_error</span><span class="special">();</span>
        <span class="special">}</span>
        <span class="preprocessor">#endif</span>
        <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">tmp_lock_</span><span class="special">)</span> <span class="identifier">tmp_lock_</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span> <span class="comment">// ensures it is locked </span>
    <span class="special">}</span>
    <span class="special">~</span><span class="identifier">nested_strict_lock</span><span class="special">()</span> <span class="special">{</span>
        <span class="identifier">lock_</span><span class="special">=</span><span class="identifier">tmp_lock_</span><span class="special">.</span><span class="identifier">move</span><span class="special">();</span> <span class="comment">// Move ownership to nesting locker </span>
    <span class="special">}</span>
    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">()</span> <span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="keyword">true</span><span class="special">;</span> <span class="special">}</span>
    <span class="identifier">lockable_type</span><span class="special">*</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">tmp_lock_</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">();</span> <span class="special">}</span>
    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">lockable_type</span><span class="special">*</span> <span class="identifier">l</span><span class="special">)</span> <span class="keyword">const</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">l</span><span class="special">==</span><span class="identifier">mutex</span><span class="special">();</span> <span class="special">}</span>


<span class="keyword">private</span><span class="special">:</span>
    <span class="identifier">Locker</span><span class="special">&amp;</span> <span class="identifier">lock_</span><span class="special">;</span>
    <span class="identifier">Locker</span> <span class="identifier">tmp_lock_</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
            The <code class="computeroutput"><span class="identifier">externally_locked</span></code>
            get function is now a template function taking a Locker as parameters
            instead of a <code class="computeroutput"><span class="identifier">strict_lock</span></code>.
            We can add test in debug mode that ensure that the Lockable object is
            locked.
          </p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span>  <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">externally_locked</span> <span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="comment">// ...</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Locker</span><span class="special">&gt;</span>
    <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">Locker</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">BOOST_CONCEPT_ASSERT</span><span class="special">((</span><span class="identifier">StrictLockerConcept</span><span class="special">&lt;</span><span class="identifier">Locker</span><span class="special">&gt;));</span>

        <span class="identifier">BOOST_STATIC_ASSERT</span><span class="special">((</span><span class="identifier">is_strict_lock</span><span class="special">&lt;</span><span class="identifier">Locker</span><span class="special">&gt;::</span><span class="identifier">value</span><span class="special">));</span> <span class="comment">// locker is a strict locker "sur parole" </span>
        <span class="identifier">BOOST_STATIC_ASSERT</span><span class="special">((</span><span class="identifier">is_same</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">,</span>
                <span class="keyword">typename</span> <span class="identifier">lockable_type</span><span class="special">&lt;</span><span class="identifier">Locker</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">&gt;::</span><span class="identifier">value</span><span class="special">));</span> <span class="comment">// that locks the same type </span>
<span class="preprocessor">#ifndef</span> <span class="identifier">BOOST_THREAD_EXTERNALLY_LOCKED_DONT_CHECK_OWNERSHIP</span>  <span class="comment">// define BOOST_THREAD_EXTERNALLY_LOCKED_NO_CHECK_OWNERSHIP if you don't want to check locker ownership</span>
        <span class="keyword">if</span> <span class="special">(!</span> <span class="identifier">lock</span> <span class="special">)</span> <span class="keyword">throw</span> <span class="identifier">lock_error</span><span class="special">();</span> <span class="comment">// run time check throw if no locked </span>
<span class="preprocessor">#endif</span>
<span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED</span>
        <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">lock</span><span class="special">.</span><span class="identifier">owns_lock</span><span class="special">(&amp;</span><span class="identifier">lockable_</span><span class="special">))</span> <span class="keyword">throw</span> <span class="identifier">lock_error</span><span class="special">();</span>
<span class="preprocessor">#endif</span>
        <span class="keyword">return</span> <span class="identifier">obj_</span><span class="special">;</span>
    <span class="special">}</span>
<span class="special">};</span>
</pre>
<p>
            The <code class="computeroutput"><span class="identifier">AccountManager</span><span class="special">::</span><span class="identifier">AMoreComplicatedFunction</span></code> function needs
            only to replace the <code class="computeroutput"><span class="identifier">strict_lock</span></code>
            by a <code class="computeroutput"><span class="identifier">nested_strict_lock</span></code>.
          </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">AccountManager</span><span class="special">::</span><span class="identifier">AMoreComplicatedChecking2Savings</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">amount</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">AccountManager</span><span class="special">&gt;</span> <span class="identifier">guard1</span><span class="special">(*</span><span class="keyword">this</span><span class="special">);</span>
    <span class="keyword">if</span> <span class="special">(</span><span class="identifier">some_condition</span><span class="special">())</span> <span class="special">{</span>
        <span class="identifier">guard1</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span>
    <span class="special">}</span>
    <span class="special">{</span>
        <span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">AccountManager</span><span class="special">&gt;</span> <span class="special">&gt;</span> <span class="identifier">guard</span><span class="special">(</span><span class="identifier">guard1</span><span class="special">);</span>
        <span class="identifier">checkingAcct_</span><span class="special">.</span><span class="identifier">get</span><span class="special">(</span><span class="identifier">guard</span><span class="special">).</span><span class="identifier">Withdraw</span><span class="special">(</span><span class="identifier">amount</span><span class="special">);</span>
        <span class="identifier">savingsAcct_</span><span class="special">.</span><span class="identifier">get</span><span class="special">(</span><span class="identifier">guard</span><span class="special">).</span><span class="identifier">Deposit</span><span class="special">(</span><span class="identifier">amount</span><span class="special">);</span>
    <span class="special">}</span>
    <span class="identifier">guard1</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">();</span>
<span class="special">}</span>
</pre>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.tutorial.with"></a><a class="link" href="synchronization.html#thread.synchronization.tutorial.with" title="Executing Around a Function">Executing Around
        a Function</a>
</h4></div></div></div>
<p>
          In particular, the library provides a way to lock around the execution
          of a function.
        </p>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lockable</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Function</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Args</span><span class="special">&gt;</span>
<span class="keyword">auto</span> <span class="identifier">with_lock_guard</span><span class="special">(</span>
    <span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span>
    <span class="identifier">Function</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">,</span>
    <span class="identifier">Args</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span>
<span class="special">)</span> <span class="special">-&gt;</span> <span class="keyword">decltype</span><span class="special">(</span><span class="identifier">func</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">)...))</span> <span class="special">{</span>
  <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">lock</span><span class="special">(</span><span class="identifier">m</span><span class="special">);</span>
  <span class="keyword">return</span> <span class="identifier">func</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">)...);</span>
<span class="special">}</span>
</pre>
<p>
          that can be used with regular functions:
        </p>
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">func</span><span class="special">(</span><span class="keyword">int</span><span class="special">,</span> <span class="keyword">int</span><span class="special">&amp;);</span>
<span class="comment">//...</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span> <span class="identifier">m</span><span class="special">;</span>
<span class="keyword">int</span> <span class="identifier">a</span><span class="special">;</span>
<span class="keyword">int</span> <span class="identifier">result</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">with_lock_guard</span><span class="special">(</span><span class="identifier">m</span><span class="special">,</span> <span class="identifier">func</span><span class="special">,</span> <span class="number">1</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ref</span><span class="special">(</span><span class="identifier">a</span><span class="special">));</span>
</pre>
<p>
          with boost::bind:
        </p>
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">result</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">with_lock_guard</span><span class="special">(</span>
    <span class="identifier">m</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">bind</span><span class="special">(</span><span class="identifier">func</span><span class="special">,</span> <span class="number">2</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">ref</span><span class="special">(</span><span class="identifier">a</span><span class="special">))</span>
<span class="special">);</span>
</pre>
<p>
          or with lambda expression:
        </p>
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">a</span><span class="special">;</span>
<span class="keyword">int</span> <span class="identifier">result</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">with_lock_guard</span><span class="special">(</span>
    <span class="identifier">m</span><span class="special">,</span>
    <span class="special">[&amp;</span><span class="identifier">a</span><span class="special">](</span><span class="keyword">int</span> <span class="identifier">x</span><span class="special">)</span> <span class="special">{</span>
      <span class="comment">// this scope is protected by mutex m</span>
      <span class="identifier">a</span> <span class="special">=</span> <span class="number">3</span><span class="special">;</span>
      <span class="keyword">return</span> <span class="identifier">x</span> <span class="special">+</span> <span class="number">4</span><span class="special">;</span>
    <span class="special">},</span>
    <span class="number">5</span>
<span class="special">);</span>
</pre>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.mutex_concepts"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts" title="Mutex Concepts">Mutex Concepts</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable"><code class="computeroutput"><span class="identifier">BasicLockable</span></code> Concept</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.lockable"><code class="computeroutput"><span class="identifier">Lockable</span></code> Concept</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.recursive">Recursive
        Lockable Concept</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable"><code class="computeroutput"><span class="identifier">TimedLockable</span></code> Concept</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable"><code class="computeroutput"><span class="identifier">SharedLockable</span></code> Concept -- C++14</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable"><code class="computeroutput"><span class="identifier">UpgradeLockable</span></code> Concept -- EXTENSION</a></span></dt>
</dl></div>
<p>
        A mutex object facilitates protection against data races and allows thread-safe
        synchronization of data between threads. A thread obtains ownership of a
        mutex object by calling one of the lock functions and relinquishes ownership
        by calling the corresponding unlock function. Mutexes may be either recursive
        or non-recursive, and may grant simultaneous ownership to one or many threads.
        <span class="bold"><strong>Boost.Thread</strong></span> supplies recursive and non-recursive
        mutexes with exclusive ownership semantics, along with a shared ownership
        (multiple-reader / single-writer) mutex.
      </p>
<p>
        <span class="bold"><strong>Boost.Thread</strong></span> supports four basic concepts
        for lockable objects: <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a>, <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable" title="TimedLockable Concept"><code class="computeroutput"><span class="identifier">TimedLockable</span></code></a>, <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code></a> and <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable" title="UpgradeLockable Concept -- EXTENSION"><code class="computeroutput"><span class="identifier">UpgradeLockable</span></code></a>. Each mutex type
        implements one or more of these concepts, as do the various lock types.
      </p>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_concepts.basic_lockable"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable" title="BasicLockable Concept"><code class="computeroutput"><span class="identifier">BasicLockable</span></code> Concept</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">();</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.is_basic_lockable"><code class="computeroutput"><span class="identifier">is_basic_lockable</span></code> trait -- EXTENSION</a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lockable_concepts.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">L</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">BasicLockable</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
<span class="special">}</span>
</pre>
<p>
          The <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable" title="BasicLockable Concept"><code class="computeroutput"><span class="identifier">BasicLockable</span></code></a> concept models exclusive
          ownership. A type <code class="computeroutput"><span class="identifier">L</span></code> meets
          the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable" title="BasicLockable Concept"><code class="computeroutput"><span class="identifier">BasicLockable</span></code></a> requirements if
          the following expressions are well-formed and have the specified semantics
          (<code class="computeroutput"><span class="identifier">m</span></code> denotes a value of type
          <code class="computeroutput"><span class="identifier">L</span></code>):
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span></code></a><span class="special">();</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span></code></a><span class="special">();</span></code>
            </li>
</ul></div>
<p>
          Lock ownership acquired through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>
          must be released through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.basic_lockable.lock"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">();</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The calling thread doesn't owns the mutex if the mutex is not recursive.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The current thread blocks until ownership can be obtained for the
                  current thread.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  Prior <code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code>
                  operations on the same object synchronizes with this operation.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  The current thread owns <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Return type:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">void</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock_error</span></code> if an
                  error occurs.
                </p></dd>
<dt><span class="term">Error Conditions:</span></dt>
<dd>
<p>
                  <span class="bold"><strong>operation_not_permitted</strong></span>: if the
                  thread does not have the privilege to perform the operation.
                </p>
<p>
                  <span class="bold"><strong>resource_deadlock_would_occur</strong></span>:
                  if the implementation detects that a deadlock would occur.
                </p>
<p>
                  <span class="bold"><strong>device_or_resource_busy</strong></span>: if the
                  mutex is already locked and blocking is not possible.
                </p>
</dd>
<dt><span class="term">Thread safety:</span></dt>
<dd><p>
                  If an exception is thrown then a lock shall not have been acquired
                  for the current thread.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.basic_lockable.unlock"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">();</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The current thread owns <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  This operation synchronizes with subsequent lock operations that
                  obtain ownership on the same object.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Releases a lock on <code class="computeroutput"><span class="identifier">m</span></code>
                  by the current thread.
                </p></dd>
<dt><span class="term">Return type:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">void</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.basic_lockable.is_basic_lockable"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.is_basic_lockable" title="is_basic_lockable trait -- EXTENSION"><code class="computeroutput"><span class="identifier">is_basic_lockable</span></code> trait -- EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lockable_traits.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">namespace</span> <span class="identifier">sync</span>
  <span class="special">{</span>
    <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">L</span><span class="special">&gt;</span>
    <span class="keyword">class</span> <span class="identifier">is_basic_lockable</span><span class="special">;//</span> <span class="identifier">EXTENSION</span>
  <span class="special">}</span>
<span class="special">}</span>
</pre>
<p>
            Some of the algorithms on mutexes use this trait via SFINAE.
          </p>
<p>
            This trait is true_type if the parameter L meets the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> requirements.
          </p>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
              If BOOST_THREAD_NO_AUTO_DETECT_MUTEX_TYPES is defined you will need
              to specialize this traits for the models of BasicLockable you could
              build.
            </p></td></tr>
</table></div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_concepts.lockable"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code> Concept</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.lockable.is_lockable"><code class="computeroutput"><span class="identifier">is_lockable</span></code> trait -- EXTENSION</a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lockable_concepts.hpp&gt; </span>
<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">L</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">Lockable</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
          A type <code class="computeroutput"><span class="identifier">L</span></code> meets the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> requirements if it meets
          the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable" title="BasicLockable Concept"><code class="computeroutput"><span class="identifier">BasicLockable</span></code></a> requirements and
          the following expressions are well-formed and have the specified semantics
          (<code class="computeroutput"><span class="identifier">m</span></code> denotes a value of type
          <code class="computeroutput"><span class="identifier">L</span></code>):
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span></code></a><span class="special">()</span></code>
            </li></ul></div>
<p>
          Lock ownership acquired through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
          must be released through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.lockable.try_lock"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The calling thread doesn't owns the mutex if the mutex is not recursive.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Attempt to obtain ownership for the current thread without blocking.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code>
                  returns true, prior <code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code> operations on the same object
                  synchronize with this operation.
                </p></dd>
<dt><span class="term">Note:</span></dt>
<dd><p>
                  Since <code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code>
                  does not synchronize with a failed subsequent <code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code>, the visibility rules are weak
                  enough that little would be known about the state after a failure,
                  even in the absence of spurious failures.
                </p></dd>
<dt><span class="term">Return type:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">bool</span></code>.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if ownership
                  was obtained for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread owns the <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.lockable.is_lockable"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.is_lockable" title="is_lockable trait -- EXTENSION"><code class="computeroutput"><span class="identifier">is_lockable</span></code> trait -- EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lockable_traits.hpp&gt; </span>
<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">namespace</span> <span class="identifier">sync</span>
  <span class="special">{</span>
    <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">L</span><span class="special">&gt;</span>
    <span class="keyword">class</span> <span class="identifier">is_lockable</span><span class="special">;//</span> <span class="identifier">EXTENSION</span>
  <span class="special">}</span>
<span class="special">}</span>
</pre>
<p>
            Some of the algorithms on mutexes use this trait via SFINAE.
          </p>
<p>
            This trait is true_type if the parameter L meets the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> requirements.
          </p>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
              If BOOST_THREAD_NO_AUTO_DETECT_MUTEX_TYPES is defined you will need
              to specialize this traits for the models of Lockable you could build.
            </p></td></tr>
</table></div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_concepts.recursive"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.recursive" title="Recursive Lockable Concept">Recursive
        Lockable Concept</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.recursive.is_recursive_mutex_sur_parole"><code class="computeroutput"><span class="identifier">is_recursive_mutex_sur_parole</span></code> trait --
          EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.recursive.is_recursive_basic_lockable"><code class="computeroutput"><span class="identifier">is_recursive_basic_lockable</span></code> trait --
          EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.recursive.is_recursive_lockable"><code class="computeroutput"><span class="identifier">is_recursive_lockable</span></code> trait -- EXTENSION</a></span></dt>
</dl></div>
<p>
          The user could require that the mutex passed to an algorithm is a recursive
          one. Whether a lockable is recursive or not can not be checked using template
          meta-programming. This is the motivation for the following trait.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.recursive.is_recursive_mutex_sur_parole"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.recursive.is_recursive_mutex_sur_parole" title="is_recursive_mutex_sur_parole trait -- EXTENSION"><code class="computeroutput"><span class="identifier">is_recursive_mutex_sur_parole</span></code> trait --
          EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lockable_traits.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">namespace</span> <span class="identifier">sync</span>
  <span class="special">{</span>
    <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">L</span><span class="special">&gt;</span>
    <span class="keyword">class</span> <span class="identifier">is_recursive_mutex_sur_parole</span><span class="special">:</span> <span class="identifier">false_type</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
    <span class="keyword">template</span><span class="special">&lt;&gt;</span>
    <span class="keyword">class</span> <span class="identifier">is_recursive_mutex_sur_parole</span><span class="special">&lt;</span><span class="identifier">recursive_mutex</span><span class="special">&gt;:</span> <span class="identifier">true_type</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
    <span class="keyword">template</span><span class="special">&lt;&gt;</span>
    <span class="keyword">class</span> <span class="identifier">is_recursive_mutex_sur_parole</span><span class="special">&lt;</span><span class="identifier">timed_recursive_mutex</span><span class="special">&gt;:</span> <span class="identifier">true_type</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
  <span class="special">}</span>
<span class="special">}</span>
</pre>
<p>
            The trait <code class="computeroutput"><span class="identifier">is_recursive_mutex_sur_parole</span></code>
            is <code class="computeroutput"><span class="identifier">false_type</span></code> by default
            and is specialized for the provide <code class="computeroutput"><span class="identifier">recursive_mutex</span></code>
            and <code class="computeroutput"><span class="identifier">timed_recursive_mutex</span></code>.
          </p>
<p>
            It should be specialized by the user providing other model of recursive
            lockable.
          </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.recursive.is_recursive_basic_lockable"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.recursive.is_recursive_basic_lockable" title="is_recursive_basic_lockable trait -- EXTENSION"><code class="computeroutput"><span class="identifier">is_recursive_basic_lockable</span></code> trait --
          EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lockable_traits.hpp&gt; </span>
<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">namespace</span> <span class="identifier">sync</span>
  <span class="special">{</span>
    <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">L</span><span class="special">&gt;</span>
    <span class="keyword">class</span> <span class="identifier">is_recursive_basic_lockable</span><span class="special">;//</span> <span class="identifier">EXTENSION</span>
  <span class="special">}</span>
<span class="special">}</span>
</pre>
<p>
            This traits is true_type if is_basic_lockable and is_recursive_mutex_sur_parole.
          </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.recursive.is_recursive_lockable"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.recursive.is_recursive_lockable" title="is_recursive_lockable trait -- EXTENSION"><code class="computeroutput"><span class="identifier">is_recursive_lockable</span></code> trait -- EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lockable_traits.hpp&gt; </span>
<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">namespace</span> <span class="identifier">sync</span>
  <span class="special">{</span>
    <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">L</span><span class="special">&gt;</span>
    <span class="keyword">class</span> <span class="identifier">is_recursive_lockable</span><span class="special">;//</span> <span class="identifier">EXTENSION</span>
  <span class="special">}</span>
<span class="special">}</span>
</pre>
<p>
            This traits is true_type if is_lockable and is_recursive_mutex_sur_parole.
          </p>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_concepts.timed_lockable"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable" title="TimedLockable Concept"><code class="computeroutput"><span class="identifier">TimedLockable</span></code> Concept</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_for"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock_duration"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lockable_concepts.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">L</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">TimedLockable</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
<span class="special">}</span>
</pre>
<p>
          The <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable" title="TimedLockable Concept"><code class="computeroutput"><span class="identifier">TimedLockable</span></code> concept</a> refines
          the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code> concept</a> to add support
          for timeouts when trying to acquire the lock.
        </p>
<p>
          A type <code class="computeroutput"><span class="identifier">L</span></code> meets the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable" title="TimedLockable Concept"><code class="computeroutput"><span class="identifier">TimedLockable</span></code></a> requirements if
          it meets the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> requirements and the
          following expressions are well-formed and have the specified semantics.
        </p>
<p>
          <span class="bold"><strong>Variables:</strong></span>
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span></code> denotes a value of
              type <code class="computeroutput"><span class="identifier">L</span></code>,
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">rel_time</span></code> denotes a
              value of an instantiation of <code class="computeroutput"><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span></code>,
              and
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">abs_time</span></code> denotes a
              value of an instantiation of <code class="computeroutput"><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span></code>:
            </li>
</ul></div>
<p>
          <span class="bold"><strong>Expressions:</strong></span>
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_for" title="m.try_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until" title="m.try_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code>
            </li>
</ul></div>
<p>
          Lock ownership acquired through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_for" title="m.try_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_for</span></code></a> or <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until" title="m.try_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_until</span></code></a> must be released
          through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span></code></a>.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.timed_lockable.try_lock_until"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until" title="m.try_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The calling thread doesn't owns the mutex if the mutex is not recursive.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Attempt to obtain ownership for the current thread. Blocks until
                  ownership can be obtained, or the specified time is reached. If
                  the specified time has already passed, behaves as <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><span class="identifier">try_lock_until</span><span class="special">()</span></code> returns true, prior <code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code>
                  operations on the same object synchronize with this operation.
                </p></dd>
<dt><span class="term">Return type:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">bool</span></code>.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if ownership
                  was obtained for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread owns <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.timed_lockable.try_lock_for"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_for" title="m.try_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The calling thread doesn't owns the mutex if the mutex is not recursive.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  As-if <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until" title="m.try_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_until</span></code></a><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">steady_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special">+</span> <span class="identifier">rel_time</span><span class="special">)</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><span class="identifier">try_lock_for</span><span class="special">()</span></code> returns true, prior <code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code>
                  operations on the same object synchronize with this operation.
                </p></dd>
</dl>
</div>
</div>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top">
<p>
            DEPRECATED since 4.00. The following expressions were required on version
            2, but are now deprecated.
          </p>
<p>
            Use instead <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_for" title="m.try_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_for</span></code></a>, <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until" title="m.try_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_until</span></code></a>.
          </p>
</td></tr>
</table></div>
<p>
          <span class="bold"><strong>Variables:</strong></span>
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">rel_time</span></code> denotes a
              value of an instantiation of an unspecified <code class="computeroutput"><span class="identifier">DurationType</span></code>
              arithmetic compatible with <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span></code>,
              and
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">abs_time</span></code> denotes a
              value of an instantiation of <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span></code>:
            </li>
</ul></div>
<p>
          <span class="bold"><strong>Expressions:</strong></span>
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock_duration" title="m.timed_lock(rel_time)"><code class="computeroutput"><span class="identifier">timed_lock</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code>
            </li>
</ul></div>
<p>
          Lock ownership acquired through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">()</span></code></a>
          must be released through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.timed_lockable.timed_lock"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Attempt to obtain ownership for the current thread. Blocks until
                  ownership can be obtained, or the specified time is reached. If
                  the specified time has already passed, behaves as <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if ownership
                  was obtained for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread owns <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock_error</span></code> if an
                  error occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.timed_lockable.timed_lock_duration"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock_duration" title="m.timed_lock(rel_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  As-if <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">get_system_time</span><span class="special">()+</span><span class="identifier">rel_time</span><span class="special">)</span></code></a>.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_concepts.shared_lockable"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code> Concept -- C++14</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock_shared</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_shared</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_for"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_shared_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_until"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_shared_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">))</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.unlock_shared"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_shared</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.timed_lock_shared"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock_shared</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lockable_concepts.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">L</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">SharedLockable</span><span class="special">;</span>  <span class="comment">// C++14</span>
<span class="special">}</span>
</pre>
<p>
          The <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code> concept</a> is a refinement
          of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable" title="TimedLockable Concept"><code class="computeroutput"><span class="identifier">TimedLockable</span></code> concept</a> that allows
          for <span class="emphasis"><em>shared ownership</em></span> as well as <span class="emphasis"><em>exclusive
          ownership</em></span>. This is the standard multiple-reader / single-write
          model: at most one thread can have exclusive ownership, and if any thread
          does have exclusive ownership, no other threads can have shared or exclusive
          ownership. Alternatively, many threads may have shared ownership.
        </p>
<p>
          A type <code class="computeroutput"><span class="identifier">L</span></code> meets the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code></a> requirements if
          it meets the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable" title="TimedLockable Concept"><code class="computeroutput"><span class="identifier">TimedLockable</span></code></a> requirements and
          the following expressions are well-formed and have the specified semantics.
        </p>
<p>
          <span class="bold"><strong>Variables:</strong></span>
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span></code> denotes a value of
              type <code class="computeroutput"><span class="identifier">L</span></code>,
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">rel_time</span></code> denotes a
              value of an instantiation of <code class="computeroutput"><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span></code>,
              and
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">abs_time</span></code> denotes a
              value of an instantiation of <code class="computeroutput"><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span></code>:
            </li>
</ul></div>
<p>
          <span class="bold"><strong>Expressions:</strong></span>
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared" title="m.lock_shared()"><code class="computeroutput"><span class="identifier">lock_shared</span><span class="special">()</span></code></a><span class="special">();</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared" title="m.try_lock_shared()"><code class="computeroutput"><span class="identifier">try_lock_shared</span></code></a><span class="special">()</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_for" title="m.try_lock_shared_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_shared_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_until" title="m.try_lock_shared_until(abs_time))"><code class="computeroutput"><span class="identifier">try_lock_shared_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.unlock_shared" title="m.unlock_shared()"><code class="computeroutput"><span class="identifier">unlock_shared</span><span class="special">()</span></code></a><span class="special">();</span></code>
            </li>
</ul></div>
<p>
          Lock ownership acquired through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared" title="m.lock_shared()"><code class="computeroutput"><span class="identifier">lock_shared</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared" title="m.try_lock_shared()"><code class="computeroutput"><span class="identifier">try_lock_shared</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_for" title="m.try_lock_shared_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_shared_for</span></code></a> or <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_until" title="m.try_lock_shared_until(abs_time))"><code class="computeroutput"><span class="identifier">try_lock_shared_until</span></code></a> must be
          released through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.unlock_shared" title="m.unlock_shared()"><code class="computeroutput"><span class="identifier">unlock_shared</span><span class="special">()</span></code></a>.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.shared_lockable.lock_shared"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared" title="m.lock_shared()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock_shared</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The current thread blocks until shared ownership can be obtained
                  for the current thread.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  The current thread has shared ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock_error</span></code> if an
                  error occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared" title="m.try_lock_shared()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_shared</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Attempt to obtain shared ownership for the current thread without
                  blocking.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if shared ownership
                  was obtained for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has shared ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock_error</span></code> if an
                  error occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_for"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_for" title="m.try_lock_shared_for(rel_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_shared_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Attempt to obtain shared ownership for the current thread. Blocks
                  until shared ownership can be obtained, or the specified duration
                  is elapsed. If the specified duration is already elapsed, behaves
                  as <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared" title="m.try_lock_shared()"><code class="computeroutput"><span class="identifier">try_lock_shared</span><span class="special">()</span></code></a>.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if shared ownership
                  was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has shared ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock_error</span></code> if an
                  error occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_until"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_until" title="m.try_lock_shared_until(abs_time))"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_shared_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">))</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Attempt to obtain shared ownership for the current thread. Blocks
                  until shared ownership can be obtained, or the specified time is
                  reached. If the specified time has already passed, behaves as
                  <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared" title="m.try_lock_shared()"><code class="computeroutput"><span class="identifier">try_lock_shared</span><span class="special">()</span></code></a>.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if shared ownership
                  was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has shared ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock_error</span></code> if an
                  error occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.shared_lockable.unlock_shared"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.unlock_shared" title="m.unlock_shared()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_shared</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The current thread has shared ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Releases shared ownership of <code class="computeroutput"><span class="identifier">m</span></code>
                  by the current thread.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  The current thread no longer has shared ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
</dl>
</div>
</div>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top">
<p>
            DEPRECATED since 3.00. The following expressions were required on version
            2, but are now deprecated.
          </p>
<p>
            Use instead <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_for" title="m.try_lock_shared_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_shared_for</span></code></a>, <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_until" title="m.try_lock_shared_until(abs_time))"><code class="computeroutput"><span class="identifier">try_lock_shared_until</span></code></a>.
          </p>
</td></tr>
</table></div>
<p>
          <span class="bold"><strong>Variables:</strong></span>
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
              <code class="computeroutput"><span class="identifier">abs_time</span></code> denotes a
              value of an instantiation of <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span></code>:
            </li></ul></div>
<p>
          <span class="bold"><strong>Expressions:</strong></span>
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock_shared</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">);</span></code>
            </li></ul></div>
<p>
          Lock ownership acquired through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.timed_lock_shared" title="m.timed_lock_shared(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock_shared</span><span class="special">()</span></code></a>
          must be released through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.unlock_shared" title="m.unlock_shared()"><code class="computeroutput"><span class="identifier">unlock_shared</span><span class="special">()</span></code></a>.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.shared_lockable.timed_lock_shared"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.timed_lock_shared" title="m.timed_lock_shared(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock_shared</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Attempt to obtain shared ownership for the current thread. Blocks
                  until shared ownership can be obtained, or the specified time is
                  reached. If the specified time has already passed, behaves as
                  <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared" title="m.try_lock_shared()"><code class="computeroutput"><span class="identifier">try_lock_shared</span><span class="special">()</span></code></a>.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if shared ownership
                  was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has shared ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock_error</span></code> if an
                  error occurs.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable" title="UpgradeLockable Concept -- EXTENSION"><code class="computeroutput"><span class="identifier">UpgradeLockable</span></code> Concept -- EXTENSION</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.lock_upgrade"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock_upgrade</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_upgrade</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_upgrade</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade_for"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_upgrade_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade_until"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_upgrade_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_for"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_until"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_and_lock_shared"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_and_lock_shared</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock_upgrade</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade_for"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock_upgrade_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade_until"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock_upgrade_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_and_lock_upgrade"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_and_lock_upgrade</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade_and_lock"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_upgrade_and_lock</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_upgrade_and_lock</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock_for"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_upgrade_and_lock_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock_until"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_upgrade_and_lock_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade_and_lock_shared"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_upgrade_and_lock_shared</span><span class="special">()</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lockable_concepts.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">L</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">UpgradeLockable</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
<span class="special">}</span>
</pre>
<p>
          The <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable" title="UpgradeLockable Concept -- EXTENSION"><code class="computeroutput"><span class="identifier">UpgradeLockable</span></code> concept</a> is a refinement
          of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code> concept</a> that allows
          for <span class="emphasis"><em>upgradable ownership</em></span> as well as <span class="emphasis"><em>shared
          ownership</em></span> and <span class="emphasis"><em>exclusive ownership</em></span>. This
          is an extension to the multiple-reader / single-write model provided by
          the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code> concept</a>: a single
          thread may have <span class="emphasis"><em>upgradable ownership</em></span> at the same time
          as others have <span class="emphasis"><em>shared ownership</em></span>. The thread with
          <span class="emphasis"><em>upgradable ownership</em></span> may at any time attempt to upgrade
          that ownership to <span class="emphasis"><em>exclusive ownership</em></span>. If no other
          threads have shared ownership, the upgrade is completed immediately, and
          the thread now has <span class="emphasis"><em>exclusive ownership</em></span>, which must
          be relinquished by a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>,
          just as if it had been acquired by a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>.
        </p>
<p>
          If a thread with <span class="emphasis"><em>upgradable ownership</em></span> tries to upgrade
          whilst other threads have <span class="emphasis"><em>shared ownership</em></span>, the attempt
          will fail and the thread will block until <span class="emphasis"><em>exclusive ownership</em></span>
          can be acquired.
        </p>
<p>
          Ownership can also be <span class="emphasis"><em>downgraded</em></span> as well as <span class="emphasis"><em>upgraded</em></span>:
          exclusive ownership of an implementation of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable" title="UpgradeLockable Concept -- EXTENSION"><code class="computeroutput"><span class="identifier">UpgradeLockable</span></code> concept</a> can be
          downgraded to upgradable ownership or shared ownership, and upgradable
          ownership can be downgraded to plain shared ownership.
        </p>
<p>
          A type <code class="computeroutput"><span class="identifier">L</span></code> meets the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable" title="UpgradeLockable Concept -- EXTENSION"><code class="computeroutput"><span class="identifier">UpgradeLockable</span></code></a> requirements if
          it meets the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code></a> requirements and
          the following expressions are well-formed and have the specified semantics.
        </p>
<p>
          <span class="bold"><strong>Variables:</strong></span>
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span></code> denotes a value of
              type <code class="computeroutput"><span class="identifier">L</span></code>,
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">rel_time</span></code> denotes a
              value of an instantiation of <code class="computeroutput"><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span></code>,
              and
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">abs_time</span></code> denotes a
              value of an instantiation of <code class="computeroutput"><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span></code>:
            </li>
</ul></div>
<p>
          <span class="bold"><strong>Expressions:</strong></span>
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.lock_upgrade" title="m.lock_upgrade()"><code class="computeroutput"><span class="identifier">lock_upgrade</span></code></a><span class="special">();</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">unlock_upgrade</span></code></a><span class="special">()</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade" title="m.try_lock_upgrade()"><code class="computeroutput"><span class="identifier">try_lock_upgrade</span></code></a><span class="special">()</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade_for" title="m.try_lock_upgrade_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_upgrade_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade_until" title="m.try_lock_upgrade_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_upgrade_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_and_lock_shared" title="m.unlock_and_lock_shared()"><code class="computeroutput"><span class="identifier">unlock_and_lock_shared</span></code></a><span class="special">()</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_and_lock_upgrade" title="m.unlock_and_lock_upgrade()"><code class="computeroutput"><span class="identifier">unlock_and_lock_upgrade</span></code></a><span class="special">();</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade_and_lock" title="m.unlock_upgrade_and_lock()"><code class="computeroutput"><span class="identifier">unlock_upgrade_and_lock</span></code></a><span class="special">();</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock" title="m.try_unlock_upgrade_and_lock()"><code class="computeroutput"><span class="identifier">try_unlock_upgrade_and_lock</span></code></a><span class="special">()</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock_for" title="m.try_unlock_upgrade_and_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_unlock_upgrade_and_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock_until" title="m.try_unlock_upgrade_and_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_unlock_upgrade_and_lock_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade_and_lock_shared" title="m.unlock_upgrade_and_lock_shared()"><code class="computeroutput"><span class="identifier">unlock_upgrade_and_lock_shared</span></code></a><span class="special">();</span></code>
            </li>
</ul></div>
<p>
          If `BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION is defined the
          following expressions are also required:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock" title="m.try_unlock_shared_and_lock()"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock</span></code></a><span class="special">();</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_for" title="m.try_unlock_shared_and_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">);</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_until" title="m.try_unlock_shared_and_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">);</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade" title="m.try_unlock_shared_and_lock_upgrade()"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_upgrade</span></code></a><span class="special">();</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade_for" title="m.try_unlock_shared_and_lock_upgrade_for(rel_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_upgrade_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">);</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade_until" title="m.try_unlock_shared_and_lock_upgrade_until(abs_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_upgrade_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">);</span></code>
            </li>
</ul></div>
<p>
          Lock ownership acquired through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.lock_upgrade" title="m.lock_upgrade()"><code class="computeroutput"><span class="identifier">lock_upgrade</span><span class="special">()</span></code></a>
          must be released through a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">unlock_upgrade</span><span class="special">()</span></code></a>.
          If the ownership type is changed through a call to one of the <code class="computeroutput"><span class="identifier">unlock_xxx_and_lock_yyy</span><span class="special">()</span></code>
          functions, ownership must be released through a call to the unlock function
          corresponding to the new level of ownership.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.lock_upgrade"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.lock_upgrade" title="m.lock_upgrade()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock_upgrade</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread has no ownership of the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The current thread blocks until upgrade ownership can be obtained
                  for the current thread.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  The current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  Prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">unlock_upgrade</span></code></a><span class="special">()</span></code> operations on the same object
                  synchronize with this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock_error</span></code> if an
                  error occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_upgrade</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Releases upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>
                  by the current thread.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  The current thread no longer has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  This operation synchronizes with subsequent lock operations that
                  obtain ownership on the same object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade" title="m.try_lock_upgrade()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_upgrade</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread has no ownership of the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Attempts to obtain upgrade ownership of the mutex for the calling
                  thread without blocking. If upgrade ownership is not obtained,
                  there is no effect and try_lock_upgrade() immediately returns.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if upgrade ownership
                  was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade" title="m.try_lock_upgrade()"><code class="computeroutput"><span class="identifier">try_lock_upgrade</span></code></a><span class="special">()</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">unlock_upgrade</span></code></a><span class="special">()</span></code> operations on the same object
                  synchronize with this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade_for"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade_for" title="m.try_lock_upgrade_for(rel_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_upgrade_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread has no ownership of the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  If the tick period of <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  is not exactly convertible to the native tick period, the duration
                  shall be rounded up to the nearest native tick period. Attempts
                  to obtain upgrade lock ownership for the calling thread within
                  the relative timeout specified by <code class="computeroutput"><span class="identifier">rel_time</span></code>.
                  If the time specified by <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  is less than or equal to <code class="computeroutput"><span class="identifier">rel_time</span><span class="special">.</span><span class="identifier">zero</span><span class="special">()</span></code>, the function attempts to obtain
                  ownership without blocking (as if by calling <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade" title="m.try_lock_upgrade()"><code class="computeroutput"><span class="identifier">try_lock_upgrade</span></code></a><span class="special">()</span></code>). The function returns within
                  the timeout specified by <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  only if it has obtained upgrade ownership of the mutex object.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if upgrade ownership
                  was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade_for" title="m.try_lock_upgrade_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_upgrade_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">unlock_upgrade</span></code></a><span class="special">()</span></code> operations on the same object
                  synchronize with this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade_until"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade_until" title="m.try_lock_upgrade_until(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_upgrade_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread has no ownership of the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The function attempts to obtain upgrade ownership of the mutex.
                  If <code class="computeroutput"><span class="identifier">abs_time</span></code> has
                  already passed, the function attempts to obtain upgrade ownership
                  without blocking (as if by calling <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade" title="m.try_lock_upgrade()"><code class="computeroutput"><span class="identifier">try_lock_upgrade</span></code></a><span class="special">()</span></code>). The function returns before
                  the absolute timeout specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>
                  only if it has obtained upgrade ownership of the mutex object.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if upgrade ownership
                  was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_lock_upgrade_until" title="m.try_lock_upgrade_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_upgrade_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">unlock_upgrade</span></code></a><span class="special">()</span></code> operations on the same object
                  synchronize with this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock" title="m.try_unlock_shared_and_lock()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread must hold a shared lock on the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The function attempts to atomically convert the ownership from
                  shared to exclusive for the calling thread without blocking. For
                  this conversion to be successful, this thread must be the only
                  thread holding any ownership of the lock. If the conversion is
                  not successful, the shared ownership of m is retained.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if exclusive
                  ownership was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has exclusive ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock" title="m.try_unlock_shared_and_lock()"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock</span></code></a><span class="special">()</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span></code></a><span class="special">()</span></code>
                  and subsequent lock operations on the same object synchronize with
                  this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span></code>
                  and <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_for"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_for" title="m.try_unlock_shared_and_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread shall hold a shared lock on the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  If the tick period of <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  is not exactly convertible to the native tick period, the duration
                  shall be rounded up to the nearest native tick period. The function
                  attempts to atomically convert the ownership from shared to exclusive
                  for the calling thread within the relative timeout specified by
                  <code class="computeroutput"><span class="identifier">rel_time</span></code>. If the
                  time specified by <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  is less than or equal to <code class="computeroutput"><span class="identifier">rel_time</span><span class="special">.</span><span class="identifier">zero</span><span class="special">()</span></code>, the function attempts to obtain
                  exclusive ownership without blocking (as if by calling <code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock</span><span class="special">()</span></code>).
                  The function shall return within the timeout specified by <code class="computeroutput"><span class="identifier">rel_time</span></code> only if it has obtained
                  exclusive ownership of the mutex object. For this conversion to
                  be successful, this thread must be the only thread holding any
                  ownership of the lock at the moment of conversion. If the conversion
                  is not successful, the shared ownership of the mutex is retained.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if exclusive
                  ownership was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has exclusive ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_for" title="m.try_unlock_shared_and_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span></code></a><span class="special">()</span></code>
                  and subsequent lock operations on the same object synchronize with
                  this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span></code>
                  and <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_until"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_until" title="m.try_unlock_shared_and_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread shall hold a shared lock on the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The function attempts to atomically convert the ownership from
                  shared to exclusive for the calling thread within the absolute
                  timeout specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>.
                  If <code class="computeroutput"><span class="identifier">abs_time</span></code> has
                  already passed, the function attempts to obtain exclusive ownership
                  without blocking (as if by calling <code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock</span><span class="special">()</span></code>). The function shall return before
                  the absolute timeout specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>
                  only if it has obtained exclusive ownership of the mutex object.
                  For this conversion to be successful, this thread must be the only
                  thread holding any ownership of the lock at the moment of conversion.
                  If the conversion is not successful, the shared ownership of the
                  mutex is retained.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if exclusive
                  ownership was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has exclusive ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_until" title="m.try_unlock_shared_and_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_until</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span></code></a><span class="special">()</span></code>
                  and subsequent lock operations on the same object synchronize with
                  this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span></code>
                  and <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.unlock_and_lock_shared"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_and_lock_shared" title="m.unlock_and_lock_shared()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_and_lock_shared</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread shall hold an exclusive lock on <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically converts the ownership from exclusive to shared for
                  the calling thread.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  The current thread has shared ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  This operation synchronizes with subsequent lock operations that
                  obtain ownership of the same object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade" title="m.try_unlock_shared_and_lock_upgrade()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock_upgrade</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread shall hold a shared lock on the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The function attempts to atomically convert the ownership from
                  shared to upgrade for the calling thread without blocking. For
                  this conversion to be successful, there must be no thread holding
                  upgrade ownership of this object. If the conversion is not successful,
                  the shared ownership of the mutex is retained.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if upgrade ownership
                  was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade" title="m.try_unlock_shared_and_lock_upgrade()"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_upgrade</span></code></a><span class="special">()</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">unlock_upgrade</span></code></a><span class="special">()</span></code> and subsequent lock operations
                  on the same object synchronize with this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span></code>
                  and <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade_for"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade_for" title="m.try_unlock_shared_and_lock_upgrade_for(rel_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock_upgrade_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread shall hold a shared lock on the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  If the tick period of <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  is not exactly convertible to the native tick period, the duration
                  shall be rounded up to the nearest native tick period. The function
                  attempts to atomically convert the ownership from shared to upgrade
                  for the calling thread within the relative timeout specified by
                  <code class="computeroutput"><span class="identifier">rel_time</span></code>. If the
                  time specified by <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  is less than or equal to <code class="computeroutput"><span class="identifier">rel_time</span><span class="special">.</span><span class="identifier">zero</span><span class="special">()</span></code>, the function attempts to obtain
                  upgrade ownership without blocking (as if by calling <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade" title="m.try_unlock_shared_and_lock_upgrade()"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_upgrade</span></code></a><span class="special">()</span></code>). The function shall return within
                  the timeout specified by <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  only if it has obtained exclusive ownership of the mutex object.
                  For this conversion to be successful, there must be no thread holding
                  upgrade ownership of this object at the moment of conversion. If
                  the conversion is not successful, the shared ownership of m is
                  retained.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if upgrade ownership
                  was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade_for" title="m.try_unlock_shared_and_lock_upgrade_for(rel_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_upgrade_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">unlock_upgrade</span></code></a><span class="special">()</span></code> and subsequent lock operations
                  on the same object synchronize with this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span></code>
                  and <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade_until"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade_until" title="m.try_unlock_shared_and_lock_upgrade_until(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_shared_and_lock_upgrade_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread shall hold a shared lock on the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The function attempts to atomically convert the ownership from
                  shared to upgrade for the calling thread within the absolute timeout
                  specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>.
                  If <code class="computeroutput"><span class="identifier">abs_time</span></code> has
                  already passed, the function attempts to obtain upgrade ownership
                  without blocking (as if by calling <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade" title="m.try_unlock_shared_and_lock_upgrade()"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_upgrade</span></code></a><span class="special">()</span></code>). The function shall return before
                  the absolute timeout specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>
                  only if it has obtained upgrade ownership of the mutex object.
                  For this conversion to be successful, there must be no thread holding
                  upgrade ownership of this object at the moment of conversion. If
                  the conversion is not successful, the shared ownership of the mutex
                  is retained.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if upgrade ownership
                  was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_upgrade_until" title="m.try_unlock_shared_and_lock_upgrade_until(abs_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_upgrade_until</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">unlock_upgrade</span></code></a><span class="special">()</span></code> and subsequent lock operations
                  on the same object synchronize with this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span></code>
                  and <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.unlock_and_lock_upgrade"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_and_lock_upgrade" title="m.unlock_and_lock_upgrade()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_and_lock_upgrade</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The current thread has exclusive ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically releases exclusive ownership of <code class="computeroutput"><span class="identifier">m</span></code>
                  by the current thread and acquires upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code> without blocking.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  The current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  This operation synchronizes with subsequent lock operations that
                  obtain ownership of the same object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade_and_lock"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade_and_lock" title="m.unlock_upgrade_and_lock()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_upgrade_and_lock</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically releases upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>
                  by the current thread and acquires exclusive ownership of <code class="computeroutput"><span class="identifier">m</span></code>. If any other threads have
                  shared ownership, blocks until exclusive ownership can be acquired.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  The current thread has exclusive ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  This operation synchronizes with prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.unlock_shared" title="m.unlock_shared()"><code class="computeroutput"><span class="identifier">unlock_shared</span><span class="special">()</span></code></a><span class="special">()</span></code> and subsequent lock operations
                  that obtain ownership of the same object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock" title="m.try_unlock_upgrade_and_lock()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_upgrade_and_lock</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread shall hold an upgrade lock on the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The function attempts to atomically convert the ownership from
                  upgrade to exclusive for the calling thread without blocking. For
                  this conversion to be successful, this thread must be the only
                  thread holding any ownership of the lock. If the conversion is
                  not successful, the upgrade ownership of m is retained.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if exclusive
                  ownership was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has exclusive ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock" title="m.try_unlock_upgrade_and_lock()"><code class="computeroutput"><span class="identifier">try_unlock_upgrade_and_lock</span></code></a><span class="special">()</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span></code></a><span class="special">()</span></code>
                  and subsequent lock operations on the same object synchronize with
                  this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock_for"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock_for" title="m.try_unlock_upgrade_and_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_upgrade_and_lock_for</span><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread shall hold an upgrade lock on the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  If the tick period of <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  is not exactly convertible to the native tick period, the duration
                  shall be rounded up to the nearest native tick period. The function
                  attempts to atomically convert the ownership from upgrade to exclusive
                  for the calling thread within the relative timeout specified by
                  <code class="computeroutput"><span class="identifier">rel_time</span></code>. If the
                  time specified by <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  is less than or equal to <code class="computeroutput"><span class="identifier">rel_time</span><span class="special">.</span><span class="identifier">zero</span><span class="special">()</span></code>, the function attempts to obtain
                  exclusive ownership without blocking (as if by calling <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock" title="m.try_unlock_upgrade_and_lock()"><code class="computeroutput"><span class="identifier">try_unlock_upgrade_and_lock</span></code></a><span class="special">()</span></code>). The function shall return within
                  the timeout specified by <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  only if it has obtained exclusive ownership of the mutex object.
                  For this conversion to be successful, this thread shall be the
                  only thread holding any ownership of the lock at the moment of
                  conversion. If the conversion is not successful, the upgrade ownership
                  of m is retained.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if exclusive
                  ownership was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has exclusive ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock_for" title="m.try_unlock_upgrade_and_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_unlock_upgrade_and_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span></code></a><span class="special">()</span></code>
                  and subsequent lock operations on the same object synchronize with
                  this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock_until"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock_until" title="m.try_unlock_upgrade_and_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_unlock_upgrade_and_lock_until</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The calling thread shall hold an upgrade lock on the mutex.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The function attempts to atomically convert the ownership from
                  upgrade to exclusive for the calling thread within the absolute
                  timeout specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>.
                  If <code class="computeroutput"><span class="identifier">abs_time</span></code> has
                  already passed, the function attempts to obtain exclusive ownership
                  without blocking (as if by calling <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock" title="m.try_unlock_upgrade_and_lock()"><code class="computeroutput"><span class="identifier">try_unlock_upgrade_and_lock</span></code></a><span class="special">()</span></code>). The function shall return before
                  the absolute timeout specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>
                  only if it has obtained exclusive ownership of the mutex object.
                  For this conversion to be successful, this thread shall be the
                  only thread holding any ownership of the lock at the moment of
                  conversion. If the conversion is not successful, the upgrade ownership
                  of m is retained.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if exclusive
                  ownership was acquired for the current thread, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  If the call returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  the current thread has exclusive ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  If <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_upgrade_and_lock_for" title="m.try_unlock_upgrade_and_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_unlock_upgrade_and_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code> returns true, prior <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span></code></a><span class="special">()</span></code>
                  and subsequent lock operations on the same object synchronize with
                  this operation.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade_and_lock_shared"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade_and_lock_shared" title="m.unlock_upgrade_and_lock_shared()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock_upgrade_and_lock_shared</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The current thread has upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically releases upgrade ownership of <code class="computeroutput"><span class="identifier">m</span></code>
                  by the current thread and acquires shared ownership of <code class="computeroutput"><span class="identifier">m</span></code> without blocking.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  The current thread has shared ownership of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                  This operation synchronizes with prior <code class="computeroutput"><span class="identifier">unlock_shared</span><span class="special">()</span></code> and subsequent lock operations
                  that obtain ownership of the same object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing
                </p></dd>
</dl>
</div>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.lock_option"></a><a class="link" href="synchronization.html#thread.synchronization.lock_option" title="Lock Options">Lock Options</a>
</h3></div></div></div>
<div class="toc"><dl class="toc"><dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_option.lock_tags">Lock
        option tags</a></span></dt></dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt; </span>
<span class="comment">// #include &lt;boost/thread/locks_options.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">struct</span> <span class="identifier">defer_lock_t</span> <span class="special">{};</span>
  <span class="keyword">struct</span> <span class="identifier">try_to_lock_t</span> <span class="special">{};</span>
  <span class="keyword">struct</span> <span class="identifier">adopt_lock_t</span> <span class="special">{};</span>
  <span class="keyword">constexpr</span> <span class="identifier">defer_lock_t</span> <span class="identifier">defer_lock</span><span class="special">;</span>
  <span class="keyword">constexpr</span> <span class="identifier">try_to_lock_t</span> <span class="identifier">try_to_lock</span><span class="special">;</span>
  <span class="keyword">constexpr</span> <span class="identifier">adopt_lock_t</span> <span class="identifier">adopt_lock</span><span class="special">;</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_option.lock_tags"></a><a class="link" href="synchronization.html#thread.synchronization.lock_option.lock_tags" title="Lock option tags">Lock
        option tags</a>
</h4></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">locks</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">locks_options</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">struct</span> <span class="identifier">defer_lock_t</span> <span class="special">{};</span>
<span class="keyword">struct</span> <span class="identifier">try_to_lock_t</span> <span class="special">{};</span>
<span class="keyword">struct</span> <span class="identifier">adopt_lock_t</span> <span class="special">{};</span>
<span class="keyword">const</span> <span class="identifier">defer_lock_t</span> <span class="identifier">defer_lock</span><span class="special">;</span>
<span class="keyword">const</span> <span class="identifier">try_to_lock_t</span> <span class="identifier">try_to_lock</span><span class="special">;</span>
<span class="keyword">const</span> <span class="identifier">adopt_lock_t</span> <span class="identifier">adopt_lock</span><span class="special">;</span>
</pre>
<p>
          These tags are used in scoped locks constructors to specify a specific
          behavior.
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">defer_lock_t</span></code>: is used
              to construct the scoped lock without locking it.
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">try_to_lock_t</span></code>: is used
              to construct the scoped lock trying to lock it.
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">adopt_lock_t</span></code>: is used
              to construct the scoped lock without locking it but adopting ownership.
            </li>
</ul></div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.lock_guard"></a><a class="link" href="synchronization.html#thread.synchronization.lock_guard" title="Lock Guard">Lock Guard</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_guard.lock_guard">Class
        template <code class="computeroutput"><span class="identifier">lock_guard</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_guard.make_lock_guard">Non
        Member Function <code class="computeroutput"><span class="identifier">make_lock_guard</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_guard.make_lock_guard_adopt">Non
        Member Function <code class="computeroutput"><span class="identifier">make_lock_guard</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt; </span>
<span class="comment">// #include &lt;boost/thread/lock_guard.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">lock_guard</span>
<span class="preprocessor">#if</span> <span class="special">!</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_NO_MAKE_LOCK_GUARD</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">adopt_lock_t</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
<span class="preprocessor">#endif</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_guard.lock_guard"></a><a class="link" href="synchronization.html#thread.synchronization.lock_guard.lock_guard" title="Class template lock_guard">Class
        template <code class="computeroutput"><span class="identifier">lock_guard</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_guard.lock_guard.constructor"><code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_guard.lock_guard.constructor_adopt"><code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_guard.lock_guard.destructor"><code class="computeroutput"><span class="special">~</span><span class="identifier">lock_guard</span><span class="special">()</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt;</span>
<span class="comment">// #include &lt;boost/thread/lock_guard.hpp&gt; </span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">lock_guard</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">explicit</span> <span class="identifier">lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">);</span>
    <span class="identifier">lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">);</span>

    <span class="special">~</span><span class="identifier">lock_guard</span><span class="special">();</span>
<span class="special">};</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.lock_guard.lock_guard" title="Class template lock_guard"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span></code></a> is very simple: on
          construction it acquires ownership of the implementation of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code> concept</a> supplied as the
          constructor parameter. On destruction, the ownership is released. This
          provides simple RAII-style locking of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object, to facilitate
          exception-safe locking and unlocking. In addition, the <a class="link" href="synchronization.html#thread.synchronization.lock_guard.lock_guard.constructor_adopt" title="lock_guard(Lockable &amp; m,boost::adopt_lock_t)"><code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code>
          constructor</a> allows the <a class="link" href="synchronization.html#thread.synchronization.lock_guard.lock_guard" title="Class template lock_guard"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span></code></a> object to take ownership
          of a lock already held by the current thread.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.lock_guard.lock_guard.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.lock_guard.lock_guard.constructor" title="lock_guard(Lockable &amp; m)"><code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exception thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.lock_guard.lock_guard.constructor_adopt"></a><a class="link" href="synchronization.html#thread.synchronization.lock_guard.lock_guard.constructor_adopt" title="lock_guard(Lockable &amp; m,boost::adopt_lock_t)"><code class="computeroutput"><span class="identifier">lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The current thread owns a lock on <code class="computeroutput"><span class="identifier">m</span></code>
                  equivalent to one obtained by a call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Takes ownership of the lock state of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.lock_guard.lock_guard.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.lock_guard.lock_guard.destructor" title="~lock_guard()"><code class="computeroutput"><span class="special">~</span><span class="identifier">lock_guard</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code></a>
                  on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object passed
                  to the constructor.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_guard.make_lock_guard"></a><a class="link" href="synchronization.html#thread.synchronization.lock_guard.make_lock_guard" title="Non Member Function make_lock_guard">Non
        Member Function <code class="computeroutput"><span class="identifier">make_lock_guard</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                a lock_guard as if initialized with <code class="computeroutput"><span class="special">{</span><span class="identifier">m</span><span class="special">}</span></code>.
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                Any exception thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
              </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_guard.make_lock_guard_adopt"></a><a class="link" href="synchronization.html#thread.synchronization.lock_guard.make_lock_guard_adopt" title="Non Member Function make_lock_guard">Non
        Member Function <code class="computeroutput"><span class="identifier">make_lock_guard</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span> <span class="identifier">adopt_lock_t</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                a lock_guard as if initialized with <code class="computeroutput"><span class="special">{</span><span class="identifier">m</span><span class="special">,</span> <span class="identifier">adopt_lock</span><span class="special">}</span></code>.
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                Any exception thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
              </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.with_lock_guard"></a><a class="link" href="synchronization.html#thread.synchronization.with_lock_guard" title="With Lock Guard">With Lock Guard</a>
</h3></div></div></div>
<div class="toc"><dl class="toc"><dt><span class="section"><a href="synchronization.html#thread.synchronization.with_lock_guard.with_lock_guard">Non
        Member Function <code class="computeroutput"><span class="identifier">with_lock_guard</span></code></a></span></dt></dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/with_lock_guard.hpp&gt;</span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lockable</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Function</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Args</span><span class="special">&gt;</span>
  <span class="keyword">auto</span> <span class="identifier">with_lock_guard</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span> <span class="identifier">Function</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">,</span> <span class="identifier">Args</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span><span class="special">)</span> <span class="special">-&gt;</span> <span class="keyword">decltype</span><span class="special">(</span><span class="identifier">func</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">)...));</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.with_lock_guard.with_lock_guard"></a><a class="link" href="synchronization.html#thread.synchronization.with_lock_guard.with_lock_guard" title="Non Member Function with_lock_guard">Non
        Member Function <code class="computeroutput"><span class="identifier">with_lock_guard</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lockable</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Function</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Args</span><span class="special">&gt;</span>
<span class="keyword">auto</span> <span class="identifier">with_lock_guard</span><span class="special">(</span>
    <span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span>
    <span class="identifier">Function</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">,</span>
    <span class="identifier">Args</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span>
<span class="special">)</span> <span class="special">-&gt;</span> <span class="keyword">decltype</span><span class="special">(</span><span class="identifier">func</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">)...));</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                <code class="computeroutput"><span class="identifier">m</span></code> must be in unlocked
                state
              </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                call <code class="computeroutput"><span class="identifier">func</span></code> in scope
                locked by <code class="computeroutput"><span class="identifier">m</span></code>
              </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                Result of <code class="computeroutput"><span class="identifier">func</span><span class="special">(</span><span class="identifier">args</span><span class="special">...)</span></code>
                call
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                Any exception thrown by the call to <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span></code>
                and <code class="computeroutput"><span class="identifier">func</span><span class="special">(</span><span class="identifier">args</span><span class="special">...)</span></code>
              </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                <code class="computeroutput"><span class="identifier">m</span></code> is in unlocked
                state
              </p></dd>
<dt><span class="term">Limitations:</span></dt>
<dd><p>
                Without c++11 variadic templates support number of arguments is limited
                to <code class="computeroutput"><span class="number">4</span></code>
              </p></dd>
<dt><span class="term"></span></dt>
<dd><p>
                Without rvalue references support calling class method with <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">bind</span></code> must be const
              </p></dd>
<dt><span class="term"></span></dt>
<dd><p>
                For correct work with lambda macro <code class="computeroutput"><span class="identifier">BOOST_RESULT_OF_USE_DECLTYPE</span></code>
                may be needed to define
              </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.lock_concepts"></a><a class="link" href="synchronization.html#thread.synchronization.lock_concepts" title="Lock Concepts">Lock Concepts</a>
</h3></div></div></div>
<div class="toc"><dl class="toc"><dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_concepts.StrictLock">StrictLock
        -- EXTENSION</a></span></dt></dl></div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_concepts.StrictLock"></a><a class="link" href="synchronization.html#thread.synchronization.lock_concepts.StrictLock" title="StrictLock -- EXTENSION">StrictLock
        -- EXTENSION</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_concepts.StrictLock.mutex_type"><code class="computeroutput"><span class="identifier">L</span><span class="special">::</span><span class="identifier">mutex_type</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_concepts.StrictLock.is_strict_lock_sur_parole"><code class="computeroutput"><span class="identifier">is_strict_lock_sur_parole</span><span class="special">&lt;</span><span class="identifier">L</span><span class="special">&gt;</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_concepts.StrictLock.owns_lock"><code class="computeroutput"><span class="identifier">cl</span><span class="special">.</span><span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">m</span><span class="special">);</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_concepts.StrictLock.models">Models</a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/lock_concepts.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">StrictLock</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
          A StrictLock is a lock that ensures that the associated mutex is locked
          during the lifetime of the lock.
        </p>
<p>
          A type <code class="computeroutput"><span class="identifier">L</span></code> meets the StrictLock
          requirements if the following expressions are well-formed and have the
          specified semantics
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">L</span><span class="special">::</span><span class="identifier">mutex_type</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">is_strict_lock</span><span class="special">&lt;</span><span class="identifier">L</span><span class="special">&gt;</span></code>
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">cl</span><span class="special">.</span><span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">m</span><span class="special">);</span></code>
            </li>
</ul></div>
<p>
          and BasicLockable&lt;L::mutex_type&gt;
        </p>
<p>
          where
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              <code class="computeroutput"><span class="identifier">cl</span></code> denotes a value
              of type <code class="computeroutput"><span class="identifier">L</span> <span class="keyword">const</span><span class="special">&amp;</span></code>,
            </li>
<li class="listitem">
              <code class="computeroutput"><span class="identifier">m</span></code> denotes a value of
              type <code class="computeroutput"><span class="identifier">L</span><span class="special">::</span><span class="identifier">mutex_type</span> <span class="keyword">const</span><span class="special">*</span></code>,
            </li>
</ul></div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.lock_concepts.StrictLock.mutex_type"></a><a class="link" href="synchronization.html#thread.synchronization.lock_concepts.StrictLock.mutex_type" title="L::mutex_type"><code class="computeroutput"><span class="identifier">L</span><span class="special">::</span><span class="identifier">mutex_type</span></code></a>
</h5></div></div></div>
<p>
            The type L::mutex_type denotes the mutex that is locked by this lock.
          </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.lock_concepts.StrictLock.is_strict_lock_sur_parole"></a><a class="link" href="synchronization.html#thread.synchronization.lock_concepts.StrictLock.is_strict_lock_sur_parole" title="is_strict_lock_sur_parole&lt;L&gt;"><code class="computeroutput"><span class="identifier">is_strict_lock_sur_parole</span><span class="special">&lt;</span><span class="identifier">L</span><span class="special">&gt;</span></code></a>
</h5></div></div></div>
<p>
            As the semantic "ensures that the associated mutex is locked during
            the lifetime of the lock. " can not be described by syntactic requirements
            a <code class="computeroutput"><span class="identifier">is_strict_lock_sur_parole</span></code>
            trait must be specialized by the user defining the lock so that the following
            assertion is true:
          </p>
<pre class="programlisting"><span class="identifier">is_strict_lock_sur_parole</span><span class="special">&lt;</span><span class="identifier">L</span><span class="special">&gt;::</span><span class="identifier">value</span> <span class="special">==</span> <span class="keyword">true</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.lock_concepts.StrictLock.owns_lock"></a><a class="link" href="synchronization.html#thread.synchronization.lock_concepts.StrictLock.owns_lock" title="cl.owns_lock(m);"><code class="computeroutput"><span class="identifier">cl</span><span class="special">.</span><span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">m</span><span class="special">);</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return Type:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">bool</span></code>
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  Whether the strict lock is locking the mutex <code class="computeroutput"><span class="identifier">m</span></code>
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.lock_concepts.StrictLock.models"></a><a class="link" href="synchronization.html#thread.synchronization.lock_concepts.StrictLock.models" title="Models">Models</a>
</h5></div></div></div>
<p>
            The following classes are models of <code class="computeroutput"><span class="identifier">StrictLock</span></code>:
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
                strict_lock: ensured by construction,
              </li>
<li class="listitem">
                nested_strict_lock: "sur parole" as the user could use
                adopt_lock_t on unique_lock constructor overload without having locked
                the mutex,
              </li>
<li class="listitem">
                <a class="link" href="synchronization.html#thread.synchronization.lock_guard.lock_guard" title="Class template lock_guard"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span></code></a>: "sur parole"
                as the user could use adopt_lock_t constructor overload without having
                locked the mutex.
              </li>
</ul></div>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.locks"></a><a class="link" href="synchronization.html#thread.synchronization.locks" title="Lock Types">Lock Types</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock">Class template
        <code class="computeroutput"><span class="identifier">unique_lock</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock">Class template
        <code class="computeroutput"><span class="identifier">shared_lock</span></code> - C++14</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.upgrade_lock">Class template
        <code class="computeroutput"><span class="identifier">upgrade_lock</span></code> - EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.upgrade_to_unique_lock">Class
        template <code class="computeroutput"><span class="identifier">upgrade_to_unique_lock</span></code>
        -- EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.scoped_try_lock">Mutex-specific
        class <code class="computeroutput"><span class="identifier">scoped_try_lock</span></code> --
        DEPRECATED</a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt; </span>
<span class="comment">// #include &lt;boost/thread/lock_types.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">unique_lock</span><span class="special">;</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Mutex</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">unique_lock</span> <span class="special">&lt;</span><span class="identifier">Mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lhs</span><span class="special">,</span> <span class="identifier">unique_lock</span> <span class="special">&lt;</span><span class="identifier">Mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">shared_lock</span><span class="special">;</span> <span class="comment">// C++14</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Mutex</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">Mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lhs</span><span class="special">,</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">Mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">rhs</span><span class="special">);</span> <span class="comment">// C++14</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">upgrade_lock</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Mutex</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">upgrade_lock</span> <span class="special">&lt;</span><span class="identifier">Mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lhs</span><span class="special">,</span> <span class="identifier">upgrade_lock</span> <span class="special">&lt;</span><span class="identifier">Mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">rhs</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Mutex</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">upgrade_to_unique_lock</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.locks.unique_lock"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock">Class template
        <code class="computeroutput"><span class="identifier">unique_lock</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.defaultconstructor"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.constructor"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_adopt"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_defer"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">defer_lock_t</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_try"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">try_to_lock_t</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_sh_try"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;</span>
          <span class="identifier">sl</span><span class="special">,</span>
          <span class="identifier">try_to_lock_t</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_sh_until"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_sh_for"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_abs_time"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_time_point"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
          <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_duration"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
          <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.destructor"><code class="computeroutput"><span class="special">~</span><span class="identifier">unique_lock</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock"><code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">()</span> <span class="keyword">const</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.mutex"><code class="computeroutput"><span class="identifier">Lockable</span><span class="special">*</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.explicit_bool_conversion"><code class="computeroutput"><span class="keyword">explicit</span> <span class="keyword">operator</span>
          <span class="keyword">bool</span><span class="special">()</span>
          <span class="keyword">const</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.unique_lock.release"><code class="computeroutput"><span class="identifier">Lockable</span><span class="special">*</span> <span class="identifier">release</span><span class="special">()</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt;</span>
<span class="comment">// #include &lt;boost/thread/lock_types.hpp&gt; </span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">unique_lock</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span> <span class="identifier">Lockable</span> <span class="identifier">mutex_type</span><span class="special">;</span>
    <span class="identifier">unique_lock</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
    <span class="keyword">explicit</span> <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">);</span>
    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">adopt_lock_t</span><span class="special">);</span>
    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">defer_lock_t</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">try_to_lock_t</span><span class="special">);</span>

<span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span>
    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">sl</span><span class="special">,</span> <span class="identifier">try_to_lock_t</span><span class="special">);</span> <span class="comment">// C++14 </span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">sl</span><span class="special">,</span>
                <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span> <span class="comment">// C++14</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">sl</span><span class="special">,</span>
                <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span> <span class="comment">// C++14</span>
<span class="preprocessor">#endif</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Mutex</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">t</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Mutex</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">d</span><span class="special">);</span>
    <span class="special">~</span><span class="identifier">unique_lock</span><span class="special">();</span>

    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">unique_lock</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">unique_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">unique_lock</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
    <span class="keyword">explicit</span> <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">upgrade_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span> <span class="comment">// EXTENSION</span>

    <span class="identifier">unique_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>

    <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">unique_lock</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
    <span class="identifier">Lockable</span><span class="special">*</span> <span class="identifier">release</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>

    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>

    <span class="keyword">explicit</span> <span class="keyword">operator</span> <span class="keyword">bool</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>

    <span class="identifier">mutex_type</span><span class="special">*</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>

<span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_USE_DATE_TIME</span> <span class="special">||</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_DONT_USE_CHRONO</span>
    <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">target_time</span><span class="special">);</span>
    <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">TimeDuration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">TimeDuration</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">relative_time</span><span class="special">);</span>
    <span class="keyword">bool</span> <span class="identifier">timed_lock</span><span class="special">(::</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">absolute_time</span><span class="special">);</span>
<span class="preprocessor">#endif</span>

<span class="special">};</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a> is more complex than
          <a class="link" href="synchronization.html#thread.synchronization.lock_guard.lock_guard" title="Class template lock_guard"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span></code></a>: not only does it provide
          for RAII-style locking, it also allows for deferring acquiring the lock
          until the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>
          member function is called explicitly, or trying to acquire the lock in
          a non-blocking fashion, or with a timeout. Consequently, <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>
          is only called in the destructor if the lock object has locked the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object, or otherwise
          adopted a lock on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object.
        </p>
<p>
          Specializations of <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a> model the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable" title="TimedLockable Concept"><code class="computeroutput"><span class="identifier">TimedLockable</span></code></a> concept if the supplied
          <code class="computeroutput"><span class="identifier">Lockable</span></code> type itself models
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable" title="TimedLockable Concept"><code class="computeroutput"><span class="identifier">TimedLockable</span></code></a> concept (e.g. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">timed_mutex</span><span class="special">&gt;</span></code>),
          or the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> concept if the supplied
          <code class="computeroutput"><span class="identifier">Lockable</span></code> type itself models
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> concept (e.g. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span></code>),
          or the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable" title="BasicLockable Concept"><code class="computeroutput"><span class="identifier">BasicLockable</span></code></a> concept if the supplied
          <code class="computeroutput"><span class="identifier">Lockable</span></code> type itself models
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable" title="BasicLockable Concept"><code class="computeroutput"><span class="identifier">BasicLockable</span></code></a> concept.
        </p>
<p>
          An instance of <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a> is said to <span class="emphasis"><em>own</em></span>
          the lock state of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> <code class="computeroutput"><span class="identifier">m</span></code>
          if <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
          returns a pointer to <code class="computeroutput"><span class="identifier">m</span></code>
          and <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
          returns <code class="computeroutput"><span class="keyword">true</span></code>. If an object
          that <span class="emphasis"><em>owns</em></span> the lock state of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object is destroyed,
          then the destructor will invoke <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()-&gt;</span><span class="identifier">unlock</span><span class="special">()</span></code></a>.
        </p>
<p>
          The member functions of <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a> are not thread-safe.
          In particular, <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a> is intended to model
          the ownership of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object by a particular
          thread, and the member functions that release ownership of the lock state
          (including the destructor) must be called by the same thread that acquired
          ownership of the lock state.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.defaultconstructor"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.defaultconstructor" title="unique_lock()"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Creates a lock object with no associated mutex.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>. <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="identifier">NULL</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.constructor" title="unique_lock(Lockable &amp; m)"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>. <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exception thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.constructor_adopt"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_adopt" title="unique_lock(Lockable &amp; m,boost::adopt_lock_t)"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The current thread owns an exclusive lock on <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Takes ownership of the lock state of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>. <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.constructor_defer"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_defer" title="unique_lock(Lockable &amp; m,boost::defer_lock_t)"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">defer_lock_t</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>. <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.constructor_try"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_try" title="unique_lock(Lockable &amp; m,boost::try_to_lock_t)"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">try_to_lock_t</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock</span><span class="special">()</span></code></a>,
                  and takes ownership of the lock state if the call returns <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                  If the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                  returned <code class="computeroutput"><span class="keyword">true</span></code>, then
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>, otherwise
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.constructor_sh_try"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_sh_try" title="unique_lock(shared_lock&lt;mutex_type&gt;&amp;&amp; sl, try_to_lock_t)"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;</span>
          <span class="identifier">sl</span><span class="special">,</span>
          <span class="identifier">try_to_lock_t</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The supplied <code class="computeroutput"><span class="identifier">Mutex</span></code>
                  type must implement <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock" title="m.try_unlock_shared_and_lock()"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock</span></code></a><span class="special">()</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Constructs an object of type <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a>. Let <code class="computeroutput"><span class="identifier">pm</span></code> be the pointer to the mutex
                  and <code class="computeroutput"><span class="identifier">owns</span></code> the ownership
                  state. Initializes <code class="computeroutput"><span class="identifier">pm</span></code>
                  with nullptr and <code class="computeroutput"><span class="identifier">owns</span></code>
                  with false. If <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span> <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a><span class="special">()</span></code> returns <code class="computeroutput"><span class="keyword">false</span></code>,
                  sets <code class="computeroutput"><span class="identifier">pm</span></code> to the
                  return value of <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">release</span><span class="special">()</span></code>. Else <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span> <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a><span class="special">()</span></code> returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  and in this case if <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">()-&gt;</span><span class="identifier">try_unlock_shared_and_lock</span><span class="special">()</span></code> returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  sets <code class="computeroutput"><span class="identifier">pm</span></code> to the
                  value returned by <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">release</span><span class="special">()</span></code> and sets <code class="computeroutput"><span class="identifier">owns</span></code>
                  to <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Note:</span></dt>
<dd><p>
                  If <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">owns_lock</span><span class="special">()</span></code>
                  returns <code class="computeroutput"><span class="keyword">true</span></code> and
                  <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">()-&gt;</span><span class="identifier">try_unlock_shared_and_lock</span><span class="special">()</span></code>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>, <code class="computeroutput"><span class="identifier">sl</span></code> is not modified.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span></code>
                  and <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.constructor_sh_until"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_sh_until" title="unique_lock(shared_lock&lt;mutex_type&gt;&amp;&amp;, const chrono::time_point&lt;Clock, Duration&gt;&amp;)"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;)</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
<span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">sl</span><span class="special">,</span>
            <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The supplied <code class="computeroutput"><span class="identifier">Mutex</span></code>
                  type shall implement <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_until" title="m.try_unlock_shared_and_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Constructs an object of type <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a></code>, initializing
                  <code class="computeroutput"><span class="identifier">pm</span></code> with <code class="computeroutput"><span class="keyword">nullptr</span></code> and <code class="computeroutput"><span class="identifier">owns</span></code>
                  with <code class="computeroutput"><span class="keyword">false</span></code>. If <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a><span class="special">()</span></code> returns <code class="computeroutput"><span class="keyword">false</span></code>,
                  sets <code class="computeroutput"><span class="identifier">pm</span></code> to the
                  return value of <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">release</span><span class="special">()</span></code>. Else <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span> <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a><span class="special">()</span></code> returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  and in this case if <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">()-&gt;</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_until" title="m.try_unlock_shared_and_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code> returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  sets <code class="computeroutput"><span class="identifier">pm</span></code> to the
                  value returned by <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">release</span><span class="special">()</span></code> and sets <code class="computeroutput"><span class="identifier">owns</span></code>
                  to <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Note:</span></dt>
<dd><p>
                  If <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">owns_lock</span><span class="special">()</span></code>
                  returns <code class="computeroutput"><span class="keyword">true</span></code> and
                  <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">()-&gt;</span>
                  <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_until" title="m.try_unlock_shared_and_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code> returns <code class="computeroutput"><span class="keyword">false</span></code>,
                  <code class="computeroutput"><span class="identifier">sl</span></code> is not modified.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span></code>
                  and <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.constructor_sh_for"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_sh_for" title="unique_lock(shared_lock&lt;mutex_type&gt;&amp;&amp;, const chrono::duration&lt;Rep, Period&gt;&amp;)"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;)</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
<span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">sl</span><span class="special">,</span>
            <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The supplied <code class="computeroutput"><span class="identifier">Mutex</span></code>
                  type shall implement <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_for" title="m.try_unlock_shared_and_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Constructs an object of type <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a></code>, initializing
                  <code class="computeroutput"><span class="identifier">pm</span></code> with <code class="computeroutput"><span class="keyword">nullptr</span></code> and <code class="computeroutput"><span class="identifier">owns</span></code>
                  with <code class="computeroutput"><span class="keyword">false</span></code>. If <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a><span class="special">()</span></code> returns <code class="computeroutput"><span class="keyword">false</span></code>,
                  sets <code class="computeroutput"><span class="identifier">pm</span></code> to the
                  return value of <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">release</span><span class="special">()</span></code>. Else <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">owns_lock</span><span class="special">()</span></code> returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  and in this case if <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">()-&gt;</span> <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_for" title="m.try_unlock_shared_and_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code> returns <code class="computeroutput"><span class="keyword">true</span></code>,
                  sets <code class="computeroutput"><span class="identifier">pm</span></code> to the
                  value returned by <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">release</span><span class="special">()</span></code> and sets <code class="computeroutput"><span class="identifier">owns</span></code>
                  to <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Note:</span></dt>
<dd><p>
                  If <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">owns_lock</span><span class="special">()</span></code>
                  returns <code class="computeroutput"><span class="keyword">true</span></code> and
                  <code class="computeroutput"><span class="identifier">sl</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">()-&gt;</span>
                  <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.try_unlock_shared_and_lock_for" title="m.try_unlock_shared_and_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_unlock_shared_and_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code> returns <code class="computeroutput"><span class="keyword">false</span></code>,
                  <code class="computeroutput"><span class="identifier">sl</span></code> is not modified.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  .
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  Available only if <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span></code>
                  and <code class="computeroutput"><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span></code>
                  is defined on Windows platform
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.constructor_abs_time"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_abs_time" title="unique_lock(Lockable &amp; m,boost::system_time const&amp; abs_time)"><code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>,
                  and takes ownership of the lock state if the call returns <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                  If the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">()</span></code></a>
                  returned <code class="computeroutput"><span class="keyword">true</span></code>, then
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>, otherwise
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exceptions thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.constructor_time_point"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_time_point" title="template &lt;class Clock, class Duration&gt; unique_lock(Lockable &amp; m,const chrono::time_point&lt;Clock, Duration&gt;&amp; abs_time)"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
          <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until" title="m.try_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code>, and takes ownership of the lock
                  state if the call returns <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                  If the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until" title="m.try_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_until</span></code></a> returned
                  <code class="computeroutput"><span class="keyword">true</span></code>, then <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>, otherwise
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exceptions thrown by the call to <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until" title="m.try_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_until</span></code></a><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.constructor_duration"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.constructor_duration" title="template &lt;class Rep, class Period&gt; unique_lock(Lockable &amp; m,const chrono::duration&lt;Rep, Period&gt;&amp; abs_time)"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
          <span class="identifier">unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_for" title="m.try_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code>,
                  and takes ownership of the lock state if the call returns <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                  If the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_for" title="m.try_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_for</span></code></a> returned
                  <code class="computeroutput"><span class="keyword">true</span></code>, then <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>, otherwise
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exceptions thrown by the call to <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_for" title="m.try_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_for</span></code></a><span class="special">(</span><span class="identifier">rel_time</span><span class="special">)</span></code>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.destructor" title="~unique_lock()"><code class="computeroutput"><span class="special">~</span><span class="identifier">unique_lock</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Invokes <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a><code class="computeroutput"><span class="special">-&gt;</span></code> <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>
                  if <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.owns_lock"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">()</span> <span class="keyword">const</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if the <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  owns the lock on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object associated
                  with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.mutex"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">Lockable</span><span class="special">*</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  A pointer to the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object associated
                  with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                  or <code class="computeroutput"><span class="identifier">NULL</span></code> if there
                  is no such object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.explicit_bool_conversion"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.explicit_bool_conversion" title="explicit operator bool() const"><code class="computeroutput"><span class="keyword">explicit</span> <span class="keyword">operator</span>
          <span class="keyword">bool</span><span class="special">()</span>
          <span class="keyword">const</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a><span class="special">()</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.unique_lock.release"></a><a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.release" title="Lockable* release()"><code class="computeroutput"><span class="identifier">Lockable</span><span class="special">*</span> <span class="identifier">release</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The association between <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> and the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object is removed,
                  without affecting the lock state of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object. If <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  would have returned <code class="computeroutput"><span class="keyword">true</span></code>,
                  it is the responsibility of the calling code to ensure that the
                  <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> is correctly
                  unlocked.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  A pointer to the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object associated
                  with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  at the point of the call, or <code class="computeroutput"><span class="identifier">NULL</span></code>
                  if there is no such object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  is no longer associated with any <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object. <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="identifier">NULL</span></code> and
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.locks.shared_lock"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock" title="Class template shared_lock - C++14">Class template
        <code class="computeroutput"><span class="identifier">shared_lock</span></code> - C++14</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.defaultconstructor"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.constructor"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.constructor_adopt"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.constructor_defer"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">defer_lock_t</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.constructor_try"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">try_to_lock_t</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.constructor_abs_time"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.destructor"><code class="computeroutput"><span class="special">~</span><span class="identifier">shared_lock</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock"><code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">()</span> <span class="keyword">const</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.mutex"><code class="computeroutput"><span class="identifier">Lockable</span><span class="special">*</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.explicit_operator_bool"><code class="computeroutput"><span class="keyword">explicit</span> <span class="keyword">operator</span>
          <span class="keyword">bool</span><span class="special">()</span>
          <span class="keyword">const</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.locks.shared_lock.release"><code class="computeroutput"><span class="identifier">Lockable</span><span class="special">*</span> <span class="identifier">release</span><span class="special">()</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt;</span>
<span class="comment">// #include &lt;boost/thread/lock_types.hpp&gt; </span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">shared_lock</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span> <span class="identifier">Lockable</span> <span class="identifier">mutex_type</span><span class="special">;</span>

    <span class="comment">// Shared locking</span>
    <span class="identifier">shared_lock</span><span class="special">();</span>
    <span class="keyword">explicit</span> <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">);</span>
    <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">adopt_lock_t</span><span class="special">);</span>
    <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">defer_lock_t</span><span class="special">);</span>
    <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">try_to_lock_t</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Mutex</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">t</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Mutex</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">d</span><span class="special">);</span>
    <span class="special">~</span><span class="identifier">shared_lock</span><span class="special">();</span>

    <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">shared_lock</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">shared_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">shared_lock</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
    <span class="identifier">shared_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>

    <span class="comment">// Conversion from upgrade locking</span>
    <span class="keyword">explicit</span> <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">upgrade_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

    <span class="comment">// Conversion from exclusive locking</span>
    <span class="keyword">explicit</span> <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>

    <span class="comment">// Setters</span>
    <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">);</span>
    <span class="identifier">mutex_type</span><span class="special">*</span> <span class="identifier">release</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>

    <span class="comment">// Getters</span>
    <span class="keyword">explicit</span> <span class="keyword">operator</span> <span class="keyword">bool</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
    <span class="identifier">mutex_type</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>

<span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_USE_DATE_TIME</span> <span class="special">||</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_DONT_USE_CHRONO</span>
    <span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">target_time</span><span class="special">);</span>
    <span class="keyword">bool</span> <span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">target_time</span><span class="special">);</span>
<span class="preprocessor">#endif</span>
<span class="special">};</span>
</pre>
<p>
          Like <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a>, <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock" title="Class template shared_lock - C++14"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_lock</span></code></a> models the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code> concept</a>, but rather than
          acquiring unique ownership of the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object, locking an instance
          of <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock" title="Class template shared_lock - C++14"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_lock</span></code></a> acquires shared ownership.
        </p>
<p>
          Like <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a>, not only does it
          provide for RAII-style locking, it also allows for deferring acquiring
          the lock until the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>
          member function is called explicitly, or trying to acquire the lock in
          a non-blocking fashion, or with a timeout. Consequently, <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>
          is only called in the destructor if the lock object has locked the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object, or otherwise
          adopted a lock on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object.
        </p>
<p>
          An instance of <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock" title="Class template shared_lock - C++14"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_lock</span></code></a> is said to <span class="emphasis"><em>own</em></span>
          the lock state of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> <code class="computeroutput"><span class="identifier">m</span></code>
          if <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
          returns a pointer to <code class="computeroutput"><span class="identifier">m</span></code>
          and <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
          returns <code class="computeroutput"><span class="keyword">true</span></code>. If an object
          that <span class="emphasis"><em>owns</em></span> the lock state of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object is destroyed,
          then the destructor will invoke <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.unlock_shared" title="m.unlock_shared()"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()-&gt;</span><span class="identifier">unlock_shared</span><span class="special">()</span></code></a>.
        </p>
<p>
          The member functions of <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock" title="Class template shared_lock - C++14"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_lock</span></code></a> are not thread-safe.
          In particular, <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock" title="Class template shared_lock - C++14"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_lock</span></code></a> is intended to model
          the shared ownership of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object by a particular
          thread, and the member functions that release ownership of the lock state
          (including the destructor) must be called by the same thread that acquired
          ownership of the lock state.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.defaultconstructor"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.defaultconstructor" title="shared_lock()"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Creates a lock object with no associated mutex.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>. <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="identifier">NULL</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.constructor" title="shared_lock(Lockable &amp; m)"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared" title="m.lock_shared()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock_shared</span><span class="special">()</span></code></a>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>. <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exception thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared" title="m.lock_shared()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock_shared</span><span class="special">()</span></code></a>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.constructor_adopt"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.constructor_adopt" title="shared_lock(Lockable &amp; m,boost::adopt_lock_t)"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The current thread owns an exclusive lock on <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Takes ownership of the lock state of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>. <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.constructor_defer"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.constructor_defer" title="shared_lock(Lockable &amp; m,boost::defer_lock_t)"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">defer_lock_t</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>. <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.constructor_try"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.constructor_try" title="shared_lock(Lockable &amp; m,boost::try_to_lock_t)"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">try_to_lock_t</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared" title="m.try_lock_shared()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock_shared</span><span class="special">()</span></code></a>,
                  and takes ownership of the lock state if the call returns <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                  If the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared" title="m.try_lock_shared()"><code class="computeroutput"><span class="identifier">try_lock_shared</span><span class="special">()</span></code></a>
                  returned <code class="computeroutput"><span class="keyword">true</span></code>, then
                  <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>, otherwise
                  <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.constructor_abs_time"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.constructor_abs_time" title="shared_lock(Lockable &amp; m,boost::system_time const&amp; abs_time)"><code class="computeroutput"><span class="identifier">shared_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.timed_lock_shared" title="m.timed_lock_shared(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>,
                  and takes ownership of the lock state if the call returns <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="special">&amp;</span><span class="identifier">m</span></code>.
                  If the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.timed_lock_shared" title="m.timed_lock_shared(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock_shared</span><span class="special">()</span></code></a>
                  returned <code class="computeroutput"><span class="keyword">true</span></code>, then
                  <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>, otherwise
                  <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exceptions thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.timed_lock_shared" title="m.timed_lock_shared(abs_time)"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">abs_time</span><span class="special">)</span></code></a>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.destructor" title="~shared_lock()"><code class="computeroutput"><span class="special">~</span><span class="identifier">shared_lock</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Invokes <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a><code class="computeroutput"><span class="special">-&gt;</span></code> <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.unlock_shared" title="m.unlock_shared()"><code class="computeroutput"><span class="identifier">unlock_shared</span><span class="special">()</span></code></a>
                  if <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">true</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.owns_lock"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">()</span> <span class="keyword">const</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> if the <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  owns the lock on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object associated
                  with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.mutex"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.mutex" title="Lockable* mutex() const"><code class="computeroutput"><span class="identifier">Lockable</span><span class="special">*</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  A pointer to the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object associated
                  with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                  or <code class="computeroutput"><span class="identifier">NULL</span></code> if there
                  is no such object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.explicit_operator_bool"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.explicit_operator_bool" title="explicit operator bool() const"><code class="computeroutput"><span class="keyword">explicit</span> <span class="keyword">operator</span>
          <span class="keyword">bool</span><span class="special">()</span>
          <span class="keyword">const</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.locks.shared_lock.release"></a><a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.release" title="Lockable* release()"><code class="computeroutput"><span class="identifier">Lockable</span><span class="special">*</span> <span class="identifier">release</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The association between <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> and the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object is removed,
                  without affecting the lock state of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object. If <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  would have returned <code class="computeroutput"><span class="keyword">true</span></code>,
                  it is the responsibility of the calling code to ensure that the
                  <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> is correctly
                  unlocked.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  A pointer to the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object associated
                  with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  at the point of the call, or <code class="computeroutput"><span class="identifier">NULL</span></code>
                  if there is no such object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  is no longer associated with any <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object. <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="identifier">NULL</span></code> and
                  <a class="link" href="synchronization.html#thread.synchronization.locks.shared_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
                  returns <code class="computeroutput"><span class="keyword">false</span></code>.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.locks.upgrade_lock"></a><a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_lock" title="Class template upgrade_lock - EXTENSION">Class template
        <code class="computeroutput"><span class="identifier">upgrade_lock</span></code> - EXTENSION</a>
</h4></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt;</span>
<span class="comment">// #include &lt;boost/thread/lock_types.hpp&gt; </span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">upgrade_lock</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span> <span class="identifier">Lockable</span> <span class="identifier">mutex_type</span><span class="special">;</span>

    <span class="comment">// Upgrade locking</span>

    <span class="identifier">upgrade_lock</span><span class="special">();</span>
    <span class="keyword">explicit</span> <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">);</span>
    <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span> <span class="identifier">defer_lock_t</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
    <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span> <span class="identifier">try_to_lock_t</span><span class="special">);</span>
    <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span> <span class="identifier">adopt_lock_t</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span>
                 <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span>
                 <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="special">~</span><span class="identifier">upgrade_lock</span><span class="special">();</span>

    <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">upgrade_lock</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">upgrade_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="keyword">const</span> <span class="identifier">upgrade_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">upgrade_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
    <span class="identifier">upgrade_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">upgrade_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>

<span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSION</span>
   <span class="comment">// Conversion from shared locking</span>
    <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">sl</span><span class="special">,</span> <span class="identifier">try_to_lock_t</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">sl</span><span class="special">,</span>
                   <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">shared_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">sl</span><span class="special">,</span>
                   <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
<span class="preprocessor">#endif</span>

    <span class="comment">// Conversion from exclusive locking</span>
    <span class="keyword">explicit</span> <span class="identifier">upgrade_lock</span><span class="special">(</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>

    <span class="comment">// Setters</span>
    <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">upgrade_lock</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">);</span>
    <span class="identifier">mutex_type</span><span class="special">*</span> <span class="identifier">release</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>

    <span class="comment">// Getters</span>
    <span class="keyword">explicit</span> <span class="keyword">operator</span> <span class="keyword">bool</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
    <span class="identifier">mutex_type</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
          Like <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a>, <a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_lock" title="Class template upgrade_lock - EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">upgrade_lock</span></code></a> models the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code> concept</a>, but rather than
          acquiring unique ownership of the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object, locking an instance
          of <a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_lock" title="Class template upgrade_lock - EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">upgrade_lock</span></code></a> acquires upgrade
          ownership.
        </p>
<p>
          Like <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a>, not only does it
          provide for RAII-style locking, it also allows for deferring acquiring
          the lock until the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>
          member function is called explicitly, or trying to acquire the lock in
          a non-blocking fashion, or with a timeout. Consequently, <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>
          is only called in the destructor if the lock object has locked the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object, or otherwise
          adopted a lock on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object.
        </p>
<p>
          An instance of <a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_lock" title="Class template upgrade_lock - EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">upgrade_lock</span></code></a> is said to <span class="emphasis"><em>own</em></span>
          the lock state of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> <code class="computeroutput"><span class="identifier">m</span></code>
          if <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.mutex" title="Lockable* mutex() const noexcept"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code></a>
          returns a pointer to <code class="computeroutput"><span class="identifier">m</span></code>
          and <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a>
          returns <code class="computeroutput"><span class="keyword">true</span></code>. If an object
          that <span class="emphasis"><em>owns</em></span> the lock state of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object is destroyed,
          then the destructor will invoke <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable.unlock_upgrade" title="m.unlock_upgrade()"><code class="computeroutput"><span class="identifier">mutex</span><span class="special">()-&gt;</span><span class="identifier">unlock_upgrade</span><span class="special">()</span></code></a>.
        </p>
<p>
          The member functions of <a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_lock" title="Class template upgrade_lock - EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">upgrade_lock</span></code></a> are not thread-safe.
          In particular, <a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_lock" title="Class template upgrade_lock - EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">upgrade_lock</span></code></a> is intended to model
          the upgrade ownership of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable" title="UpgradeLockable Concept -- EXTENSION"><code class="computeroutput"><span class="identifier">UpgradeLockable</span></code></a> object by a particular
          thread, and the member functions that release ownership of the lock state
          (including the destructor) must be called by the same thread that acquired
          ownership of the lock state.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.locks.upgrade_to_unique_lock"></a><a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_to_unique_lock" title="Class template upgrade_to_unique_lock -- EXTENSION">Class
        template <code class="computeroutput"><span class="identifier">upgrade_to_unique_lock</span></code>
        -- EXTENSION</a>
</h4></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt;</span>
<span class="comment">// #include &lt;boost/thread/lock_types.hpp&gt; </span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">upgrade_to_unique_lock</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span> <span class="identifier">Lockable</span> <span class="identifier">mutex_type</span><span class="special">;</span>
    <span class="keyword">explicit</span> <span class="identifier">upgrade_to_unique_lock</span><span class="special">(</span><span class="identifier">upgrade_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;&amp;</span> <span class="identifier">m_</span><span class="special">);</span>
    <span class="special">~</span><span class="identifier">upgrade_to_unique_lock</span><span class="special">();</span>

    <span class="identifier">upgrade_to_unique_lock</span><span class="special">(</span><span class="identifier">upgrade_to_unique_lock</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">upgrade_to_unique_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">upgrade_to_unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">upgrade_to_unique_lock</span><span class="special">(</span><span class="identifier">upgrade_to_unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
    <span class="identifier">upgrade_to_unique_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">upgrade_to_unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>

    <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">upgrade_to_unique_lock</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">);</span>

    <span class="keyword">explicit</span> <span class="keyword">operator</span> <span class="keyword">bool</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
    <span class="identifier">mutex_type</span><span class="special">*</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>

<span class="special">};</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_to_unique_lock" title="Class template upgrade_to_unique_lock -- EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">upgrade_to_unique_lock</span></code></a> allows
          for a temporary upgrade of an <a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_lock" title="Class template upgrade_lock - EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">upgrade_lock</span></code></a> to exclusive ownership.
          When constructed with a reference to an instance of <a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_lock" title="Class template upgrade_lock - EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">upgrade_lock</span></code></a>, if that instance
          has upgrade ownership on some <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object, that ownership
          is upgraded to exclusive ownership. When the <a class="link" href="synchronization.html#thread.synchronization.locks.upgrade_to_unique_lock" title="Class template upgrade_to_unique_lock -- EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">upgrade_to_unique_lock</span></code></a> instance
          is destroyed, the ownership of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> is downgraded back to
          <span class="emphasis"><em>upgrade ownership</em></span>.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.locks.scoped_try_lock"></a><a class="link" href="synchronization.html#thread.synchronization.locks.scoped_try_lock" title="Mutex-specific class scoped_try_lock -- DEPRECATED">Mutex-specific
        class <code class="computeroutput"><span class="identifier">scoped_try_lock</span></code> --
        DEPRECATED</a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span>
<span class="special">{</span>
<span class="keyword">private</span><span class="special">:</span>
    <span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">(</span><span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">&lt;</span><span class="identifier">MutexType</span><span class="special">&gt;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
    <span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">&lt;</span><span class="identifier">MutexType</span><span class="special">&gt;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">();</span>
    <span class="keyword">explicit</span> <span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">(</span><span class="identifier">MutexType</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">);</span>
    <span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">(</span><span class="identifier">MutexType</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">adopt_lock_t</span><span class="special">);</span>
    <span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">(</span><span class="identifier">MutexType</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">defer_lock_t</span><span class="special">);</span>
    <span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">(</span><span class="identifier">MutexType</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">try_to_lock_t</span><span class="special">);</span>

    <span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">(</span><span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">&lt;</span><span class="identifier">MutexType</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
    <span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">&lt;</span><span class="identifier">MutexType</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>

    <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">MutexType</span><span class="special">::</span><span class="identifier">scoped_try_lock</span><span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>

    <span class="identifier">MutexType</span><span class="special">*</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
    <span class="identifier">MutexType</span><span class="special">*</span> <span class="identifier">release</span><span class="special">();</span>

    <span class="keyword">explicit</span> <span class="keyword">operator</span> <span class="keyword">bool</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
          The member typedef <code class="computeroutput"><span class="identifier">scoped_try_lock</span></code>
          is provided for each distinct <code class="computeroutput"><span class="identifier">MutexType</span></code>
          as a typedef to a class with the preceding definition. The semantics of
          each constructor and member function are identical to those of <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">MutexType</span><span class="special">&gt;</span></code></a>
          for the same <code class="computeroutput"><span class="identifier">MutexType</span></code>,
          except that the constructor that takes a single reference to a mutex will
          call <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">try_lock</span><span class="special">()</span></code></a> rather than <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code>.
        </p>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.other_locks"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks" title="Other Lock Types - EXTENSION">Other Lock Types
      - EXTENSION</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.strict_locks">Strict
        Locks</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.lock_ptrs">Locking
        pointers</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.externally_locked">Externally
        Locked</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard">Class
        template <code class="computeroutput"><span class="identifier">shared_lock_guard</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.reverse_lock">Class
        template <code class="computeroutput"><span class="identifier">reverse_lock</span></code></a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.other_locks.strict_locks"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks" title="Strict Locks">Strict
        Locks</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.strict_locks.strict_lock">Class
          template <code class="computeroutput"><span class="identifier">strict_lock</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.strict_locks.nested_strict_lock">Class
          template <code class="computeroutput"><span class="identifier">nested_strict_lock</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.strict_locks.make_strict_lock">Non
          Member Function <code class="computeroutput"><span class="identifier">make_strict_lock</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.strict_locks.make_nested_strict_lock">Non
          Member Function <code class="computeroutput"><span class="identifier">make_nested_strict_lock</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt; </span>
<span class="comment">// #include &lt;boost/thread/strict_lock.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">strict_lock</span><span class="special">;</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">nested_strict_lock</span><span class="special">;</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="keyword">struct</span> <span class="identifier">is_strict_lock_sur_parole</span><span class="special">&lt;</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">&gt;;</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="keyword">struct</span> <span class="identifier">is_strict_lock_sur_parole</span><span class="special">&lt;</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;</span> <span class="special">&gt;;</span>

<span class="preprocessor">#if</span> <span class="special">!</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_NO_MAKE_STRICT_LOCK</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_strict_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">);</span>
<span class="preprocessor">#endif</span>
<span class="preprocessor">#if</span> <span class="special">!</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_NO_MAKE_NESTED_STRICT_LOCK</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;</span> <span class="identifier">make_nested_strict_lock</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
<span class="preprocessor">#endif</span>

<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.strict_locks.strict_lock"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.strict_lock" title="Class template strict_lock">Class
          template <code class="computeroutput"><span class="identifier">strict_lock</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt;</span>
<span class="comment">// #include &lt;boost/thread/strict_lock.hpp&gt; </span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">BasicLockable</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">strict_lock</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span> <span class="identifier">BasicLockable</span> <span class="identifier">mutex_type</span><span class="special">;</span>
    <span class="identifier">strict_lock</span><span class="special">(</span><span class="identifier">strict_lock</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">strict_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">strict_lock</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="keyword">explicit</span> <span class="identifier">strict_lock</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">);</span>
    <span class="special">~</span><span class="identifier">strict_lock</span><span class="special">();</span>

    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">mutex_type</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">l</span><span class="special">)</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
            <a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.strict_lock" title="Class template strict_lock"><code class="computeroutput"><span class="identifier">strict_lock</span></code></a> is a model of <a class="link" href="synchronization.html#thread.synchronization.lock_concepts.StrictLock" title="StrictLock -- EXTENSION"><code class="computeroutput"><span class="identifier">StrictLock</span></code></a>.
          </p>
<p>
            <a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.strict_lock" title="Class template strict_lock"><code class="computeroutput"><span class="identifier">strict_lock</span></code></a> is the simplest
            <a class="link" href="synchronization.html#thread.synchronization.lock_concepts.StrictLock" title="StrictLock -- EXTENSION"><code class="computeroutput"><span class="identifier">StrictLock</span></code></a>: on construction
            it acquires ownership of the implementation of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable" title="BasicLockable Concept"><code class="computeroutput"><span class="identifier">BasicLockable</span></code></a> concept supplied
            as the constructor parameter. On destruction, the ownership is released.
            This provides simple RAII-style locking of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable" title="BasicLockable Concept"><code class="computeroutput"><span class="identifier">BasicLockable</span></code></a> object, to facilitate
            exception-safe locking and unlocking.
          </p>
<h6>
<a name="thread.synchronization.other_locks.strict_locks.strict_lock.h0"></a>
            <span class="phrase"><a name="thread.synchronization.other_locks.strict_locks.strict_lock.see_also__link_linkend__thread_synchronization_lock_guard_lock_guard___code__phrase_role__identifier__boost__phrase__phrase_role__special______phrase__phrase_role__identifier__lock_guard__phrase___code___link_"></a></span><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.strict_lock.see_also__link_linkend__thread_synchronization_lock_guard_lock_guard___code__phrase_role__identifier__boost__phrase__phrase_role__special______phrase__phrase_role__identifier__lock_guard__phrase___code___link_">See
            also <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span></code></a>
          </h6>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.strict_locks.strict_lock.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.strict_lock.constructor" title="strict_lock(Lockable &amp; m)"><code class="computeroutput"><span class="identifier">strict_lock</span><span class="special">(</span><span class="identifier">Lockable</span> <span class="special">&amp;</span>
            <span class="identifier">m</span><span class="special">)</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                    Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.strict_locks.strict_lock.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.strict_lock.destructor" title="~strict_lock()"><code class="computeroutput"><span class="special">~</span><span class="identifier">strict_lock</span><span class="special">()</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code></a>
                    on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object passed
                    to the constructor.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.strict_locks.nested_strict_lock"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.nested_strict_lock" title="Class template nested_strict_lock">Class
          template <code class="computeroutput"><span class="identifier">nested_strict_lock</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt;</span>
<span class="comment">// #include &lt;boost/thread/strict_lock.hpp&gt; </span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">nested_strict_lock</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span> <span class="identifier">BasicLockable</span> <span class="identifier">mutex_type</span><span class="special">;</span>
    <span class="identifier">nested_strict_lock</span><span class="special">(</span><span class="identifier">nested_strict_lock</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">nested_strict_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">nested_strict_lock</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="keyword">explicit</span> <span class="identifier">nested_strict_lock</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">),</span>
    <span class="special">~</span><span class="identifier">nested_strict_lock</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>

    <span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">mutex_type</span> <span class="keyword">const</span><span class="special">*</span> <span class="identifier">l</span><span class="special">)</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
            <a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.nested_strict_lock" title="Class template nested_strict_lock"><code class="computeroutput"><span class="identifier">nested_strict_lock</span></code></a> is a model
            of <a class="link" href="synchronization.html#thread.synchronization.lock_concepts.StrictLock" title="StrictLock -- EXTENSION"><code class="computeroutput"><span class="identifier">StrictLock</span></code></a>.
          </p>
<p>
            A nested strict lock is a scoped lock guard ensuring a mutex is locked
            on its scope, by taking ownership of a nesting lock, locking the mutex
            on construction if not already locked and restoring the ownership to
            the nesting lock on destruction.
          </p>
<h6>
<a name="thread.synchronization.other_locks.strict_locks.nested_strict_lock.h0"></a>
            <span class="phrase"><a name="thread.synchronization.other_locks.strict_locks.nested_strict_lock.see_also__link_linkend__thread_synchronization_other_locks_strict_locks_strict_lock___code__phrase_role__identifier__strict_lock__phrase___code___link_____link_linkend__thread_synchronization_locks_unique_lock___code__phrase_role__identifier__boost__phrase__phrase_role__special______phrase__phrase_role__identifier__unique_lock__phrase___code___link_"></a></span><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.nested_strict_lock.see_also__link_linkend__thread_synchronization_other_locks_strict_locks_strict_lock___code__phrase_role__identifier__strict_lock__phrase___code___link_____link_linkend__thread_synchronization_locks_unique_lock___code__phrase_role__identifier__boost__phrase__phrase_role__special______phrase__phrase_role__identifier__unique_lock__phrase___code___link_">See
            also <code class="computeroutput"><span class="identifier">strict_lock</span></code>, <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a>
          </h6>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.strict_locks.nested_strict_lock.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.nested_strict_lock.constructor" title="nested_strict_lock(Lock &amp; lk)"><code class="computeroutput"><span class="identifier">nested_strict_lock</span><span class="special">(</span><span class="identifier">Lock</span> <span class="special">&amp;</span>
            <span class="identifier">lk</span><span class="special">)</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">lk</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">()</span>
                    <span class="special">!=</span> <span class="identifier">null_ptr</span></code>.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Stores the reference to the lock parameter <code class="computeroutput"><span class="identifier">lk</span></code>
                    and takes ownership on it. If the lock doesn't owns the mutex
                    lock it.
                  </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">lk</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">())</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - lock_error when BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED
                    is defined and lk.mutex() == null_ptr
                  </p>
<p>
                    - Any exception that @c lk.lock() can throw.
                  </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.strict_locks.nested_strict_lock.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.nested_strict_lock.destructor" title="~nested_strict_lock() noexcept"><code class="computeroutput"><span class="special">~</span><span class="identifier">nested_strict_lock</span><span class="special">()</span> <span class="keyword">noexcept</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Restores ownership to the nesting lock.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.strict_locks.nested_strict_lock.owns_lock"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.nested_strict_lock.owns_lock" title="bool owns_lock(mutex_type const* l) const noexcept"><code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">owns_lock</span><span class="special">(</span><span class="identifier">mutex_type</span>
            <span class="keyword">const</span><span class="special">*</span>
            <span class="identifier">l</span><span class="special">)</span>
            <span class="keyword">const</span> <span class="keyword">noexcept</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    Whether if this lock is locking that mutex.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.strict_locks.make_strict_lock"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.make_strict_lock" title="Non Member Function make_strict_lock">Non
          Member Function <code class="computeroutput"><span class="identifier">make_strict_lock</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_strict_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">m</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  a strict_lock as if initialized with <code class="computeroutput"><span class="special">{</span><span class="identifier">m</span><span class="special">}</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exception thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.strict_locks.make_nested_strict_lock"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.strict_locks.make_nested_strict_lock" title="Non Member Function make_nested_strict_lock">Non
          Member Function <code class="computeroutput"><span class="identifier">make_nested_strict_lock</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
<span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;</span> <span class="identifier">make_nested_strict_lock</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  a nested_strict_lock as if initialized with <code class="computeroutput"><span class="special">{</span><span class="identifier">lk</span><span class="special">}</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exception thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lk</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs" title="Locking pointers">Locking
        pointers</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr">Class
          template <code class="computeroutput"><span class="identifier">const_strict_lock_ptr</span>
          </code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr">Class
          template <code class="computeroutput"><span class="identifier">strict_lock_ptr</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/synchroniezd_value.hpp&gt; </span>
<span class="comment">// #include &lt;boost/thread/strict_lock_ptr.hpp&gt; </span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Lockable</span> <span class="special">=</span> <span class="identifier">mutex</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">strict_lock_ptr</span><span class="special">;</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Lockable</span> <span class="special">=</span> <span class="identifier">mutex</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">const_strict_lock_ptr</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr" title="Class template const_strict_lock_ptr">Class
          template <code class="computeroutput"><span class="identifier">const_strict_lock_ptr</span>
          </code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/synchroniezd_value.hpp&gt; </span>
<span class="comment">// #include &lt;boost/thread/strict_lock_ptr.hpp&gt; </span>


<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Lockable</span> <span class="special">=</span> <span class="identifier">mutex</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">const_strict_lock_ptr</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
  <span class="keyword">typedef</span> <span class="identifier">T</span> <span class="identifier">value_type</span><span class="special">;</span>
  <span class="keyword">typedef</span> <span class="identifier">Lockable</span> <span class="identifier">mutex_type</span><span class="special">;</span>

  <span class="identifier">const_strict_lock_ptr</span><span class="special">(</span><span class="identifier">const_strict_lock_ptr</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
  <span class="identifier">const_strict_lock_ptr</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">const_strict_lock_ptr</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

  <span class="identifier">const_strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">val</span><span class="special">,</span> <span class="identifier">Lockable</span> <span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">);</span>
  <span class="identifier">const_strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">val</span><span class="special">,</span> <span class="identifier">Lockable</span> <span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">adopt_lock_t</span> <span class="identifier">tag</span><span class="special">);</span>

  <span class="special">~</span><span class="identifier">const_strict_lock_ptr</span><span class="special">();</span>

  <span class="keyword">const</span> <span class="identifier">T</span><span class="special">*</span> <span class="keyword">operator</span><span class="special">-&gt;()</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">*()</span> <span class="keyword">const</span><span class="special">;</span>

<span class="special">};</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr.constructor" title="const_strict_lock_ptr(T const&amp;,Lockable&amp;)"><code class="computeroutput"><span class="identifier">const_strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;,</span><span class="identifier">Lockable</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">const_strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">val</span><span class="special">,</span> <span class="identifier">Lockable</span> <span class="special">&amp;</span> <span class="identifier">m</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>,
                    stores a reference to it and to the value type <code class="computeroutput"><span class="identifier">val</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr.constructor_adopt"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr.constructor_adopt" title="const_strict_lock_ptr(T const&amp;,Lockable&amp;,adopt_lock_t)"><code class="computeroutput"><span class="identifier">const_strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;,</span><span class="identifier">Lockable</span><span class="special">&amp;,</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">const_strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">val</span><span class="special">,</span> <span class="identifier">Lockable</span> <span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span> <span class="identifier">adopt_lock_t</span> <span class="identifier">tag</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Stores a reference to it and to the value type <code class="computeroutput"><span class="identifier">val</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr.destructor" title="~const_strict_lock_ptr()"><code class="computeroutput"><span class="special">~</span><span class="identifier">const_strict_lock_ptr</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">const_strict_lock_ptr</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code></a>
                    on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object passed
                    to the constructor.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr.indir"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr.indir" title="operator-&gt;() const"><code class="computeroutput"><span class="keyword">operator</span><span class="special">-&gt;()</span>
            <span class="keyword">const</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">const</span> <span class="identifier">T</span><span class="special">*</span> <span class="keyword">operator</span><span class="special">-&gt;()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    return a constant pointer to the protected value.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr.deref"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.const_strict_lock_ptr.deref" title="operator*() const"><code class="computeroutput"><span class="keyword">operator</span><span class="special">*()</span>
            <span class="keyword">const</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">*()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    return a constant reference to the protected value.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr" title="Class template strict_lock_ptr">Class
          template <code class="computeroutput"><span class="identifier">strict_lock_ptr</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/synchroniezd_value.hpp&gt; </span>
<span class="comment">// #include &lt;boost/thread/strict_lock_ptr.hpp&gt; </span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Lockable</span> <span class="special">=</span> <span class="identifier">mutex</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">strict_lock_ptr</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">const_strict_lock_ptr</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">,</span><span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
  <span class="identifier">strict_lock_ptr</span><span class="special">(</span><span class="identifier">strict_lock_ptr</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
  <span class="identifier">strict_lock_ptr</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">strict_lock_ptr</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

  <span class="identifier">strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="special">&amp;</span> <span class="identifier">val</span><span class="special">,</span> <span class="identifier">Lockable</span> <span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">);</span>
  <span class="identifier">strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="special">&amp;</span> <span class="identifier">val</span><span class="special">,</span> <span class="identifier">Lockable</span> <span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">adopt_lock_t</span> <span class="identifier">tag</span><span class="special">);</span>
  <span class="special">~</span><span class="identifier">strict_lock_ptr</span><span class="special">();</span>

  <span class="identifier">T</span><span class="special">*</span> <span class="keyword">operator</span><span class="special">-&gt;();</span>
  <span class="identifier">T</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">*();</span>

<span class="special">};</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr.constructor" title="strict_lock_ptr(T const&amp;,Lockable&amp;)"><code class="computeroutput"><span class="identifier">strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;,</span><span class="identifier">Lockable</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">val</span><span class="special">,</span> <span class="identifier">Lockable</span> <span class="special">&amp;</span> <span class="identifier">m</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>,
                    stores a reference to it and to the value type <code class="computeroutput"><span class="identifier">val</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code></a>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr.constructor_adopt"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr.constructor_adopt" title="strict_lock_ptr(T const&amp;,Lockable&amp;,adopt_lock_t)"><code class="computeroutput"><span class="identifier">strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;,</span><span class="identifier">Lockable</span><span class="special">&amp;,</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">strict_lock_ptr</span><span class="special">(</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">val</span><span class="special">,</span> <span class="identifier">Lockable</span> <span class="special">&amp;</span> <span class="identifier">m</span><span class="special">,</span> <span class="identifier">adopt_lock_t</span> <span class="identifier">tag</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Stores a reference to it and to the value type <code class="computeroutput"><span class="identifier">val</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr.destructor" title="~strict_lock_ptr()"><code class="computeroutput"><span class="special">~</span><span class="identifier">strict_lock_ptr</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span> <span class="identifier">strict_lock_ptr</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Invokes <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code></a>
                    on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> object passed
                    to the constructor.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr.indir"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr.indir" title="operator-&gt;()"><code class="computeroutput"><span class="keyword">operator</span><span class="special">-&gt;()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">T</span><span class="special">*</span> <span class="keyword">operator</span><span class="special">-&gt;();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    return a pointer to the protected value.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr.deref"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.lock_ptrs.strict_lock_ptr.deref" title="operator*()"><code class="computeroutput"><span class="keyword">operator</span><span class="special">*()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">T</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">*();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    return a reference to the protected value.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.other_locks.externally_locked"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked" title="Externally Locked">Externally
        Locked</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked">Template
          Class <code class="computeroutput"><span class="identifier">externally_locked</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked_ref">Template
          Class <code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&amp;&gt;</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.externally_locked.swap"><code class="computeroutput"><span class="identifier">swap</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;,</span>
          <span class="identifier">externally_locked</span><span class="special">&amp;)</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/externally_locked.hpp&gt;</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">MutexType</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">externally_locked</span><span class="special">;</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">MutexType</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&amp;,</span> <span class="identifier">MutexType</span><span class="special">&gt;;</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">MutexType</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">MutexType</span><span class="special">&gt;</span> <span class="special">&amp;</span> <span class="identifier">lhs</span><span class="special">,</span> <span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">MutexType</span><span class="special">&gt;</span> <span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked" title="Template Class externally_locked">Template
          Class <code class="computeroutput"><span class="identifier">externally_locked</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/externally_locked.hpp&gt;</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">MutexType</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">externally_locked</span>
<span class="special">{</span>
  <span class="comment">//BOOST_CONCEPT_ASSERT(( CopyConstructible&lt;T&gt; ));</span>
  <span class="identifier">BOOST_CONCEPT_ASSERT</span><span class="special">((</span> <span class="identifier">BasicLockable</span><span class="special">&lt;</span><span class="identifier">MutexType</span><span class="special">&gt;</span> <span class="special">));</span>

<span class="keyword">public</span><span class="special">:</span>
  <span class="keyword">typedef</span> <span class="identifier">MutexType</span> <span class="identifier">mutex_type</span><span class="special">;</span>

  <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">obj</span><span class="special">);</span>
  <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span><span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="identifier">obj</span><span class="special">);</span>
  <span class="keyword">explicit</span> <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">);</span>
  <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
  <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
  <span class="identifier">externally_locked</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">externally_locked</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
  <span class="identifier">externally_locked</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>

  <span class="comment">// observers</span>
  <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
  <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>

 <span class="identifier">mutex_type</span><span class="special">*</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="comment">// modifiers</span>
  <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
  <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>
  <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>
  <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;);</span>
<span class="special">};</span>
</pre>
<p>
            <code class="computeroutput"><span class="identifier">externally_locked</span></code> is
            a model of <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a>, it cloaks an object
            of type <code class="computeroutput"><span class="identifier">T</span></code>, and actually
            provides full access to that object through the get and set member functions,
            provided you pass a reference to a strict lock object.
          </p>
<p>
            Only the specificities respect to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> are described here.
          </p>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked.constructor1"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked.constructor1" title="externally_locked(mutex_type&amp;, const T&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;,</span>
            <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">obj</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    T is a model of CopyConstructible.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs an externally locked object copying the cloaked type.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <code class="computeroutput"><span class="identifier">T</span><span class="special">(</span><span class="identifier">obj</span><span class="special">)</span></code>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked.constructor2"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked.constructor2" title="externally_locked(mutex_type&amp;, T&amp;&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;,</span>
            <span class="identifier">T</span><span class="special">&amp;&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span><span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="identifier">obj</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    T is a model of Movable.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs an externally locked object by moving the cloaked
                    type.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <code class="computeroutput"><span class="identifier">T</span><span class="special">(</span><span class="identifier">obj</span><span class="special">)</span></code>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked.constructor3"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked.constructor3" title="externally_locked(mutex_type&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    T is a model of DefaultConstructible.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs an externally locked object by default constructing
                    the cloaked type.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <code class="computeroutput"><span class="identifier">T</span><span class="special">()</span></code>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked.constructor4"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked.constructor4" title="externally_locked(externally_locked&amp;&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    T is a model of Movable.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Move constructs an externally locked object by moving the cloaked
                    type and copying the mutex reference
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <code class="computeroutput"><span class="identifier">T</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;&amp;)</span></code>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked.constructor5"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked.constructor5" title="externally_locked(externally_locked&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    T is a model of Copyable.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Copy constructs an externally locked object by copying the cloaked
                    type and copying the mutex reference
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <code class="computeroutput"><span class="identifier">T</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;)</span></code>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked.assign4"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked.assign4" title="externally_locked(externally_locked&amp;&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    T is a model of Movable.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Move assigns an externally locked object by moving the cloaked
                    type and copying the mutex reference
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="identifier">T</span><span class="special">&amp;&amp;)</span></code>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked.assign5"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked.assign5" title="externally_locked(externally_locked&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">externally_locked</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    T is a model of Copyable.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Copy assigns an externally locked object by copying the cloaked
                    type and copying the mutex reference
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="identifier">T</span><span class="special">&amp;)</span></code>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked.get1"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked.get1" title="get(strict_lock&lt;mutex_type&gt;&amp;)"><code class="computeroutput"><span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
<span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    The <code class="computeroutput"><span class="identifier">lk</span></code> parameter
                    must be locking the associated mutex.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    A reference to the cloaked object
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">lock_error</span></code> if
                    <code class="computeroutput"><span class="identifier">BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED</span></code>
                    is defined and the run-time preconditions are not satisfied .
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked.get2"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked.get2" title="get(nested_strict_lock&lt;Lock&gt;&amp;)"><code class="computeroutput"><span class="identifier">get</span><span class="special">(</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
<span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
<span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">is_same</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">,</span>
                    <span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">::</span><span class="identifier">mutex_type</span><span class="special">&gt;</span></code> and the <code class="computeroutput"><span class="identifier">lk</span></code>
                    parameter must be locking the associated mutex.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    A reference to the cloaked object
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">lock_error</span></code> if
                    <code class="computeroutput"><span class="identifier">BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED</span></code>
                    is defined and the run-time preconditions are not satisfied .
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked.get3"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked.get3" title="get(Lock&amp;)"><code class="computeroutput"><span class="identifier">get</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
<span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
<span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">Lock</span></code> is a model
                    of <a class="link" href="synchronization.html#thread.synchronization.lock_concepts.StrictLock" title="StrictLock -- EXTENSION"><code class="computeroutput"><span class="identifier">StrictLock</span></code></a>, <code class="computeroutput"><span class="identifier">is_same</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">,</span>
                    <span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">::</span><span class="identifier">mutex_type</span><span class="special">&gt;</span></code> and the <code class="computeroutput"><span class="identifier">lk</span></code>
                    parameter must be locking the associated mutex.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    A reference to the cloaked object
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">lock_error</span></code> if
                    <code class="computeroutput"><span class="identifier">BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED</span></code>
                    is defined and the run-time preconditions are not satisfied .
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked_ref"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked_ref" title="Template Class externally_locked&lt;T&amp;&gt;">Template
          Class <code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&amp;&gt;</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/externally_locked.hpp&gt;</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">MutexType</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&amp;,</span> <span class="identifier">MutexType</span><span class="special">&gt;</span>
<span class="special">{</span>
  <span class="comment">//BOOST_CONCEPT_ASSERT(( CopyConstructible&lt;T&gt; ));</span>
  <span class="identifier">BOOST_CONCEPT_ASSERT</span><span class="special">((</span> <span class="identifier">BasicLockable</span><span class="special">&lt;</span><span class="identifier">MutexType</span><span class="special">&gt;</span> <span class="special">));</span>

<span class="keyword">public</span><span class="special">:</span>
  <span class="keyword">typedef</span> <span class="identifier">MutexType</span> <span class="identifier">mutex_type</span><span class="special">;</span>

  <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">obj</span><span class="special">);</span>
  <span class="keyword">explicit</span> <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">);</span>
  <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="identifier">externally_locked</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">externally_locked</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="identifier">externally_locked</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="comment">// observers</span>
  <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
  <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>

 <span class="identifier">mutex_type</span><span class="special">*</span> <span class="identifier">mutex</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="comment">// modifiers</span>
  <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
  <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>
  <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>
  <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;)</span> <span class="keyword">noexcept</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
            <code class="computeroutput"><span class="identifier">externally_locked</span></code> is
            a model of <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a>, it cloaks an object
            of type <code class="computeroutput"><span class="identifier">T</span></code>, and actually
            provides full access to that object through the get and set member functions,
            provided you pass a reference to a strict lock object.
          </p>
<p>
            Only the specificities respect to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> are described here.
          </p>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked_ref.constructor1"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked_ref.constructor1" title="externally_locked&lt;T&amp;&gt;(mutex_type&amp;, T&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&amp;&gt;(</span><span class="identifier">mutex_type</span><span class="special">&amp;,</span>
            <span class="identifier">T</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&amp;&gt;(</span><span class="identifier">mutex_type</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">obj</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs an externally locked object copying the cloaked reference.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked_ref.constructor4"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked_ref.constructor4" title="externally_locked&lt;T&amp;&gt;(externally_locked&amp;&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&amp;&gt;(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Moves an externally locked object by moving the cloaked type
                    and copying the mutex reference
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked_ref.assign4"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked_ref.assign4" title="externally_locked(externally_locked&amp;&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">externally_locked</span><span class="special">&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Move assigns an externally locked object by copying the cloaked
                    reference and copying the mutex reference
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked_ref.assign5"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked_ref.assign5" title="externally_locked(externally_locked&amp;)"><code class="computeroutput"><span class="identifier">externally_locked</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">externally_locked</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">externally_locked</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    T is a model of Copyable.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Copy assigns an externally locked object by copying the cloaked
                    reference and copying the mutex reference
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exception thrown by the call to <code class="computeroutput"><span class="identifier">T</span><span class="special">::</span><span class="keyword">operator</span><span class="special">=(</span><span class="identifier">T</span><span class="special">&amp;)</span></code>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked_ref.get1"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked_ref.get1" title="get(strict_lock&lt;mutex_type&gt;&amp;)"><code class="computeroutput"><span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
<span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">strict_lock</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    The <code class="computeroutput"><span class="identifier">lk</span></code> parameter
                    must be locking the associated mutex.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    A reference to the cloaked object
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">lock_error</span></code> if
                    <code class="computeroutput"><span class="identifier">BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED</span></code>
                    is defined and the run-time preconditions are not satisfied .
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked_ref.get2"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked_ref.get2" title="get(nested_strict_lock&lt;Lock&gt;&amp;)"><code class="computeroutput"><span class="identifier">get</span><span class="special">(</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
<span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
<span class="keyword">const</span> <span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">nested_strict_lock</span><span class="special">&lt;</span><span class="identifier">Lock</span><span class="special">&gt;&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">is_same</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">,</span>
                    <span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">::</span><span class="identifier">mutex_type</span><span class="special">&gt;</span></code> and the <code class="computeroutput"><span class="identifier">lk</span></code>
                    parameter must be locking the associated mutex.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    A reference to the cloaked object
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">lock_error</span></code> if
                    <code class="computeroutput"><span class="identifier">BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED</span></code>
                    is defined and the run-time preconditions are not satisfied .
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.other_locks.externally_locked.externally_locked_ref.get3"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.externally_locked_ref.get3" title="get(Lock&amp;)"><code class="computeroutput"><span class="identifier">get</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
<span class="identifier">T</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
<span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">lk</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">Lock</span></code> is a model
                    of <a class="link" href="synchronization.html#thread.synchronization.lock_concepts.StrictLock" title="StrictLock -- EXTENSION"><code class="computeroutput"><span class="identifier">StrictLock</span></code></a>, <code class="computeroutput"><span class="identifier">is_same</span><span class="special">&lt;</span><span class="identifier">mutex_type</span><span class="special">,</span>
                    <span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">::</span><span class="identifier">mutex_type</span><span class="special">&gt;</span></code> and the <code class="computeroutput"><span class="identifier">lk</span></code>
                    parameter must be locking the associated mutex.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    A reference to the cloaked object
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">lock_error</span></code> if
                    <code class="computeroutput"><span class="identifier">BOOST_THREAD_THROW_IF_PRECONDITION_NOT_SATISFIED</span></code>
                    is defined and the run-time preconditions are not satisfied .
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.externally_locked.swap"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.externally_locked.swap" title="swap(externally_locked&amp;, externally_locked&amp;)"><code class="computeroutput"><span class="identifier">swap</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&amp;,</span>
          <span class="identifier">externally_locked</span><span class="special">&amp;)</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">MutexType</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">MutexType</span><span class="special">&gt;</span> <span class="special">&amp;</span> <span class="identifier">lhs</span><span class="special">,</span> <span class="identifier">externally_locked</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">,</span> <span class="identifier">MutexType</span><span class="special">&gt;</span> <span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">)</span>
</pre>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.other_locks.shared_lock_guard"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard" title="Class template shared_lock_guard">Class
        template <code class="computeroutput"><span class="identifier">shared_lock_guard</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard.constructor"><code class="computeroutput"><span class="identifier">shared_lock_guard</span><span class="special">(</span><span class="identifier">SharedLockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard.constructor_adopt"><code class="computeroutput"><span class="identifier">shared_lock_guard</span><span class="special">(</span><span class="identifier">SharedLockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard.destructor"><code class="computeroutput"><span class="special">~</span><span class="identifier">shared_lock_guard</span><span class="special">()</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/shared_lock_guard.hpp&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">SharedLockable</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">shared_lock_guard</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
      <span class="identifier">shared_lock_guard</span><span class="special">(</span><span class="identifier">shared_lock_guard</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
      <span class="identifier">shared_lock_guard</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">shared_lock_guard</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

      <span class="keyword">explicit</span> <span class="identifier">shared_lock_guard</span><span class="special">(</span><span class="identifier">SharedLockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">);</span>
      <span class="identifier">shared_lock_guard</span><span class="special">(</span><span class="identifier">SharedLockable</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">);</span>

      <span class="special">~</span><span class="identifier">shared_lock_guard</span><span class="special">();</span>
  <span class="special">};</span>
<span class="special">}</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard" title="Class template shared_lock_guard"><code class="computeroutput"><span class="identifier">shared_lock_guard</span></code></a> is very simple:
          on construction it acquires shared ownership of the implementation of the
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code> concept</a> supplied
          as the constructor parameter. On destruction, the ownership is released.
          This provides simple RAII-style locking of a <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code></a> object, to facilitate
          exception-safe shared locking and unlocking. In addition, the <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard" title="Class template shared_lock_guard"><code class="computeroutput"><span class="identifier">shared_lock_guard</span></code></a><span class="special">(</span><span class="identifier">SharedLockable</span> <span class="special">&amp;</span><span class="identifier">m</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code> constructor allows the <a class="link" href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard" title="Class template shared_lock_guard"><code class="computeroutput"><span class="identifier">shared_lock_guard</span></code></a> object to take
          shared ownership of a lock already held by the current thread.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.shared_lock_guard.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard.constructor" title="shared_lock_guard(SharedLockable &amp; m)"><code class="computeroutput"><span class="identifier">shared_lock_guard</span><span class="special">(</span><span class="identifier">SharedLockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared" title="m.lock_shared()"><code class="computeroutput"><span class="identifier">lock_shared</span><span class="special">()</span></code></a><span class="special">()</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exception thrown by the call to <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared" title="m.lock_shared()"><code class="computeroutput"><span class="identifier">lock_shared</span><span class="special">()</span></code></a><span class="special">()</span></code>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.shared_lock_guard.constructor_adopt"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard.constructor_adopt" title="shared_lock_guard(SharedLockable &amp; m,boost::adopt_lock_t)"><code class="computeroutput"><span class="identifier">shared_lock_guard</span><span class="special">(</span><span class="identifier">SharedLockable</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">adopt_lock_t</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  The current thread owns a lock on <code class="computeroutput"><span class="identifier">m</span></code>
                  equivalent to one obtained by a call to <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared" title="m.lock_shared()"><code class="computeroutput"><span class="identifier">lock_shared</span><span class="special">()</span></code></a><span class="special">()</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Takes ownership of the lock state of <code class="computeroutput"><span class="identifier">m</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.shared_lock_guard.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.shared_lock_guard.destructor" title="~shared_lock_guard()"><code class="computeroutput"><span class="special">~</span><span class="identifier">shared_lock_guard</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Invokes <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.unlock_shared" title="m.unlock_shared()"><code class="computeroutput"><span class="identifier">unlock_shared</span><span class="special">()</span></code></a><span class="special">()</span></code> on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code></a> object
                  passed to the constructor.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.other_locks.reverse_lock"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.reverse_lock" title="Class template reverse_lock">Class
        template <code class="computeroutput"><span class="identifier">reverse_lock</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.reverse_lock.constructor"><code class="computeroutput"><span class="identifier">reverse_lock</span><span class="special">(</span><span class="identifier">Lock</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.other_locks.reverse_lock.destructor"><code class="computeroutput"><span class="special">~</span><span class="identifier">reverse_lock</span><span class="special">()</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/reverse_lock.hpp&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lock</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">reverse_lock</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
      <span class="identifier">reverse_lock</span><span class="special">(</span><span class="identifier">reverse_lock</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
      <span class="identifier">reverse_lock</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">reverse_lock</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

      <span class="keyword">explicit</span> <span class="identifier">reverse_lock</span><span class="special">(</span><span class="identifier">Lock</span><span class="special">&amp;</span> <span class="identifier">m_</span><span class="special">);</span>
      <span class="special">~</span><span class="identifier">reverse_lock</span><span class="special">();</span>
  <span class="special">};</span>
<span class="special">}</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.other_locks.reverse_lock" title="Class template reverse_lock"><code class="computeroutput"><span class="identifier">reverse_lock</span></code></a> reverse the operations
          of a lock: it provide for RAII-style, that unlocks the lock at construction
          time and lock it at destruction time. In addition, it transfer ownership
          temporarily, so that the mutex can not be locked using the Lock.
        </p>
<p>
          An instance of <a class="link" href="synchronization.html#thread.synchronization.other_locks.reverse_lock" title="Class template reverse_lock"><code class="computeroutput"><span class="identifier">reverse_lock</span></code></a> doesn't <span class="emphasis"><em>own</em></span>
          the lock never.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.reverse_lock.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.reverse_lock.constructor" title="reverse_lock(Lock &amp; m)"><code class="computeroutput"><span class="identifier">reverse_lock</span><span class="special">(</span><span class="identifier">Lock</span> <span class="special">&amp;</span>
          <span class="identifier">m</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Stores a reference to <code class="computeroutput"><span class="identifier">m</span></code>.
                  Invokes <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span></code></a><span class="special">()</span></code>
                  if <code class="computeroutput"><span class="identifier">m</span></code> owns his lock
                  and then stores the mutex by calling <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><span class="identifier">release</span><span class="special">()</span></code>.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="special">!</span><span class="identifier">m</span><span class="special">.</span> <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock.owns_lock" title="bool owns_lock() const"><code class="computeroutput"><span class="identifier">owns_lock</span><span class="special">()</span></code></a><span class="special">()</span> <span class="special">&amp;&amp;</span>
                  <span class="identifier">m</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">()==</span><span class="number">0</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exception thrown by the call to <code class="computeroutput"><span class="identifier">m</span><span class="special">.</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span></code></a><span class="special">()</span></code>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.other_locks.reverse_lock.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.other_locks.reverse_lock.destructor" title="~reverse_lock()"><code class="computeroutput"><span class="special">~</span><span class="identifier">reverse_lock</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Let be mtx the stored mutex*. If not 0 Invokes <code class="computeroutput"><span class="identifier">mtx</span><span class="special">-&gt;</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span></code></a><span class="special">()</span></code>
                  and gives again the <code class="computeroutput"><span class="identifier">mtx</span></code>
                  to the <code class="computeroutput"><span class="identifier">Lock</span></code> using
                  the <code class="computeroutput"><span class="identifier">adopt_lock_t</span></code>
                  overload.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exception thrown by <code class="computeroutput"><span class="identifier">mtx</span><span class="special">-&gt;</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span></code></a><span class="special">()</span></code>.
                </p></dd>
<dt><span class="term">Remarks:</span></dt>
<dd><p>
                  Note that if <code class="computeroutput"><span class="identifier">mtx</span><span class="special">-&gt;</span><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span></code></a><span class="special">()</span></code>
                  throws an exception while unwinding the program will terminate,
                  so don't use reverse_lock if an exception can be thrown.
                </p></dd>
</dl>
</div>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.lock_functions"></a><a class="link" href="synchronization.html#thread.synchronization.lock_functions" title="Lock functions">Lock functions</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_functions.lock_multiple">Non-member
        function <code class="computeroutput"><span class="identifier">lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">,...)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_functions.lock_range">Non-member
        function <code class="computeroutput"><span class="identifier">lock</span><span class="special">(</span><span class="identifier">begin</span><span class="special">,</span><span class="identifier">end</span><span class="special">)</span></code> //
        EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_functions.try_lock_multiple">Non-member
        function <code class="computeroutput"><span class="identifier">try_lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">,...)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_functions.try_lock_range">Non-member
        function <code class="computeroutput"><span class="identifier">try_lock</span><span class="special">(</span><span class="identifier">begin</span><span class="special">,</span><span class="identifier">end</span><span class="special">)</span></code> //
        EXTENSION</a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_functions.lock_multiple"></a><a class="link" href="synchronization.html#thread.synchronization.lock_functions.lock_multiple" title="Non-member function lock(Lockable1,Lockable2,...)">Non-member
        function <code class="computeroutput"><span class="identifier">lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">,...)</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/locks.hpp&gt;</span>
<span class="comment">// #include &lt;boost/thread/lock_algorithms.hpp&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable2</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">&amp;</span> <span class="identifier">l1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">&amp;</span> <span class="identifier">l2</span><span class="special">);</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable3</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">&amp;</span> <span class="identifier">l1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">&amp;</span> <span class="identifier">l2</span><span class="special">,</span><span class="identifier">Lockable3</span><span class="special">&amp;</span> <span class="identifier">l3</span><span class="special">);</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable3</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable4</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">&amp;</span> <span class="identifier">l1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">&amp;</span> <span class="identifier">l2</span><span class="special">,</span><span class="identifier">Lockable3</span><span class="special">&amp;</span> <span class="identifier">l3</span><span class="special">,</span><span class="identifier">Lockable4</span><span class="special">&amp;</span> <span class="identifier">l4</span><span class="special">);</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable3</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable4</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable5</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">&amp;</span> <span class="identifier">l1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">&amp;</span> <span class="identifier">l2</span><span class="special">,</span><span class="identifier">Lockable3</span><span class="special">&amp;</span> <span class="identifier">l3</span><span class="special">,</span><span class="identifier">Lockable4</span><span class="special">&amp;</span> <span class="identifier">l4</span><span class="special">,</span><span class="identifier">Lockable5</span><span class="special">&amp;</span> <span class="identifier">l5</span><span class="special">);</span>

<span class="special">}</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                Locks the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects supplied
                as arguments in an unspecified and indeterminate order in a way that
                avoids deadlock. It is safe to call this function concurrently from
                multiple threads for any set of mutexes (or other lockable objects)
                in any order without risk of deadlock. If any of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>
                or <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                operations on the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects throws
                an exception any locks acquired by the function will be released
                before the function exits.
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                Any exceptions thrown by calling <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>
                or <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                on the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects.
              </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                All the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects are locked
                by the calling thread.
              </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_functions.lock_range"></a><a class="link" href="synchronization.html#thread.synchronization.lock_functions.lock_range" title="Non-member function lock(begin,end) // EXTENSION">Non-member
        function <code class="computeroutput"><span class="identifier">lock</span><span class="special">(</span><span class="identifier">begin</span><span class="special">,</span><span class="identifier">end</span><span class="special">)</span></code> //
        EXTENSION</a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">ForwardIterator</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">lock</span><span class="special">(</span><span class="identifier">ForwardIterator</span> <span class="identifier">begin</span><span class="special">,</span><span class="identifier">ForwardIterator</span> <span class="identifier">end</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Preconditions:</span></dt>
<dd><p>
                The <code class="computeroutput"><span class="identifier">value_type</span></code> of
                <code class="computeroutput"><span class="identifier">ForwardIterator</span></code> must
                implement the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code> concept</a>
              </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                Locks all the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects in the
                supplied range in an unspecified and indeterminate order in a way
                that avoids deadlock. It is safe to call this function concurrently
                from multiple threads for any set of mutexes (or other lockable objects)
                in any order without risk of deadlock. If any of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>
                or <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                operations on the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects in the
                supplied range throws an exception any locks acquired by the function
                will be released before the function exits.
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                Any exceptions thrown by calling <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>
                or <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                on the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects.
              </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                All the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects in the
                supplied range are locked by the calling thread.
              </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_functions.try_lock_multiple"></a><a class="link" href="synchronization.html#thread.synchronization.lock_functions.try_lock_multiple" title="Non-member function try_lock(Lockable1,Lockable2,...)">Non-member
        function <code class="computeroutput"><span class="identifier">try_lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">,...)</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable2</span><span class="special">&gt;</span>
<span class="keyword">int</span> <span class="identifier">try_lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">&amp;</span> <span class="identifier">l1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">&amp;</span> <span class="identifier">l2</span><span class="special">);</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable3</span><span class="special">&gt;</span>
<span class="keyword">int</span> <span class="identifier">try_lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">&amp;</span> <span class="identifier">l1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">&amp;</span> <span class="identifier">l2</span><span class="special">,</span><span class="identifier">Lockable3</span><span class="special">&amp;</span> <span class="identifier">l3</span><span class="special">);</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable3</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable4</span><span class="special">&gt;</span>
<span class="keyword">int</span> <span class="identifier">try_lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">&amp;</span> <span class="identifier">l1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">&amp;</span> <span class="identifier">l2</span><span class="special">,</span><span class="identifier">Lockable3</span><span class="special">&amp;</span> <span class="identifier">l3</span><span class="special">,</span><span class="identifier">Lockable4</span><span class="special">&amp;</span> <span class="identifier">l4</span><span class="special">);</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable3</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable4</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">Lockable5</span><span class="special">&gt;</span>
<span class="keyword">int</span> <span class="identifier">try_lock</span><span class="special">(</span><span class="identifier">Lockable1</span><span class="special">&amp;</span> <span class="identifier">l1</span><span class="special">,</span><span class="identifier">Lockable2</span><span class="special">&amp;</span> <span class="identifier">l2</span><span class="special">,</span><span class="identifier">Lockable3</span><span class="special">&amp;</span> <span class="identifier">l3</span><span class="special">,</span><span class="identifier">Lockable4</span><span class="special">&amp;</span> <span class="identifier">l4</span><span class="special">,</span><span class="identifier">Lockable5</span><span class="special">&amp;</span> <span class="identifier">l5</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                Calls <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                on each of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects supplied
                as arguments. If any of the calls to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                returns <code class="computeroutput"><span class="keyword">false</span></code> then all
                locks acquired are released and the zero-based index of the failed
                lock is returned.
              </p>
<p>
                If any of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                operations on the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects throws
                an exception any locks acquired by the function will be released
                before the function exits.
              </p>
</dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                <code class="computeroutput"><span class="special">-</span><span class="number">1</span></code>
                if all the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects are now
                locked by the calling thread, the zero-based index of the object
                which could not be locked otherwise.
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                Any exceptions thrown by calling <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                on the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects.
              </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                If the function returns <code class="computeroutput"><span class="special">-</span><span class="number">1</span></code>, all the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects are locked
                by the calling thread. Otherwise any locks acquired by this function
                will have been released.
              </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_functions.try_lock_range"></a><a class="link" href="synchronization.html#thread.synchronization.lock_functions.try_lock_range" title="Non-member function try_lock(begin,end) // EXTENSION">Non-member
        function <code class="computeroutput"><span class="identifier">try_lock</span><span class="special">(</span><span class="identifier">begin</span><span class="special">,</span><span class="identifier">end</span><span class="special">)</span></code> //
        EXTENSION</a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">ForwardIterator</span><span class="special">&gt;</span>
<span class="identifier">ForwardIterator</span> <span class="identifier">try_lock</span><span class="special">(</span><span class="identifier">ForwardIterator</span> <span class="identifier">begin</span><span class="special">,</span><span class="identifier">ForwardIterator</span> <span class="identifier">end</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Preconditions:</span></dt>
<dd><p>
                The <code class="computeroutput"><span class="identifier">value_type</span></code> of
                <code class="computeroutput"><span class="identifier">ForwardIterator</span></code> must
                implement the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code> concept</a>
              </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                Calls <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                on each of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects in the
                supplied range. If any of the calls to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                returns <code class="computeroutput"><span class="keyword">false</span></code> then all
                locks acquired are released and an iterator referencing the failed
                lock is returned.
              </p>
<p>
                If any of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                operations on the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects throws
                an exception any locks acquired by the function will be released
                before the function exits.
              </p>
</dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                <code class="computeroutput"><span class="identifier">end</span></code> if all the supplied
                <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects are now
                locked by the calling thread, an iterator referencing the object
                which could not be locked otherwise.
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                Any exceptions thrown by calling <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
                on the supplied <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects.
              </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                If the function returns <code class="computeroutput"><span class="identifier">end</span></code>
                then all the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code></a> objects in the
                supplied range are locked by the calling thread, otherwise all locks
                acquired by the function have been released.
              </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.lock_factories"></a><a class="link" href="synchronization.html#thread.synchronization.lock_factories" title="Lock Factories - EXTENSION">Lock Factories
      - EXTENSION</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_factories.make_unique_lock">Non
        Member Function <code class="computeroutput"><span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_factories.make_unique_lock_t">Non
        Member Function <code class="computeroutput"><span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;,</span><span class="identifier">tag</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.lock_factories.make_unique_locks">Non
        Member Function <code class="computeroutput"><span class="identifier">make_unique_locks</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="special">...)</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">adopt_lock_t</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">defer_lock_t</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">try_to_lock_t</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="preprocessor">#if</span> <span class="special">!</span> <span class="identifier">defined</span><span class="special">(</span><span class="identifier">BOOST_THREAD_NO_MAKE_UNIQUE_LOCKS</span><span class="special">)</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="special">...</span><span class="identifier">Lockable</span><span class="special">&gt;</span>
  <span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">...&gt;</span> <span class="identifier">make_unique_locks</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="special">...</span><span class="identifier">mtx</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
<span class="preprocessor">#endif</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_factories.make_unique_lock"></a><a class="link" href="synchronization.html#thread.synchronization.lock_factories.make_unique_lock" title="Non Member Function make_unique_lock(Lockable&amp;)">Non
        Member Function <code class="computeroutput"><span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;)</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                a <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a> as if initialized
                with <code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;(</span><span class="identifier">mtx</span><span class="special">)</span></code>.
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                Any exception thrown by the call to <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;(</span><span class="identifier">mtx</span><span class="special">)</span></code>.
              </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_factories.make_unique_lock_t"></a><a class="link" href="synchronization.html#thread.synchronization.lock_factories.make_unique_lock_t" title="Non Member Function make_unique_lock(Lockable&amp;,tag)">Non
        Member Function <code class="computeroutput"><span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;,</span><span class="identifier">tag</span><span class="special">)</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">adopt_lock_t</span> <span class="identifier">tag</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">defer_lock_t</span> <span class="identifier">tag</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="identifier">make_unique_lock</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">try_to_lock_t</span> <span class="identifier">tag</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                a <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a> as if initialized
                with <code class="computeroutput"><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;(</span><span class="identifier">mtx</span><span class="special">,</span> <span class="identifier">tag</span><span class="special">)</span></code>.
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                Any exception thrown by the call to <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;(</span><span class="identifier">mtx</span><span class="special">,</span>
                <span class="identifier">tag</span><span class="special">)</span></code>.
              </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.lock_factories.make_unique_locks"></a><a class="link" href="synchronization.html#thread.synchronization.lock_factories.make_unique_locks" title="Non Member Function make_unique_locks(Lockable&amp; ...)">Non
        Member Function <code class="computeroutput"><span class="identifier">make_unique_locks</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="special">...)</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="special">...</span><span class="identifier">Lockable</span><span class="special">&gt;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">Lockable</span><span class="special">&gt;</span> <span class="special">...&gt;</span> <span class="identifier">make_unique_locks</span><span class="special">(</span><span class="identifier">Lockable</span><span class="special">&amp;</span> <span class="special">...</span><span class="identifier">mtx</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effect:</span></dt>
<dd><p>
                Locks all the mutexes.
              </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                a std::tuple of unique <a class="link" href="synchronization.html#thread.synchronization.locks.unique_lock" title="Class template unique_lock"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span></code></a> owning each
                one of the mutex.
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                Any exception thrown by <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock</span><span class="special">(</span><span class="identifier">mtx</span><span class="special">...)</span></code>.
              </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.mutex_types"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types" title="Mutex Types">Mutex Types</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.mutex">Class <code class="computeroutput"><span class="identifier">mutex</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.try_mutex">Typedef
        <code class="computeroutput"><span class="identifier">try_mutex</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.timed_mutex">Class
        <code class="computeroutput"><span class="identifier">timed_mutex</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.recursive_mutex">Class
        <code class="computeroutput"><span class="identifier">recursive_mutex</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.recursive_try_mutex">Typedef
        <code class="computeroutput"><span class="identifier">recursive_try_mutex</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.recursive_timed_mutex">Class
        <code class="computeroutput"><span class="identifier">recursive_timed_mutex</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.shared_mutex">Class
        <code class="computeroutput"><span class="identifier">shared_mutex</span></code> -- C++14</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.upgrade_mutex">Class
        <code class="computeroutput"><span class="identifier">upgrade_mutex</span></code> -- EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.null_mutex">Class
        <code class="computeroutput"><span class="identifier">null_mutex</span></code> -- EXTENSION</a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_types.mutex"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.mutex" title="Class mutex">Class <code class="computeroutput"><span class="identifier">mutex</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc"><dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.mutex.nativehandle">Member
          function <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code></a></span></dt></dl></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">mutex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">class</span> <span class="identifier">mutex</span><span class="special">:</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">noncopyable</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">mutex</span><span class="special">();</span>
    <span class="special">~</span><span class="identifier">mutex</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>

    <span class="keyword">typedef</span> <span class="identifier">platform</span><span class="special">-</span><span class="identifier">specific</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">native_handle_type</span><span class="special">;</span>
    <span class="identifier">native_handle_type</span> <span class="identifier">native_handle</span><span class="special">();</span>

    <span class="keyword">typedef</span> <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">scoped_lock</span><span class="special">;</span>
    <span class="keyword">typedef</span> <span class="identifier">unspecified</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">scoped_try_lock</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.mutex_types.mutex" title="Class mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span></code></a> implements the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code> concept</a> to provide an
          exclusive-ownership mutex. At most one thread can own the lock on a given
          instance of <a class="link" href="synchronization.html#thread.synchronization.mutex_types.mutex" title="Class mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span></code></a> at any time. Multiple concurrent
          calls to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
          and <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>
          shall be permitted.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_types.mutex.nativehandle"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.mutex.nativehandle" title="Member function native_handle()">Member
          function <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">platform</span><span class="special">-</span><span class="identifier">specific</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">native_handle_type</span><span class="special">;</span>
<span class="identifier">native_handle_type</span> <span class="identifier">native_handle</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Returns an instance of <code class="computeroutput"><span class="identifier">native_handle_type</span></code>
                  that can be used with platform-specific APIs to manipulate the
                  underlying implementation. If no such instance exists, <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code>
                  and <code class="computeroutput"><span class="identifier">native_handle_type</span></code>
                  are not present.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_types.try_mutex"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.try_mutex" title="Typedef try_mutex">Typedef
        <code class="computeroutput"><span class="identifier">try_mutex</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">mutex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">typedef</span> <span class="identifier">mutex</span> <span class="identifier">try_mutex</span><span class="special">;</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.mutex_types.try_mutex" title="Typedef try_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">try_mutex</span></code></a> is a <code class="computeroutput"><span class="keyword">typedef</span></code>
          to <a class="link" href="synchronization.html#thread.synchronization.mutex_types.mutex" title="Class mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span></code></a>, provided for backwards
          compatibility with previous releases of boost.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_types.timed_mutex"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.timed_mutex" title="Class timed_mutex">Class
        <code class="computeroutput"><span class="identifier">timed_mutex</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc"><dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.timed_mutex.nativehandle">Member
          function <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code></a></span></dt></dl></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">mutex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">class</span> <span class="identifier">timed_mutex</span><span class="special">:</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">noncopyable</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">timed_mutex</span><span class="special">();</span>
    <span class="special">~</span><span class="identifier">timed_mutex</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">t</span><span class="special">);</span>

    <span class="keyword">typedef</span> <span class="identifier">platform</span><span class="special">-</span><span class="identifier">specific</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">native_handle_type</span><span class="special">;</span>
    <span class="identifier">native_handle_type</span> <span class="identifier">native_handle</span><span class="special">();</span>

    <span class="keyword">typedef</span> <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">timed_mutex</span><span class="special">&gt;</span> <span class="identifier">scoped_timed_lock</span><span class="special">;</span>
    <span class="keyword">typedef</span> <span class="identifier">unspecified</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">scoped_try_lock</span><span class="special">;</span>
    <span class="keyword">typedef</span> <span class="identifier">scoped_timed_lock</span> <span class="identifier">scoped_lock</span><span class="special">;</span>

<span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_PROVIDES_DATE_TIME</span> <span class="special">||</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_DONT_USE_CHRONO</span>
    <span class="keyword">bool</span> <span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">system_time</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">TimeDuration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">TimeDuration</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">relative_time</span><span class="special">);</span>
<span class="preprocessor">#endif</span>

<span class="special">};</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.mutex_types.timed_mutex" title="Class timed_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">timed_mutex</span></code></a> implements the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable" title="TimedLockable Concept"><code class="computeroutput"><span class="identifier">TimedLockable</span></code> concept</a> to provide
          an exclusive-ownership mutex. At most one thread can own the lock on a
          given instance of <a class="link" href="synchronization.html#thread.synchronization.mutex_types.timed_mutex" title="Class timed_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">timed_mutex</span></code></a> at any time. Multiple
          concurrent calls to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock_duration" title="m.timed_lock(rel_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">()</span></code></a>
          and <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>
          shall be permitted.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_types.timed_mutex.nativehandle"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.timed_mutex.nativehandle" title="Member function native_handle()">Member
          function <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">platform</span><span class="special">-</span><span class="identifier">specific</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">native_handle_type</span><span class="special">;</span>
<span class="identifier">native_handle_type</span> <span class="identifier">native_handle</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Returns an instance of <code class="computeroutput"><span class="identifier">native_handle_type</span></code>
                  that can be used with platform-specific APIs to manipulate the
                  underlying implementation. If no such instance exists, <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code>
                  and <code class="computeroutput"><span class="identifier">native_handle_type</span></code>
                  are not present.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_types.recursive_mutex"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_mutex" title="Class recursive_mutex">Class
        <code class="computeroutput"><span class="identifier">recursive_mutex</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc"><dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.recursive_mutex.nativehandle">Member
          function <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code></a></span></dt></dl></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">recursive_mutex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">class</span> <span class="identifier">recursive_mutex</span><span class="special">:</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">noncopyable</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">recursive_mutex</span><span class="special">();</span>
    <span class="special">~</span><span class="identifier">recursive_mutex</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>

    <span class="keyword">typedef</span> <span class="identifier">platform</span><span class="special">-</span><span class="identifier">specific</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">native_handle_type</span><span class="special">;</span>
    <span class="identifier">native_handle_type</span> <span class="identifier">native_handle</span><span class="special">();</span>

    <span class="keyword">typedef</span> <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">recursive_mutex</span><span class="special">&gt;</span> <span class="identifier">scoped_lock</span><span class="special">;</span>
    <span class="keyword">typedef</span> <span class="identifier">unspecified</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">scoped_try_lock</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_mutex" title="Class recursive_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">recursive_mutex</span></code></a> implements the
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable" title="Lockable Concept"><code class="computeroutput"><span class="identifier">Lockable</span></code> concept</a> to provide an
          exclusive-ownership recursive mutex. At most one thread can own the lock
          on a given instance of <a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_mutex" title="Class recursive_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">recursive_mutex</span></code></a> at any time. Multiple
          concurrent calls to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
          and <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>
          shall be permitted. A thread that already has exclusive ownership of a
          given <a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_mutex" title="Class recursive_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">recursive_mutex</span></code></a> instance can call
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>
          or <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
          to acquire an additional level of ownership of the mutex. <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>
          must be called once for each level of ownership acquired by a single thread
          before ownership can be acquired by another thread.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_types.recursive_mutex.nativehandle"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_mutex.nativehandle" title="Member function native_handle()">Member
          function <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">platform</span><span class="special">-</span><span class="identifier">specific</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">native_handle_type</span><span class="special">;</span>
<span class="identifier">native_handle_type</span> <span class="identifier">native_handle</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Returns an instance of <code class="computeroutput"><span class="identifier">native_handle_type</span></code>
                  that can be used with platform-specific APIs to manipulate the
                  underlying implementation. If no such instance exists, <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code>
                  and <code class="computeroutput"><span class="identifier">native_handle_type</span></code>
                  are not present.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_types.recursive_try_mutex"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_try_mutex" title="Typedef recursive_try_mutex">Typedef
        <code class="computeroutput"><span class="identifier">recursive_try_mutex</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">recursive_mutex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">typedef</span> <span class="identifier">recursive_mutex</span> <span class="identifier">recursive_try_mutex</span><span class="special">;</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_try_mutex" title="Typedef recursive_try_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">recursive_try_mutex</span></code></a> is a <code class="computeroutput"><span class="keyword">typedef</span></code> to <a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_mutex" title="Class recursive_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">recursive_mutex</span></code></a>, provided for
          backwards compatibility with previous releases of boost.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_types.recursive_timed_mutex"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_timed_mutex" title="Class recursive_timed_mutex">Class
        <code class="computeroutput"><span class="identifier">recursive_timed_mutex</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc"><dt><span class="section"><a href="synchronization.html#thread.synchronization.mutex_types.recursive_timed_mutex.nativehandle">Member
          function <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code></a></span></dt></dl></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">recursive_mutex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">class</span> <span class="identifier">recursive_timed_mutex</span><span class="special">:</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">noncopyable</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">recursive_timed_mutex</span><span class="special">();</span>
    <span class="special">~</span><span class="identifier">recursive_timed_mutex</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>


    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">t</span><span class="special">);</span>

    <span class="keyword">typedef</span> <span class="identifier">platform</span><span class="special">-</span><span class="identifier">specific</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">native_handle_type</span><span class="special">;</span>
    <span class="identifier">native_handle_type</span> <span class="identifier">native_handle</span><span class="special">();</span>

    <span class="keyword">typedef</span> <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">recursive_timed_mutex</span><span class="special">&gt;</span> <span class="identifier">scoped_lock</span><span class="special">;</span>
    <span class="keyword">typedef</span> <span class="identifier">unspecified</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">scoped_try_lock</span><span class="special">;</span>
    <span class="keyword">typedef</span> <span class="identifier">scoped_lock</span> <span class="identifier">scoped_timed_lock</span><span class="special">;</span>

<span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_PROVIDES_DATE_TIME</span> <span class="special">||</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_DONT_USE_CHRONO</span>
    <span class="keyword">bool</span> <span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">system_time</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">TimeDuration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">TimeDuration</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">relative_time</span><span class="special">);</span>
<span class="preprocessor">#endif</span>

<span class="special">};</span>
</pre>
<p>
          <a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_timed_mutex" title="Class recursive_timed_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">recursive_timed_mutex</span></code></a> implements
          the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable" title="TimedLockable Concept"><code class="computeroutput"><span class="identifier">TimedLockable</span></code> concept</a> to provide
          an exclusive-ownership recursive mutex. At most one thread can own the
          lock on a given instance of <a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_timed_mutex" title="Class recursive_timed_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">recursive_timed_mutex</span></code></a> at any time.
          Multiple concurrent calls to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock_duration" title="m.timed_lock(rel_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">()</span></code></a>
          and <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>
          shall be permitted. A thread that already has exclusive ownership of a
          given <a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_timed_mutex" title="Class recursive_timed_mutex"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">recursive_timed_mutex</span></code></a> instance
          can call <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock_duration" title="m.timed_lock(rel_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">()</span></code></a>
          or <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>
          to acquire an additional level of ownership of the mutex. <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.unlock" title="m.unlock();"><code class="computeroutput"><span class="identifier">unlock</span><span class="special">()</span></code></a>
          must be called once for each level of ownership acquired by a single thread
          before ownership can be acquired by another thread.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.mutex_types.recursive_timed_mutex.nativehandle"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.recursive_timed_mutex.nativehandle" title="Member function native_handle()">Member
          function <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">typedef</span> <span class="identifier">platform</span><span class="special">-</span><span class="identifier">specific</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">native_handle_type</span><span class="special">;</span>
<span class="identifier">native_handle_type</span> <span class="identifier">native_handle</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Returns an instance of <code class="computeroutput"><span class="identifier">native_handle_type</span></code>
                  that can be used with platform-specific APIs to manipulate the
                  underlying implementation. If no such instance exists, <code class="computeroutput"><span class="identifier">native_handle</span><span class="special">()</span></code>
                  and <code class="computeroutput"><span class="identifier">native_handle_type</span></code>
                  are not present.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_types.shared_mutex"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.shared_mutex" title="Class shared_mutex -- C++14">Class
        <code class="computeroutput"><span class="identifier">shared_mutex</span></code> -- C++14</a>
</h4></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">shared_mutex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">class</span> <span class="identifier">shared_mutex</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">shared_mutex</span><span class="special">(</span><span class="identifier">shared_mutex</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">shared_mutex</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">shared_mutex</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">shared_mutex</span><span class="special">();</span>
    <span class="special">~</span><span class="identifier">shared_mutex</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock_shared</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_shared</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_shared_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_shared_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">void</span> <span class="identifier">unlock_shared</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>

<span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_PROVIDES_DEPRECATED_FEATURES_SINCE_V3_0_0</span>
    <span class="comment">// use upgrade_mutex instead.</span>
    <span class="keyword">void</span> <span class="identifier">lock_upgrade</span><span class="special">();</span> <span class="comment">// EXTENSION</span>
    <span class="keyword">void</span> <span class="identifier">unlock_upgrade</span><span class="special">();</span> <span class="comment">// EXTENSION</span>

    <span class="keyword">void</span> <span class="identifier">unlock_upgrade_and_lock</span><span class="special">();</span> <span class="comment">// EXTENSION</span>
    <span class="keyword">void</span> <span class="identifier">unlock_and_lock_upgrade</span><span class="special">();</span> <span class="comment">// EXTENSION</span>
    <span class="keyword">void</span> <span class="identifier">unlock_and_lock_shared</span><span class="special">();</span> <span class="comment">// EXTENSION</span>
    <span class="keyword">void</span> <span class="identifier">unlock_upgrade_and_lock_shared</span><span class="special">();</span> <span class="comment">// EXTENSION</span>
<span class="preprocessor">#endif</span>

<span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_USES_DATETIME</span>
    <span class="keyword">bool</span> <span class="identifier">timed_lock_shared</span><span class="special">(</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">timeout</span><span class="special">);</span> <span class="comment">// DEPRECATED</span>
    <span class="keyword">bool</span> <span class="identifier">timed_lock</span><span class="special">(</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">timeout</span><span class="special">);</span> <span class="comment">// DEPRECATED</span>
<span class="preprocessor">#endif</span>

<span class="special">};</span>
</pre>
<p>
          The class <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_mutex</span></code> provides an implementation
          of a multiple-reader / single-writer mutex. It implements the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable" title="SharedLockable Concept -- C++14"><code class="computeroutput"><span class="identifier">SharedLockable</span></code> concept</a>.
        </p>
<p>
          Multiple concurrent calls to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>,
          <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_for" title="m.try_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_for</span></code></a><span class="special">()</span></code>,
          <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until" title="m.try_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_until</span></code></a><span class="special">()</span></code>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared" title="m.lock_shared()"><code class="computeroutput"><span class="identifier">lock_shared</span><span class="special">()</span></code></a>,
          <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_for" title="m.try_lock_shared_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_shared_for</span></code></a><span class="special">()</span></code>,
          <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_until" title="m.try_lock_shared_until(abs_time))"><code class="computeroutput"><span class="identifier">try_lock_shared_until</span></code></a><span class="special">()</span></code>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared" title="m.try_lock_shared()"><code class="computeroutput"><span class="identifier">try_lock_shared</span><span class="special">()</span></code></a>
          and <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.timed_lock_shared" title="m.timed_lock_shared(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock_shared</span><span class="special">()</span></code></a>
          are permitted.
        </p>
<p>
          Note the the lack of reader-writer priority policies in shared_mutex. This
          is due to an algorithm credited to Alexander Terekhov which lets the OS
          decide which thread is the next to get the lock without caring whether
          a unique lock or shared lock is being sought. This results in a complete
          lack of reader or writer starvation. It is simply fair.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_types.upgrade_mutex"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.upgrade_mutex" title="Class upgrade_mutex -- EXTENSION">Class
        <code class="computeroutput"><span class="identifier">upgrade_mutex</span></code> -- EXTENSION</a>
</h4></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">shared_mutex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">class</span> <span class="identifier">upgrade_mutex</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">upgrade_mutex</span><span class="special">(</span><span class="identifier">upgrade_mutex</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">upgrade_mutex</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">upgrade_mutex</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">upgrade_mutex</span><span class="special">();</span>
    <span class="special">~</span><span class="identifier">upgrade_mutex</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock_shared</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_shared</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_shared_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_shared_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">void</span> <span class="identifier">unlock_shared</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock_upgrade</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_upgrade_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_upgrade_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">void</span> <span class="identifier">unlock_upgrade</span><span class="special">();</span>

    <span class="comment">// Shared &lt;-&gt; Exclusive</span>

<span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSIONS</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
<span class="preprocessor">#endif</span>
    <span class="keyword">void</span> <span class="identifier">unlock_and_lock_shared</span><span class="special">();</span>

    <span class="comment">// Shared &lt;-&gt; Upgrade</span>

<span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_PROVIDES_SHARED_MUTEX_UPWARDS_CONVERSIONS</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock_upgrade</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock_upgrade_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock_upgrade_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
<span class="preprocessor">#endif</span>
    <span class="keyword">void</span> <span class="identifier">unlock_upgrade_and_lock_shared</span><span class="special">();</span>

    <span class="comment">// Upgrade &lt;-&gt; Exclusive</span>

    <span class="keyword">void</span> <span class="identifier">unlock_upgrade_and_lock</span><span class="special">();</span>
<span class="preprocessor">#if</span>    <span class="identifier">defined</span><span class="special">(</span><span class="identifier">BOOST_THREAD_PLATFORM_PTHREAD</span><span class="special">)</span>
    <span class="special">||</span> <span class="identifier">defined</span><span class="special">(</span><span class="identifier">BOOST_THREAD_PROVIDES_GENERIC_SHARED_MUTEX_ON_WIN</span><span class="special">)</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_upgrade_and_lock</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_upgrade_and_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_upgrade_and_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
<span class="preprocessor">#endif</span>
    <span class="keyword">void</span> <span class="identifier">unlock_and_lock_upgrade</span><span class="special">();</span>
<span class="special">};</span>
</pre>
<p>
          The class <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">upgrade_mutex</span></code> provides an implementation
          of a multiple-reader / single-writer mutex. It implements the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable" title="UpgradeLockable Concept -- EXTENSION"><code class="computeroutput"><span class="identifier">UpgradeLockable</span></code> concept</a>.
        </p>
<p>
          Multiple concurrent calls to <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.basic_lockable.lock" title="m.lock();"><code class="computeroutput"><span class="identifier">lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.lockable.try_lock" title="m.try_lock()"><code class="computeroutput"><span class="identifier">try_lock</span><span class="special">()</span></code></a>,
          <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_for" title="m.try_lock_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_for</span></code></a><span class="special">()</span></code>,
          <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.try_lock_until" title="m.try_lock_until(abs_time)"><code class="computeroutput"><span class="identifier">try_lock_until</span></code></a><span class="special">()</span></code>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.timed_lockable.timed_lock" title="m.timed_lock(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock</span><span class="special">()</span></code></a>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.lock_shared" title="m.lock_shared()"><code class="computeroutput"><span class="identifier">lock_shared</span><span class="special">()</span></code></a>,
          <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_for" title="m.try_lock_shared_for(rel_time)"><code class="computeroutput"><span class="identifier">try_lock_shared_for</span></code></a><span class="special">()</span></code>,
          <code class="computeroutput"><a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared_until" title="m.try_lock_shared_until(abs_time))"><code class="computeroutput"><span class="identifier">try_lock_shared_until</span></code></a><span class="special">()</span></code>,
          <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.try_lock_shared" title="m.try_lock_shared()"><code class="computeroutput"><span class="identifier">try_lock_shared</span><span class="special">()</span></code></a>
          and <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.shared_lockable.timed_lock_shared" title="m.timed_lock_shared(abs_time)"><code class="computeroutput"><span class="identifier">timed_lock_shared</span><span class="special">()</span></code></a>
          are permitted.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.mutex_types.null_mutex"></a><a class="link" href="synchronization.html#thread.synchronization.mutex_types.null_mutex" title="Class null_mutex -- EXTENSION">Class
        <code class="computeroutput"><span class="identifier">null_mutex</span></code> -- EXTENSION</a>
</h4></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">null_mutex</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">class</span> <span class="identifier">null_mutex</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">null_mutex</span><span class="special">(</span><span class="identifier">null_mutex</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">null_mutex</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">null_mutex</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">null_mutex</span><span class="special">();</span>
    <span class="special">~</span><span class="identifier">null_mutex</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock_shared</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_shared</span><span class="special">();</span>
 <span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_USES_CHRONO</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_shared_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_shared_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
 <span class="preprocessor">#endif</span>
    <span class="keyword">void</span> <span class="identifier">unlock_shared</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock</span><span class="special">();</span>
 <span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_USES_CHRONO</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
 <span class="preprocessor">#endif</span>
    <span class="keyword">void</span> <span class="identifier">unlock</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">lock_upgrade</span><span class="special">();</span>
 <span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_USES_CHRONO</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_upgrade_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_lock_upgrade_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
 <span class="preprocessor">#endif</span>
    <span class="keyword">void</span> <span class="identifier">unlock_upgrade</span><span class="special">();</span>

    <span class="comment">// Shared &lt;-&gt; Exclusive</span>

    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock</span><span class="special">();</span>
 <span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_USES_CHRONO</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
 <span class="preprocessor">#endif</span>
    <span class="keyword">void</span> <span class="identifier">unlock_and_lock_shared</span><span class="special">();</span>

    <span class="comment">// Shared &lt;-&gt; Upgrade</span>

    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock_upgrade</span><span class="special">();</span>
 <span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_USES_CHRONO</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock_upgrade_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_shared_and_lock_upgrade_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
 <span class="preprocessor">#endif</span>
    <span class="keyword">void</span> <span class="identifier">unlock_upgrade_and_lock_shared</span><span class="special">();</span>

    <span class="comment">// Upgrade &lt;-&gt; Exclusive</span>

    <span class="keyword">void</span> <span class="identifier">unlock_upgrade_and_lock</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_upgrade_and_lock</span><span class="special">();</span>
 <span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_USES_CHRONO</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_upgrade_and_lock_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">try_unlock_upgrade_and_lock_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
 <span class="preprocessor">#endif</span>
    <span class="keyword">void</span> <span class="identifier">unlock_and_lock_upgrade</span><span class="special">();</span>
<span class="special">};</span>
</pre>
<p>
          The class <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">null_mutex</span></code> provides a no-op implementation
          of a multiple-reader / single-writer mutex. It is a model of the <a class="link" href="synchronization.html#thread.synchronization.mutex_concepts.upgrade_lockable" title="UpgradeLockable Concept -- EXTENSION"><code class="computeroutput"><span class="identifier">UpgradeLockable</span></code></a> concept.
        </p>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.condvar_ref"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref" title="Condition Variables">Condition Variables</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable">Class
        <code class="computeroutput"><span class="identifier">condition_variable</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any">Class
        <code class="computeroutput"><span class="identifier">condition_variable_any</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition">Typedef
        <code class="computeroutput"><span class="identifier">condition</span></code> DEPRECATED V3</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.notify_all_at_thread_exit">Non-member
        Function <code class="computeroutput"><span class="identifier">notify_all_at_thread_exit</span></code>()</a></span></dt>
</dl></div>
<h5>
<a name="thread.synchronization.condvar_ref.h0"></a>
        <span class="phrase"><a name="thread.synchronization.condvar_ref.synopsis"></a></span><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.synopsis">Synopsis</a>
      </h5>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">enum</span> <span class="keyword">class</span> <span class="identifier">cv_status</span><span class="special">;</span>
  <span class="special">{</span>
    <span class="identifier">no_timeout</span><span class="special">,</span>
    <span class="identifier">timeout</span>
  <span class="special">};</span>
  <span class="keyword">class</span> <span class="identifier">condition_variable</span><span class="special">;</span>
  <span class="keyword">class</span> <span class="identifier">condition_variable_any</span><span class="special">;</span>
  <span class="keyword">void</span> <span class="identifier">notify_all_at_thread_exit</span><span class="special">(</span><span class="identifier">condition_variable</span><span class="special">&amp;</span> <span class="identifier">cond</span><span class="special">,</span> <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">lk</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
        The classes <code class="computeroutput"><span class="identifier">condition_variable</span></code>
        and <code class="computeroutput"><span class="identifier">condition_variable_any</span></code>
        provide a mechanism for one thread to wait for notification from another
        thread that a particular condition has become true. The general usage pattern
        is that one thread locks a mutex and then calls <code class="computeroutput"><span class="identifier">wait</span></code>
        on an instance of <code class="computeroutput"><span class="identifier">condition_variable</span></code>
        or <code class="computeroutput"><span class="identifier">condition_variable_any</span></code>.
        When the thread is woken from the wait, then it checks to see if the appropriate
        condition is now true, and continues if so. If the condition is not true,
        then the thread then calls <code class="computeroutput"><span class="identifier">wait</span></code>
        again to resume waiting. In the simplest case, this condition is just a boolean
        variable:
      </p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">condition_variable</span> <span class="identifier">cond</span><span class="special">;</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span> <span class="identifier">mut</span><span class="special">;</span>
<span class="keyword">bool</span> <span class="identifier">data_ready</span><span class="special">;</span>

<span class="keyword">void</span> <span class="identifier">process_data</span><span class="special">();</span>

<span class="keyword">void</span> <span class="identifier">wait_for_data_to_process</span><span class="special">()</span>
<span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">lock</span><span class="special">(</span><span class="identifier">mut</span><span class="special">);</span>
    <span class="keyword">while</span><span class="special">(!</span><span class="identifier">data_ready</span><span class="special">)</span>
    <span class="special">{</span>
        <span class="identifier">cond</span><span class="special">.</span><span class="identifier">wait</span><span class="special">(</span><span class="identifier">lock</span><span class="special">);</span>
    <span class="special">}</span>
    <span class="identifier">process_data</span><span class="special">();</span>
<span class="special">}</span>
</pre>
<p>
        Notice that the <code class="computeroutput"><span class="identifier">lock</span></code> is passed
        to <code class="computeroutput"><span class="identifier">wait</span></code>: <code class="computeroutput"><span class="identifier">wait</span></code>
        will atomically add the thread to the set of threads waiting on the condition
        variable, and unlock the mutex. When the thread is woken, the mutex will
        be locked again before the call to <code class="computeroutput"><span class="identifier">wait</span></code>
        returns. This allows other threads to acquire the mutex in order to update
        the shared data, and ensures that the data associated with the condition
        is correctly synchronized.
      </p>
<p>
        In the mean time, another thread sets the condition to <code class="computeroutput"><span class="keyword">true</span></code>,
        and then calls either <code class="computeroutput"><span class="identifier">notify_one</span></code>
        or <code class="computeroutput"><span class="identifier">notify_all</span></code> on the condition
        variable to wake one waiting thread or all the waiting threads respectively.
      </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">retrieve_data</span><span class="special">();</span>
<span class="keyword">void</span> <span class="identifier">prepare_data</span><span class="special">();</span>

<span class="keyword">void</span> <span class="identifier">prepare_data_for_processing</span><span class="special">()</span>
<span class="special">{</span>
    <span class="identifier">retrieve_data</span><span class="special">();</span>
    <span class="identifier">prepare_data</span><span class="special">();</span>
    <span class="special">{</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">lock_guard</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">lock</span><span class="special">(</span><span class="identifier">mut</span><span class="special">);</span>
        <span class="identifier">data_ready</span><span class="special">=</span><span class="keyword">true</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="identifier">cond</span><span class="special">.</span><span class="identifier">notify_one</span><span class="special">();</span>
<span class="special">}</span>
</pre>
<p>
        Note that the same mutex is locked before the shared data is updated, but
        that the mutex does not have to be locked across the call to <code class="computeroutput"><span class="identifier">notify_one</span></code>.
      </p>
<p>
        This example uses an object of type <code class="computeroutput"><span class="identifier">condition_variable</span></code>,
        but would work just as well with an object of type <code class="computeroutput"><span class="identifier">condition_variable_any</span></code>:
        <code class="computeroutput"><span class="identifier">condition_variable_any</span></code> is
        more general, and will work with any kind of lock or mutex, whereas <code class="computeroutput"><span class="identifier">condition_variable</span></code> requires that the lock
        passed to <code class="computeroutput"><span class="identifier">wait</span></code> is an instance
        of <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span></code>.
        This enables <code class="computeroutput"><span class="identifier">condition_variable</span></code>
        to make optimizations in some cases, based on the knowledge of the mutex
        type; <code class="computeroutput"><span class="identifier">condition_variable_any</span></code>
        typically has a more complex implementation than <code class="computeroutput"><span class="identifier">condition_variable</span></code>.
      </p>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable" title="Class condition_variable">Class
        <code class="computeroutput"><span class="identifier">condition_variable</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.constructor"><code class="computeroutput"><span class="identifier">condition_variable</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.destructor"><code class="computeroutput"><span class="special">~</span><span class="identifier">condition_variable</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.notify_one"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">notify_one</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.notify_all"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">notify_all</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_predicate"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span> <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="identifier">predicate_type</span> <span class="identifier">pred</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.timed_wait"><code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span>
          <span class="keyword">const</span><span class="special">&amp;</span>
          <span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.timed_wait_rel"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">duration_type</span><span class="special">&gt;</span> <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span><span class="identifier">duration_type</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.timed_wait_predicate"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span> <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">predicate_type</span>
          <span class="identifier">pred</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_until"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
          <span class="identifier">cv_status</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span>
          <span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_for"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
          <span class="identifier">cv_status</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span>
          <span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_until_predicate"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span> <span class="keyword">bool</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">Predicate</span>
          <span class="identifier">pred</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_for_predicate"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span> <span class="keyword">bool</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">,</span> <span class="identifier">Predicate</span>
          <span class="identifier">pred</span><span class="special">)</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">//#include &lt;boost/thread/condition_variable.hpp&gt;</span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
    <span class="keyword">class</span> <span class="identifier">condition_variable</span>
    <span class="special">{</span>
    <span class="keyword">public</span><span class="special">:</span>
        <span class="identifier">condition_variable</span><span class="special">();</span>
        <span class="special">~</span><span class="identifier">condition_variable</span><span class="special">();</span>

        <span class="keyword">void</span> <span class="identifier">notify_one</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
        <span class="keyword">void</span> <span class="identifier">notify_all</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>

        <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">);</span>

        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
        <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">predicate_type</span> <span class="identifier">predicate</span><span class="special">);</span>

        <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
        <span class="keyword">typename</span> <span class="identifier">cv_status</span><span class="special">::</span><span class="identifier">type</span>
        <span class="identifier">wait_until</span><span class="special">(</span>
            <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span>
            <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">t</span><span class="special">);</span>

        <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span>
        <span class="keyword">bool</span>
        <span class="identifier">wait_until</span><span class="special">(</span>
            <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span>
            <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">t</span><span class="special">,</span>
            <span class="identifier">Predicate</span> <span class="identifier">pred</span><span class="special">);</span>

        <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
        <span class="keyword">typename</span> <span class="identifier">cv_status</span><span class="special">::</span><span class="identifier">type</span>
        <span class="identifier">wait_for</span><span class="special">(</span>
            <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span>
            <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">d</span><span class="special">);</span>

        <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span>
        <span class="keyword">bool</span>
        <span class="identifier">wait_for</span><span class="special">(</span>
            <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span>
            <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">d</span><span class="special">,</span>
            <span class="identifier">Predicate</span> <span class="identifier">pred</span><span class="special">);</span>

    <span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_USES_DATETIME</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">duration_type</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">duration_type</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">,</span><span class="identifier">predicate_type</span> <span class="identifier">predicate</span><span class="special">);</span>
        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">duration_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">duration_type</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rel_time</span><span class="special">,</span><span class="identifier">predicate_type</span> <span class="identifier">predicate</span><span class="special">);</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">xtime</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>

        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">xtime</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">,</span><span class="identifier">predicate_type</span> <span class="identifier">predicate</span><span class="special">);</span>
    <span class="preprocessor">#endif</span>

    <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.constructor" title="condition_variable()"><code class="computeroutput"><span class="identifier">condition_variable</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Constructs an object of class <code class="computeroutput"><span class="identifier">condition_variable</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.destructor" title="~condition_variable()"><code class="computeroutput"><span class="special">~</span><span class="identifier">condition_variable</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  All threads waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> have been notified by a call
                  to <code class="computeroutput"><span class="identifier">notify_one</span></code> or
                  <code class="computeroutput"><span class="identifier">notify_all</span></code> (though
                  the respective calls to <code class="computeroutput"><span class="identifier">wait</span></code>
                  or <code class="computeroutput"><span class="identifier">timed_wait</span></code> need
                  not have returned).
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Destroys the object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.notify_one"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.notify_one" title="void notify_one()"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">notify_one</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  If any threads are currently <span class="emphasis"><em>blocked</em></span> waiting
                  on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  in a call to <code class="computeroutput"><span class="identifier">wait</span></code>
                  or <code class="computeroutput"><span class="identifier">timed_wait</span></code>,
                  unblocks one of those threads.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.notify_all"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.notify_all" title="void notify_all()"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">notify_all</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  If any threads are currently <span class="emphasis"><em>blocked</em></span> waiting
                  on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  in a call to <code class="computeroutput"><span class="identifier">wait</span></code>
                  or <code class="computeroutput"><span class="identifier">timed_wait</span></code>,
                  unblocks all of those threads.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.wait"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait" title="void wait(boost::unique_lock&lt;boost::mutex&gt;&amp; lock)"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread, and either no other thread is currently
                  waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                  or the execution of the <code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code> member function on the <code class="computeroutput"><span class="identifier">lock</span></code> objects supplied in the
                  calls to <code class="computeroutput"><span class="identifier">wait</span></code> or
                  <code class="computeroutput"><span class="identifier">timed_wait</span></code> in all
                  the threads currently waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> would return the same value
                  as <code class="computeroutput"><span class="identifier">lock</span><span class="special">-&gt;</span><span class="identifier">mutex</span><span class="special">()</span></code>
                  for this call to <code class="computeroutput"><span class="identifier">wait</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically call <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code> and blocks the current thread.
                  The thread will unblock when notified by a call to <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_one</span><span class="special">()</span></code>
                  or <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_all</span><span class="special">()</span></code>,
                  or spuriously. When the thread is unblocked (for whatever reason),
                  the lock is reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> before the call to <code class="computeroutput"><span class="identifier">wait</span></code> returns. The lock is also
                  reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> if the function exits with an
                  exception.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.wait_predicate"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_predicate" title="template&lt;typename predicate_type&gt; void wait(boost::unique_lock&lt;boost::mutex&gt;&amp; lock, predicate_type pred)"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span> <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="identifier">predicate_type</span> <span class="identifier">pred</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  As-if
</p>
<pre class="programlisting"><span class="keyword">while</span><span class="special">(!</span><span class="identifier">pred</span><span class="special">())</span>
<span class="special">{</span>
    <span class="identifier">wait</span><span class="special">(</span><span class="identifier">lock</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
                </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.timed_wait"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.timed_wait" title="bool timed_wait(boost::unique_lock&lt;boost::mutex&gt;&amp; lock,boost::system_time const&amp; abs_time)"><code class="computeroutput"><span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span>
          <span class="keyword">const</span><span class="special">&amp;</span>
          <span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread, and either no other thread is currently
                  waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                  or the execution of the <code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code> member function on the <code class="computeroutput"><span class="identifier">lock</span></code> objects supplied in the
                  calls to <code class="computeroutput"><span class="identifier">wait</span></code> or
                  <code class="computeroutput"><span class="identifier">timed_wait</span></code> in all
                  the threads currently waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> would return the same value
                  as <code class="computeroutput"><span class="identifier">lock</span><span class="special">-&gt;</span><span class="identifier">mutex</span><span class="special">()</span></code>
                  for this call to <code class="computeroutput"><span class="identifier">wait</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically call <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code> and blocks the current thread.
                  The thread will unblock when notified by a call to <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_one</span><span class="special">()</span></code>
                  or <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_all</span><span class="special">()</span></code>,
                  when the time as reported by <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">get_system_time</span><span class="special">()</span></code> would be equal to or later than
                  the specified <code class="computeroutput"><span class="identifier">abs_time</span></code>,
                  or spuriously. When the thread is unblocked (for whatever reason),
                  the lock is reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> before the call to <code class="computeroutput"><span class="identifier">wait</span></code> returns. The lock is also
                  reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> if the function exits with an
                  exception.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">false</span></code> if the call
                  is returning because the time specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>
                  was reached, <code class="computeroutput"><span class="keyword">true</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.timed_wait_rel"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.timed_wait_rel" title="template&lt;typename duration_type&gt; bool timed_wait(boost::unique_lock&lt;boost::mutex&gt;&amp; lock,duration_type const&amp; rel_time)"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">duration_type</span><span class="special">&gt;</span> <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span><span class="identifier">duration_type</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread, and either no other thread is currently
                  waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                  or the execution of the <code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code> member function on the <code class="computeroutput"><span class="identifier">lock</span></code> objects supplied in the
                  calls to <code class="computeroutput"><span class="identifier">wait</span></code> or
                  <code class="computeroutput"><span class="identifier">timed_wait</span></code> in all
                  the threads currently waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> would return the same value
                  as <code class="computeroutput"><span class="identifier">lock</span><span class="special">-&gt;</span><span class="identifier">mutex</span><span class="special">()</span></code>
                  for this call to <code class="computeroutput"><span class="identifier">wait</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically call <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code> and blocks the current thread.
                  The thread will unblock when notified by a call to <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_one</span><span class="special">()</span></code>
                  or <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_all</span><span class="special">()</span></code>,
                  after the period of time indicated by the <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  argument has elapsed, or spuriously. When the thread is unblocked
                  (for whatever reason), the lock is reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code>
                  before the call to <code class="computeroutput"><span class="identifier">wait</span></code>
                  returns. The lock is also reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code>
                  if the function exits with an exception.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">false</span></code> if the call
                  is returning because the time period specified by <code class="computeroutput"><span class="identifier">rel_time</span></code> has elapsed, <code class="computeroutput"><span class="keyword">true</span></code> otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p></dd>
</dl>
</div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
              The duration overload of timed_wait is difficult to use correctly.
              The overload taking a predicate should be preferred in most cases.
            </p></td></tr>
</table></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.timed_wait_predicate"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.timed_wait_predicate" title="template&lt;typename predicate_type&gt; bool timed_wait(boost::unique_lock&lt;boost::mutex&gt;&amp; lock, boost::system_time const&amp; abs_time, predicate_type pred)"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span> <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">predicate_type</span>
          <span class="identifier">pred</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  As-if
</p>
<pre class="programlisting"><span class="keyword">while</span><span class="special">(!</span><span class="identifier">pred</span><span class="special">())</span>
<span class="special">{</span>
    <span class="keyword">if</span><span class="special">(!</span><span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock</span><span class="special">,</span><span class="identifier">abs_time</span><span class="special">))</span>
    <span class="special">{</span>
        <span class="keyword">return</span> <span class="identifier">pred</span><span class="special">();</span>
    <span class="special">}</span>
<span class="special">}</span>
<span class="keyword">return</span> <span class="keyword">true</span><span class="special">;</span>
</pre>
<p>
                </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.wait_until"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_until" title="template &lt;class Clock, class Duration&gt; cv_status wait_until(boost::unique_lock&lt;boost::mutex&gt;&amp; lock, const chrono::time_point&lt;Clock, Duration&gt;&amp; abs_time)"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
          <span class="identifier">cv_status</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span>
          <span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread, and either no other thread is currently
                  waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                  or the execution of the <code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code> member function on the <code class="computeroutput"><span class="identifier">lock</span></code> objects supplied in the
                  calls to <code class="computeroutput"><span class="identifier">wait</span></code> or
                  <code class="computeroutput"><span class="identifier">wait_for</span></code> or <code class="computeroutput"><span class="identifier">wait_until</span></code> in all the threads
                  currently waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> would return the same value
                  as <code class="computeroutput"><span class="identifier">lock</span><span class="special">-&gt;</span><span class="identifier">mutex</span><span class="special">()</span></code>
                  for this call to <code class="computeroutput"><span class="identifier">wait</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically call <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code> and blocks the current thread.
                  The thread will unblock when notified by a call to <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_one</span><span class="special">()</span></code>
                  or <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_all</span><span class="special">()</span></code>,
                  when the time as reported by <code class="computeroutput"><span class="identifier">Clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span></code> would be equal to or later than
                  the specified <code class="computeroutput"><span class="identifier">abs_time</span></code>,
                  or spuriously. When the thread is unblocked (for whatever reason),
                  the lock is reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> before the call to <code class="computeroutput"><span class="identifier">wait</span></code> returns. The lock is also
                  reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> if the function exits with an
                  exception.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">cv_status</span><span class="special">::</span><span class="identifier">timeout</span></code> if the call is returning
                  because the time specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>
                  was reached, <code class="computeroutput"><span class="identifier">cv_status</span><span class="special">::</span><span class="identifier">no_timeout</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.wait_for"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_for" title="template &lt;class Rep, class Period&gt; cv_status wait_for(boost::unique_lock&lt;boost::mutex&gt;&amp; lock, const chrono::duration&lt;Rep, Period&gt;&amp; rel_time)"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
          <span class="identifier">cv_status</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span>
          <span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread, and either no other thread is currently
                  waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                  or the execution of the <code class="computeroutput"><span class="identifier">mutex</span><span class="special">()</span></code> member function on the <code class="computeroutput"><span class="identifier">lock</span></code> objects supplied in the
                  calls to <code class="computeroutput"><span class="identifier">wait</span></code> or
                  <code class="computeroutput"><span class="identifier">wait_until</span></code> or
                  <code class="computeroutput"><span class="identifier">wait_for</span></code> in all
                  the threads currently waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> would return the same value
                  as <code class="computeroutput"><span class="identifier">lock</span><span class="special">-&gt;</span><span class="identifier">mutex</span><span class="special">()</span></code>
                  for this call to <code class="computeroutput"><span class="identifier">wait</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically call <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code> and blocks the current thread.
                  The thread will unblock when notified by a call to <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_one</span><span class="special">()</span></code>
                  or <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_all</span><span class="special">()</span></code>,
                  after the period of time indicated by the <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  argument has elapsed, or spuriously. When the thread is unblocked
                  (for whatever reason), the lock is reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code>
                  before the call to <code class="computeroutput"><span class="identifier">wait</span></code>
                  returns. The lock is also reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code>
                  if the function exits with an exception.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">cv_status</span><span class="special">::</span><span class="identifier">timeout</span> </code> if the call is returning
                  because the time period specified by <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  has elapsed, <code class="computeroutput"><span class="identifier">cv_status</span><span class="special">::</span><span class="identifier">no_timeout</span>
                  </code> otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p></dd>
</dl>
</div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
              The duration overload of timed_wait is difficult to use correctly.
              The overload taking a predicate should be preferred in most cases.
            </p></td></tr>
</table></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.wait_until_predicate"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_until_predicate" title="template &lt;class Clock, class Duration, class Predicate&gt; bool wait_until(boost::unique_lock&lt;boost::mutex&gt;&amp; lock, const chrono::time_point&lt;Clock, Duration&gt;&amp; abs_time, Predicate pred)"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span> <span class="keyword">bool</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">Predicate</span>
          <span class="identifier">pred</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  As-if
</p>
<pre class="programlisting"><span class="keyword">while</span><span class="special">(!</span><span class="identifier">pred</span><span class="special">())</span>
<span class="special">{</span>
    <span class="keyword">if</span><span class="special">(!</span><span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">lock</span><span class="special">,</span><span class="identifier">abs_time</span><span class="special">))</span>
    <span class="special">{</span>
        <span class="keyword">return</span> <span class="identifier">pred</span><span class="special">();</span>
    <span class="special">}</span>
<span class="special">}</span>
<span class="keyword">return</span> <span class="keyword">true</span><span class="special">;</span>
</pre>
<p>
                </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable.wait_for_predicate"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_for_predicate" title="template &lt;class Rep, class Period, class Predicate&gt; bool wait_for(boost::unique_lock&lt;boost::mutex&gt;&amp; lock, const chrono::duration&lt;Rep, Period&gt;&amp; rel_time, Predicate pred)"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span> <span class="keyword">bool</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">,</span> <span class="identifier">Predicate</span>
          <span class="identifier">pred</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  As-if
</p>
<pre class="programlisting"><span class="keyword">return</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">lock</span><span class="special">,</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">steady_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special">+</span> <span class="identifier">d</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">pred</span><span class="special">));</span>
</pre>
<p>
                </p>
</dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any" title="Class condition_variable_any">Class
        <code class="computeroutput"><span class="identifier">condition_variable_any</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.constructor"><code class="computeroutput"><span class="identifier">condition_variable_any</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.destructor"><code class="computeroutput"><span class="special">~</span><span class="identifier">condition_variable_any</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.notify_one"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">notify_one</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.notify_all"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">notify_all</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">&gt;</span> <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span>
          <span class="identifier">lock</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_predicate"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
          <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="identifier">predicate_type</span>
          <span class="identifier">pred</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.timed_wait"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">&gt;</span> <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.timed_wait_rel"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">duration_type</span><span class="special">&gt;</span>
          <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">duration_type</span>
          <span class="keyword">const</span><span class="special">&amp;</span>
          <span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.timed_wait_predicate"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
          <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span>
          <span class="keyword">const</span><span class="special">&amp;</span>
          <span class="identifier">abs_time</span><span class="special">,</span>
          <span class="identifier">predicate_type</span> <span class="identifier">pred</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_until"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">cv_status</span>
          <span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_for"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">cv_status</span>
          <span class="identifier">wait_for</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_until_predicate"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span>
          <span class="keyword">bool</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span>
          <span class="identifier">abs_time</span><span class="special">,</span>
          <span class="identifier">Predicate</span> <span class="identifier">pred</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_for_predicate"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span>
          <span class="keyword">bool</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span>
          <span class="identifier">rel_time</span><span class="special">,</span>
          <span class="identifier">Predicate</span> <span class="identifier">pred</span><span class="special">)</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">//#include &lt;boost/thread/condition_variable.hpp&gt;</span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
    <span class="keyword">class</span> <span class="identifier">condition_variable_any</span>
    <span class="special">{</span>
    <span class="keyword">public</span><span class="special">:</span>
        <span class="identifier">condition_variable_any</span><span class="special">();</span>
        <span class="special">~</span><span class="identifier">condition_variable_any</span><span class="special">();</span>

        <span class="keyword">void</span> <span class="identifier">notify_one</span><span class="special">();</span>
        <span class="keyword">void</span> <span class="identifier">notify_all</span><span class="special">();</span>

        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">&gt;</span>
        <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">);</span>

        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
        <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">predicate_type</span> <span class="identifier">predicate</span><span class="special">);</span>

        <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
        <span class="identifier">cv_status</span> <span class="identifier">wait_until</span><span class="special">(</span>
            <span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span>
            <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">t</span><span class="special">);</span>

        <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">wait_until</span><span class="special">(</span>
            <span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span>
            <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">t</span><span class="special">,</span>
            <span class="identifier">Predicate</span> <span class="identifier">pred</span><span class="special">);</span>


        <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
        <span class="identifier">cv_status</span> <span class="identifier">wait_for</span><span class="special">(</span>
            <span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span>
            <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">d</span><span class="special">);</span>

        <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">wait_for</span><span class="special">(</span>
            <span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span>
            <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">d</span><span class="special">,</span>
            <span class="identifier">Predicate</span> <span class="identifier">pred</span><span class="special">);</span>

    <span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_USES_DATETIME</span>
        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">duration_type</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">duration_type</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">,</span><span class="identifier">predicate_type</span> <span class="identifier">predicate</span><span class="special">);</span>
        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">duration_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">duration_type</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rel_time</span><span class="special">,</span><span class="identifier">predicate_type</span> <span class="identifier">predicate</span><span class="special">);</span>
        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&gt;&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">xtime</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
        <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
        <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">xtime</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">,</span><span class="identifier">predicate_type</span> <span class="identifier">predicate</span><span class="special">);</span>
    <span class="preprocessor">#endif</span>
    <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.constructor" title="condition_variable_any()"><code class="computeroutput"><span class="identifier">condition_variable_any</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Constructs an object of class <code class="computeroutput"><span class="identifier">condition_variable_any</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.destructor" title="~condition_variable_any()"><code class="computeroutput"><span class="special">~</span><span class="identifier">condition_variable_any</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  All threads waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> have been notified by a call
                  to <code class="computeroutput"><span class="identifier">notify_one</span></code> or
                  <code class="computeroutput"><span class="identifier">notify_all</span></code> (though
                  the respective calls to <code class="computeroutput"><span class="identifier">wait</span></code>
                  or <code class="computeroutput"><span class="identifier">timed_wait</span></code> need
                  not have returned).
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Destroys the object.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.notify_one"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.notify_one" title="void notify_one()"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">notify_one</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  If any threads are currently <span class="emphasis"><em>blocked</em></span> waiting
                  on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  in a call to <code class="computeroutput"><span class="identifier">wait</span></code>
                  or <code class="computeroutput"><span class="identifier">timed_wait</span></code>,
                  unblocks one of those threads.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.notify_all"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.notify_all" title="void notify_all()"><code class="computeroutput"><span class="keyword">void</span> <span class="identifier">notify_all</span><span class="special">()</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  If any threads are currently <span class="emphasis"><em>blocked</em></span> waiting
                  on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  in a call to <code class="computeroutput"><span class="identifier">wait</span></code>
                  or <code class="computeroutput"><span class="identifier">timed_wait</span></code>,
                  unblocks all of those threads.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.wait"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait" title="template&lt;typename lock_type&gt; void wait(lock_type&amp; lock)"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">&gt;</span> <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span>
          <span class="identifier">lock</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically call <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code> and blocks the current thread.
                  The thread will unblock when notified by a call to <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_one</span><span class="special">()</span></code>
                  or <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_all</span><span class="special">()</span></code>,
                  or spuriously. When the thread is unblocked (for whatever reason),
                  the lock is reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> before the call to <code class="computeroutput"><span class="identifier">wait</span></code> returns. The lock is also
                  reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> if the function exits with an
                  exception.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.wait_predicate"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_predicate" title="template&lt;typename lock_type,typename predicate_type&gt; void wait(lock_type&amp; lock, predicate_type pred)"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
          <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="identifier">predicate_type</span>
          <span class="identifier">pred</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  As-if
</p>
<pre class="programlisting"><span class="keyword">while</span><span class="special">(!</span><span class="identifier">pred</span><span class="special">())</span>
<span class="special">{</span>
    <span class="identifier">wait</span><span class="special">(</span><span class="identifier">lock</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
                </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.timed_wait"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.timed_wait" title="template&lt;typename lock_type&gt; bool timed_wait(lock_type&amp; lock,boost::system_time const&amp; abs_time)"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">&gt;</span> <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically call <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code> and blocks the current thread.
                  The thread will unblock when notified by a call to <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_one</span><span class="special">()</span></code>
                  or <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_all</span><span class="special">()</span></code>,
                  when the time as reported by <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">get_system_time</span><span class="special">()</span></code> would be equal to or later than
                  the specified <code class="computeroutput"><span class="identifier">abs_time</span></code>,
                  or spuriously. When the thread is unblocked (for whatever reason),
                  the lock is reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> before the call to <code class="computeroutput"><span class="identifier">wait</span></code> returns. The lock is also
                  reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> if the function exits with an
                  exception.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">false</span></code> if the call
                  is returning because the time specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>
                  was reached, <code class="computeroutput"><span class="keyword">true</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.timed_wait_rel"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.timed_wait_rel" title="template&lt;typename lock_type,typename duration_type&gt; bool timed_wait(lock_type&amp; lock,duration_type const&amp; rel_time)"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">duration_type</span><span class="special">&gt;</span>
          <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span><span class="identifier">duration_type</span>
          <span class="keyword">const</span><span class="special">&amp;</span>
          <span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically call <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code> and blocks the current thread.
                  The thread will unblock when notified by a call to <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_one</span><span class="special">()</span></code>
                  or <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_all</span><span class="special">()</span></code>,
                  after the period of time indicated by the <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  argument has elapsed, or spuriously. When the thread is unblocked
                  (for whatever reason), the lock is reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code>
                  before the call to <code class="computeroutput"><span class="identifier">wait</span></code>
                  returns. The lock is also reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code>
                  if the function exits with an exception.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">false</span></code> if the call
                  is returning because the time period specified by <code class="computeroutput"><span class="identifier">rel_time</span></code> has elapsed, <code class="computeroutput"><span class="keyword">true</span></code> otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p></dd>
</dl>
</div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
              The duration overload of timed_wait is difficult to use correctly.
              The overload taking a predicate should be preferred in most cases.
            </p></td></tr>
</table></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.timed_wait_predicate"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.timed_wait_predicate" title="template&lt;typename lock_type,typename predicate_type&gt; bool timed_wait(lock_type&amp; lock, boost::system_time const&amp; abs_time, predicate_type pred)"><code class="computeroutput"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">lock_type</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">predicate_type</span><span class="special">&gt;</span>
          <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span>
          <span class="keyword">const</span><span class="special">&amp;</span>
          <span class="identifier">abs_time</span><span class="special">,</span>
          <span class="identifier">predicate_type</span> <span class="identifier">pred</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  As-if
</p>
<pre class="programlisting"><span class="keyword">while</span><span class="special">(!</span><span class="identifier">pred</span><span class="special">())</span>
<span class="special">{</span>
    <span class="keyword">if</span><span class="special">(!</span><span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">lock</span><span class="special">,</span><span class="identifier">abs_time</span><span class="special">))</span>
    <span class="special">{</span>
        <span class="keyword">return</span> <span class="identifier">pred</span><span class="special">();</span>
    <span class="special">}</span>
<span class="special">}</span>
<span class="keyword">return</span> <span class="keyword">true</span><span class="special">;</span>
</pre>
<p>
                </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.wait_until"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_until" title="template &lt;class lock_type, class Clock, class Duration&gt; cv_status wait_until(lock_type&amp; lock, const chrono::time_point&lt;Clock, Duration&gt;&amp; abs_time)"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">cv_status</span>
          <span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically call <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code> and blocks the current thread.
                  The thread will unblock when notified by a call to <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_one</span><span class="special">()</span></code>
                  or <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_all</span><span class="special">()</span></code>,
                  when the time as reported by <code class="computeroutput"><span class="identifier">Clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span></code> would be equal to or later than
                  the specified <code class="computeroutput"><span class="identifier">abs_time</span></code>,
                  or spuriously. When the thread is unblocked (for whatever reason),
                  the lock is reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> before the call to <code class="computeroutput"><span class="identifier">wait</span></code> returns. The lock is also
                  reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code> if the function exits with an
                  exception.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">cv_status</span><span class="special">::</span><span class="identifier">timeout</span></code> if the call is returning
                  because the time specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>
                  was reached, <code class="computeroutput"><span class="identifier">cv_status</span><span class="special">::</span><span class="identifier">no_timeout</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.wait_for"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_for" title="template &lt;class lock_type, class Rep, class Period&gt; cv_status wait_for(lock_type&amp; lock, const chrono::duration&lt;Rep, Period&gt;&amp; rel_time)"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">cv_status</span>
          <span class="identifier">wait_for</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span>
          <span class="identifier">lock</span><span class="special">,</span>
          <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Atomically call <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">()</span></code> and blocks the current thread.
                  The thread will unblock when notified by a call to <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_one</span><span class="special">()</span></code>
                  or <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">notify_all</span><span class="special">()</span></code>,
                  after the period of time indicated by the <code class="computeroutput"><span class="identifier">rel_time</span></code>
                  argument has elapsed, or spuriously. When the thread is unblocked
                  (for whatever reason), the lock is reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code>
                  before the call to <code class="computeroutput"><span class="identifier">wait</span></code>
                  returns. The lock is also reacquired by invoking <code class="computeroutput"><span class="identifier">lock</span><span class="special">.</span><span class="identifier">lock</span><span class="special">()</span></code>
                  if the function exits with an exception.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">cv_status</span><span class="special">::</span><span class="identifier">timeout</span></code> if the call is returning
                  because the time specified by <code class="computeroutput"><span class="identifier">abs_time</span></code>
                  was reached, <code class="computeroutput"><span class="identifier">cv_status</span><span class="special">::</span><span class="identifier">no_timeout</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Postcondition:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">lock</span></code> is locked
                  by the current thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p></dd>
</dl>
</div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
              The duration overload of timed_wait is difficult to use correctly.
              The overload taking a predicate should be preferred in most cases.
            </p></td></tr>
</table></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.wait_until_predicate"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_until_predicate" title="template &lt;class lock_type, class Clock, class Duration, class Predicate&gt; bool wait_until(lock_type&amp; lock, const chrono::time_point&lt;Clock, Duration&gt;&amp; abs_time, Predicate pred)"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span>
          <span class="keyword">bool</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span>
          <span class="identifier">abs_time</span><span class="special">,</span>
          <span class="identifier">Predicate</span> <span class="identifier">pred</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  As-if
</p>
<pre class="programlisting"><span class="keyword">while</span><span class="special">(!</span><span class="identifier">pred</span><span class="special">())</span>
<span class="special">{</span>
    <span class="keyword">if</span><span class="special">(!</span><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_until" title="template &lt;class lock_type, class Clock, class Duration&gt; cv_status wait_until(lock_type&amp; lock, const chrono::time_point&lt;Clock, Duration&gt;&amp; abs_time)"><code class="computeroutput"><span class="identifier">wait_until</span></code></a><span class="special">(</span><span class="identifier">lock</span><span class="special">,</span><span class="identifier">abs_time</span><span class="special">))</span>
    <span class="special">{</span>
        <span class="keyword">return</span> <span class="identifier">pred</span><span class="special">();</span>
    <span class="special">}</span>
<span class="special">}</span>
<span class="keyword">return</span> <span class="keyword">true</span><span class="special">;</span>
</pre>
<p>
                </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.condvar_ref.condition_variable_any.wait_for_predicate"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable_any.wait_for_predicate" title="template &lt;class lock_type, class Rep, class Period, class Predicate&gt; bool wait_for(lock_type&amp; lock, const chrono::duration&lt;Rep, Period&gt;&amp; rel_time, Predicate pred)"><code class="computeroutput"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Predicate</span><span class="special">&gt;</span>
          <span class="keyword">bool</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="identifier">lock_type</span><span class="special">&amp;</span> <span class="identifier">lock</span><span class="special">,</span> <span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span>
          <span class="identifier">rel_time</span><span class="special">,</span>
          <span class="identifier">Predicate</span> <span class="identifier">pred</span><span class="special">)</span></code></a>
</h5></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  As-if
</p>
<pre class="programlisting"><span class="keyword">return</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="identifier">lock</span><span class="special">,</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">steady_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special">+</span> <span class="identifier">d</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">pred</span><span class="special">));</span>
</pre>
<p>
                </p>
</dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.condvar_ref.condition"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition" title="Typedef condition DEPRECATED V3">Typedef
        <code class="computeroutput"><span class="identifier">condition</span></code> DEPRECATED V3</a>
</h4></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/condition.hpp&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>

  <span class="keyword">typedef</span> <span class="identifier">condition_variable_any</span> <span class="identifier">condition</span><span class="special">;</span>

<span class="special">}</span>
</pre>
<p>
          The typedef <code class="computeroutput"><span class="identifier">condition</span></code> is
          provided for backwards compatibility with previous boost releases.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.condvar_ref.notify_all_at_thread_exit"></a><a class="link" href="synchronization.html#thread.synchronization.condvar_ref.notify_all_at_thread_exit" title="Non-member Function notify_all_at_thread_exit()">Non-member
        Function <code class="computeroutput"><span class="identifier">notify_all_at_thread_exit</span></code>()</a>
</h4></div></div></div>
<pre class="programlisting"><span class="comment">// #include &lt;boost/thread/condition_variable.hpp&gt;</span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">void</span> <span class="identifier">notify_all_at_thread_exit</span><span class="special">(</span><span class="identifier">condition_variable</span><span class="special">&amp;</span> <span class="identifier">cond</span><span class="special">,</span> <span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">lk</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                <code class="computeroutput"><span class="identifier">lk</span></code> is locked by the
                calling thread and either no other thread is waiting on <code class="computeroutput"><span class="identifier">cond</span></code>, or <code class="computeroutput"><span class="identifier">lk</span><span class="special">.</span><span class="identifier">mutex</span><span class="special">()</span></code> returns the same value for each
                of the lock arguments supplied by all concurrently waiting (via
                <code class="computeroutput"><span class="identifier">wait</span></code>, <code class="computeroutput"><span class="identifier">wait_for</span></code>, or <code class="computeroutput"><span class="identifier">wait_until</span></code>)
                threads.
              </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                transfers ownership of the lock associated with <code class="computeroutput"><span class="identifier">lk</span></code>
                into internal storage and schedules <code class="computeroutput"><span class="identifier">cond</span></code>
                to be notified when the current thread exits, after all objects of
                thread storage duration associated with the current thread have been
                destroyed. This notification shall be as if
              </p>
<p>
</p>
<pre class="programlisting"><span class="identifier">lk</span><span class="special">.</span><span class="identifier">unlock</span><span class="special">();</span>
<span class="identifier">cond</span><span class="special">.</span><span class="identifier">notify_all</span><span class="special">();</span>
</pre>
<p>
              </p>
</dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.once"></a><a class="link" href="synchronization.html#thread.synchronization.once" title="One-time Initialization">One-time Initialization</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.once.once_flag">Typedef <code class="computeroutput"><span class="identifier">once_flag</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.once.call_once">Non-member function
        <code class="computeroutput"><span class="identifier">call_once</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">once</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">struct</span> <span class="identifier">once_flag</span><span class="special">;</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Function</span><span class="special">,</span> <span class="keyword">class</span> <span class="special">...</span><span class="identifier">ArgTypes</span><span class="special">&gt;</span>
  <span class="keyword">inline</span> <span class="keyword">void</span> <span class="identifier">call_once</span><span class="special">(</span><span class="identifier">once_flag</span><span class="special">&amp;</span> <span class="identifier">flag</span><span class="special">,</span> <span class="identifier">Function</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">ArgTypes</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span><span class="special">);</span>

<span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_PROVIDES_DEPRECATED_FEATURES_SINCE_V3_0_0</span>
  <span class="keyword">void</span> <span class="identifier">call_once</span><span class="special">(</span><span class="keyword">void</span> <span class="special">(*</span><span class="identifier">func</span><span class="special">)(),</span><span class="identifier">once_flag</span><span class="special">&amp;</span> <span class="identifier">flag</span><span class="special">);</span>
<span class="preprocessor">#endif</span>

<span class="special">}</span>
</pre>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
          the variadic prototype is provided only on C++11 compilers supporting variadic
          templates, otherwise the interface is limited up to 3 parameters.
        </p></td></tr>
</table></div>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
          the move semantics is ensured only on C++11 compilers supporting SFINAE
          expression, decltype N3276 and auto. Waiting for a boost::bind that is
          move aware.
        </p></td></tr>
</table></div>
<p>
        <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">call_once</span></code> provides a mechanism for ensuring
        that an initialization routine is run exactly once without data races or
        deadlocks.
      </p>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.once.once_flag"></a><a class="link" href="synchronization.html#thread.synchronization.once.once_flag" title="Typedef once_flag">Typedef <code class="computeroutput"><span class="identifier">once_flag</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_THREAD_PROVIDES_ONCE_CXX11</span>
<span class="keyword">struct</span> <span class="identifier">once_flag</span>
<span class="special">{</span>
  <span class="identifier">constexprr</span> <span class="identifier">once_flag</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="identifier">once_flag</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">once_flag</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
  <span class="identifier">once_flag</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="keyword">const</span> <span class="identifier">once_flag</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
<span class="special">};</span>
<span class="preprocessor">#else</span>
<span class="keyword">typedef</span> <span class="identifier">platform</span><span class="special">-</span><span class="identifier">specific</span><span class="special">-</span><span class="identifier">type</span> <span class="identifier">once_flag</span><span class="special">;</span>
<span class="preprocessor">#define</span> <span class="identifier">BOOST_ONCE_INIT</span> <span class="identifier">platform</span><span class="special">-</span><span class="identifier">specific</span><span class="special">-</span><span class="identifier">initializer</span>
<span class="preprocessor">#endif</span>
</pre>
<p>
          Objects of type <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">once_flag</span></code> shall be initialized with
          <code class="computeroutput"><span class="identifier">BOOST_ONCE_INIT</span></code> if BOOST_THREAD_PROVIDES_ONCE_CXX11
          is not defined
        </p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">once_flag</span> <span class="identifier">f</span><span class="special">=</span><span class="identifier">BOOST_ONCE_INIT</span><span class="special">;</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.once.call_once"></a><a class="link" href="synchronization.html#thread.synchronization.once.call_once" title="Non-member function call_once">Non-member function
        <code class="computeroutput"><span class="identifier">call_once</span></code></a>
</h4></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Function</span><span class="special">,</span> <span class="keyword">class</span> <span class="special">...</span><span class="identifier">ArgTypes</span><span class="special">&gt;</span>
<span class="keyword">inline</span> <span class="keyword">void</span> <span class="identifier">call_once</span><span class="special">(</span><span class="identifier">once_flag</span><span class="special">&amp;</span> <span class="identifier">flag</span><span class="special">,</span> <span class="identifier">Function</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">ArgTypes</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                <code class="computeroutput"><span class="identifier">Function</span></code> and each
                or the <code class="computeroutput"><span class="identifier">ArgTypes</span></code> are
                <code class="computeroutput"><span class="identifier">MoveConstructible</span></code>
                and <code class="computeroutput"><span class="identifier">invoke</span><span class="special">(</span><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Function</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">)),</span>
                <span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">ArgTypes</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">))...)</span></code>
                shall be well formed.
              </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                Calls to <code class="computeroutput"><span class="identifier">call_once</span></code>
                on the same <code class="computeroutput"><span class="identifier">once_flag</span></code>
                object are serialized. If there has been no prior effective <code class="computeroutput"><span class="identifier">call_once</span></code> on the same <code class="computeroutput"><span class="identifier">once_flag</span></code> object, the argument
                <code class="computeroutput"><span class="identifier">func</span></code> is called as-if
                by invoking <code class="computeroutput"><span class="identifier">invoke</span><span class="special">(</span><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Function</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">)),</span> <span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">ArgTypes</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">))...)</span></code>, and the invocation of <code class="computeroutput"><span class="identifier">call_once</span></code> is effective if and only
                if <code class="computeroutput"><span class="identifier">invoke</span><span class="special">(</span><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Function</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">)),</span>
                <span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">ArgTypes</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">))...)</span></code>
                returns without exception. If an exception is thrown, the exception
                is propagated to the caller. If there has been a prior effective
                <code class="computeroutput"><span class="identifier">call_once</span></code> on the
                same <code class="computeroutput"><span class="identifier">once_flag</span></code> object,
                the <code class="computeroutput"><span class="identifier">call_once</span></code> returns
                without invoking <code class="computeroutput"><span class="identifier">func</span></code>.
              </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                The completion of an effective <code class="computeroutput"><span class="identifier">call_once</span></code>
                invocation on a <code class="computeroutput"><span class="identifier">once_flag</span></code>
                object, synchronizes with all subsequent <code class="computeroutput"><span class="identifier">call_once</span></code>
                invocations on the same <code class="computeroutput"><span class="identifier">once_flag</span></code>
                object.
              </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                <code class="computeroutput"><span class="identifier">thread_resource_error</span></code>
                when the effects cannot be achieved or any exception propagated from
                <code class="computeroutput"><span class="identifier">func</span></code>.
              </p></dd>
<dt><span class="term">Note:</span></dt>
<dd><p>
                The function passed to <code class="computeroutput"><span class="identifier">call_once</span></code>
                must not also call <code class="computeroutput"><span class="identifier">call_once</span></code>
                passing the same <code class="computeroutput"><span class="identifier">once_flag</span></code>
                object. This may cause deadlock, or invoking the passed function
                a second time. The alternative is to allow the second call to return
                immediately, but that assumes the code knows it has been called recursively,
                and can proceed even though the call to <code class="computeroutput"><span class="identifier">call_once</span></code>
                didn't actually call the function, in which case it could also avoid
                calling <code class="computeroutput"><span class="identifier">call_once</span></code>
                recursively.
              </p></dd>
<dt><span class="term">Note:</span></dt>
<dd><p>
                On some compilers this function has some restrictions, e.g. if variadic
                templates are not supported the number of arguments is limited to
                3; .
              </p></dd>
</dl>
</div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">call_once</span><span class="special">(</span><span class="keyword">void</span> <span class="special">(*</span><span class="identifier">func</span><span class="special">)(),</span><span class="identifier">once_flag</span><span class="special">&amp;</span> <span class="identifier">flag</span><span class="special">);</span>
</pre>
<p>
          This second overload is provided for backwards compatibility and is deprecated.
          The effects of <code class="computeroutput"><span class="identifier">call_once</span><span class="special">(</span><span class="identifier">func</span><span class="special">,</span><span class="identifier">flag</span><span class="special">)</span></code> shall be the same as those of <code class="computeroutput"><span class="identifier">call_once</span><span class="special">(</span><span class="identifier">flag</span><span class="special">,</span><span class="identifier">func</span><span class="special">)</span></code>.
        </p>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.barriers"></a><a class="link" href="synchronization.html#thread.synchronization.barriers" title="Barriers -- EXTENSION">Barriers -- EXTENSION</a>
</h3></div></div></div>
<div class="toc"><dl class="toc"><dt><span class="section"><a href="synchronization.html#thread.synchronization.barriers.barrier">Class <code class="computeroutput"><span class="identifier">barrier</span></code></a></span></dt></dl></div>
<p>
        A barrier is a simple concept. Also known as a <span class="emphasis"><em>rendezvous</em></span>,
        it is a synchronization point between multiple threads. The barrier is configured
        for a particular number of threads (<code class="computeroutput"><span class="identifier">n</span></code>),
        and as threads reach the barrier they must wait until all <code class="computeroutput"><span class="identifier">n</span></code>
        threads have arrived. Once the <code class="computeroutput"><span class="identifier">n</span></code>-th
        thread has reached the barrier, all the waiting threads can proceed, and
        the barrier is reset.
      </p>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.barriers.barrier"></a><a class="link" href="synchronization.html#thread.synchronization.barriers.barrier" title="Class barrier">Class <code class="computeroutput"><span class="identifier">barrier</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.barriers.barrier.constructor__barrier_unsigned_int__">Constructor
          <code class="computeroutput"><span class="identifier">barrier</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.barriers.barrier.constructor__barrier_unsigned_int__f____">Constructor
          <code class="computeroutput"><span class="identifier">barrier</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.barriers.barrier.destructor___barrier___">Destructor
          <code class="computeroutput"><span class="special">~</span><span class="identifier">barrier</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.barriers.barrier.member_function__wait___">Member
          Function <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.barriers.barrier.member_function__count_down_and_wait___">Member
          Function <code class="computeroutput"><span class="identifier">count_down_and_wait</span><span class="special">()</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">barrier</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">class</span> <span class="identifier">barrier</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">barrier</span><span class="special">(</span><span class="identifier">barrier</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">barrier</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">barrier</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">barrier</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span> <span class="identifier">count</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
    <span class="identifier">barrier</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span> <span class="identifier">count</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;);</span>

    <span class="special">~</span><span class="identifier">barrier</span><span class="special">();</span>

    <span class="keyword">bool</span> <span class="identifier">wait</span><span class="special">();</span>
    <span class="keyword">void</span> <span class="identifier">count_down_and_wait</span><span class="special">();</span>
<span class="special">};</span>
</pre>
<p>
          Instances of <a class="link" href="synchronization.html#thread.synchronization.barriers.barrier" title="Class barrier"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">barrier</span></code></a> are not copyable or movable.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.barriers.barrier.constructor__barrier_unsigned_int__"></a><a class="link" href="synchronization.html#thread.synchronization.barriers.barrier.constructor__barrier_unsigned_int__" title="Constructor barrier(unsigned int)">Constructor
          <code class="computeroutput"><span class="identifier">barrier</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span><span class="special">)</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="identifier">barrier</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span> <span class="identifier">count</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Construct a barrier for <code class="computeroutput"><span class="identifier">count</span></code>
                  threads.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.barriers.barrier.constructor__barrier_unsigned_int__f____"></a><a class="link" href="synchronization.html#thread.synchronization.barriers.barrier.constructor__barrier_unsigned_int__f____" title="Constructor barrier(unsigned int, F&amp;&amp;)">Constructor
          <code class="computeroutput"><span class="identifier">barrier</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;)</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="identifier">barrier</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">int</span> <span class="identifier">count</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">completion</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The result type of the completion function call <code class="computeroutput"><span class="identifier">completion</span><span class="special">()</span></code> is <code class="computeroutput"><span class="keyword">void</span></code>
                  or <code class="computeroutput"><span class="keyword">unsigned</span> <span class="keyword">int</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Construct a barrier for <code class="computeroutput"><span class="identifier">count</span></code>
                  threads and a completion function <code class="computeroutput"><span class="identifier">completion</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.barriers.barrier.destructor___barrier___"></a><a class="link" href="synchronization.html#thread.synchronization.barriers.barrier.destructor___barrier___" title="Destructor ~barrier()">Destructor
          <code class="computeroutput"><span class="special">~</span><span class="identifier">barrier</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">barrier</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  No threads are waiting on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Destroys <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.barriers.barrier.member_function__wait___"></a><a class="link" href="synchronization.html#thread.synchronization.barriers.barrier.member_function__wait___" title="Member Function wait()">Member
          Function <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">wait</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Block until <code class="computeroutput"><span class="identifier">count</span></code>
                  threads have called <code class="computeroutput"><span class="identifier">wait</span></code>
                  or <code class="computeroutput"><span class="identifier">count_down_and_wait</span></code>
                  on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                  When the <code class="computeroutput"><span class="identifier">count</span></code>-th
                  thread calls <code class="computeroutput"><span class="identifier">wait</span></code>,
                  the barrier is reset and all waiting threads are unblocked. The
                  reset depends on whether the barrier was constructed with a completion
                  function or not. If there is no completion function or if the completion
                  function result is void, the reset consists in restoring the original
                  count. Otherwise the rest consist in assigning the result of the
                  completion function (which must not be 0).
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="keyword">true</span></code> for exactly one
                  thread from each batch of waiting threads, <code class="computeroutput"><span class="keyword">false</span></code>
                  otherwise.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p>
</dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code>
                  is an <span class="emphasis"><em>interruption point</em></span>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.barriers.barrier.member_function__count_down_and_wait___"></a><a class="link" href="synchronization.html#thread.synchronization.barriers.barrier.member_function__count_down_and_wait___" title="Member Function count_down_and_wait()">Member
          Function <code class="computeroutput"><span class="identifier">count_down_and_wait</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">count_down_and_wait</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Block until <code class="computeroutput"><span class="identifier">count</span></code>
                  threads have called <code class="computeroutput"><span class="identifier">wait</span></code>
                  or <code class="computeroutput"><span class="identifier">count_down_and_wait</span></code>
                  on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                  When the <code class="computeroutput"><span class="identifier">count</span></code>-th
                  thread calls <code class="computeroutput"><span class="identifier">wait</span></code>,
                  the barrier is reset and all waiting threads are unblocked. The
                  reset depends on whether the barrier was constructed with a completion
                  function or not. If there is no completion function or if the completion
                  function result is void, the reset consists in restoring the original
                  count. Otherwise the rest consist in assigning the result of the
                  completion function (which must not be 0).
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p>
</dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">count_down_and_wait</span><span class="special">()</span></code> is an <span class="emphasis"><em>interruption
                  point</em></span>.
                </p></dd>
</dl>
</div>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.latches"></a><a class="link" href="synchronization.html#thread.synchronization.latches" title="Latches -- EXPERIMENTAL">Latches -- EXPERIMENTAL</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.introdcution">Introdcution</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.examples">Examples</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.latch">Class <code class="computeroutput"><span class="identifier">latch</span></code></a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.latches.introdcution"></a><a class="link" href="synchronization.html#thread.synchronization.latches.introdcution" title="Introdcution">Introdcution</a>
</h4></div></div></div>
<p>
          Latches are a thread co-ordination mechanism that allow one or more threads
          to block until one or more threads have reached a point.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.latches.examples"></a><a class="link" href="synchronization.html#thread.synchronization.latches.examples" title="Examples">Examples</a>
</h4></div></div></div>
<p>
          Sample use cases for the latch include:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              Setting multiple threads to perform a task, and then waiting until
              all threads have reached a common point.
            </li>
<li class="listitem">
              Creating multiple threads, which wait for a signal before advancing
              beyond a common point.
            </li>
</ul></div>
<p>
          An example of the first use case would be as follows:
        </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">DoWork</span><span class="special">(</span><span class="identifier">thread_pool</span><span class="special">*</span> <span class="identifier">pool</span><span class="special">)</span> <span class="special">{</span>
  <span class="identifier">latch</span> <span class="identifier">completion_latch</span><span class="special">(</span><span class="identifier">NTASKS</span><span class="special">);</span>
  <span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">NTASKS</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">pool</span><span class="special">-&gt;</span><span class="identifier">submit</span><span class="special">([&amp;]</span> <span class="special">{</span>
      <span class="comment">// perform work</span>
      <span class="special">...</span>
      <span class="identifier">completion_latch</span><span class="special">.</span><span class="identifier">count_down</span><span class="special">();</span>
    <span class="special">}));</span>
  <span class="special">}</span>
  <span class="comment">// Block until work is done</span>
  <span class="identifier">completion_latch</span><span class="special">.</span><span class="identifier">wait</span><span class="special">();</span>
<span class="special">}</span>
</pre>
<p>
          An example of the second use case is shown below. We need to load data
          and then process it using a number of threads. Loading the data is I/O
          bound, whereas starting threads and creating data structures is CPU bound.
          By running these in parallel, throughput can be increased.
        </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">DoWork</span><span class="special">()</span> <span class="special">{</span>
  <span class="identifier">latch</span> <span class="identifier">start_latch</span><span class="special">(</span><span class="number">1</span><span class="special">);</span>
  <span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">thread</span><span class="special">*&gt;</span> <span class="identifier">workers</span><span class="special">;</span>
  <span class="keyword">for</span> <span class="special">(</span><span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">NTHREADS</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span><span class="special">)</span> <span class="special">{</span>
    <span class="identifier">workers</span><span class="special">.</span><span class="identifier">push_back</span><span class="special">(</span><span class="keyword">new</span> <span class="identifier">thread</span><span class="special">([&amp;]</span> <span class="special">{</span>
      <span class="comment">// Initialize data structures. This is CPU bound.</span>
      <span class="special">...</span>
      <span class="identifier">start_latch</span><span class="special">.</span><span class="identifier">wait</span><span class="special">();</span>
      <span class="comment">// perform work</span>
      <span class="special">...</span>
    <span class="special">}));</span>
  <span class="special">}</span>
  <span class="comment">// Load input data. This is I/O bound.</span>
  <span class="special">...</span>
  <span class="comment">// Threads can now start processing</span>
  <span class="identifier">start_latch</span><span class="special">.</span><span class="identifier">count_down</span><span class="special">();</span>
  <span class="special">}</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.latches.latch"></a><a class="link" href="synchronization.html#thread.synchronization.latches.latch" title="Class latch">Class <code class="computeroutput"><span class="identifier">latch</span></code></a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.latch.constructor__latch_std__size_t__">Constructor
          <code class="computeroutput"><span class="identifier">latch</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">)</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.latch.destructor___latch___">Destructor
          <code class="computeroutput"><span class="special">~</span><span class="identifier">latch</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.latch.wait">Member
          Function <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.latch.try_wait">Member
          Function <code class="computeroutput"><span class="identifier">try_wait</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.latch.wait_for">Member
          Function <code class="computeroutput"><span class="identifier">wait_for</span><span class="special">()</span>
          </code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.latch.wait_until">Member
          Function <code class="computeroutput"><span class="identifier">wait_until</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.latch.count_down">Member
          Function <code class="computeroutput"><span class="identifier">count_down</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.latch.count_down_and_wait">Member
          Function <code class="computeroutput"><span class="identifier">count_down_and_wait</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.latches.latch.reset">Member
          Function <code class="computeroutput"><span class="identifier">reset</span><span class="special">()</span></code></a></span></dt>
</dl></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">latch</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>

<span class="keyword">class</span> <span class="identifier">latch</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">latch</span><span class="special">(</span><span class="identifier">latch</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">latch</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">latch</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">latch</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">count</span><span class="special">);</span>
    <span class="special">~</span><span class="identifier">latch</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">try_wait</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="identifier">cv_status</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="identifier">cv_status</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">void</span> <span class="identifier">count_down</span><span class="special">();</span>
    <span class="keyword">void</span> <span class="identifier">count_down_and_wait</span><span class="special">();</span>

<span class="special">};</span>
</pre>
<p>
          A latch maintains an internal counter that is initialized when the latch
          is created. One or more threads may block waiting until the counter is
          decremented to 0.
        </p>
<p>
          Instances of <a class="link" href="synchronization.html#thread.synchronization.latches.latch" title="Class latch"><code class="computeroutput"><span class="identifier">latch</span></code></a> are not copyable or movable.
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.latches.latch.constructor__latch_std__size_t__"></a><a class="link" href="synchronization.html#thread.synchronization.latches.latch.constructor__latch_std__size_t__" title="Constructor latch(std::size_t)">Constructor
          <code class="computeroutput"><span class="identifier">latch</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span><span class="special">)</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="identifier">latch</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">count</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Construct a latch with is initial value for the internal counter.
                </p></dd>
<dt><span class="term">Note:</span></dt>
<dd><p>
                  The counter could be zero.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.latches.latch.destructor___latch___"></a><a class="link" href="synchronization.html#thread.synchronization.latches.latch.destructor___latch___" title="Destructor ~latch()">Destructor
          <code class="computeroutput"><span class="special">~</span><span class="identifier">latch</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">latch</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Precondition:</span></dt>
<dd><p>
                  No threads are waiting or invoking count_down on <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Destroys <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                  latch.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Nothing.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.latches.latch.wait"></a><a class="link" href="synchronization.html#thread.synchronization.latches.latch.wait" title="Member Function wait()">Member
          Function <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">wait</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Block the calling thread until the internal count reaches the value
                  zero. Then all waiting threads are unblocked.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p>
</dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code>
                  is an <span class="emphasis"><em>interruption point</em></span>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.latches.latch.try_wait"></a><a class="link" href="synchronization.html#thread.synchronization.latches.latch.try_wait" title="Member Function try_wait()">Member
          Function <code class="computeroutput"><span class="identifier">try_wait</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">try_wait</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  Returns true if the internal count is 0, and false otherwise. Does
                  not block the calling thread.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.latches.latch.wait_for"></a><a class="link" href="synchronization.html#thread.synchronization.latches.latch.wait_for" title="Member Function wait_for()">Member
          Function <code class="computeroutput"><span class="identifier">wait_for</span><span class="special">()</span>
          </code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
<span class="identifier">cv_status</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Block the calling thread until the internal count reaches the value
                  zero or the duration has been elapsed. If no timeout, all waiting
                  threads are unblocked.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  cv_status::no_timeout if the internal count is 0, and cv_status::timeout
                  if duration has been elapsed.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p>
</dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">wait_for</span><span class="special">()</span></code>
                  is an <span class="emphasis"><em>interruption point</em></span>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.latches.latch.wait_until"></a><a class="link" href="synchronization.html#thread.synchronization.latches.latch.wait_until" title="Member Function wait_until()">Member
          Function <code class="computeroutput"><span class="identifier">wait_until</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">lock_type</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
<span class="identifier">cv_status</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Block the calling thread until the internal count reaches the value
                  zero or the time_point has been reached. If no timeout, all waiting
                  threads are unblocked.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  cv_status::no_timeout if the internal count is 0, and cv_status::timeout
                  if time_point has been reached.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p>
</dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">wait_until</span><span class="special">()</span></code>
                  is an <span class="emphasis"><em>interruption point</em></span>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.latches.latch.count_down"></a><a class="link" href="synchronization.html#thread.synchronization.latches.latch.count_down" title="Member Function count_down()">Member
          Function <code class="computeroutput"><span class="identifier">count_down</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">count_down</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The internal counter is non zero.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Decrements the internal count by 1, and returns. If the count reaches
                  0, any threads blocked in wait() will be released.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p>
</dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">count_down</span><span class="special">()</span></code>
                  is an <span class="emphasis"><em>interruption point</em></span>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.latches.latch.count_down_and_wait"></a><a class="link" href="synchronization.html#thread.synchronization.latches.latch.count_down_and_wait" title="Member Function count_down_and_wait()">Member
          Function <code class="computeroutput"><span class="identifier">count_down_and_wait</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">count_down_and_wait</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  The internal counter is non zero.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Decrements the internal count by 1. If the resulting count is not
                  0, blocks the calling thread until the internal count is decremented
                  to 0 by one or more other threads calling count_down() or count_down_and_wait().
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the wait
                  was interrupted by a call to <a class="link" href="thread_management.html#thread.thread_management.thread.interrupt" title="Member function interrupt() EXTENSION"><code class="computeroutput"><span class="identifier">interrupt</span><span class="special">()</span></code></a>
                  on the <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code></a> object associated
                  with the current thread of execution.
                </p>
</dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">count_down_and_wait</span><span class="special">()</span></code> is an <span class="emphasis"><em>interruption
                  point</em></span>.
                </p></dd>
</dl>
</div>
</div>
<p>
          [
        </p>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.latches.latch.reset"></a><a class="link" href="synchronization.html#thread.synchronization.latches.latch.reset" title="Member Function reset()">Member
          Function <code class="computeroutput"><span class="identifier">reset</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="identifier">reset</span><span class="special">(</span> <span class="identifier">size_t</span> <span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  This function may only be invoked when there are no other threads
                  currently inside the waiting functions.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  Resets the latch with a new value for the initial thread count.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_resource_error</span></code> if an error
                  occurs.
                </p></dd>
</dl>
</div>
</div>
<p>
          ]
        </p>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.executors"></a><a class="link" href="synchronization.html#thread.synchronization.executors" title="Executors and Schedulers -- EXPERIMENTAL">Executors and Schedulers
      -- EXPERIMENTAL</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.introduction">Introduction</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.examples">Examples</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.rationale">Design
        Rationale</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref">Reference</a></span></dt>
</dl></div>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
          These features are experimental and subject to change in future versions.
          There are not too much tests yet, so it is possible that you can find out
          some trivial bugs :(
        </p></td></tr>
</table></div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
          These features are based on the <a href="http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2013/n3785.pdf" target="_top"><span class="bold"><strong>N3785 - Executors and Schedulers revision 3</strong></span></a>
          C++1y proposal from Chris Mysen, Niklas Gustafsson, Matt Austern, Jeffrey
          Yasskin. The text that follows has been adapted from this paper to show
          the differences.
        </p></td></tr>
</table></div>
<p>
        Executors are objects that can execute units of work packaged as function
        objects. Boost.Thread differs from N3785 mainly in the an Executor doesn't
        needs to inherit from an abstract class Executor. Static polymorphism is
        used instead and type erasure is used internally.
      </p>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.executors.introduction"></a><a class="link" href="synchronization.html#thread.synchronization.executors.introduction" title="Introduction">Introduction</a>
</h4></div></div></div>
<p>
          Multithreaded programs often involve discrete (sometimes small) units of
          work that are executed asynchronously. This often involves passing work
          units to some component that manages execution. We already have boost::async,
          which potentially executes a function asynchronously and eventually returns
          its result in a future. (&#8220;As if&#8221; by launching a new thread.)
        </p>
<p>
          If there is a regular stream of small work items then we almost certainly
          don&#8217;t want to launch a new thread for each, and it&#8217;s likely that we
          want at least some control over which thread(s) execute which items. It
          is often convenient to represent that control as multiple executor objects.
          This allows programs to start executors when necessary, switch from one
          executor to another to control execution policy, and use multiple executors
          to prevent interference and thread exhaustion. Several possible implementations
          exist of the executor class and in practice there are a number of main
          groups of executors which have been found to be useful in real-world code
          (more implementations exist, this is simply a high level classification
          of them). These differ along a couple main dimensions, how many execution
          contexts will be used, how they are selected, and how they are prioritized.
        </p>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
              Thread Pools
              <div class="orderedlist"><ol class="orderedlist" type="a">
<li class="listitem">
                    Simple unbounded thread pool, which can queue up an unbounded
                    amount of work and maintains a dedicated set of threads (up to
                    some maximum) which dequeue and execute work as available.
                  </li>
<li class="listitem">
                    Bounded thread pools, which can be implemented as a specialization
                    of the previous ones with a bounded queue or semaphore, which
                    limits the amount of queuing in an attempt to bound the time
                    spent waiting to execute and/or limit resource utilization for
                    work tasks which hold state which is expensive to hold.
                  </li>
<li class="listitem">
                    Thread-spawning executors, in which each work always executes
                    in a new thread.
                  </li>
<li class="listitem">
                    Prioritized thread pools, which have works which are not equally
                    prioritized such that work can move to the front of the execution
                    queue if necessary. This requires a special comparator or prioritization
                    function to allow for work ordering and normally is implemented
                    as a blocking priority queue in front of the pool instead of
                    a blocking queue. This has many uses but is a somewhat specialized
                    in nature and would unnecessarily clutter the initial interface.
                  </li>
<li class="listitem">
                    Work stealing thread pools, this is a specialized use case and
                    is encapsulated in the ForkJoinPool in java, which allows lightweight
                    work to be created by tasks in the pool and either run by the
                    same thread for invocation efficiency or stolen by another thread
                    without additional work. These have been left out until there
                    is a more concrete fork-join proposal or until there is a more
                    clear need as these can be complicated to implement
                  </li>
</ol></div>
            </li>
<li class="listitem">
              Mutual exclusion executors
              <div class="orderedlist"><ol class="orderedlist" type="a">
<li class="listitem">
                    Serial executors, which guarantee all work to be executed such
                    that no two works will execute concurrently. This allows for
                    a sequence of operations to be queued in sequence and that sequential
                    order is maintained and work can be queued on a separate thread
                    but with no mutual exclusion required.
                  </li>
<li class="listitem">
                    Loop executor, in which one thread donates itself to the executor
                    to execute all queued work. This is related to the serial executor
                    in that it guarantees mutual exclusion, but instead guarantees
                    a particular thread will execute the work. These are particularly
                    useful for testing purposes where code assumes an executor but
                    testing code desires control over execution.
                  </li>
<li class="listitem">
                    GUI thread executor, where a GUI framework can expose an executor
                    interface to allow other threads to queue up work to be executed
                    as part of the GUI thread. This behaves similarly to a loop executor,
                    but must be implemented as a custom interface as part of the
                    framework.
                  </li>
</ol></div>
            </li>
<li class="listitem">
              Inline executors, which execute inline to the thread which calls submit().
              This has no queuing and behaves like a normal executor, but always
              uses the caller&#8217;s thread to execute. This allows parallel execution
              of works, though. This type of executor is often useful when there
              is an executor required by an interface, but when for performance reasons
              it&#8217;s better not to queue work or switch threads. This is often very
              useful as an optimization for work continuations which should execute
              immediately or quickly and can also be useful for optimizations when
              an interface requires an executor but the work tasks are too small
              to justify the overhead of a full thread pool.
            </li>
</ol></div>
<p>
          A question arises of which of these executors (or others) be included in
          this library. There are use cases for these and many other executors. Often
          it is useful to have more than one implemented executor (e.g. the thread
          pool) to have more precise control of where the work is executed due to
          the existence of a GUI thread, or for testing purposes. A few core executors
          are frequently useful and these have been outlined here as the core of
          what should be in this library, if common use cases arise for alternative
          executor implementations, they can be added in the future. The current
          set provided here are: a basic thread pool <code class="computeroutput"><span class="identifier">basic_thread_pool</span></code>,
          a serial executor <code class="computeroutput"><span class="identifier">serial_executor</span></code>,
          a loop executor <code class="computeroutput"><span class="identifier">loop_executor</span></code>,
          an inline executor <code class="computeroutput"><span class="identifier">inline_executor</span></code>
          and a thread-spawning executor <code class="computeroutput"><span class="identifier">thread_executor</span></code>.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.executors.examples"></a><a class="link" href="synchronization.html#thread.synchronization.executors.examples" title="Examples">Examples</a>
</h4></div></div></div>
<div class="toc"><dl class="toc"><dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.examples.quick_sort">Parallel
          Quick Sort</a></span></dt></dl></div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.examples.quick_sort"></a><a class="link" href="synchronization.html#thread.synchronization.executors.examples.quick_sort" title="Parallel Quick Sort">Parallel
          Quick Sort</a>
</h5></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">executors</span><span class="special">/</span><span class="identifier">basic_thread_pool</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">future</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">numeric</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">algorithm</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">functional</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">list</span><span class="special">&gt;</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">struct</span> <span class="identifier">sorter</span>
<span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">basic_thread_pool</span> <span class="identifier">pool</span><span class="special">;</span>
    <span class="keyword">typedef</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">return_type</span><span class="special">;</span>

    <span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">do_sort</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">chunk_data</span><span class="special">)</span>
    <span class="special">{</span>
        <span class="keyword">if</span><span class="special">(</span><span class="identifier">chunk_data</span><span class="special">.</span><span class="identifier">empty</span><span class="special">())</span> <span class="special">{</span>
            <span class="keyword">return</span> <span class="identifier">chunk_data</span><span class="special">;</span>
        <span class="special">}</span>

        <span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">result</span><span class="special">;</span>
        <span class="identifier">result</span><span class="special">.</span><span class="identifier">splice</span><span class="special">(</span><span class="identifier">result</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span><span class="identifier">chunk_data</span><span class="special">,</span> <span class="identifier">chunk_data</span><span class="special">.</span><span class="identifier">begin</span><span class="special">());</span>
        <span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">partition_val</span><span class="special">=*</span><span class="identifier">result</span><span class="special">.</span><span class="identifier">begin</span><span class="special">();</span>

        <span class="keyword">typename</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">iterator</span> <span class="identifier">divide_point</span> <span class="special">=</span>
            <span class="identifier">std</span><span class="special">::</span><span class="identifier">partition</span><span class="special">(</span><span class="identifier">chunk_data</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">chunk_data</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span>
                           <span class="special">[&amp;](</span><span class="identifier">T</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">val</span><span class="special">){</span><span class="keyword">return</span> <span class="identifier">val</span><span class="special">&lt;</span><span class="identifier">partition_val</span><span class="special">;});</span>

        <span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">new_lower_chunk</span><span class="special">;</span>
        <span class="identifier">new_lower_chunk</span><span class="special">.</span><span class="identifier">splice</span><span class="special">(</span><span class="identifier">new_lower_chunk</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span> <span class="identifier">chunk_data</span><span class="special">,</span>
                               <span class="identifier">chunk_data</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span> <span class="identifier">divide_point</span><span class="special">);</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="special">&gt;</span> <span class="identifier">new_lower</span> <span class="special">=</span>
             <span class="identifier">boost</span><span class="special">::</span><span class="identifier">async</span><span class="special">(</span><span class="identifier">pool</span><span class="special">,</span> <span class="special">&amp;</span><span class="identifier">sorter</span><span class="special">::</span><span class="identifier">do_sort</span><span class="special">,</span> <span class="keyword">this</span><span class="special">,</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">new_lower_chunk</span><span class="special">));</span>
        <span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">new_higher</span><span class="special">(</span><span class="identifier">do_sort</span><span class="special">(</span><span class="identifier">chunk_data</span><span class="special">));</span>
        <span class="identifier">result</span><span class="special">.</span><span class="identifier">splice</span><span class="special">(</span><span class="identifier">result</span><span class="special">.</span><span class="identifier">end</span><span class="special">(),</span><span class="identifier">new_higher</span><span class="special">);</span>
        <span class="keyword">while</span><span class="special">(!</span><span class="identifier">new_lower</span><span class="special">.</span><span class="identifier">is_ready</span><span class="special">())</span> <span class="special">{</span>
            <span class="identifier">pool</span><span class="special">.</span><span class="identifier">schedule_one_or_yield</span><span class="special">();</span>
        <span class="special">}</span>
        <span class="identifier">result</span><span class="special">.</span><span class="identifier">splice</span><span class="special">(</span><span class="identifier">result</span><span class="special">.</span><span class="identifier">begin</span><span class="special">(),</span><span class="identifier">new_lower</span><span class="special">.</span><span class="identifier">get</span><span class="special">());</span>
        <span class="keyword">return</span> <span class="identifier">result</span><span class="special">;</span>
    <span class="special">}</span>
<span class="special">};</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">parallel_quick_sort</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">list</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;&amp;</span> <span class="identifier">input</span><span class="special">)</span> <span class="special">{</span>
    <span class="keyword">if</span><span class="special">(</span><span class="identifier">input</span><span class="special">.</span><span class="identifier">empty</span><span class="special">())</span> <span class="special">{</span>
        <span class="keyword">return</span> <span class="identifier">input</span><span class="special">;</span>
    <span class="special">}</span>
    <span class="identifier">sorter</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">s</span><span class="special">;</span>
    <span class="keyword">return</span> <span class="identifier">s</span><span class="special">.</span><span class="identifier">do_sort</span><span class="special">(</span><span class="identifier">input</span><span class="special">);</span>
<span class="special">}</span>
</pre>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.executors.rationale"></a><a class="link" href="synchronization.html#thread.synchronization.executors.rationale" title="Design Rationale">Design
        Rationale</a>
</h4></div></div></div>
<p>
          The authors of Boost.Thread have taken a different approach respect to
          N3785. Instead of basing all the design on an abstract executor class we
          make executor concepts. We believe that this is the good direction as a
          static polymorphic executor can be seen as a dynamic polymorphic executor
          using a simple adaptor. We believe also that it would make the library
          more usable, and more convenient for users.
        </p>
<p>
          The major design decisions concern deciding what a unit of work is, how
          to manage with units of work and time related functions in a polymorphic
          way.
        </p>
<p>
          An Executor is an object that schedules the closures that have been submitted
          to it, usually asynchronously. There could be multiple models of the Executor
          class. Some specific design notes:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              Thread pools are well know models of the Executor concept, and this
              library does indeed include a basic_thread_pool class, but other implementations
              also exist, including the ability to schedule work on GUI threads,
              scheduling work on a donor thread, as well as several specializations
              of thread pools.
            </li>
<li class="listitem">
              The choice of which executor to use is explicit. This is important
              for reasons described in the Motivation section. In particular, consider
              the common case of an asynchronous operation that itself spawns asynchronous
              operations. If both operations ran on the same executor, and if that
              executor had a bounded number of worker threads, then we could get
              deadlock. Programs often deal with such issues by splitting different
              kinds of work between different executors.
            </li>
<li class="listitem">
              Even if there could be a strong value in having a default executor,
              that can be used when detailed control is unnecessary, the authors
              don't know how to implement it in a portable and robust way.
            </li>
<li class="listitem">
              The library provides Executors based on static and dynamic polymorphism.
              The static polymorphism interface is intended to be used on contexts
              that need to have the best performances. The dynamic polymorphism interface
              has the advantage to been able to change the executor a function is
              using without making it a template and is possible to pass executors
              across a binary interface. For some applications, the cost of an additional
              virtual dispatch could be almost certainly negligible compared to the
              other operations involved.
            </li>
<li class="listitem">
              Conceptually, an executor puts closures on a queue and at some point
              executes them. The queue is always unbounded, so adding a closure to
              an executor never blocks. (Defining &#8220;never blocks&#8221; formally is
              challenging, but informally we just mean that submit() is an ordinary
              function that executes something and returns, rather than waiting for
              the completion of some potentially long running operation in another
              thread.)
            </li>
</ul></div>
<h6>
<a name="thread.synchronization.executors.rationale.h0"></a>
          <span class="phrase"><a name="thread.synchronization.executors.rationale.closure"></a></span><a class="link" href="synchronization.html#thread.synchronization.executors.rationale.closure">Closure</a>
        </h6>
<p>
          One important question is just what a closure is. This library has a very
          simple answer: a closure is a <code class="computeroutput"><span class="identifier">Callable</span></code>
          with no parameters and returning <code class="computeroutput"><span class="keyword">void</span></code>.
        </p>
<p>
          N3785 choose the more specific <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">function</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">()&gt;</span></code> as it provides only dynamic polymorphism
          and states that in practice the implementation of a template based approach
          or another approach is impractical. The authors of this library think that
          the template based approach is compatible with a dynamic based approach.
          They give some arguments:
        </p>
<p>
          The first one is that a virtual function can not be a template. This is
          true but it is also true that the executor interface can provide the template
          functions that call to the virtual public functions. Another reason they
          give is that "a template parameter would complicate the interface
          without adding any real generality. In the end an executor class is going
          to need some kind of type erasure to handle all the different kinds of
          function objects with <code class="computeroutput"><span class="keyword">void</span><span class="special">()</span></code> signature, and that&#8217;s exactly what
          std::function already does". We think that it is up to the executor
          to manage with this implementation details, not to the user.
        </p>
<p>
          We share all the argument they give related to the <code class="computeroutput"><span class="keyword">void</span><span class="special">()</span></code> interface of the work unit. A work unit
          is a closure that takes no arguments and returns no value. This is indeed
          a limitation on user code, but combined with <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">async</span></code>
          taking executors as parameters the user has all what she needs.
        </p>
<p>
          The third one is related to performance. They assert that "any mechanism
          for storing closures on an executor&#8217;s queue will have to use some form
          of type erasure. There&#8217;s no reason to believe that a custom closure mechanism,
          written just for std::executor and used nowhere else within the standard
          library, would be better in that respect than <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">function</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">()&gt;</span></code>". We believe that the implementation
          can do better that storing the closure on a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">function</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">()&gt;</span></code>. e.g. the implementation can use
          intrusive data to store the closure and the pointers to other nodes needed
          to store the closures in a given order.
        </p>
<p>
          In addition <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">function</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">()&gt;</span></code>
          can not be constructed by moving the closure, so e.g. <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">packaged_task</span></code>
          could not be a Closure.
        </p>
<h6>
<a name="thread.synchronization.executors.rationale.h1"></a>
          <span class="phrase"><a name="thread.synchronization.executors.rationale.scheduled_work"></a></span><a class="link" href="synchronization.html#thread.synchronization.executors.rationale.scheduled_work">Scheduled
          work</a>
        </h6>
<p>
          The approach of this library respect to scheduled work of the N3785 proposal
          is quite different. Instead of adding the scheduled operations to a specific
          scheduled_executor polymorphic interface, we opt by adding a specific
          <code class="computeroutput"><span class="identifier">scheduler</span></code> class that is
          not an executor and knows how to manage with the scheduling of timed tasks
          <code class="computeroutput"><span class="identifier">submit_at</span></code>/<code class="computeroutput"><span class="identifier">submit_after</span></code>.
        </p>
<p>
          <code class="computeroutput"><span class="identifier">scheduler</span></code> provides executor
          factories <code class="computeroutput"><span class="identifier">at</span></code>/<code class="computeroutput"><span class="identifier">after</span></code> given a specific <code class="computeroutput"><span class="identifier">time_point</span></code> or a <code class="computeroutput"><span class="identifier">duration</span></code>.
          The built executors wrap a reference to this scheduler and the time at
          which the submitted task will be executed.
        </p>
<p>
          If we want to schedule these operations on an existing executor (as <code class="computeroutput"><span class="identifier">serial_executor</span></code> does), these classes
          provide a <code class="computeroutput"><span class="identifier">on</span></code> factory taking
          another executor as parameter and wraps both instance on the returned executor.
        </p>
<pre class="programlisting"><span class="identifier">sch</span><span class="special">.</span><span class="identifier">on</span><span class="special">(</span><span class="identifier">tp</span><span class="special">).</span><span class="identifier">after</span><span class="special">(</span><span class="identifier">seconds</span><span class="special">(</span><span class="identifier">i</span><span class="special">)).</span><span class="identifier">submit</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">bind</span><span class="special">(</span><span class="identifier">fn</span><span class="special">,</span><span class="identifier">i</span><span class="special">));</span>
</pre>
<p>
          This has several advantages:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              The scheduled operations are available for all the executors via wrappers.
            </li>
<li class="listitem">
              The template functions could accept any chrono <code class="computeroutput"><span class="identifier">time_point</span></code>
              and <code class="computeroutput"><span class="identifier">duration</span></code> respectively
              as we are not working with virtual functions.
            </li>
</ul></div>
<p>
          In order to manage with all the clocks, this library propose generic solution.
          <code class="computeroutput"><span class="identifier">scheduler</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">&gt;</span></code>
          know how to manage with the <code class="computeroutput"><span class="identifier">submit_at</span></code>/<code class="computeroutput"><span class="identifier">submit_after</span></code> <code class="computeroutput"><span class="identifier">Clock</span><span class="special">::</span><span class="identifier">time_point</span></code>/<code class="computeroutput"><span class="identifier">Clock</span><span class="special">::</span><span class="identifier">duration</span></code> tasks. Note that the durations
          on different clocks differ.
        </p>
<h6>
<a name="thread.synchronization.executors.rationale.h2"></a>
          <span class="phrase"><a name="thread.synchronization.executors.rationale.not_handled_exceptions"></a></span><a class="link" href="synchronization.html#thread.synchronization.executors.rationale.not_handled_exceptions">Not
          Handled Exceptions</a>
        </h6>
<p>
          As in N3785 and based on the same design decision than <code class="computeroutput"><span class="identifier">std</span></code>/<code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span></code> if a user closure throws an exception,
          the executor must call the <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">terminate</span></code>
          function. Note that when we combine <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">async</span></code>
          and <code class="computeroutput"><span class="identifier">Executors</span></code>, the exception
          will be caught by the closure associated to the returned future, so that
          the exception is stored on the returned future, as for the other <code class="computeroutput"><span class="identifier">async</span></code> overloads.
        </p>
<h6>
<a name="thread.synchronization.executors.rationale.h3"></a>
          <span class="phrase"><a name="thread.synchronization.executors.rationale.at_thread_entry"></a></span><a class="link" href="synchronization.html#thread.synchronization.executors.rationale.at_thread_entry">At
          thread entry</a>
        </h6>
<p>
          It is common idiom to set some thread local variable at the beginning of
          a thread. As Executors could instantiate threads internally these Executors
          shall have the ability to call a user specific function at thread entry
          on the executor constructor.
        </p>
<p>
          For executors that don't instantiate any thread and that would use the
          current thread this function shall be called only for the thread calling
          the <code class="computeroutput"><span class="identifier">at_thread_entry</span></code> member
          function.
        </p>
<h6>
<a name="thread.synchronization.executors.rationale.h4"></a>
          <span class="phrase"><a name="thread.synchronization.executors.rationale.cancelation"></a></span><a class="link" href="synchronization.html#thread.synchronization.executors.rationale.cancelation">Cancelation</a>
        </h6>
<p>
          The library does not provision yet for the ability to cancel/interrupt
          work, though this is a commonly requested feature.
        </p>
<p>
          This could be managed externally by an additional cancelation object that
          can be shared between the creator of the unit of work and the unit of work.
        </p>
<p>
          We can think also of a cancelable closure that could be used in a more
          transparent way.
        </p>
<p>
          An alternative is to make async return a cancelable_task but this will
          need also a cancelable closure.
        </p>
<h6>
<a name="thread.synchronization.executors.rationale.h5"></a>
          <span class="phrase"><a name="thread.synchronization.executors.rationale.current_executor"></a></span><a class="link" href="synchronization.html#thread.synchronization.executors.rationale.current_executor">Current
          executor</a>
        </h6>
<p>
          The library does not provision for the ability to get the current executor,
          though having access to it could simplify a lot the user code.
        </p>
<p>
          The reason is that the user can always use a thread_local variable and
          reset it using the <code class="computeroutput"><span class="identifier">at_thread_entry</span>
          </code> member function.
        </p>
<pre class="programlisting"><span class="keyword">thread_local</span> <span class="identifier">current_executor_state_type</span> <span class="identifier">current_executor_state</span><span class="special">;</span>
<span class="identifier">executor</span><span class="special">*</span> <span class="identifier">current_executor</span><span class="special">()</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">current_executor_state</span><span class="special">.</span><span class="identifier">current_executor</span><span class="special">();</span> <span class="special">}</span>
<span class="identifier">basic_thread_pool</span> <span class="identifier">pool</span><span class="special">(</span>
	<span class="comment">// at_thread_entry</span>
	<span class="special">[](</span><span class="identifier">basic_thread_pool</span><span class="special">&amp;</span> <span class="identifier">pool</span><span class="special">)</span> <span class="special">{</span>
		<span class="identifier">current_executor_state</span><span class="special">.</span><span class="identifier">set_current_executor</span><span class="special">(</span><span class="identifier">pool</span><span class="special">);</span>
	<span class="special">}</span>
<span class="special">);</span>
</pre>
<p>
          [
        </p>
<h6>
<a name="thread.synchronization.executors.rationale.h6"></a>
          <span class="phrase"><a name="thread.synchronization.executors.rationale.default_executor"></a></span><a class="link" href="synchronization.html#thread.synchronization.executors.rationale.default_executor">Default
          executor</a>
        </h6>
<p>
          The library authors share some of the concerns of the C++ standard committee
          (introduction of a new single shared resource, a singleton, could make
          it difficult to make it portable to all the environments) and that this
          library doesn't need to provide a default executor for the time been.
        </p>
<p>
          The user can always define his default executor himself.
        </p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">generic_executor_ref</span> <span class="identifier">default_executor</span><span class="special">()</span>
<span class="special">{</span>
    <span class="keyword">static</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">basic_thread_pool</span> <span class="identifier">tp</span><span class="special">(</span><span class="number">4</span><span class="special">);</span>
    <span class="keyword">return</span> <span class="identifier">generic_executor_ref</span><span class="special">(</span><span class="identifier">tp</span><span class="special">);</span>
<span class="special">}</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.executors.ref"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref" title="Reference">Reference</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.concept_closure">Concept
          <code class="computeroutput"><span class="identifier">Closure</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.concept_executor">Concept
          <code class="computeroutput"><span class="identifier">Executor</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.work">Class
          <code class="computeroutput"><span class="identifier">work</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.executor">Class
          <code class="computeroutput"><span class="identifier">executor</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.executor_adaptor">Template
          Class <code class="computeroutput"><span class="identifier">executor_adaptor</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.generic_executor_ref">Class
          <code class="computeroutput"><span class="identifier">generic_executor_ref</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.scheduler">Template
          Class <code class="computeroutput"><span class="identifier">scheduler</span> </code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.at_executor">Template
          Class <code class="computeroutput"><span class="identifier">at_executor</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.scheduler_executor_wrapper">Template
          Class <code class="computeroutput"><span class="identifier">scheduler_executor_wrapper</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.resubmit_at_executor">Template
          Class <code class="computeroutput"><span class="identifier">resubmit_at_executor</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.serial_executor">Template
          Class <code class="computeroutput"><span class="identifier">serial_executor</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.generic_serial_executor">Class
          <code class="computeroutput"><span class="identifier">generic_serial_executor</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.inline_executor">Class
          <code class="computeroutput"><span class="identifier">inline_executor</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.basic_thread_pool">Class
          <code class="computeroutput"><span class="identifier">basic_thread_pool</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.thread_executor">Class
          <code class="computeroutput"><span class="identifier">thread_executor</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.executors.ref.loop_executor">Class
          <code class="computeroutput"><span class="identifier">loop_executor</span></code></a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.concept_closure"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.concept_closure" title="Concept Closure">Concept
          <code class="computeroutput"><span class="identifier">Closure</span></code></a>
</h5></div></div></div>
<p>
            A type <code class="computeroutput"><span class="identifier">E</span></code> meets the <code class="computeroutput"><span class="identifier">Closure</span></code> requirements if is a model
            of <code class="computeroutput"><span class="identifier">Callable</span><span class="special">(</span><span class="keyword">void</span><span class="special">())</span></code>
            and a model of <code class="computeroutput"><span class="identifier">CopyConstructible</span></code>/<code class="computeroutput"><span class="identifier">MoveConstructible</span></code>.
          </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.concept_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.concept_executor" title="Concept Executor">Concept
          <code class="computeroutput"><span class="identifier">Executor</span></code></a>
</h5></div></div></div>
<p>
            The <code class="computeroutput"><span class="identifier">Executor</span></code> concept
            models the common operations of all the executors.
          </p>
<p>
            A type <code class="computeroutput"><span class="identifier">E</span></code> meets the <code class="computeroutput"><span class="identifier">Executor</span></code> requirements if the following
            expressions are well-formed and have the specified semantics
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
                <code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">submit</span><span class="special">(</span><span class="identifier">lc</span><span class="special">);</span></code>
              </li>
<li class="listitem">
                <code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">submit</span><span class="special">(</span><span class="identifier">rc</span><span class="special">);</span></code>
              </li>
<li class="listitem">
                <code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">close</span><span class="special">();</span></code>
              </li>
<li class="listitem">
                <code class="computeroutput"><span class="identifier">b</span> <span class="special">=</span>
                <span class="identifier">e</span><span class="special">.</span><span class="identifier">closed</span><span class="special">();</span></code>
              </li>
<li class="listitem">
                <code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">try_executing_one</span><span class="special">();</span></code>
              </li>
<li class="listitem">
                <code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">reschedule_until</span><span class="special">(</span><span class="identifier">p</span><span class="special">);</span></code>
              </li>
</ul></div>
<p>
            where
          </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
                <code class="computeroutput"><span class="identifier">e</span></code> denotes a value
                of type <code class="computeroutput"><span class="identifier">E</span></code>,
              </li>
<li class="listitem">
                <code class="computeroutput"><span class="identifier">lc</span></code> denotes a lvalue
                reference of type <code class="computeroutput"><span class="identifier">Closure</span></code>,
              </li>
<li class="listitem">
                <code class="computeroutput"><span class="identifier">rc</span></code> denotes a rvalue
                reference of type <code class="computeroutput"><span class="identifier">Closure</span></code>
              </li>
<li class="listitem">
                <code class="computeroutput"><span class="identifier">p</span></code> denotes a value
                of type <code class="computeroutput"><span class="identifier">Predicate</span></code>
              </li>
</ul></div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.concept_executor.submitlc"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.concept_executor.submitlc" title="e.submit(lc);"><code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">submit</span><span class="special">(</span><span class="identifier">lc</span><span class="special">);</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    The specified closure will be scheduled for execution at some
                    point in the future. If invoked closure throws an exception the
                    executor will call std::terminate, as is the case with threads.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    completion of closure on a particular thread happens before destruction
                    of thread's thread local variables.
                  </p></dd>
<dt><span class="term">Return type:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">void</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    sync_queue_is_closed if the thread pool is closed. Whatever exception
                    that can be throw while storing the closure.
                  </p></dd>
<dt><span class="term">Exception safety:</span></dt>
<dd><p>
                    If an exception is thrown then the executor state is unmodified.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.concept_executor.submitrc"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.concept_executor.submitrc" title="e.submit(rc);"><code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">submit</span><span class="special">(</span><span class="identifier">rc</span><span class="special">);</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    The specified closure will be scheduled for execution at some
                    point in the future. If invoked closure throws an exception the
                    executor will call std::terminate, as is the case with threads.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    completion of closure on a particular thread happens before destruction
                    of thread's thread local variables.
                  </p></dd>
<dt><span class="term">Return type:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">void</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    sync_queue_is_closed if the thread pool is closed. Whatever exception
                    that can be throw while storing the closure.
                  </p></dd>
<dt><span class="term">Exception safety:</span></dt>
<dd><p>
                    If an exception is thrown then the executor state is unmodified.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.concept_executor.close"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.concept_executor.close" title="e.close();"><code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">close</span><span class="special">();</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    close the executor <code class="computeroutput"><span class="identifier">e</span></code>
                    for submissions.
                  </p></dd>
<dt><span class="term">Remark:</span></dt>
<dd><p>
                    The worker threads will work until there is no more closures
                    to run.
                  </p></dd>
<dt><span class="term">Return type:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">void</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever exception that can be thrown while ensuring the thread
                    safety.
                  </p></dd>
<dt><span class="term">Exception safety:</span></dt>
<dd><p>
                    If an exception is thrown then the executor state is unmodified.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.concept_executor.closed"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.concept_executor.closed" title="b = e.closed();"><code class="computeroutput"><span class="identifier">b</span> <span class="special">=</span> <span class="identifier">e</span><span class="special">.</span><span class="identifier">closed</span><span class="special">();</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return type:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">bool</span></code>.
                  </p></dd>
<dt><span class="term">Return:</span></dt>
<dd><p>
                    whether the executor is closed for submissions.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever exception that can be throw while ensuring the thread
                    safety.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.concept_executor.try_executing_one"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.concept_executor.try_executing_one" title="e.try_executing_one();"><code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">try_executing_one</span><span class="special">();</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    try to execute one work.
                  </p></dd>
<dt><span class="term">Remark:</span></dt>
<dd><p>
                    whether a work has been executed.
                  </p></dd>
<dt><span class="term">Return type:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">bool</span></code>.
                  </p></dd>
<dt><span class="term">Return:</span></dt>
<dd><p>
                    Whether a work has been executed.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    whatever the current work constructor throws or the <code class="computeroutput"><span class="identifier">work</span><span class="special">()</span></code>
                    throws.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.concept_executor.reschedule_until"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.concept_executor.reschedule_until" title="e.reschedule_until(p);"><code class="computeroutput"><span class="identifier">e</span><span class="special">.</span><span class="identifier">reschedule_until</span><span class="special">(</span><span class="identifier">p</span><span class="special">);</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    This must be called from a scheduled work
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    reschedule works until <code class="computeroutput"><span class="identifier">p</span><span class="special">()</span></code>.
                  </p></dd>
<dt><span class="term">Return type:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">bool</span></code>.
                  </p></dd>
<dt><span class="term">Return:</span></dt>
<dd><p>
                    Whether a work has been executed.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    whatever the current work constructor throws or the <code class="computeroutput"><span class="identifier">work</span><span class="special">()</span></code>
                    throws.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.work"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.work" title="Class work">Class
          <code class="computeroutput"><span class="identifier">work</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">work</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">typedef</span> <span class="char">'implementation_defined'</span> <span class="identifier">work</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  work is a model of 'Closure'
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.executor" title="Class executor">Class
          <code class="computeroutput"><span class="identifier">executor</span></code></a>
</h5></div></div></div>
<p>
            Executor abstract base class.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">executor</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">class</span> <span class="identifier">executor</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span>  <span class="identifier">boost</span><span class="special">::</span><span class="identifier">work</span> <span class="identifier">work</span><span class="special">;</span>

    <span class="identifier">executor</span><span class="special">(</span><span class="identifier">executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">executor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">executor</span><span class="special">();</span>
    <span class="keyword">virtual</span> <span class="special">~</span><span class="identifier">executor</span><span class="special">()</span> <span class="special">{};</span>

    <span class="keyword">virtual</span> <span class="keyword">void</span> <span class="identifier">close</span><span class="special">()</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
    <span class="keyword">virtual</span> <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">()</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>

    <span class="keyword">virtual</span> <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">work</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">)</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
    <span class="keyword">virtual</span> <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">work</span><span class="special">&amp;</span> <span class="identifier">closure</span><span class="special">)</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">virtual</span> <span class="keyword">bool</span> <span class="identifier">try_executing_one</span><span class="special">()</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Pred</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">reschedule_until</span><span class="special">(</span><span class="identifier">Pred</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">pred</span><span class="special">);</span>
  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.executor.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.executor.constructor" title="Constructor executor()">Constructor
            <code class="computeroutput"><span class="identifier">executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs an executor.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.executor.constructor0"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.executor.constructor0" title="Destructor ~executor()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">virtual</span> <span class="special">~</span><span class="identifier">executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the executor.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.executor_adaptor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.executor_adaptor" title="Template Class executor_adaptor">Template
          Class <code class="computeroutput"><span class="identifier">executor_adaptor</span></code></a>
</h5></div></div></div>
<p>
            Polymorphic adaptor of a model of Executor to an executor.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">executor</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">executor_adaptor</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">executor</span>
  <span class="special">{</span>
    <span class="identifier">Executor</span> <span class="identifier">ex</span><span class="special">;</span> <span class="comment">// for exposition only</span>
  <span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">typedef</span>  <span class="identifier">executor</span><span class="special">::</span><span class="identifier">work</span> <span class="identifier">work</span><span class="special">;</span>

    <span class="identifier">executor_adaptor</span><span class="special">(</span><span class="identifier">executor_adaptor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">executor_adaptor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">executor_adaptor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="special">...</span><span class="identifier">Args</span><span class="special">&gt;</span>
    <span class="identifier">executor_adaptor</span><span class="special">(</span><span class="identifier">Args</span><span class="special">&amp;&amp;</span> <span class="special">...</span> <span class="identifier">args</span><span class="special">);</span>

    <span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">underlying_executor</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">work</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">work</span><span class="special">&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">bool</span> <span class="identifier">try_executing_one</span><span class="special">();</span>

  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.executor_adaptor.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.executor_adaptor.constructor" title="Constructor executor_adaptor(Args&amp;&amp; ...)">Constructor
            <code class="computeroutput"><span class="identifier">executor_adaptor</span><span class="special">(</span><span class="identifier">Args</span><span class="special">&amp;&amp;</span>
            <span class="special">...)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="special">...</span><span class="identifier">Args</span><span class="special">&gt;</span>
<span class="identifier">executor_adaptor</span><span class="special">(</span><span class="identifier">Args</span><span class="special">&amp;&amp;</span> <span class="special">...</span> <span class="identifier">args</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs an executor_adaptor.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.executor_adaptor.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.executor_adaptor.destructor" title="Destructor ~executor_adaptor()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">executor_adaptor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">virtual</span> <span class="special">~</span><span class="identifier">executor_adaptor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the executor_adaptor.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.executor_adaptor.underlying_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.executor_adaptor.underlying_executor" title="Function member underlying_executor()">Function
            member <code class="computeroutput"><span class="identifier">underlying_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">underlying_executor</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    The underlying executor instance.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.generic_executor_ref"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.generic_executor_ref" title="Class generic_executor_ref">Class
          <code class="computeroutput"><span class="identifier">generic_executor_ref</span></code></a>
</h5></div></div></div>
<p>
            Executor abstract base class.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">generic_executor_ref</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">class</span> <span class="identifier">generic_executor_ref</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">generic_executor_ref</span><span class="special">(</span><span class="identifier">generic_executor_ref</span> <span class="keyword">const</span><span class="special">&amp;);</span>
    <span class="identifier">generic_executor_ref</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">generic_executor_ref</span> <span class="keyword">const</span><span class="special">&amp;);</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
    <span class="identifier">generic_executor_ref</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">);</span>
    <span class="identifier">generic_executor_ref</span><span class="special">()</span> <span class="special">{};</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">()</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">()</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">virtual</span> <span class="keyword">bool</span> <span class="identifier">try_executing_one</span><span class="special">()</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Pred</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">reschedule_until</span><span class="special">(</span><span class="identifier">Pred</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">pred</span><span class="special">);</span>
  <span class="special">};</span>
<span class="special">}</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.scheduler"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler" title="Template Class scheduler">Template
          Class <code class="computeroutput"><span class="identifier">scheduler</span> </code></a>
</h5></div></div></div>
<p>
            Scheduler providing time related functions. Note that <code class="computeroutput"><span class="identifier">scheduler</span></code>
            is not an Executor.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">executors</span><span class="special">/</span><span class="identifier">scheduler</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">=</span><span class="identifier">steady_clock</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">scheduler</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">using</span> <span class="identifier">work</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">function</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">()&gt;</span> <span class="special">;</span>
    <span class="keyword">using</span> <span class="identifier">clock</span> <span class="special">=</span> <span class="identifier">Clock</span><span class="special">;</span>

    <span class="identifier">scheduler</span><span class="special">(</span><span class="identifier">scheduler</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">scheduler</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">scheduler</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">scheduler</span><span class="special">();</span>
    <span class="special">~</span><span class="identifier">scheduler</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit_at</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">clock</span><span class="special">,</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit_after</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span><span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">rel_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="identifier">at_executor</span><span class="special">&lt;</span><span class="identifier">scheduler</span><span class="special">&gt;</span> <span class="identifier">submit_at</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">clock</span><span class="special">,</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="identifier">at_executor</span><span class="special">&lt;</span><span class="identifier">scheduler</span><span class="special">&gt;</span> <span class="identifier">submit_after</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span><span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">rel_time</span><span class="special">);</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
    <span class="identifier">scheduler_executor_wrapper</span><span class="special">&lt;</span><span class="identifier">scheduler</span><span class="special">,</span> <span class="identifier">Executor</span><span class="special">&gt;</span> <span class="identifier">on</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">);</span>

  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler.constructor" title="Constructor scheduler()">Constructor
            <code class="computeroutput"><span class="identifier">scheduler</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">scheduler</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a <code class="computeroutput"><span class="identifier">scheduler</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler.destructor" title="Destructor ~scheduler()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">scheduler</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">scheduler</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the scheduler.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler.submit_at"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler.submit_at" title="Template Function Member submit_at()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit_at</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit_at</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Schedule a <code class="computeroutput"><span class="identifier">closure</span></code>
                    to be executed at <code class="computeroutput"><span class="identifier">abs_time</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler.submit_after"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler.submit_after" title="Template Function Member submit_after()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit_after</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit_after</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span><span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">rel_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Schedule a <code class="computeroutput"><span class="identifier">closure</span></code>
                    to be executed after <code class="computeroutput"><span class="identifier">rel_time</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.at_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.at_executor" title="Template Class at_executor">Template
          Class <code class="computeroutput"><span class="identifier">at_executor</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">executors</span><span class="special">/</span><span class="identifier">scheduler</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Scheduler</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">at_executor</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">using</span> <span class="identifier">work</span> <span class="special">=</span> <span class="identifier">Scheduler</span><span class="special">::</span><span class="identifier">work</span><span class="special">;</span>
    <span class="keyword">using</span> <span class="identifier">clock</span> <span class="special">=</span> <span class="identifier">Scheduler</span><span class="special">::</span><span class="identifier">clock</span><span class="special">;</span>

    <span class="identifier">at_executor</span><span class="special">(</span><span class="identifier">at_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>
    <span class="identifier">at_executor</span><span class="special">(</span><span class="identifier">at_executor</span> <span class="special">&amp;&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>
    <span class="identifier">at_executor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">at_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>
    <span class="identifier">at_executor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">at_executor</span> <span class="special">&amp;&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>

    <span class="identifier">at_executor</span><span class="special">(</span><span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">sch</span><span class="special">,</span> <span class="identifier">clock</span><span class="special">::</span><span class="identifier">time_point</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">tp</span><span class="special">);</span>
    <span class="special">~</span><span class="identifier">at_executor</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">underlying_scheduler</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Work</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit_at</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">clock</span><span class="special">,</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Work</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit_after</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span><span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">rel_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
    <span class="identifier">resubmit_at_executor</span><span class="special">&lt;</span><span class="identifier">Scheduler</span><span class="special">,</span> <span class="identifier">Executor</span><span class="special">&gt;</span> <span class="identifier">on</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">);</span>

  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.at_executor.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.at_executor.constructor" title="Constructor at_executor(Scheduler&amp;, clock::time_point const&amp;)">Constructor
            <code class="computeroutput"><span class="identifier">at_executor</span><span class="special">(</span><span class="identifier">Scheduler</span><span class="special">&amp;,</span>
            <span class="identifier">clock</span><span class="special">::</span><span class="identifier">time_point</span> <span class="keyword">const</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">at_executor</span><span class="special">(</span><span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">sch</span><span class="special">,</span> <span class="identifier">clock</span><span class="special">::</span><span class="identifier">time_point</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">tp</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a <code class="computeroutput"><span class="identifier">at_executor</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.at_executor.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.at_executor.destructor" title="Destructor ~at_executor()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">at_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">at_executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the <code class="computeroutput"><span class="identifier">at_executor</span></code>.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.at_executor.underlying_scheduler"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.at_executor.underlying_scheduler" title="Function member underlying_scheduler()">Function
            member <code class="computeroutput"><span class="identifier">underlying_scheduler</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">underlying_scheduler</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    The underlying scheduler instance.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.at_executor.submit_at"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.at_executor.submit_at" title="Template Function Member submit()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Schedule the <code class="computeroutput"><span class="identifier">closure</span></code>
                    to be executed at the <code class="computeroutput"><span class="identifier">abs_time</span></code>
                    given at construction time.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.at_executor.submit_at0"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.at_executor.submit_at0" title="Template Function Member submit_at()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit_at</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit_at</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Schedule a <code class="computeroutput"><span class="identifier">closure</span></code>
                    to be executed at <code class="computeroutput"><span class="identifier">abs_time</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.at_executor.submit_after"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.at_executor.submit_after" title="Template Function Member submit_after()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit_after</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit_after</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span><span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">rel_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Schedule a <code class="computeroutput"><span class="identifier">closure</span></code>
                    to be executed after <code class="computeroutput"><span class="identifier">rel_time</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.scheduler_executor_wrapper"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler_executor_wrapper" title="Template Class scheduler_executor_wrapper">Template
          Class <code class="computeroutput"><span class="identifier">scheduler_executor_wrapper</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">executors</span><span class="special">/</span><span class="identifier">scheduler</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Scheduler</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">scheduler_executor_wrapper</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">using</span> <span class="identifier">work</span> <span class="special">=</span> <span class="identifier">Scheduler</span><span class="special">::</span><span class="identifier">work</span><span class="special">;</span>
    <span class="keyword">using</span> <span class="identifier">clock</span> <span class="special">=</span> <span class="identifier">Scheduler</span><span class="special">::</span><span class="identifier">clock</span><span class="special">;</span>

    <span class="identifier">scheduler_executor_wrapper</span><span class="special">(</span><span class="identifier">scheduler_executor_wrapper</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>
    <span class="identifier">scheduler_executor_wrapper</span><span class="special">(</span><span class="identifier">scheduler_executor_wrapper</span> <span class="special">&amp;&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>
    <span class="identifier">scheduler_executor_wrapper</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">scheduler_executor_wrapper</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>
    <span class="identifier">scheduler_executor_wrapper</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">scheduler_executor_wrapper</span> <span class="special">&amp;&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>

    <span class="identifier">scheduler_executor_wrapper</span><span class="special">(</span><span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">sch</span><span class="special">,</span> <span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">);</span>

    <span class="special">~</span><span class="identifier">scheduler_executor_wrapper</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">underlying_executor</span><span class="special">();</span>
    <span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">underlying_scheduler</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Work</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit_at</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">clock</span><span class="special">,</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Work</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit_after</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span><span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">rel_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="identifier">resubmit_at_executor</span><span class="special">&lt;</span><span class="identifier">Scheduler</span><span class="special">,</span> <span class="identifier">Executor</span><span class="special">&gt;</span> <span class="identifier">at</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">clock</span><span class="special">,</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">abs_time</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
    <span class="identifier">resubmit_at_executor</span><span class="special">&lt;</span><span class="identifier">Scheduler</span><span class="special">,</span> <span class="identifier">Executor</span><span class="special">&gt;</span> <span class="identifier">after</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span><span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">rel_time</span><span class="special">);</span>

  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler_executor_wrapper.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler_executor_wrapper.constructor" title="Constructor scheduler_executor_wrapper(Scheduler&amp;, Executor&amp;)">Constructor
            <code class="computeroutput"><span class="identifier">scheduler_executor_wrapper</span><span class="special">(</span><span class="identifier">Scheduler</span><span class="special">&amp;,</span> <span class="identifier">Executor</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">scheduler_executor_wrapper</span><span class="special">(</span><span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">sch</span><span class="special">,</span> <span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a <code class="computeroutput"><span class="identifier">scheduler_executor_wrapper</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler_executor_wrapper.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler_executor_wrapper.destructor" title="Destructor ~scheduler_executor_wrapper()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">scheduler_executor_wrapper</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">scheduler_executor_wrapper</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the <code class="computeroutput"><span class="identifier">scheduler_executor_wrapper</span></code>.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler_executor_wrapper.underlying_scheduler"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler_executor_wrapper.underlying_scheduler" title="Function member underlying_scheduler()">Function
            member <code class="computeroutput"><span class="identifier">underlying_scheduler</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">underlying_scheduler</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    The underlying scheduler instance.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler_executor_wrapper.underlying_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler_executor_wrapper.underlying_executor" title="Function member underlying_executor()">Function
            member <code class="computeroutput"><span class="identifier">underlying_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">underlying_executor</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    The underlying executor instance.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler_executor_wrapper.submit_at"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler_executor_wrapper.submit_at" title="Template Function Member submit()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Submit the <code class="computeroutput"><span class="identifier">closure</span></code>
                    on the underlying executor.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler_executor_wrapper.submit_at0"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler_executor_wrapper.submit_at0" title="Template Function Member submit_at()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit_at</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit_at</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Resubmit the <code class="computeroutput"><span class="identifier">closure</span></code>
                    to be executed on the underlying executor at <code class="computeroutput"><span class="identifier">abs_time</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.scheduler_executor_wrapper.submit_after"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.scheduler_executor_wrapper.submit_after" title="Template Function Member submit_after()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit_after</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit_after</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span><span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">rel_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Resubmit the <code class="computeroutput"><span class="identifier">closure</span></code>
                    to be executed on the underlying executor after <code class="computeroutput"><span class="identifier">rel_time</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.resubmit_at_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.resubmit_at_executor" title="Template Class resubmit_at_executor">Template
          Class <code class="computeroutput"><span class="identifier">resubmit_at_executor</span></code></a>
</h5></div></div></div>
<p>
            <code class="computeroutput"><span class="identifier">Executor</span></code> wrapping an
            <code class="computeroutput"><span class="identifier">Scheduler</span></code>, an <code class="computeroutput"><span class="identifier">Executor</span></code> and a <code class="computeroutput"><span class="identifier">time_point</span></code>
            providing an <code class="computeroutput"><span class="identifier">Executor</span></code>
            interface.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">executors</span><span class="special">/</span><span class="identifier">scheduler</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Scheduler</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">resubmit_at_executor</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
    <span class="keyword">using</span> <span class="identifier">work</span> <span class="special">=</span> <span class="identifier">Scheduler</span><span class="special">::</span><span class="identifier">work</span><span class="special">;</span>
    <span class="keyword">using</span> <span class="identifier">clock</span> <span class="special">=</span> <span class="identifier">Scheduler</span><span class="special">::</span><span class="identifier">clock</span><span class="special">;</span>

    <span class="identifier">resubmit_at_executor</span><span class="special">(</span><span class="identifier">resubmit_at_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>
    <span class="identifier">resubmit_at_executor</span><span class="special">(</span><span class="identifier">resubmit_at_executor</span> <span class="special">&amp;&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>
    <span class="identifier">resubmit_at_executor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">resubmit_at_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>
    <span class="identifier">resubmit_at_executor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">resubmit_at_executor</span> <span class="special">&amp;&amp;)</span> <span class="special">=</span> <span class="keyword">default</span><span class="special">;</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
    <span class="identifier">resubmit_at_executor</span><span class="special">(</span><span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">sch</span><span class="special">,</span> <span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">,</span> <span class="identifier">clock</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">tp</span><span class="special">);</span>
    <span class="special">~</span><span class="identifier">resubmit_at_executor</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">underlying_executor</span><span class="special">();</span>
    <span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">underlying_scheduler</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Work</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit_at</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">clock</span><span class="special">,</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Work</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit_after</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span><span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">rel_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.resubmit_at_executor.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.resubmit_at_executor.constructor" title="Constructor resubmit_at_executor(Scheduler&amp;, Executor&amp;, clock::time_point&lt;Duration&gt;)">Constructor
            <code class="computeroutput"><span class="identifier">resubmit_at_executor</span><span class="special">(</span><span class="identifier">Scheduler</span><span class="special">&amp;,</span> <span class="identifier">Executor</span><span class="special">&amp;,</span> <span class="identifier">clock</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Duration</span><span class="special">&gt;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
<span class="identifier">resubmit_at_executor</span><span class="special">(</span><span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">sch</span><span class="special">,</span> <span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">,</span> <span class="identifier">clock</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">tp</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a <code class="computeroutput"><span class="identifier">resubmit_at_executor</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.resubmit_at_executor.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.resubmit_at_executor.destructor" title="Destructor ~resubmit_at_executor()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">resubmit_at_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">resubmit_at_executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the executor_adaptor.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.resubmit_at_executor.underlying_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.resubmit_at_executor.underlying_executor" title="Function member underlying_executor()">Function
            member <code class="computeroutput"><span class="identifier">underlying_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">underlying_executor</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    The underlying executor instance.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.resubmit_at_executor.underlying_scheduler"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.resubmit_at_executor.underlying_scheduler" title="Function member underlying_scheduler()">Function
            member <code class="computeroutput"><span class="identifier">underlying_scheduler</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">Scheduler</span><span class="special">&amp;</span> <span class="identifier">underlying_scheduler</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    The underlying scheduler instance.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.resubmit_at_executor.submit_at"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.resubmit_at_executor.submit_at" title="Template Function Member submit()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Resubmit the <code class="computeroutput"><span class="identifier">closure</span></code>
                    to be executed on the underlying executor at the <code class="computeroutput"><span class="identifier">abs_time</span></code> given at construction
                    time.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.resubmit_at_executor.submit_at0"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.resubmit_at_executor.submit_at0" title="Template Function Member submit_at()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit_at</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit_at</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span><span class="identifier">Duration</span><span class="special">&gt;</span> <span class="identifier">abs_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Resubmit the <code class="computeroutput"><span class="identifier">closure</span></code>
                    to be executed on the underlying executor at <code class="computeroutput"><span class="identifier">abs_time</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.resubmit_at_executor.submit_after"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.resubmit_at_executor.submit_after" title="Template Function Member submit_after()">Template
            Function Member <code class="computeroutput"><span class="identifier">submit_after</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">submit_after</span><span class="special">(</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span><span class="identifier">Period</span><span class="special">&gt;</span> <span class="identifier">rel_time</span><span class="special">,</span> <span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Resubmit the <code class="computeroutput"><span class="identifier">closure</span></code>
                    to be executed on the underlying executor after <code class="computeroutput"><span class="identifier">rel_time</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.serial_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.serial_executor" title="Template Class serial_executor">Template
          Class <code class="computeroutput"><span class="identifier">serial_executor</span></code></a>
</h5></div></div></div>
<p>
            A serial executor ensuring that there are no two work units that executes
            concurrently.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">serial_executor</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">serial_executor</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">serial_executor</span><span class="special">(</span><span class="identifier">serial_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">serial_executor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">serial_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
    <span class="identifier">serial_executor</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">);</span>

    <span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">underlying_executor</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">bool</span> <span class="identifier">try_executing_one</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Pred</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">reschedule_until</span><span class="special">(</span><span class="identifier">Pred</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">pred</span><span class="special">);</span>

  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.serial_executor.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.serial_executor.constructor" title="Constructor serial_executor(Executor&amp;)">Constructor
            <code class="computeroutput"><span class="identifier">serial_executor</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
<span class="identifier">serial_executor</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a serial_executor.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.serial_executor.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.serial_executor.destructor" title="Destructor ~serial_executor()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">serial_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">serial_executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the serial_executor.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.serial_executor.underlying_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.serial_executor.underlying_executor" title="Function member underlying_executor()">Function
            member <code class="computeroutput"><span class="identifier">underlying_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">generic_executor_ref</span><span class="special">&amp;</span> <span class="identifier">underlying_executor</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    The underlying executor instance.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.generic_serial_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.generic_serial_executor" title="Class generic_serial_executor">Class
          <code class="computeroutput"><span class="identifier">generic_serial_executor</span></code></a>
</h5></div></div></div>
<p>
            A serial executor ensuring that there are no two work units that executes
            concurrently.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">generic_serial_executor</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">class</span> <span class="identifier">generic_serial_executor</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">generic_serial_executor</span><span class="special">(</span><span class="identifier">generic_serial_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">generic_serial_executor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">generic_serial_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
    <span class="identifier">generic_serial_executor</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">);</span>

    <span class="identifier">generic_executor_ref</span><span class="special">&amp;</span> <span class="identifier">underlying_executor</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">bool</span> <span class="identifier">try_executing_one</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Pred</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">reschedule_until</span><span class="special">(</span><span class="identifier">Pred</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">pred</span><span class="special">);</span>

  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.generic_serial_executor.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.generic_serial_executor.constructor" title="Constructor generic_serial_executor(Executor&amp;)">Constructor
            <code class="computeroutput"><span class="identifier">generic_serial_executor</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">&amp;)</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">&gt;</span>
<span class="identifier">generic_serial_executor</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">ex</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a serial_executor.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.generic_serial_executor.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.generic_serial_executor.destructor" title="Destructor ~serial_executor()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">serial_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">generic_serial_executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the serial_executor.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.generic_serial_executor.underlying_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.generic_serial_executor.underlying_executor" title="Function member underlying_executor()">Function
            member <code class="computeroutput"><span class="identifier">underlying_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">Executor</span><span class="special">&amp;</span> <span class="identifier">underlying_executor</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    The underlying executor instance.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.inline_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.inline_executor" title="Class inline_executor">Class
          <code class="computeroutput"><span class="identifier">inline_executor</span></code></a>
</h5></div></div></div>
<p>
            A serial executor ensuring that there are no two work units that executes
            concurrently.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">inline_executor</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">class</span> <span class="identifier">inline_executor</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">inline_executor</span><span class="special">(</span><span class="identifier">inline_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">inline_executor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">inline_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">inline_executor</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">bool</span> <span class="identifier">try_executing_one</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Pred</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">reschedule_until</span><span class="special">(</span><span class="identifier">Pred</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">pred</span><span class="special">);</span>

  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.inline_executor.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.inline_executor.constructor" title="Constructor inline_executor()">Constructor
            <code class="computeroutput"><span class="identifier">inline_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">inline_executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs an inline_executor.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.inline_executor.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.inline_executor.destructor" title="Destructor ~inline_executor()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">inline_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">inline_executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the inline_executor.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.basic_thread_pool"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.basic_thread_pool" title="Class basic_thread_pool">Class
          <code class="computeroutput"><span class="identifier">basic_thread_pool</span></code></a>
</h5></div></div></div>
<p>
            A thread pool with up to a fixed number of threads.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">executors</span><span class="special">/</span><span class="identifier">basic_thread_pool</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">class</span> <span class="identifier">basic_thread_pool</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>

    <span class="identifier">basic_thread_pool</span><span class="special">(</span><span class="identifier">basic_thread_pool</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">basic_thread_pool</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">basic_thread_pool</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">basic_thread_pool</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">const</span> <span class="identifier">thread_count</span> <span class="special">=</span> <span class="identifier">thread</span><span class="special">::</span><span class="identifier">hardware_concurrency</span><span class="special">());</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">AtThreadEntry</span><span class="special">&gt;</span>
    <span class="identifier">basic_thread_pool</span><span class="special">(</span> <span class="keyword">unsigned</span> <span class="keyword">const</span> <span class="identifier">thread_count</span><span class="special">,</span> <span class="identifier">AtThreadEntry</span> <span class="identifier">at_thread_entry</span><span class="special">);</span>
    <span class="special">~</span><span class="identifier">basic_thread_pool</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">bool</span> <span class="identifier">try_executing_one</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Pred</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">reschedule_until</span><span class="special">(</span><span class="identifier">Pred</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">pred</span><span class="special">);</span>

  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.basic_thread_pool.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.basic_thread_pool.constructor" title="Constructor basic_thread_pool(unsigned const)">Constructor
            <code class="computeroutput"><span class="identifier">basic_thread_pool</span><span class="special">(</span><span class="keyword">unsigned</span> <span class="keyword">const</span><span class="special">)</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    creates a thread pool that runs closures on <code class="computeroutput"><span class="identifier">thread_count</span></code>
                    threads.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever exception is thrown while initializing the needed resources.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.basic_thread_pool.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.basic_thread_pool.destructor" title="Destructor ~basic_thread_pool()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">basic_thread_pool</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">basic_thread_pool</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the thread pool.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.thread_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.thread_executor" title="Class thread_executor">Class
          <code class="computeroutput"><span class="identifier">thread_executor</span></code></a>
</h5></div></div></div>
<p>
            A thread_executor with a threads for each task.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">executors</span><span class="special">/</span><span class="identifier">thread_executor</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">class</span> <span class="identifier">thread_executor</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>

    <span class="identifier">thread_executor</span><span class="special">(</span><span class="identifier">thread_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">thread_executor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">thread_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">thread_executor</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">AtThreadEntry</span><span class="special">&gt;</span>
    <span class="identifier">basic_thread_pool</span><span class="special">(</span> <span class="keyword">unsigned</span> <span class="keyword">const</span> <span class="identifier">thread_count</span><span class="special">,</span> <span class="identifier">AtThreadEntry</span> <span class="identifier">at_thread_entry</span><span class="special">);</span>
    <span class="special">~</span><span class="identifier">thread_executor</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.thread_executor.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.thread_executor.constructor" title="Constructor thread_executor()">Constructor
            <code class="computeroutput"><span class="identifier">thread_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    creates a thread_executor.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever exception is thrown while initializing the needed resources.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.thread_executor.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.thread_executor.destructor" title="Destructor ~thread_executor()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">thread_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">thread_executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Waits for closures (if any) to complete, then joins and destroys
                    the threads.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.executors.ref.loop_executor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.loop_executor" title="Class loop_executor">Class
          <code class="computeroutput"><span class="identifier">loop_executor</span></code></a>
</h5></div></div></div>
<p>
            A user scheduled executor.
          </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">loop_executor</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">namespace</span> <span class="identifier">boost</span> <span class="special">{</span>
  <span class="keyword">class</span> <span class="identifier">loop_executor</span>
  <span class="special">{</span>
  <span class="keyword">public</span><span class="special">:</span>

    <span class="identifier">loop_executor</span><span class="special">(</span><span class="identifier">loop_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
    <span class="identifier">loop_executor</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">loop_executor</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

    <span class="identifier">loop_executor</span><span class="special">();</span>
    <span class="special">~</span><span class="identifier">loop_executor</span><span class="special">();</span>

    <span class="keyword">void</span> <span class="identifier">close</span><span class="special">();</span>
    <span class="keyword">bool</span> <span class="identifier">closed</span><span class="special">();</span>

    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Closure</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">submit</span><span class="special">(</span><span class="identifier">Closure</span><span class="special">&amp;&amp;</span> <span class="identifier">closure</span><span class="special">);</span>

    <span class="keyword">bool</span> <span class="identifier">try_executing_one</span><span class="special">();</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Pred</span><span class="special">&gt;</span>
    <span class="keyword">bool</span> <span class="identifier">reschedule_until</span><span class="special">(</span><span class="identifier">Pred</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">pred</span><span class="special">);</span>

    <span class="keyword">void</span> <span class="identifier">loop</span><span class="special">();</span>
    <span class="keyword">void</span> <span class="identifier">run_queued_closures</span><span class="special">();</span>
  <span class="special">};</span>
<span class="special">}</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.loop_executor.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.loop_executor.constructor" title="Constructor loop_executor()">Constructor
            <code class="computeroutput"><span class="identifier">loop_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">loop_executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    creates an executor that runs closures using one of its closure-executing
                    methods.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever exception is thrown while initializing the needed resources.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.loop_executor.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.loop_executor.destructor" title="Destructor ~loop_executor()">Destructor
            <code class="computeroutput"><span class="special">~</span><span class="identifier">loop_executor</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">virtual</span> <span class="special">~</span><span class="identifier">loop_executor</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys the executor.
                  </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd><p>
                    The completion of all the closures happen before the completion
                    of the executor destructor.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.loop_executor.loop"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.loop_executor.loop" title="Function member loop()">Function
            member <code class="computeroutput"><span class="identifier">loop</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">loop</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    reschedule works until <code class="computeroutput"><span class="identifier">closed</span><span class="special">()</span></code> or empty.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    whatever the current work constructor throws or the <code class="computeroutput"><span class="identifier">work</span><span class="special">()</span></code>
                    throws.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.executors.ref.loop_executor.run_queued_closures"></a><a class="link" href="synchronization.html#thread.synchronization.executors.ref.loop_executor.run_queued_closures" title="Function member run_queued_closures()">Function
            member <code class="computeroutput"><span class="identifier">run_queued_closures</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">run_queued_closures</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Return:</span></dt>
<dd><p>
                    reschedule the enqueued works.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    whatever the current work constructor throws or the <code class="computeroutput"><span class="identifier">work</span><span class="special">()</span></code>
                    throws.
                  </p></dd>
</dl>
</div>
</div>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="thread.synchronization.futures"></a><a class="link" href="synchronization.html#thread.synchronization.futures" title="Futures">Futures</a>
</h3></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.overview">Overview</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.creating">Creating asynchronous
        values</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.lazy_futures">Wait Callbacks
        and Lazy Futures</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.at_thread_exit">Handling
        Detached Threads and Thread Specific Variables</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.async">Executing asynchronously</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.shared">Shared Futures</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.make_ready_future">Making
        immediate futures easier</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.then">Associating future
        continuations</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference">Futures Reference</a></span></dt>
</dl></div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.futures.overview"></a><a class="link" href="synchronization.html#thread.synchronization.futures.overview" title="Overview">Overview</a>
</h4></div></div></div>
<p>
          The futures library provides a means of handling synchronous future values,
          whether those values are generated by another thread, or on a single thread
          in response to external stimuli, or on-demand.
        </p>
<p>
          This is done through the provision of four class templates: <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> and <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a> which are used to
          retrieve the asynchronous results, and <a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code></a> and <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a> which are used to
          generate the asynchronous results.
        </p>
<p>
          An instance of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> holds the one and only
          reference to a result. Ownership can be transferred between instances using
          the move constructor or move-assignment operator, but at most one instance
          holds a reference to a given asynchronous result. When the result is ready,
          it is returned from <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get" title="Member function get()"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">get</span><span class="special">()</span></code></a>
          by rvalue-reference to allow the result to be moved or copied as appropriate
          for the type.
        </p>
<p>
          On the other hand, many instances of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a> may reference the
          same result. Instances can be freely copied and assigned, and <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get" title="Member function get()"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">get</span><span class="special">()</span></code></a>
          returns a <code class="computeroutput"><span class="keyword">const</span></code> reference
          so that multiple calls to <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get" title="Member function get()"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">get</span><span class="special">()</span></code></a>
          are safe. You can move an instance of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> into an instance of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a>, thus transferring
          ownership of the associated asynchronous result, but not vice-versa.
        </p>
<p>
          <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">async</span></code> is a simple way of running asynchronous
          tasks. A call to <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">async</span></code>
          returns a <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> that will contain the result
          of the task.
        </p>
<p>
          You can wait for futures either individually or with one of the <a class="link" href="synchronization.html#thread.synchronization.futures.reference.wait_for_any" title="Non-member function wait_for_any() - EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">wait_for_any</span><span class="special">()</span></code></a>
          and <a class="link" href="synchronization.html#thread.synchronization.futures.reference.wait_for_all" title="Non-member function wait_for_all() - EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">wait_for_all</span><span class="special">()</span></code></a>
          functions.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.futures.creating"></a><a class="link" href="synchronization.html#thread.synchronization.futures.creating" title="Creating asynchronous values">Creating asynchronous
        values</a>
</h4></div></div></div>
<p>
          You can set the value in a future with either a <a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code></a> or a <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a>. A <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a> is a callable object
          that wraps a function or callable object. When the packaged task is invoked,
          it invokes the contained function in turn, and populates a future with
          the return value. This is an answer to the perennial question: "how
          do I return a value from a thread?": package the function you wish
          to run as a <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a> and pass the packaged
          task to the thread constructor. The future retrieved from the packaged
          task can then be used to obtain the return value. If the function throws
          an exception, that is stored in the future in place of the return value.
        </p>
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">calculate_the_answer_to_life_the_universe_and_everything</span><span class="special">()</span>
<span class="special">{</span>
    <span class="keyword">return</span> <span class="number">42</span><span class="special">;</span>
<span class="special">}</span>

<span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">pt</span><span class="special">(</span><span class="identifier">calculate_the_answer_to_life_the_universe_and_everything</span><span class="special">);</span>
<span class="identifier">boost</span><span class="special">::</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">fi</span><span class="special">=</span><span class="identifier">pt</span><span class="special">.</span><span class="identifier">get_future</span><span class="special">();</span>

<span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span> <span class="identifier">task</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">pt</span><span class="special">));</span> <span class="comment">// launch task on a thread</span>

<span class="identifier">fi</span><span class="special">.</span><span class="identifier">wait</span><span class="special">();</span> <span class="comment">// wait for it to finish</span>

<span class="identifier">assert</span><span class="special">(</span><span class="identifier">fi</span><span class="special">.</span><span class="identifier">is_ready</span><span class="special">());</span>
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">fi</span><span class="special">.</span><span class="identifier">has_value</span><span class="special">());</span>
<span class="identifier">assert</span><span class="special">(!</span><span class="identifier">fi</span><span class="special">.</span><span class="identifier">has_exception</span><span class="special">());</span>
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">fi</span><span class="special">.</span><span class="identifier">get_state</span><span class="special">()==</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span><span class="special">);</span>
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">fi</span><span class="special">.</span><span class="identifier">get</span><span class="special">()==</span><span class="number">42</span><span class="special">);</span>
</pre>
<p>
          A <a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code></a> is a bit more low level:
          it just provides explicit functions to store a value or an exception in
          the associated future. A promise can therefore be used where the value
          may come from more than one possible source, or where a single operation
          may produce multiple values.
        </p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">pi</span><span class="special">;</span>
<span class="identifier">boost</span><span class="special">::</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">fi</span><span class="special">;</span>
<span class="identifier">fi</span><span class="special">=</span><span class="identifier">pi</span><span class="special">.</span><span class="identifier">get_future</span><span class="special">();</span>

<span class="identifier">pi</span><span class="special">.</span><span class="identifier">set_value</span><span class="special">(</span><span class="number">42</span><span class="special">);</span>

<span class="identifier">assert</span><span class="special">(</span><span class="identifier">fi</span><span class="special">.</span><span class="identifier">is_ready</span><span class="special">());</span>
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">fi</span><span class="special">.</span><span class="identifier">has_value</span><span class="special">());</span>
<span class="identifier">assert</span><span class="special">(!</span><span class="identifier">fi</span><span class="special">.</span><span class="identifier">has_exception</span><span class="special">());</span>
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">fi</span><span class="special">.</span><span class="identifier">get_state</span><span class="special">()==</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span><span class="special">);</span>
<span class="identifier">assert</span><span class="special">(</span><span class="identifier">fi</span><span class="special">.</span><span class="identifier">get</span><span class="special">()==</span><span class="number">42</span><span class="special">);</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.futures.lazy_futures"></a><a class="link" href="synchronization.html#thread.synchronization.futures.lazy_futures" title="Wait Callbacks and Lazy Futures">Wait Callbacks
        and Lazy Futures</a>
</h4></div></div></div>
<p>
          Both <a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code></a> and <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a> support <span class="emphasis"><em>wait
          callbacks</em></span> that are invoked when a thread blocks in a call to
          <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code>
          or <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code>
          on a future that is waiting for the result from the <a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code></a> or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a>, in the thread that
          is doing the waiting. These can be set using the <code class="computeroutput"><span class="identifier">set_wait_callback</span><span class="special">()</span></code> member function on the <a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code></a> or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a> in question.
        </p>
<p>
          This allows <span class="emphasis"><em>lazy futures</em></span> where the result is not actually
          computed until it is needed by some thread. In the example below, the call
          to <code class="computeroutput"><span class="identifier">f</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span></code>
          invokes the callback <code class="computeroutput"><span class="identifier">invoke_lazy_task</span></code>,
          which runs the task to set the value. If you remove the call to <code class="computeroutput"><span class="identifier">f</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span></code>, the task is not ever run.
        </p>
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">calculate_the_answer_to_life_the_universe_and_everything</span><span class="special">()</span>
<span class="special">{</span>
    <span class="keyword">return</span> <span class="number">42</span><span class="special">;</span>
<span class="special">}</span>

<span class="keyword">void</span> <span class="identifier">invoke_lazy_task</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;&amp;</span> <span class="identifier">task</span><span class="special">)</span>
<span class="special">{</span>
    <span class="keyword">try</span>
    <span class="special">{</span>
        <span class="identifier">task</span><span class="special">();</span>
    <span class="special">}</span>
    <span class="keyword">catch</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">task_already_started</span><span class="special">&amp;)</span>
    <span class="special">{}</span>
<span class="special">}</span>

<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
<span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">task</span><span class="special">(</span><span class="identifier">calculate_the_answer_to_life_the_universe_and_everything</span><span class="special">);</span>
    <span class="identifier">task</span><span class="special">.</span><span class="identifier">set_wait_callback</span><span class="special">(</span><span class="identifier">invoke_lazy_task</span><span class="special">);</span>
    <span class="identifier">boost</span><span class="special">::</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">f</span><span class="special">(</span><span class="identifier">task</span><span class="special">.</span><span class="identifier">get_future</span><span class="special">());</span>

    <span class="identifier">assert</span><span class="special">(</span><span class="identifier">f</span><span class="special">.</span><span class="identifier">get</span><span class="special">()==</span><span class="number">42</span><span class="special">);</span>
<span class="special">}</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.futures.at_thread_exit"></a><a class="link" href="synchronization.html#thread.synchronization.futures.at_thread_exit" title="Handling Detached Threads and Thread Specific Variables">Handling
        Detached Threads and Thread Specific Variables</a>
</h4></div></div></div>
<p>
          Detached threads pose a problem for objects with thread storage duration.
          If we use a mechanism other than <code class="computeroutput"><span class="identifier">thread</span><span class="special">::</span><span class="identifier">__join</span></code>
          to wait for a <a class="link" href="thread_management.html#thread.thread_management.thread" title="Class thread"><code class="computeroutput"><span class="identifier">thread</span></code></a> to complete its work -
          such as waiting for a future to be ready - then the destructors of thread
          specific variables will still be running after the waiting thread has resumed.
          This section explain how the standard mechanism can be used to make such
          synchronization safe by ensuring that the objects with thread storage duration
          are destroyed prior to the future being made ready. e.g.
        </p>
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">find_the_answer</span><span class="special">();</span> <span class="comment">// uses thread specific objects</span>
<span class="keyword">void</span> <span class="identifier">thread_func</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;&amp;&amp;</span> <span class="identifier">p</span><span class="special">)</span>
<span class="special">{</span>
    <span class="identifier">p</span><span class="special">.</span><span class="identifier">set_value_at_thread_exit</span><span class="special">(</span><span class="identifier">find_the_answer</span><span class="special">());</span>
<span class="special">}</span>

<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
<span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">p</span><span class="special">;</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread</span> <span class="identifier">t</span><span class="special">(</span><span class="identifier">thread_func</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">p</span><span class="special">));</span>
    <span class="identifier">t</span><span class="special">.</span><span class="identifier">detach</span><span class="special">();</span> <span class="comment">// we're going to wait on the future</span>
    <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span><span class="special">&lt;&lt;</span><span class="identifier">p</span><span class="special">.</span><span class="identifier">get_future</span><span class="special">().</span><span class="identifier">get</span><span class="special">()&lt;&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
          When the call to <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code>
          returns, we know that not only is the future value ready, but the thread
          specific variables on the other thread have also been destroyed.
        </p>
<p>
          Such mechanisms are provided for <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">condition_variable</span></code>,
          <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code> and <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code>.
          e.g.
        </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">task_executor</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">(</span><span class="keyword">int</span><span class="special">)&gt;</span> <span class="identifier">task</span><span class="special">,</span><span class="keyword">int</span> <span class="identifier">param</span><span class="special">)</span>
<span class="special">{</span>
    <span class="identifier">task</span><span class="special">.</span><span class="identifier">make_ready_at_thread_exit</span><span class="special">(</span><span class="identifier">param</span><span class="special">);</span> <span class="comment">// execute stored task</span>
<span class="special">}</span> <span class="comment">// destroy thread specific and wake threads waiting on futures from task</span>
</pre>
<p>
          Other threads can wait on a future obtained from the task without having
          to worry about races due to the execution of destructors of the thread
          specific objects from the task's thread.
        </p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">condition_variable</span> <span class="identifier">cv</span><span class="special">;</span>
<span class="identifier">boost</span><span class="special">::</span><span class="identifier">mutex</span> <span class="identifier">m</span><span class="special">;</span>
<span class="identifier">complex_type</span> <span class="identifier">the_data</span><span class="special">;</span>
<span class="keyword">bool</span> <span class="identifier">data_ready</span><span class="special">;</span>

<span class="keyword">void</span> <span class="identifier">thread_func</span><span class="special">()</span>
<span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">lk</span><span class="special">(</span><span class="identifier">m</span><span class="special">);</span>
    <span class="identifier">the_data</span><span class="special">=</span><span class="identifier">find_the_answer</span><span class="special">();</span>
    <span class="identifier">data_ready</span><span class="special">=</span><span class="keyword">true</span><span class="special">;</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">notify_all_at_thread_exit</span><span class="special">(</span><span class="identifier">cv</span><span class="special">,</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">lk</span><span class="special">));</span>
<span class="special">}</span> <span class="comment">// destroy thread specific objects, notify cv, unlock mutex</span>

<span class="keyword">void</span> <span class="identifier">waiting_thread</span><span class="special">()</span>
<span class="special">{</span>
    <span class="identifier">boost</span><span class="special">::</span><span class="identifier">unique_lock</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">mutex</span><span class="special">&gt;</span> <span class="identifier">lk</span><span class="special">(</span><span class="identifier">m</span><span class="special">);</span>
    <span class="keyword">while</span><span class="special">(!</span><span class="identifier">data_ready</span><span class="special">)</span>
    <span class="special">{</span>
        <span class="identifier">cv</span><span class="special">.</span><span class="identifier">wait</span><span class="special">(</span><span class="identifier">lk</span><span class="special">);</span>
    <span class="special">}</span>
    <span class="identifier">process</span><span class="special">(</span><span class="identifier">the_data</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<p>
          The waiting thread is guaranteed that the thread specific objects used
          by <code class="computeroutput"><span class="identifier">thread_func</span><span class="special">()</span></code>
          have been destroyed by the time <code class="computeroutput"><span class="identifier">process</span><span class="special">(</span><span class="identifier">the_data</span><span class="special">)</span></code> is called. If the lock on <code class="computeroutput"><span class="identifier">m</span></code> is released and re-acquired after setting
          <code class="computeroutput"><span class="identifier">data_ready</span></code> and before calling
          <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">notify_all_at_thread_exit</span><span class="special">()</span></code>
          then this does NOT hold, since the thread may return from the wait due
          to a spurious wake-up.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.futures.async"></a><a class="link" href="synchronization.html#thread.synchronization.futures.async" title="Executing asynchronously">Executing asynchronously</a>
</h4></div></div></div>
<p>
          <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">async</span></code> is a simple way of running asynchronous
          tasks to make use of the available hardware concurrency. A call to <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">async</span></code> returns a <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future</span></code>
          that will contain the result of the task. Depending on the launch policy,
          the task is either run asynchronously on its own thread or synchronously
          on whichever thread calls the <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code> member functions on that <code class="computeroutput"><span class="identifier">future</span></code>.
        </p>
<p>
          A launch policy of either boost::launch::async, which asks the runtime
          to create an asynchronous thread, or boost::launch::deferred, which indicates
          you simply want to defer the function call until a later time (lazy evaluation).
          This argument is optional - if you omit it your function will use the default
          policy.
        </p>
<p>
          For example, consider computing the sum of a very large array. The first
          task is to not compute asynchronously when the overhead would be significant.
          The second task is to split the work into two pieces, one executed by the
          host thread and one executed asynchronously.
        </p>
<pre class="programlisting"><span class="keyword">int</span> <span class="identifier">parallel_sum</span><span class="special">(</span><span class="keyword">int</span><span class="special">*</span> <span class="identifier">data</span><span class="special">,</span> <span class="keyword">int</span> <span class="identifier">size</span><span class="special">)</span>
<span class="special">{</span>
  <span class="keyword">int</span> <span class="identifier">sum</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span>
  <span class="keyword">if</span> <span class="special">(</span> <span class="identifier">size</span> <span class="special">&lt;</span> <span class="number">1000</span> <span class="special">)</span>
    <span class="keyword">for</span> <span class="special">(</span> <span class="keyword">int</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special">&lt;</span> <span class="identifier">size</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span> <span class="special">)</span>
      <span class="identifier">sum</span> <span class="special">+=</span> <span class="identifier">data</span><span class="special">[</span><span class="identifier">i</span><span class="special">];</span>
  <span class="keyword">else</span> <span class="special">{</span>
    <span class="keyword">auto</span> <span class="identifier">handle</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">async</span><span class="special">(</span><span class="identifier">parallel_sum</span><span class="special">,</span> <span class="identifier">data</span><span class="special">+</span><span class="identifier">size</span><span class="special">/</span><span class="number">2</span><span class="special">,</span> <span class="identifier">size</span><span class="special">-</span><span class="identifier">size</span><span class="special">/</span><span class="number">2</span><span class="special">);</span>
    <span class="identifier">sum</span> <span class="special">+=</span> <span class="identifier">parallel_sum</span><span class="special">(</span><span class="identifier">data</span><span class="special">,</span> <span class="identifier">size</span><span class="special">/</span><span class="number">2</span><span class="special">);</span>
    <span class="identifier">sum</span> <span class="special">+=</span> <span class="identifier">handle</span><span class="special">.</span><span class="identifier">get</span><span class="special">();</span>
  <span class="special">}</span>
  <span class="keyword">return</span> <span class="identifier">sum</span><span class="special">;</span>
<span class="special">}</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.futures.shared"></a><a class="link" href="synchronization.html#thread.synchronization.futures.shared" title="Shared Futures">Shared Futures</a>
</h4></div></div></div>
<p>
          <code class="computeroutput"><span class="identifier">shared_future</span></code> is designed
          to be shared between threads, that is to allow multiple concurrent get
          operations.
        </p>
<h6>
<a name="thread.synchronization.futures.shared.h0"></a>
          <span class="phrase"><a name="thread.synchronization.futures.shared.multiple_get"></a></span><a class="link" href="synchronization.html#thread.synchronization.futures.shared.multiple_get">Multiple get</a>
        </h6>
<p>
          The second <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code>
          call in the following example is undefined.
        </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">bad_second_use</span><span class="special">(</span> <span class="identifier">type</span> <span class="identifier">arg</span> <span class="special">)</span> <span class="special">{</span>

  <span class="keyword">auto</span> <span class="identifier">ftr</span> <span class="special">=</span> <span class="identifier">async</span><span class="special">(</span> <span class="special">[=]{</span> <span class="keyword">return</span> <span class="identifier">work</span><span class="special">(</span> <span class="identifier">arg</span> <span class="special">);</span> <span class="special">}</span> <span class="special">);</span>
    <span class="keyword">if</span> <span class="special">(</span> <span class="identifier">cond1</span> <span class="special">)</span>
    <span class="special">{</span>
        <span class="identifier">use1</span><span class="special">(</span> <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span>
    <span class="special">}</span> <span class="keyword">else</span>
    <span class="special">{</span>
        <span class="identifier">use2</span><span class="special">(</span> <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span>
    <span class="special">}</span>
    <span class="identifier">use3</span><span class="special">(</span> <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span> <span class="comment">// second use is undefined</span>
<span class="special">}</span>
</pre>
<p>
          Using a <code class="computeroutput"><span class="identifier">shared_future</span></code> solves
          the issue
        </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">good_second_use</span><span class="special">(</span> <span class="identifier">type</span> <span class="identifier">arg</span> <span class="special">)</span> <span class="special">{</span>

   <span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">type</span><span class="special">&gt;</span> <span class="identifier">ftr</span> <span class="special">=</span> <span class="identifier">async</span><span class="special">(</span> <span class="special">[=]{</span> <span class="keyword">return</span> <span class="identifier">work</span><span class="special">(</span> <span class="identifier">arg</span> <span class="special">);</span> <span class="special">}</span> <span class="special">);</span>
    <span class="keyword">if</span> <span class="special">(</span> <span class="identifier">cond1</span> <span class="special">)</span>
    <span class="special">{</span>
        <span class="identifier">use1</span><span class="special">(</span> <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span>
    <span class="special">}</span> <span class="keyword">else</span>
    <span class="special">{</span>
        <span class="identifier">use2</span><span class="special">(</span>  <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span>
    <span class="special">}</span>
    <span class="identifier">use3</span><span class="special">(</span> <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span> <span class="comment">// second use is defined</span>
<span class="special">}</span>
</pre>
<h6>
<a name="thread.synchronization.futures.shared.h1"></a>
          <span class="phrase"><a name="thread.synchronization.futures.shared.share__"></a></span><a class="link" href="synchronization.html#thread.synchronization.futures.shared.share__">share()</a>
        </h6>
<p>
          Naming the return type when declaring the <code class="computeroutput"><span class="identifier">shared_future</span></code>
          is needed; auto is not available within template argument lists. Here
          <code class="computeroutput"><span class="identifier">share</span><span class="special">()</span></code>
          could be used to simplify the code
        </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">better_second_use</span><span class="special">(</span> <span class="identifier">type</span> <span class="identifier">arg</span> <span class="special">)</span> <span class="special">{</span>

   <span class="keyword">auto</span> <span class="identifier">ftr</span> <span class="special">=</span> <span class="identifier">async</span><span class="special">(</span> <span class="special">[=]{</span> <span class="keyword">return</span> <span class="identifier">work</span><span class="special">(</span> <span class="identifier">arg</span> <span class="special">);</span> <span class="special">}</span> <span class="special">).</span><span class="identifier">share</span><span class="special">();</span>
    <span class="keyword">if</span> <span class="special">(</span> <span class="identifier">cond1</span> <span class="special">)</span>
    <span class="special">{</span>
        <span class="identifier">use1</span><span class="special">(</span> <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span>
    <span class="special">}</span> <span class="keyword">else</span>
    <span class="special">{</span>
        <span class="identifier">use2</span><span class="special">(</span>  <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span>
    <span class="special">}</span>
    <span class="identifier">use3</span><span class="special">(</span> <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span> <span class="comment">// second use is defined</span>
<span class="special">}</span>
</pre>
<h6>
<a name="thread.synchronization.futures.shared.h2"></a>
          <span class="phrase"><a name="thread.synchronization.futures.shared.writing_on_get__"></a></span><a class="link" href="synchronization.html#thread.synchronization.futures.shared.writing_on_get__">Writing
          on get()</a>
        </h6>
<p>
          The user can either read or write the future variable.
        </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">write_to_get</span><span class="special">(</span> <span class="identifier">type</span> <span class="identifier">arg</span> <span class="special">)</span> <span class="special">{</span>

   <span class="keyword">auto</span> <span class="identifier">ftr</span> <span class="special">=</span> <span class="identifier">async</span><span class="special">(</span> <span class="special">[=]{</span> <span class="keyword">return</span> <span class="identifier">work</span><span class="special">(</span> <span class="identifier">arg</span> <span class="special">);</span> <span class="special">}</span> <span class="special">).</span><span class="identifier">share</span><span class="special">();</span>
    <span class="keyword">if</span> <span class="special">(</span> <span class="identifier">cond1</span> <span class="special">)</span>
    <span class="special">{</span>
        <span class="identifier">use1</span><span class="special">(</span> <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span>
    <span class="special">}</span> <span class="keyword">else</span>
    <span class="special">{</span>
      <span class="keyword">if</span> <span class="special">(</span> <span class="identifier">cond2</span> <span class="special">)</span>
        <span class="identifier">use2</span><span class="special">(</span>  <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span>
      <span class="keyword">else</span>
        <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">=</span> <span class="identifier">something</span><span class="special">();</span> <span class="comment">// assign to non-const reference.  </span>
    <span class="special">}</span>
    <span class="identifier">use3</span><span class="special">(</span> <span class="identifier">ftr</span><span class="special">.</span><span class="identifier">get</span><span class="special">()</span> <span class="special">);</span> <span class="comment">// second use is defined</span>
<span class="special">}</span>
</pre>
<p>
          This works because the <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;&gt;::</span><span class="identifier">get</span><span class="special">()</span></code> function returns a non-const reference
          to the appropriate storage. Of course the access to this storage must be
          ensured by the user. The library doesn't ensure the access to the internal
          storage is thread safe.
        </p>
<p>
          There has been some work by the C++ standard committee on an <code class="computeroutput"><span class="identifier">atomic_future</span></code> that behaves as an <code class="computeroutput"><span class="identifier">atomic</span></code> variable, that is thread_safe,
          and a <code class="computeroutput"><span class="identifier">shared_future</span></code> that
          can be shared between several threads, but there were not enough consensus
          and time to get it ready for C++11.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.futures.make_ready_future"></a><a class="link" href="synchronization.html#thread.synchronization.futures.make_ready_future" title="Making immediate futures easier">Making
        immediate futures easier</a>
</h4></div></div></div>
<p>
          Some functions may know the value at the point of construction. In these
          cases the value is immediately available, but needs to be returned as a
          future or shared_future. By using make_ready_future a future can be created
          which holds a pre-computed result in its shared state.
        </p>
<p>
          Without these features it is non-trivial to create a future directly from
          a value. First a promise must be created, then the promise is set, and
          lastly the future is retrieved from the promise. This can now be done with
          one operation.
        </p>
<h6>
<a name="thread.synchronization.futures.make_ready_future.h0"></a>
          <span class="phrase"><a name="thread.synchronization.futures.make_ready_future.make_ready_future"></a></span><a class="link" href="synchronization.html#thread.synchronization.futures.make_ready_future.make_ready_future">make_ready_future</a>
        </h6>
<p>
          This function creates a future for a given value. If no value is given
          then a future&lt;void&gt; is returned. This function is primarily useful
          in cases where sometimes, the return value is immediately available, but
          sometimes it is not. The example below illustrates, that in an error path
          the value is known immediately, however in other paths the function must
          return an eventual value represented as a future.
        </p>
<pre class="programlisting"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">compute</span><span class="special">(</span><span class="keyword">int</span> <span class="identifier">x</span><span class="special">)</span>
<span class="special">{</span>
  <span class="keyword">if</span> <span class="special">(</span><span class="identifier">x</span> <span class="special">==</span> <span class="number">0</span><span class="special">)</span> <span class="keyword">return</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">make_ready_future</span><span class="special">(</span><span class="number">0</span><span class="special">);</span>
  <span class="keyword">if</span> <span class="special">(</span><span class="identifier">x</span> <span class="special">&lt;</span> <span class="number">0</span><span class="special">)</span> <span class="keyword">return</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">make_ready_future</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">logic_error</span><span class="special">(</span><span class="string">"Error"</span><span class="special">));</span>
  <span class="identifier">boost</span><span class="special">::</span><span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">f1</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">async</span><span class="special">([]()</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">x</span><span class="special">+</span><span class="number">1</span><span class="special">;</span> <span class="special">});</span>
  <span class="keyword">return</span> <span class="identifier">f1</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
          There are two variations of this function. The first takes a value of any
          type, and returns a future of that type. The input value is passed to the
          shared state of the returned future. The second version takes no input
          and returns a future&lt;void&gt;.
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.futures.then"></a><a class="link" href="synchronization.html#thread.synchronization.futures.then" title="Associating future continuations">Associating future
        continuations</a>
</h4></div></div></div>
<p>
          In asynchronous programming, it is very common for one asynchronous operation,
          on completion, to invoke a second operation and pass data to it. The current
          C++ standard does not allow one to register a continuation to a future.
          With <code class="computeroutput"><span class="special">.</span><span class="identifier">then</span></code>,
          instead of waiting for the result, a continuation is "attached"
          to the asynchronous operation, which is invoked when the result is ready.
          Continuations registered using the <code class="computeroutput"><span class="special">.</span><span class="identifier">then</span></code> function will help to avoid blocking
          waits or wasting threads on polling, greatly improving the responsiveness
          and scalability of an application.
        </p>
<p>
          <code class="computeroutput"><span class="identifier">future</span><span class="special">.</span><span class="identifier">then</span><span class="special">()</span></code>
          provides the ability to sequentially compose two futures by declaring one
          to be the continuation of another. With <code class="computeroutput"><span class="special">.</span><span class="identifier">then</span><span class="special">()</span></code>
          the antecedent future is ready (has a value or exception stored in the
          shared state) before the continuation starts as instructed by the lambda
          function.
        </p>
<p>
          In the example below the <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">string</span><span class="special">&gt;</span></code> <code class="computeroutput"><span class="identifier">f2</span></code>
          is registered to be a continuation of <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span></code> <code class="computeroutput"><span class="identifier">f1</span></code>
          using the <code class="computeroutput"><span class="special">.</span><span class="identifier">then</span><span class="special">()</span></code> member function. This operation takes
          a lambda function which describes how <code class="computeroutput"><span class="identifier">f2</span></code>
          should proceed after <code class="computeroutput"><span class="identifier">f1</span></code>
          is ready.
        </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">thread</span><span class="special">/</span><span class="identifier">future</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
<span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">;</span>
<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
<span class="special">{</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">f1</span> <span class="special">=</span> <span class="identifier">async</span><span class="special">([]()</span> <span class="special">{</span> <span class="keyword">return</span> <span class="number">123</span><span class="special">;</span> <span class="special">});</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">string</span><span class="special">&gt;</span> <span class="identifier">f2</span> <span class="special">=</span> <span class="identifier">f1</span><span class="special">.</span><span class="identifier">then</span><span class="special">([](</span><span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;</span> <span class="identifier">f</span><span class="special">)</span> <span class="special">{</span> <span class="keyword">return</span> <span class="identifier">f</span><span class="special">.</span><span class="identifier">get</span><span class="special">().</span><span class="identifier">to_string</span><span class="special">();</span> <span class="comment">// here .get() won't block });</span>
<span class="special">}</span>
</pre>
<p>
          One key feature of this function is the ability to chain multiple asynchronous
          operations. In asynchronous programming, it's common to define a sequence
          of operations, in which each continuation executes only when the previous
          one completes. In some cases, the antecedent future produces a value that
          the continuation accepts as input. By using <code class="computeroutput"><span class="identifier">future</span><span class="special">.</span><span class="identifier">then</span><span class="special">()</span></code>, creating a chain of continuations becomes
          straightforward and intuitive:
        </p>
<pre class="programlisting"><span class="identifier">myFuture</span><span class="special">.</span><span class="identifier">then</span><span class="special">(...).</span><span class="identifier">then</span><span class="special">(...).</span><span class="identifier">then</span><span class="special">(...).</span>
</pre>
<p>
          Some points to note are:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              Each continuation will not begin until the preceding has completed.
            </li>
<li class="listitem">
              If an exception is thrown, the following continuation can handle it
              in a try-catch block
            </li>
</ul></div>
<p>
          Input Parameters:
        </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
              Lambda function: One option which can be considered is to take two
              functions, one for success and one for error handling. However this
              option has not been retained for the moment. The lambda function takes
              a future as its input which carries the exception through. This makes
              propagating exceptions straightforward. This approach also simplifies
              the chaining of continuations.
            </li>
<li class="listitem">
              Executor: Providing an overload to <code class="computeroutput"><span class="special">.</span><span class="identifier">then</span></code>, to take an executor reference
              places great flexibility over the execution of the future in the programmer's
              hand. As described above, often taking a launch policy is not sufficient
              for powerful asynchronous operations. The lifetime of the executor
              must outlive the continuation.
            </li>
<li class="listitem">
              Launch policy: if the additional flexibility that the executor provides
              is not required.
            </li>
</ul></div>
<p>
          Return values: The decision to return a future was based primarily on the
          ability to chain multiple continuations using <code class="computeroutput"><span class="special">.</span><span class="identifier">then</span><span class="special">()</span></code>.
          This benefit of composability gives the programmer incredible control and
          flexibility over their code. Returning a <code class="computeroutput"><span class="identifier">future</span></code>
          object rather than a <code class="computeroutput"><span class="identifier">shared_future</span></code>
          is also a much cheaper operation thereby improving performance. A <code class="computeroutput"><span class="identifier">shared_future</span></code> object is not necessary
          to take advantage of the chaining feature. It is also easy to go from a
          <code class="computeroutput"><span class="identifier">future</span></code> to a <code class="computeroutput"><span class="identifier">shared_future</span></code> when needed using future::share().
        </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="thread.synchronization.futures.reference"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference" title="Futures Reference">Futures Reference</a>
</h4></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.future_state">Enumeration
          <code class="computeroutput"><span class="identifier">state</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.future_errc">Enumeration
          <code class="computeroutput"><span class="identifier">future_errc</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.launch">Enumeration
          <code class="computeroutput"><span class="identifier">launch</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.is_error_code_enum">Specialization
          <code class="computeroutput"><span class="identifier">is_error_code_enum</span><span class="special">&lt;</span><span class="identifier">future_errc</span><span class="special">&gt;</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.make_error_code">Non-member
          function <code class="computeroutput"><span class="identifier">make_error_code</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.make_error_condition">Non-member
          function <code class="computeroutput"><span class="identifier">make_error_condition</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.future_category">Non-member
          function <code class="computeroutput"><span class="identifier">future_category</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.future_error">Class
          <code class="computeroutput"><span class="identifier">future_error</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.future_status">Enumeration
          <code class="computeroutput"><span class="identifier">future_status</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.future_error0">Class
          <code class="computeroutput"><span class="identifier">exceptional_ptr</span></code> EXPERIMENTAL</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.unique_future"><code class="computeroutput"><span class="identifier">future</span></code> class template</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.shared_future"><code class="computeroutput"><span class="identifier">shared_future</span></code> class template</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.promise"><code class="computeroutput"><span class="identifier">promise</span></code> class template</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.packaged_task"><code class="computeroutput"><span class="identifier">packaged_task</span></code> class template</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.decay_copy">Non-member
          function <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.async">Non-member
          function <code class="computeroutput"><span class="identifier">async</span><span class="special">()</span></code></a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.wait_for_any">Non-member
          function <code class="computeroutput"><span class="identifier">wait_for_any</span><span class="special">()</span></code>
          - EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.wait_for_all">Non-member
          function <code class="computeroutput"><span class="identifier">wait_for_all</span><span class="special">()</span></code>
          - EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.when_all">Non-member
          function <code class="computeroutput"><span class="identifier">when_all</span><span class="special">()</span></code>
          - EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.when_any">Non-member
          function <code class="computeroutput"><span class="identifier">when_any</span><span class="special">()</span></code>
          - EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.make_ready_future">Non-member
          function <code class="computeroutput"><span class="identifier">make_ready_future</span><span class="special">()</span></code> EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.make_exceptional_future">Non-member
          function <code class="computeroutput"><span class="identifier">make_exceptional_future</span><span class="special">()</span></code> EXTENSION</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.make_future">Non-member
          function <code class="computeroutput"><span class="identifier">make_future</span><span class="special">()</span></code>
          DEPRECATED</a></span></dt>
<dt><span class="section"><a href="synchronization.html#thread.synchronization.futures.reference.make_shared_future">Non-member
          function <code class="computeroutput"><span class="identifier">make_shared_future</span><span class="special">()</span></code> DEPRECATED</a></span></dt>
</dl></div>
<pre class="programlisting"><span class="comment">//#include &lt;boost/thread/future.hpp&gt;</span>

<span class="keyword">namespace</span> <span class="identifier">boost</span>
<span class="special">{</span>
  <span class="keyword">namespace</span> <span class="identifier">future_state</span>  <span class="comment">// EXTENSION</span>
  <span class="special">{</span>
    <span class="keyword">enum</span> <span class="identifier">state</span> <span class="special">{</span><span class="identifier">uninitialized</span><span class="special">,</span> <span class="identifier">waiting</span><span class="special">,</span> <span class="identifier">ready</span><span class="special">,</span> <span class="identifier">moved</span><span class="special">};</span>
  <span class="special">}</span>

  <span class="keyword">enum</span> <span class="keyword">class</span> <span class="identifier">future_errc</span>
  <span class="special">{</span>
    <span class="identifier">broken_promise</span><span class="special">,</span>
    <span class="identifier">future_already_retrieved</span><span class="special">,</span>
    <span class="identifier">promise_already_satisfied</span><span class="special">,</span>
    <span class="identifier">no_state</span>
  <span class="special">};</span>

  <span class="keyword">enum</span> <span class="keyword">class</span> <span class="identifier">launch</span>
  <span class="special">{</span>
    <span class="identifier">none</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">,</span>
    <span class="identifier">async</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">,</span>
    <span class="identifier">deferred</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">,</span>
    <span class="identifier">executor</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">,</span>
    <span class="identifier">inherit</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">,</span>
    <span class="identifier">any</span> <span class="special">=</span> <span class="identifier">async</span> <span class="special">|</span> <span class="identifier">deferred</span>
  <span class="special">};</span>

  <span class="keyword">enum</span> <span class="keyword">class</span> <span class="identifier">future_status</span> <span class="special">{</span>
    <span class="identifier">ready</span><span class="special">,</span>  <span class="identifier">timeout</span><span class="special">,</span> <span class="identifier">deferred</span>
  <span class="special">};</span>

  <span class="keyword">namespace</span> <span class="identifier">system</span>
  <span class="special">{</span>
    <span class="keyword">template</span> <span class="special">&lt;&gt;</span>
    <span class="keyword">struct</span> <span class="identifier">is_error_code_enum</span><span class="special">&lt;</span><span class="identifier">future_errc</span><span class="special">&gt;</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">true_type</span> <span class="special">{};</span>

    <span class="identifier">error_code</span> <span class="identifier">make_error_code</span><span class="special">(</span><span class="identifier">future_errc</span> <span class="identifier">e</span><span class="special">);</span>

    <span class="identifier">error_condition</span> <span class="identifier">make_error_condition</span><span class="special">(</span><span class="identifier">future_errc</span> <span class="identifier">e</span><span class="special">);</span>
  <span class="special">}</span>

  <span class="keyword">const</span> <span class="identifier">system</span><span class="special">::</span><span class="identifier">error_category</span><span class="special">&amp;</span> <span class="identifier">future_category</span><span class="special">();</span>

  <span class="keyword">class</span> <span class="identifier">future_error</span><span class="special">;</span>

  <span class="keyword">class</span> <span class="identifier">exceptional_ptr</span><span class="special">;</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">R</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">promise</span><span class="special">;</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">R</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">promise</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;&amp;</span> <span class="identifier">x</span><span class="special">,</span> <span class="identifier">promise</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;&amp;</span> <span class="identifier">y</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="keyword">namespace</span> <span class="identifier">container</span> <span class="special">{</span>
    <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">R</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Alloc</span><span class="special">&gt;</span>
    <span class="keyword">struct</span> <span class="identifier">uses_allocator</span><span class="special">&lt;</span><span class="identifier">promise</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;,</span> <span class="identifier">Alloc</span><span class="special">&gt;::</span> <span class="identifier">true_type</span><span class="special">;</span>
  <span class="special">}</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">R</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">future</span><span class="special">;</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">R</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">shared_future</span><span class="special">;</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">S</span><span class="special">&gt;</span>
  <span class="keyword">class</span> <span class="identifier">packaged_task</span><span class="special">;</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">&gt;</span> <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">packaged_task</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;&amp;,</span> <span class="identifier">packaged_task</span><span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;&amp;)</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">S</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Alloc</span><span class="special">&gt;</span>
  <span class="keyword">struct</span> <span class="identifier">uses_allocator</span><span class="special">&lt;</span><span class="identifier">packaged_task</span> <span class="special">&lt;</span><span class="identifier">S</span><span class="special">&gt;,</span> <span class="identifier">Alloc</span><span class="special">&gt;;</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">()&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
    <span class="identifier">async</span><span class="special">(</span><span class="identifier">F</span> <span class="identifier">f</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">()&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
    <span class="identifier">async</span><span class="special">(</span><span class="identifier">launch</span> <span class="identifier">policy</span><span class="special">,</span> <span class="identifier">F</span> <span class="identifier">f</span><span class="special">);</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Args</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">...)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
    <span class="identifier">async</span><span class="special">(</span><span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">Args</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Args</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">...)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
    <span class="identifier">async</span><span class="special">(</span><span class="identifier">launch</span> <span class="identifier">policy</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">Args</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Args</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">...)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
    <span class="identifier">async</span><span class="special">(</span><span class="identifier">Executor</span> <span class="special">&amp;</span><span class="identifier">ex</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">Args</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span><span class="special">);</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">wait_for_all</span><span class="special">(</span><span class="identifier">Iterator</span> <span class="identifier">begin</span><span class="special">,</span><span class="identifier">Iterator</span> <span class="identifier">end</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F1</span><span class="special">,</span><span class="keyword">typename</span><span class="special">...</span> <span class="identifier">FS</span><span class="special">&gt;</span>
    <span class="keyword">void</span> <span class="identifier">wait_for_all</span><span class="special">(</span><span class="identifier">F1</span><span class="special">&amp;</span> <span class="identifier">f1</span><span class="special">,</span><span class="identifier">Fs</span><span class="special">&amp;...</span> <span class="identifier">fs</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">&gt;</span>
    <span class="identifier">Iterator</span> <span class="identifier">wait_for_any</span><span class="special">(</span><span class="identifier">Iterator</span> <span class="identifier">begin</span><span class="special">,</span><span class="identifier">Iterator</span> <span class="identifier">end</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F1</span><span class="special">,</span><span class="keyword">typename</span><span class="special">...</span> <span class="identifier">Fs</span><span class="special">&gt;</span>
    <span class="keyword">unsigned</span> <span class="identifier">wait_for_any</span><span class="special">(</span><span class="identifier">F1</span><span class="special">&amp;</span> <span class="identifier">f1</span><span class="special">,</span><span class="identifier">Fs</span><span class="special">&amp;...</span> <span class="identifier">fs</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">InputIterator</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">InputIterator</span><span class="special">::</span><span class="identifier">value_type</span><span class="special">::</span><span class="identifier">value_type</span><span class="special">&gt;&gt;</span>
    <span class="identifier">when_all</span><span class="special">(</span><span class="identifier">InputIterator</span> <span class="identifier">first</span><span class="special">,</span> <span class="identifier">InputIterator</span> <span class="identifier">last</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span><span class="special">...</span> <span class="identifier">T</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="identifier">decay_t</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;...&gt;</span> <span class="identifier">when_all</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;&amp;...</span> <span class="identifier">futures</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">InputIterator</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">InputIterator</span><span class="special">::</span><span class="identifier">value_type</span><span class="special">::</span><span class="identifier">value_type</span><span class="special">&gt;&gt;</span>
    <span class="identifier">when_any</span><span class="special">(</span><span class="identifier">InputIterator</span> <span class="identifier">first</span><span class="special">,</span> <span class="identifier">InputIterator</span> <span class="identifier">last</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span><span class="special">...</span> <span class="identifier">T</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="identifier">decay_t</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;...&gt;</span> <span class="identifier">when_any</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;&amp;...</span> <span class="identifier">futures</span><span class="special">);</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span> <span class="identifier">make_future</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="identifier">value</span><span class="special">);</span>  <span class="comment">// DEPRECATED</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;</span> <span class="identifier">make_future</span><span class="special">();</span>  <span class="comment">// DEPRECATED</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
    <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span> <span class="identifier">make_ready_future</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="identifier">value</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;</span> <span class="identifier">make_ready_future</span><span class="special">();</span>  <span class="comment">// EXTENSION</span>

  <span class="identifier">exceptional_ptr</span> <span class="identifier">make_exceptional_future</span><span class="special">(</span><span class="identifier">exception_ptr</span> <span class="identifier">ex</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">E</span><span class="special">&gt;</span>
    <span class="identifier">exceptional_ptr</span> <span class="identifier">make_exceptional_future</span><span class="special">(</span><span class="identifier">E</span> <span class="identifier">ex</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
  <span class="identifier">exceptional_ptr</span> <span class="identifier">make_exceptional_future</span><span class="special">();</span>  <span class="comment">// EXTENSION</span>


  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
  <span class="identifier">shared_future</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span> <span class="identifier">make_shared_future</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="identifier">value</span><span class="special">);</span>  <span class="comment">// DEPRECATED</span>
  <span class="identifier">shared_future</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;</span> <span class="identifier">make_shared_future</span><span class="special">();</span>  <span class="comment">// DEPRECATED</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.future_state"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state">Enumeration
          <code class="computeroutput"><span class="identifier">state</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">future_state</span>
<span class="special">{</span>
  <span class="keyword">enum</span> <span class="identifier">state</span> <span class="special">{</span><span class="identifier">uninitialized</span><span class="special">,</span> <span class="identifier">waiting</span><span class="special">,</span> <span class="identifier">ready</span><span class="special">,</span> <span class="identifier">moved</span><span class="special">};</span>
<span class="special">}</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.future_errc"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_errc" title="Enumeration future_errc">Enumeration
          <code class="computeroutput"><span class="identifier">future_errc</span></code></a>
</h5></div></div></div>
<pre class="programlisting"> <span class="keyword">enum</span> <span class="keyword">class</span> <span class="identifier">future_errc</span>
 <span class="special">{</span>
   <span class="identifier">broken_promise</span> <span class="special">=</span> <span class="identifier">implementation</span> <span class="identifier">defined</span><span class="special">,</span>
   <span class="identifier">future_already_retrieved</span> <span class="special">=</span> <span class="identifier">implementation</span> <span class="identifier">defined</span><span class="special">,</span>
   <span class="identifier">promise_already_satisfied</span> <span class="special">=</span> <span class="identifier">implementation</span> <span class="identifier">defined</span><span class="special">,</span>
   <span class="identifier">no_state</span> <span class="special">=</span> <span class="identifier">implementation</span> <span class="identifier">defined</span>
 <span class="special">}</span>


<span class="identifier">The</span> <span class="keyword">enum</span> <span class="identifier">values</span> <span class="identifier">of</span> <span class="identifier">future_errc</span> <span class="identifier">are</span> <span class="identifier">distinct</span> <span class="keyword">and</span> <span class="keyword">not</span> <span class="identifier">zero</span><span class="special">.</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.launch"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.launch" title="Enumeration launch">Enumeration
          <code class="computeroutput"><span class="identifier">launch</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">enum</span> <span class="keyword">class</span> <span class="identifier">launch</span>
<span class="special">{</span>
  <span class="identifier">none</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">,</span>
  <span class="identifier">async</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">,</span>
  <span class="identifier">deferred</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">,</span>
  <span class="identifier">executor</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">,</span>
  <span class="identifier">inherit</span> <span class="special">=</span> <span class="identifier">unspecified</span><span class="special">,</span>
  <span class="identifier">any</span> <span class="special">=</span> <span class="identifier">async</span> <span class="special">|</span> <span class="identifier">deferred</span>
<span class="special">};</span>
</pre>
<p>
            The enum type launch is a bitmask type with launch::async and launch::deferred
            denoting individual bits.
          </p>
<p>
            A future created with <code class="computeroutput"><span class="identifier">promise</span><span class="special">&lt;&gt;</span></code> or with a <code class="computeroutput"><span class="identifier">packaged_task</span><span class="special">&lt;&gt;</span></code> or with <code class="computeroutput"><span class="identifier">make_ready_future</span></code>/<code class="computeroutput"><span class="identifier">make_exceptional_future</span></code> (has no associated
            launch policy), has an implicit a launch policy of <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">none</span></code>.
          </p>
<p>
            A future created by <code class="computeroutput"><span class="identifier">async</span><span class="special">(</span><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span><span class="special">,</span> <span class="special">...)</span></code>
            or <code class="computeroutput"><span class="special">::</span><span class="identifier">then</span><span class="special">(</span><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span><span class="special">,</span> <span class="special">...)</span></code>
            has associated a launch policy <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code>.
            A future created by <code class="computeroutput"><span class="identifier">async</span><span class="special">(</span><span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span><span class="special">,</span> <span class="special">...)</span></code>
            or <code class="computeroutput"><span class="special">::</span><span class="identifier">then</span><span class="special">(</span><span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span><span class="special">,</span> <span class="special">...)</span></code>
            has associated a launch policy <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>.
            A future created by <code class="computeroutput"><span class="identifier">async</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">,</span> <span class="special">...)</span></code>
            or <code class="computeroutput"><span class="special">::</span><span class="identifier">then</span><span class="special">(</span><span class="identifier">Executor</span><span class="special">,</span> <span class="special">...)</span></code>
            or <code class="computeroutput"><span class="special">::</span><span class="identifier">then</span><span class="special">(</span><span class="identifier">launch</span><span class="special">::</span><span class="identifier">executor</span><span class="special">,</span> <span class="special">...)</span></code>
            has associated a launch policy <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">executor</span></code>.
            A future created by <code class="computeroutput"><span class="identifier">async</span><span class="special">(...)</span></code> or <code class="computeroutput"><span class="special">::</span><span class="identifier">then</span><span class="special">(...)</span></code>
            has associated a launch policy <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">none</span></code>.
          </p>
<p>
            A future created by <code class="computeroutput"><span class="special">::</span><span class="identifier">then</span><span class="special">(</span><span class="identifier">launch</span><span class="special">::</span><span class="identifier">inherit</span><span class="special">,</span> <span class="special">...)</span></code>
            has associated a launch policy parent future.
          </p>
<p>
            The <code class="computeroutput"><span class="identifier">executor</span></code> and the
            <code class="computeroutput"><span class="identifier">inherit</span></code> launch policies
            have a sense only can be user only on <code class="computeroutput"><span class="identifier">then</span><span class="special">()</span></code>.
          </p>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.is_error_code_enum"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.is_error_code_enum" title="Specialization is_error_code_enum&lt;future_errc&gt;">Specialization
          <code class="computeroutput"><span class="identifier">is_error_code_enum</span><span class="special">&lt;</span><span class="identifier">future_errc</span><span class="special">&gt;</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">system</span>
<span class="special">{</span>
  <span class="keyword">template</span> <span class="special">&lt;&gt;</span>
  <span class="keyword">struct</span> <span class="identifier">is_error_code_enum</span><span class="special">&lt;</span><span class="identifier">future_errc</span><span class="special">&gt;</span> <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">true_type</span> <span class="special">{};</span>

<span class="special">}</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.make_error_code"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.make_error_code" title="Non-member function make_error_code()">Non-member
          function <code class="computeroutput"><span class="identifier">make_error_code</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">system</span>
<span class="special">{</span>
  <span class="identifier">error_code</span> <span class="identifier">make_error_code</span><span class="special">(</span><span class="identifier">future_errc</span> <span class="identifier">e</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">error_code</span><span class="special">(</span><span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;(</span><span class="identifier">e</span><span class="special">),</span>
                  <span class="identifier">future_category</span><span class="special">())</span></code>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.make_error_condition"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.make_error_condition" title="Non-member function make_error_condition()">Non-member
          function <code class="computeroutput"><span class="identifier">make_error_condition</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">namespace</span> <span class="identifier">system</span>
<span class="special">{</span>
  <span class="identifier">error_condition</span> <span class="identifier">make_error_condition</span><span class="special">(</span><span class="identifier">future_errc</span> <span class="identifier">e</span><span class="special">);</span>
<span class="special">}</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">error_condition</span><span class="special">(</span><span class="keyword">static_cast</span><span class="special">&lt;</span><span class="keyword">int</span><span class="special">&gt;(</span><span class="identifier">e</span><span class="special">),</span> <span class="identifier">future_category</span><span class="special">())</span></code>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.future_category"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_category" title="Non-member function future_category()">Non-member
          function <code class="computeroutput"><span class="identifier">future_category</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">const</span> <span class="identifier">system</span><span class="special">::</span><span class="identifier">error_category</span><span class="special">&amp;</span> <span class="identifier">future_category</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  A reference to an object of a type derived from class error_category.
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  The object's <code class="computeroutput"><span class="identifier">default_error_condition</span></code>
                  and equivalent virtual functions behave as specified for the class
                  <code class="computeroutput"><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_category</span></code>. The object's
                  <code class="computeroutput"><span class="identifier">name</span></code> virtual function
                  returns a pointer to the string "future".
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.future_error"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_error" title="Class future_error">Class
          <code class="computeroutput"><span class="identifier">future_error</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">future_error</span>
    <span class="special">:</span> <span class="keyword">public</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">logic_error</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
    <span class="identifier">future_error</span><span class="special">(</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="identifier">ec</span><span class="special">);</span>

    <span class="keyword">const</span> <span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&amp;</span> <span class="identifier">code</span><span class="special">()</span> <span class="keyword">const</span> <span class="identifier">no_except</span><span class="special">;</span>
<span class="special">};</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.future_error.constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_error.constructor" title="Constructor">Constructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">future_error</span><span class="special">(</span><span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span> <span class="identifier">ec</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a future_error.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">code</span><span class="special">()==</span><span class="identifier">ec</span></code>
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.future_error.code"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_error.code" title="Member function code()">Member
            function <code class="computeroutput"><span class="identifier">code</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">const</span> <span class="identifier">system</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&amp;</span> <span class="identifier">code</span><span class="special">()</span> <span class="keyword">const</span> <span class="identifier">no_except</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    The value of <code class="computeroutput"><span class="identifier">ec</span></code>
                    that was passed to the object's constructor.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.future_status"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_status" title="Enumeration future_status">Enumeration
          <code class="computeroutput"><span class="identifier">future_status</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">enum</span> <span class="keyword">class</span> <span class="identifier">future_status</span> <span class="special">{</span>
  <span class="identifier">ready</span><span class="special">,</span>  <span class="identifier">timeout</span><span class="special">,</span> <span class="identifier">deferred</span>
<span class="special">};</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.future_error0"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_error0" title="Class exceptional_ptr EXPERIMENTAL">Class
          <code class="computeroutput"><span class="identifier">exceptional_ptr</span></code> EXPERIMENTAL</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">exceptional_ptr</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
  <span class="identifier">exceptional_ptr</span><span class="special">();</span>
  <span class="keyword">explicit</span> <span class="identifier">exceptional_ptr</span><span class="special">(</span><span class="identifier">exception_ptr</span> <span class="identifier">ex</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">E</span><span class="special">&gt;</span>
  <span class="keyword">explicit</span> <span class="identifier">exceptional_ptr</span><span class="special">(</span><span class="identifier">E</span><span class="special">&amp;&amp;</span> <span class="identifier">ex</span><span class="special">);</span>
<span class="special">};</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.future_error.constructor0"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_error.constructor0" title="Constructor">Constructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">exceptional_ptr</span><span class="special">();</span>
<span class="keyword">explicit</span> <span class="identifier">exceptional_ptr</span><span class="special">(</span><span class="identifier">exception_ptr</span> <span class="identifier">ex</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">E</span><span class="special">&gt;</span>
<span class="keyword">explicit</span> <span class="identifier">exceptional_ptr</span><span class="special">(</span><span class="identifier">E</span><span class="special">&amp;&amp;</span> <span class="identifier">ex</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    The exception that is passed in to the constructor or the current
                    exception if no parameter is moved into the constructed <code class="computeroutput"><span class="identifier">exceptional_ptr</span></code> if it is an
                    rvalue. Otherwise the exception is copied into the constructed
                    <code class="computeroutput"><span class="identifier">exceptional_ptr</span></code>.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span>
                    <span class="special">==</span> <span class="keyword">true</span>
                    <span class="special">&amp;&amp;</span> <span class="identifier">is_ready</span><span class="special">()</span> <span class="special">=</span>
                    <span class="keyword">true</span> <span class="special">&amp;&amp;</span>
                    <span class="identifier">has_value</span><span class="special">()</span>
                    <span class="special">=</span> <span class="keyword">false</span></code>
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.unique_future"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code> class template</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">R</span><span class="special">&gt;</span>
<span class="keyword">class</span>  <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a>
<span class="special">{</span>

<span class="keyword">public</span><span class="special">:</span>
  <span class="keyword">typedef</span> <span class="identifier">R</span> <span class="identifier">value_type</span><span class="special">;</span>  <span class="comment">// EXTENSION</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="special">~</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">();</span>

  <span class="comment">// move support</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="keyword">explicit</span>  <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;&gt;&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="comment">// factories</span>
  <span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span> <span class="identifier">share</span><span class="special">();</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">then</span><span class="special">(</span><span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">S</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">then</span><span class="special">(</span><span class="identifier">Ex</span><span class="special">&amp;</span> <span class="identifier">executor</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">then</span><span class="special">(</span><span class="identifier">launch</span> <span class="identifier">policy</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

  <span class="identifier">see</span> <span class="identifier">below</span> <span class="identifier">unwrap</span><span class="special">();</span>  <span class="comment">// EXTENSION</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> <span class="identifier">fallback_to</span><span class="special">();</span>  <span class="comment">// EXTENSION</span>

  <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="comment">// retrieving the value</span>
  <span class="identifier">see</span> <span class="identifier">below</span> <span class="identifier">get</span><span class="special">();</span>
  <span class="identifier">see</span> <span class="identifier">below</span> <span class="identifier">get_or</span><span class="special">(</span><span class="identifier">see</span> <span class="identifier">below</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>

  <span class="identifier">exception_ptr</span> <span class="identifier">get_exception_ptr</span><span class="special">();</span> <span class="comment">// EXTENSION</span>

  <span class="comment">// functions to check state</span>
  <span class="keyword">bool</span> <span class="identifier">valid</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="keyword">bool</span> <span class="identifier">is_ready</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">bool</span> <span class="identifier">has_exception</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">bool</span> <span class="identifier">has_value</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// EXTENSION</span>

  <span class="comment">// waiting for the result to be ready</span>
  <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
  <span class="identifier">future_status</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
  <span class="identifier">future_status</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>

<span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_USES_DATE_TIME</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
  <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">Duration</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// DEPRECATED SINCE V3.0.0</span>
  <span class="keyword">bool</span> <span class="identifier">timed_wait_until</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// DEPRECATED SINCE V3.0.0</span>
<span class="preprocessor">#endif</span>
  <span class="keyword">typedef</span> <span class="identifier">future_state</span><span class="special">::</span><span class="identifier">state</span> <span class="identifier">state</span><span class="special">;</span>  <span class="comment">// EXTENSION</span>
  <span class="identifier">state</span> <span class="identifier">get_state</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>  <span class="comment">// EXTENSION</span>
<span class="special">};</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.default_constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.default_constructor" title="Default Constructor">Default
            Constructor</a>
</h6></div></div></div>
<pre class="programlisting"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs an uninitialized <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a>.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span></code></a> returns <code class="computeroutput"><span class="keyword">false</span></code>. <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">uninitialized</span></code></a>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.destructor" title="Destructor">Destructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.move_constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.move_constructor" title="Move Constructor">Move
            Constructor</a>
</h6></div></div></div>
<pre class="programlisting"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a new <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a>, and transfers
                    ownership of the shared state associated with <code class="computeroutput"><span class="identifier">other</span></code>
                    to <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns the value of <code class="computeroutput"><span class="identifier">other</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code> prior to the call. <code class="computeroutput"><span class="identifier">other</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">uninitialized</span></code></a>. If <code class="computeroutput"><span class="identifier">other</span></code> was associated with a
                    shared state, that result is now associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                    <code class="computeroutput"><span class="identifier">other</span></code> is not
                    associated with any shared state.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    If the compiler does not support rvalue-references, this is implemented
                    using the boost.thread move emulation.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.unwrap_move_constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.unwrap_move_constructor" title="Unwrap Move Constructor - EXTENSION">Unwrap
            Move Constructor - EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">explicit</span>  <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;&gt;&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
</pre>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
                This constructor is experimental and subject to change in future
                versions. There are not too much tests yet, so it is possible that
                you can find out some trivial bugs :(
              </p></td></tr>
</table></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd>
<p>
                    <code class="computeroutput"><span class="identifier">other</span><span class="special">.</span><span class="identifier">valid</span><span class="special">()</span></code>.
                  </p>
<p>
                    [Effects:
                  </p>
<p>
                    Constructs a new <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a>, and transfers
                    ownership of the shared state associated with <code class="computeroutput"><span class="identifier">other</span></code>
                    and unwrapping the inner future (see <code class="computeroutput"><span class="identifier">unwrap</span><span class="special">()</span></code>).
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns the value of <code class="computeroutput"><span class="identifier">other</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code> prior to the call. <code class="computeroutput"><span class="identifier">other</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">uninitialized</span></code></a>. The associated
                    shared state is now unwrapped and the inner future shared state
                    is associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>. <code class="computeroutput"><span class="identifier">other</span></code>
                    is not associated with any shared state, <code class="computeroutput"><span class="special">!</span>
                    <span class="identifier">other</span><span class="special">.</span><span class="identifier">valid</span><span class="special">()</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    If the compiler does not support rvalue-references, this is implemented
                    using the boost.thread move emulation.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.move_assignment"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.move_assignment" title="Move Assignment Operator">Move
            Assignment Operator</a>
</h6></div></div></div>
<pre class="programlisting"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Transfers ownership of the shared state associated with <code class="computeroutput"><span class="identifier">other</span></code> to <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns the value of <code class="computeroutput"><span class="identifier">other</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code> prior to the call. <code class="computeroutput"><span class="identifier">other</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">uninitialized</span></code></a>. If <code class="computeroutput"><span class="identifier">other</span></code> was associated with a
                    shared state, that result is now associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                    <code class="computeroutput"><span class="identifier">other</span></code> is not
                    associated with any shared state. If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> was associated with an asynchronous
                    result prior to the call, that result no longer has an associated
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> instance.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    If the compiler does not support rvalue-references, this is implemented
                    using the boost.thread move emulation.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.swap"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.swap" title="Member function swap()">Member
            function <code class="computeroutput"><span class="identifier">swap</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> <span class="special">&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="identifier">no_except</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Swaps ownership of the shared states associated with <code class="computeroutput"><span class="identifier">other</span></code> and <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns the value of <code class="computeroutput"><span class="identifier">other</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code> prior to the call. <code class="computeroutput"><span class="identifier">other</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code>
                    returns the value of <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code> prior to the call. If <code class="computeroutput"><span class="identifier">other</span></code> was associated with a
                    shared state, that result is now associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                    otherwise <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    has no associated result. If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> was associated with a shared
                    state, that result is now associated with <code class="computeroutput"><span class="identifier">other</span></code>,
                    otherwise <code class="computeroutput"><span class="identifier">other</span></code>
                    has no associated result.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.get"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get" title="Member function get()">Member
            function <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">R</span> <span class="identifier">get</span><span class="special">();</span>
<span class="identifier">R</span><span class="special">&amp;</span>  <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&amp;&gt;::</span><span class="identifier">get</span><span class="special">();</span>
<span class="keyword">void</span>  <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;::</span><span class="identifier">get</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready as-if by a call to <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.wait" title="Member function wait()"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">wait</span><span class="special">()</span></code></a>,
                    and retrieves the result (whether that is a value or an exception).
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&amp;&gt;::</span><span class="identifier">get</span><span class="special">()</span></code>
                    return the stored reference.
                  </p>
<p>
                    - <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;::</span><span class="identifier">get</span><span class="special">()</span></code>,
                    there is no return value.
                  </p>
<p>
                    - <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">get</span><span class="special">()</span></code>
                    returns an rvalue-reference to the value stored in the shared
                    state.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code>. <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception stored in the shared state in place of a value.
                  </p>
</dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.get_or"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_or" title="Member function get_or() - EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">get_or</span><span class="special">()</span></code>
            - EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">R</span> <span class="identifier">get_or</span><span class="special">(</span><span class="identifier">R</span><span class="special">&amp;&amp;</span> <span class="identifier">v</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
<span class="identifier">R</span> <span class="identifier">get_or</span><span class="special">(</span><span class="identifier">R</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">v</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
<span class="identifier">R</span><span class="special">&amp;</span>  <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&amp;&gt;::</span><span class="identifier">get_or</span><span class="special">(</span><span class="identifier">R</span><span class="special">&amp;</span> <span class="identifier">v</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
<span class="keyword">void</span>  <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;::</span><span class="identifier">get_or</span><span class="special">();</span>  <span class="comment">// EXTENSION</span>
</pre>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
                These functions are experimental and subject to change in future
                versions. There are not too much tests yet, so it is possible that
                you can find out some trivial bugs :(
              </p></td></tr>
</table></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready as-if by a call to <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.wait" title="Member function wait()"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">wait</span><span class="special">()</span></code></a>,
                    and depending on whether the shared state <code class="computeroutput"><span class="identifier">has_value</span><span class="special">()</span></code> the retrieves the result.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&amp;&gt;::</span><span class="identifier">get_or</span><span class="special">(</span><span class="identifier">v</span><span class="special">)</span></code>
                    return the stored reference if has_value() and the passes parameter
                    otherwise.
                  </p>
<p>
                    - <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;::</span><span class="identifier">get_or</span><span class="special">()</span></code>,
                    there is no return value, but the function doesn't throws even
                    if the shared state contained an exception.
                  </p>
<p>
                    - <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">get_or</span><span class="special">(</span><span class="identifier">v</span><span class="special">)</span></code>
                    returns an rvalue-reference to the value stored in the shared
                    state if <code class="computeroutput"><span class="identifier">has_value</span><span class="special">()</span></code> and an rvalue-reference build
                    with the parameter <code class="computeroutput"><span class="identifier">v</span></code>.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code>. <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">get_or</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.wait"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.wait" title="Member function wait()">Member
            function <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">wait</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready. If the result is not ready on entry, and the result has
                    a <span class="emphasis"><em>wait callback</em></span> set, that callback is invoked
                    prior to waiting.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception thrown by the <span class="emphasis"><em>wait callback</em></span>
                    if such a callback is called.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code>. <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.timed_wait_duration"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.timed_wait_duration" title="Member function timed_wait() DEPRECATED SINCE V3.0.0">Member
            function <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code>
            DEPRECATED SINCE V3.0.0</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
<span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">Duration</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">wait_duration</span><span class="special">);</span>
</pre>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top">
<p>
                DEPRECATED since 3.00.
              </p>
<p>
                Use instead <a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_for" title="template &lt;class Rep, class Period&gt; cv_status wait_for(boost::unique_lock&lt;boost::mutex&gt;&amp; lock, const chrono::duration&lt;Rep, Period&gt;&amp; rel_time)"><code class="computeroutput"><span class="identifier">wait_for</span></code></a>.
              </p>
</td></tr>
</table></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready, or the time specified by <code class="computeroutput"><span class="identifier">wait_duration</span></code>
                    has elapsed. If the result is not ready on entry, and the result
                    has a <span class="emphasis"><em>wait callback</em></span> set, that callback is
                    invoked prior to waiting.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, and that result is ready before
                    the specified time has elapsed, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception thrown by the <span class="emphasis"><em>wait callback</em></span>
                    if such a callback is called.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    If this call returned <code class="computeroutput"><span class="keyword">true</span></code>,
                    then <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code> and
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>. <code class="computeroutput"><span class="identifier">Duration</span></code> must be a type that
                    meets the Boost.DateTime time duration requirements.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.timed_wait_absolute"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.timed_wait_absolute" title="Member function timed_wait() DEPRECATED SINCE V3.0.0">Member
            function <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code>
            DEPRECATED SINCE V3.0.0</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">wait_timeout</span><span class="special">);</span>
</pre>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top">
<p>
                DEPRECATED since 3.00.
              </p>
<p>
                Use instead <a class="link" href="synchronization.html#thread.synchronization.condvar_ref.condition_variable.wait_until" title="template &lt;class Clock, class Duration&gt; cv_status wait_until(boost::unique_lock&lt;boost::mutex&gt;&amp; lock, const chrono::time_point&lt;Clock, Duration&gt;&amp; abs_time)"><code class="computeroutput"><span class="identifier">wait_until</span></code></a>.
              </p>
</td></tr>
</table></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready, or the time point specified by <code class="computeroutput"><span class="identifier">wait_timeout</span></code>
                    has passed. If the result is not ready on entry, and the result
                    has a <span class="emphasis"><em>wait callback</em></span> set, that callback is
                    invoked prior to waiting.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, and that result is ready before
                    the specified time has passed, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception thrown by the <span class="emphasis"><em>wait callback</em></span>
                    if such a callback is called.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    If this call returned <code class="computeroutput"><span class="keyword">true</span></code>,
                    then <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code> and
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.wait_for"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.wait_for" title="Member function wait_for()">Member
            function <code class="computeroutput"><span class="identifier">wait_for</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
<span class="identifier">future_status</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready, or the time specified by <code class="computeroutput"><span class="identifier">wait_duration</span></code>
                    has elapsed. If the result is not ready on entry, and the result
                    has a <span class="emphasis"><em>wait callback</em></span> set, that callback is
                    invoked prior to waiting.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">deferred</span></code>
                    if the shared state contains a deferred function. (Not implemented
                    yet)
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">ready</span></code>
                    if the shared state is ready.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">timeout</span></code>
                    if the function is returning because the relative timeout specified
                    by <code class="computeroutput"><span class="identifier">rel_time</span></code> has
                    expired.
                  </p>
</dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception thrown by the <span class="emphasis"><em>wait callback</em></span>
                    if such a callback is called.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    If this call returned <code class="computeroutput"><span class="keyword">true</span></code>,
                    then <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code> and
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">wait_for</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>. <code class="computeroutput"><span class="identifier">Duration</span></code> must be a type that
                    meets the Boost.DateTime time duration requirements.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.wait_until"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.wait_until" title="Member function wait_until()">Member
            function <code class="computeroutput"><span class="identifier">wait_until</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
<span class="identifier">future_status</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready, or the time point specified by <code class="computeroutput"><span class="identifier">wait_timeout</span></code>
                    has passed. If the result is not ready on entry, and the result
                    has a <span class="emphasis"><em>wait callback</em></span> set, that callback is
                    invoked prior to waiting.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">deferred</span></code>
                    if the shared state contains a deferred function. (Not implemented
                    yet)
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">ready</span></code>
                    if the shared state is ready.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">timeout</span></code>
                    if the function is returning because the absolute timeout specified
                    by <code class="computeroutput"><span class="identifier">absl_time</span></code>
                    has reached.
                  </p>
</dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception thrown by the <span class="emphasis"><em>wait callback</em></span>
                    if such a callback is called.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    If this call returned <code class="computeroutput"><span class="keyword">true</span></code>,
                    then <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code> and
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">wait_until</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.valid"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.valid" title="Member function valid()">Member
            function <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">valid</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Remarks:</span></dt>
<dd><p>
                    The result of this function is not stable and that the future
                    could become invalid even if the function returned true or vice-versa.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.is_ready"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.is_ready" title="Member function is_ready() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">is_ready</span><span class="special">()</span></code>
            EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">is_ready</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state and that result is ready for
                    retrieval, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Remarks:</span></dt>
<dd><p>
                    The result of this function is not stable and that the future
                    could become not ready even if the function returned true or
                    vice-versa.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.has_value"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.has_value" title="Member function has_value() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">has_value</span><span class="special">()</span></code>
            EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">has_value</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, that result is ready for retrieval,
                    and the result is a stored value, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Remarks:</span></dt>
<dd><p>
                    The result of this function is not stable and the future could
                    lost its value even if the function returned true or vice-versa.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.has_exception"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.has_exception" title="Member function has_exception() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">has_exception</span><span class="special">()</span></code> EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">has_exception</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, that result is ready for retrieval,
                    and the result is a stored exception, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Remarks:</span></dt>
<dd><p>
                    The result of this function is not stable and the future could
                    lost its exception even if the function returned true or vice-versa.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.get_exception_ptr"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_exception_ptr" title="Member function get_exception_ptr() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">get_exception_ptr</span><span class="special">()</span></code> EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">exception_ptr</span> <span class="identifier">get_exception_ptr</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready. If the result is not ready on entry, and the result has
                    a <span class="emphasis"><em>wait callback</em></span> set, that callback is invoked
                    prior to waiting.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    an exception_ptr, storing or not an exception.
                  </p></dd>
<dt><span class="term">Remarks:</span></dt>
<dd><p>
                    The result of this function is not stable and the future could
                    lost its exception even if the function returned a valid <code class="computeroutput"><span class="identifier">exception_ptr</span></code> or vice-versa.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever <code class="computeroutput"><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">lock</span><span class="special">()/</span><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">unlock</span><span class="special">()</span></code> can throw.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.get_state"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.get_state" title="Member function get_state() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">get_state</span><span class="special">()</span></code>
            EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">state</span> <span class="identifier">get_state</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Determine the state of the shared state associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                    if any.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">uninitialized</span></code></a> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state. <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a> if the shared
                    state associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is ready for retrieval,
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">waiting</span></code></a> otherwise.
                  </p></dd>
<dt><span class="term">Remarks:</span></dt>
<dd><p>
                    The result of this function is not stable.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.share"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.share" title="Member function share()">Member
            function <code class="computeroutput"><span class="identifier">share</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span> <span class="identifier">share</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="keyword">this</span><span class="special">))</span></code>.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">valid</span><span class="special">()</span>
                    <span class="special">==</span> <span class="keyword">false</span></code>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.then"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.then" title="Member function then() - EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">then</span><span class="special">()</span></code>
            - EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
 <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
<span class="identifier">then</span><span class="special">(</span><span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">S</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
 <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
<span class="identifier">then</span><span class="special">(</span><span class="identifier">Ex</span><span class="special">&amp;</span> <span class="identifier">executor</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
 <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
<span class="identifier">then</span><span class="special">(</span><span class="identifier">launch</span> <span class="identifier">policy</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
                These functions are experimental and subject to change in future
                versions. There are not too much tests yet, so it is possible that
                you can find out some trivial bugs :(
              </p></td></tr>
</table></div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
                These functions are based on the <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3634.pdf" target="_top"><span class="bold"><strong>N3634 - Improvements to std::future&lt;T&gt; and related
                APIs</strong></span></a> C++1y proposal by N. Gustafsson, A. Laksberg,
                H. Sutter, S. Mithani.
              </p></td></tr>
</table></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    The three functions differ only by input parameters. The first
                    only takes a callable object which accepts a future object as
                    a parameter. The second function takes an executor as the first
                    parameter and a callable object as the second parameter. The
                    third function takes a launch policy as the first parameter and
                    a callable object as the second parameter.
                  </p></dd>
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">INVOKE</span><span class="special">(</span><span class="identifier">DECAY_COPY</span> <span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">func</span><span class="special">)),</span>
                    <span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="keyword">this</span><span class="special">))</span></code>
                    shall be a valid expression.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                    All the functions create a shared state that is associated with
                    the returned future object. Additionally,
                  </p>
<p>
                    - When the object's shared state is ready, the continuation
                    <code class="computeroutput"><span class="identifier">INVOKE</span><span class="special">(</span><span class="identifier">DECAY_COPY</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">func</span><span class="special">)),</span>
                    <span class="identifier">std</span><span class="special">::</span><span class="identifier">move</span><span class="special">(*</span><span class="keyword">this</span><span class="special">))</span></code>
                    is called depending on the overload (see below) with the call
                    to DECAY_COPY() being evaluated in the thread that called then.
                  </p>
<p>
                    - Any value returned from the continuation is stored as the result
                    in the shared state of the resulting <code class="computeroutput"><span class="identifier">future</span></code>.
                    Any exception propagated from the execution of the continuation
                    is stored as the exceptional result in the shared state of the
                    resulting <code class="computeroutput"><span class="identifier">future</span></code>.
                  </p>
<p>
                    The continuation launches according to the specified policy or
                    executor or noting.
                  </p>
<p>
                    - When the launch policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">none</span></code>
                    the continuation is called on an unspecified thread of execution.
                  </p>
<p>
                    - When the launch policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code>
                    the continuation is called on a new thread of execution.
                  </p>
<p>
                    - When the launch policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>
                    the continuation is called on demand.
                  </p>
<p>
                    - When the launch policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">executor</span></code>
                    the continuation is called on one of the thread of execution
                    of the executor.
                  </p>
<p>
                    - When the launch policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">inherit</span></code>
                    the continuation inherits the parent's launch policy or executor.
                  </p>
<p>
                    - When the executor or launch policy is not provided (first overload)
                    is if as if launch::none was specified.
                  </p>
<p>
                    - When the executor is provided (second overload) the continuation
                    is called on one of the thread of execution of the executor.
                  </p>
<p>
                    - If the parent has a policy of <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>
                    and the continuation does not have a specified launch policy
                    executor, then the parent is filled by immediately calling <code class="computeroutput"><span class="special">.</span><span class="identifier">wait</span><span class="special">()</span></code>, and the policy of the antecedent
                    is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>.
                  </p>
</dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    An object of type <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">)&gt;</span></code>
                    that refers to the shared state created by the continuation.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd>
<p>
                    - Note that nested futures are not implicitly unwrapped yet.
                    This could be subject to change in future versions.
                  </p>
<p>
                    - The returned futures behave as the ones returned from boost::async,
                    the destructor of the future object returned from then will block.
                    This could be subject to change in future versions.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd>
<p>
                    - The <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a></code> object
                    passed to the parameter of the continuation function is a copy
                    of the original <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a></code>.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span>
                    <span class="special">==</span> <span class="keyword">false</span></code>
                    on original future; <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span> <span class="special">==</span>
                    <span class="keyword">true</span></code> on the <code class="computeroutput"><span class="identifier">future</span></code> returned from then.
                  </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.unique_future.unwrap"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.unwrap" title="Member function unwrap() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">unwrap</span><span class="special">()</span></code>
            EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">R2</span><span class="special">&gt;</span>
 <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R2</span><span class="special">&gt;</span>  <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R2</span><span class="special">&gt;&gt;::</span><span class="identifier">unwrap</span><span class="special">();</span>  <span class="comment">// EXTENSION</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">R2</span><span class="special">&gt;</span>
 <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a><span class="special">&lt;</span><span class="identifier">R2</span><span class="special">&gt;</span>  <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a><span class="special">&lt;</span><span class="identifier">R2</span><span class="special">&gt;&gt;::</span><span class="identifier">unwrap</span><span class="special">();</span>  <span class="comment">// EXTENSION</span>
</pre>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
                These functions are experimental and subject to change in future
                versions. There are not too much tests yet, so it is possible that
                you can find out some trivial bugs :(
              </p></td></tr>
</table></div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
                These functions are based on the <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3634.pdf" target="_top"><span class="bold"><strong>N3634 - Improvements to std::future&lt;T&gt; and related
                APIs</strong></span></a> C++1y proposal by N. Gustafsson, A. Laksberg,
                H. Sutter, S. Mithani.
              </p></td></tr>
</table></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    Removes the outermost future and returns a future with the associated
                    state been a proxy of the outer future.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    - Returns a future that becomes ready when the shared state of
                    the outer and inner future is ready. The validity of the future
                    returned from <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code> applied on the outer future
                    cannot be established a priori. If it is not valid, this future
                    is forced to be valid and becomes ready with an exception of
                    type <code class="computeroutput"><span class="identifier">future_error</span></code>,
                    with an error code of <code class="computeroutput"><span class="identifier">future_errc</span><span class="special">::</span><span class="identifier">broken_promise</span></code>.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    An object of type future with the associated state been a proxy
                    of outer future.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    - The returned future has <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span> <span class="special">==</span>
                    <span class="keyword">true</span></code>.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.shared_future"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">shared_future</span></code> class template</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">R</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">shared_future</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
  <span class="keyword">typedef</span> <span class="identifier">future_state</span><span class="special">::</span><span class="identifier">state</span> <span class="identifier">state</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">typedef</span> <span class="identifier">R</span> <span class="identifier">value_type</span><span class="special">;</span>  <span class="comment">// EXTENSION</span>

  <span class="identifier">shared_future</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="special">~</span><span class="identifier">shared_future</span><span class="special">();</span>

  <span class="comment">// copy support</span>
  <span class="identifier">shared_future</span><span class="special">(</span><span class="identifier">shared_future</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">);</span>
  <span class="identifier">shared_future</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">shared_future</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">);</span>

  <span class="comment">// move support</span>
  <span class="identifier">shared_future</span><span class="special">(</span><span class="identifier">shared_future</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="identifier">shared_future</span><span class="special">(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="identifier">shared_future</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">shared_future</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="identifier">shared_future</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="comment">// factories</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span><span class="identifier">shared_future</span><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">then</span><span class="special">(</span><span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">S</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span><span class="identifier">shared_future</span><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">then</span><span class="special">(</span><span class="identifier">S</span><span class="special">&amp;</span> <span class="identifier">scheduler</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span><span class="identifier">shared_future</span><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">then</span><span class="special">(</span><span class="identifier">launch</span> <span class="identifier">policy</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// EXTENSION</span>

  <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">shared_future</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">);</span>

  <span class="comment">// retrieving the value</span>
  <span class="identifier">see</span> <span class="identifier">below</span> <span class="identifier">get</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>

  <span class="identifier">exception_ptr</span> <span class="identifier">get_exception_ptr</span><span class="special">();</span> <span class="comment">// EXTENSION</span>

  <span class="comment">// functions to check state, and wait for ready</span>
  <span class="keyword">bool</span> <span class="identifier">valid</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="keyword">bool</span> <span class="identifier">is_ready</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">bool</span> <span class="identifier">has_exception</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
  <span class="keyword">bool</span> <span class="identifier">has_value</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span> <span class="comment">// EXTENSION</span>

  <span class="comment">// waiting for the result to be ready</span>
  <span class="keyword">void</span> <span class="identifier">wait</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
  <span class="identifier">future_status</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
  <span class="identifier">future_status</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>

<span class="preprocessor">#if</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_USES_DATE_TIME</span> <span class="special">||</span> <span class="identifier">defined</span> <span class="identifier">BOOST_THREAD_DONT_USE_CHRONO</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
  <span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">Duration</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>  <span class="comment">// DEPRECATED SINCE V3.0.0</span>
  <span class="keyword">bool</span> <span class="identifier">timed_wait_until</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>  <span class="comment">// DEPRECATED SINCE V3.0.0</span>
<span class="preprocessor">#endif</span>
  <span class="identifier">state</span> <span class="identifier">get_state</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>  <span class="comment">// EXTENSION</span>

<span class="special">};</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.default_constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.default_constructor" title="Default Constructor">Default
            Constructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">shared_future</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs an uninitialized shared_future.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span></code></a> returns <code class="computeroutput"><span class="keyword">false</span></code>. <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">uninitialized</span></code></a>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.get"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get" title="Member function get()">Member
            function <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">const</span> <span class="identifier">R</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
<span class="identifier">R</span><span class="special">&amp;</span> <span class="identifier">get</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
<span class="keyword">void</span> <span class="identifier">get</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready as-if by a call to <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.wait" title="Member function wait()"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">wait</span><span class="special">()</span></code></a>,
                    and returns a <code class="computeroutput"><span class="keyword">const</span></code>
                    reference to the result.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&amp;&gt;::</span><span class="identifier">get</span><span class="special">()</span></code> return the stored reference.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;::</span><span class="identifier">get</span><span class="special">()</span></code>, there is no return value.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">get</span><span class="special">()</span></code> returns a <code class="computeroutput"><span class="keyword">const</span></code>
                    reference to the value stored in the shared state.
                  </p>
</dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
</dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.wait"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.wait" title="Member function wait()">Member
            function <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">wait</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready. If the result is not ready on entry, and the result has
                    a <span class="emphasis"><em>wait callback</em></span> set, that callback is invoked
                    prior to waiting.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception thrown by the <span class="emphasis"><em>wait callback</em></span>
                    if such a callback is called.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code>. <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.timed_wait_duration"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.timed_wait_duration" title="Member function timed_wait()">Member
            function <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
<span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">Duration</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">wait_duration</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready, or the time specified by <code class="computeroutput"><span class="identifier">wait_duration</span></code>
                    has elapsed. If the result is not ready on entry, and the result
                    has a <span class="emphasis"><em>wait callback</em></span> set, that callback is
                    invoked prior to waiting.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, and that result is ready before
                    the specified time has elapsed, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception thrown by the <span class="emphasis"><em>wait callback</em></span>
                    if such a callback is called.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    If this call returned <code class="computeroutput"><span class="keyword">true</span></code>,
                    then <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code> and
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>. <code class="computeroutput"><span class="identifier">Duration</span></code> must be a type that
                    meets the Boost.DateTime time duration requirements.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.timed_wait_absolute"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.timed_wait_absolute" title="Member function timed_wait()">Member
            function <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">timed_wait</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">system_time</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">wait_timeout</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready, or the time point specified by <code class="computeroutput"><span class="identifier">wait_timeout</span></code>
                    has passed. If the result is not ready on entry, and the result
                    has a <span class="emphasis"><em>wait callback</em></span> set, that callback is
                    invoked prior to waiting.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, and that result is ready before
                    the specified time has passed, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception thrown by the <span class="emphasis"><em>wait callback</em></span>
                    if such a callback is called.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    If this call returned <code class="computeroutput"><span class="keyword">true</span></code>,
                    then <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code> and
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.wait_for"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.wait_for" title="Member function wait_for()">Member
            function <code class="computeroutput"><span class="identifier">wait_for</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">&gt;</span>
<span class="identifier">future_status</span> <span class="identifier">wait_for</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration</span><span class="special">&lt;</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">&gt;&amp;</span> <span class="identifier">rel_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready, or the time specified by <code class="computeroutput"><span class="identifier">wait_duration</span></code>
                    has elapsed. If the result is not ready on entry, and the result
                    has a <span class="emphasis"><em>wait callback</em></span> set, that callback is
                    invoked prior to waiting.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">deferred</span></code>
                    if the shared state contains a deferred function. (Not implemented
                    yet)
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">ready</span></code>
                    if the shared state is ready.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">timeout</span></code>
                    if the function is returning because the relative timeout specified
                    by <code class="computeroutput"><span class="identifier">rel_time</span></code> has
                    expired.
                  </p>
</dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception thrown by the <span class="emphasis"><em>wait callback</em></span>
                    if such a callback is called.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    If this call returned <code class="computeroutput"><span class="keyword">true</span></code>,
                    then <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code> and
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>. <code class="computeroutput"><span class="identifier">Duration</span></code> must be a type that
                    meets the Boost.DateTime time duration requirements.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.wait_until"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.wait_until" title="Member function wait_until()">Member
            function <code class="computeroutput"><span class="identifier">wait_until</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Clock</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Duration</span><span class="special">&gt;</span>
<span class="identifier">future_status</span> <span class="identifier">wait_until</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">chrono</span><span class="special">::</span><span class="identifier">time_point</span><span class="special">&lt;</span><span class="identifier">Clock</span><span class="special">,</span> <span class="identifier">Duration</span><span class="special">&gt;&amp;</span> <span class="identifier">abs_time</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready, or the time point specified by <code class="computeroutput"><span class="identifier">wait_timeout</span></code>
                    has passed. If the result is not ready on entry, and the result
                    has a <span class="emphasis"><em>wait callback</em></span> set, that callback is
                    invoked prior to waiting.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">deferred</span></code>
                    if the shared state contains a deferred function. (Not implemented
                    yet)
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">ready</span></code>
                    if the shared state is ready.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">future_status</span><span class="special">::</span><span class="identifier">timeout</span></code>
                    if the function is returning because the absolute timeout specified
                    by <code class="computeroutput"><span class="identifier">absl_time</span></code>
                    has reached.
                  </p>
</dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_uninitialized</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the result
                    associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is not ready at the point
                    of the call, and the current thread is interrupted.
                  </p>
<p>
                    - Any exception thrown by the <span class="emphasis"><em>wait callback</em></span>
                    if such a callback is called.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    If this call returned <code class="computeroutput"><span class="keyword">true</span></code>,
                    then <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.is_ready" title="Member function is_ready() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">is_ready</span><span class="special">()</span></code></a>
                    returns <code class="computeroutput"><span class="keyword">true</span></code> and
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get_state" title="Member function get_state() EXTENSION"><code class="computeroutput"><span class="keyword">this</span><span class="special">-&gt;</span><span class="identifier">get_state</span><span class="special">()</span></code></a>
                    returns <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a>.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">timed_wait</span><span class="special">()</span></code>
                    is an <span class="emphasis"><em>interruption point</em></span>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.valid"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.valid" title="Member function valid()">Member
            function <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">valid</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.is_ready"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.is_ready" title="Member function is_ready() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">is_ready</span><span class="special">()</span></code>
            EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">is_ready</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, and that result is ready for
                    retrieval, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever <code class="computeroutput"><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">lock</span><span class="special">()/</span><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">unlock</span><span class="special">()</span></code> can throw.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.has_value"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.has_value" title="Member function has_value() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">has_value</span><span class="special">()</span></code>
            EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">has_value</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, that result is ready for retrieval,
                    and the result is a stored value, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever <code class="computeroutput"><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">lock</span><span class="special">()/</span><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">unlock</span><span class="special">()</span></code> can throw.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.has_exception"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.has_exception" title="Member function has_exception() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">has_exception</span><span class="special">()</span></code> EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">bool</span> <span class="identifier">has_exception</span><span class="special">()</span> <span class="keyword">const</span><span class="special">;</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="keyword">true</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, that result is ready for retrieval,
                    and the result is a stored exception, <code class="computeroutput"><span class="keyword">false</span></code>
                    otherwise.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever <code class="computeroutput"><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">lock</span><span class="special">()/</span><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">unlock</span><span class="special">()</span></code> can throw.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.get_exception_ptr"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get_exception_ptr" title="Member function get_exception_ptr() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">get_exception_ptr</span><span class="special">()</span></code> EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">exception_ptr</span> <span class="identifier">get_exception_ptr</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is associated with a shared state, waits until the result is
                    ready. If the result is not ready on entry, and the result has
                    a <span class="emphasis"><em>wait callback</em></span> set, that callback is invoked
                    prior to waiting.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    an exception_ptr, storing or not an exception.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever <code class="computeroutput"><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">lock</span><span class="special">()/</span><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">unlock</span><span class="special">()</span></code> can throw.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.get_state"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.get_state" title="Member function get_state() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">get_state</span><span class="special">()</span></code>
            EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">state</span> <span class="identifier">get_state</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Determine the state of the shared state associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                    if any.
                  </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">uninitialized</span></code></a> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    is not associated with a shared state. <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">ready</span></code></a> if the shared
                    state associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is ready for retrieval,
                    <a class="link" href="synchronization.html#thread.synchronization.futures.reference.future_state" title="Enumeration state"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_state</span><span class="special">::</span><span class="identifier">waiting</span></code></a> otherwise.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Whatever <code class="computeroutput"><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">lock</span><span class="special">()/</span><span class="identifier">mutex</span><span class="special">::</span><span class="identifier">unlock</span><span class="special">()</span></code> can throw.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.shared_future.then"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.then" title="Member function then() EXTENSION">Member
            function <code class="computeroutput"><span class="identifier">then</span><span class="special">()</span></code>
            EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
 <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span><span class="identifier">shared_future</span><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
<span class="identifier">then</span><span class="special">(</span><span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">S</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
 <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span><span class="identifier">shared_future</span><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
<span class="identifier">then</span><span class="special">(</span><span class="identifier">Ex</span><span class="special">&amp;</span> <span class="identifier">executor</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
 <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span><span class="identifier">shared_future</span><span class="special">)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
<span class="identifier">then</span><span class="special">(</span><span class="identifier">launch</span> <span class="identifier">policy</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">func</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
                These functions are experimental and subject to change in future
                versions. There are not too much tests yet, so it is possible that
                you can find out some trivial bugs :(
              </p></td></tr>
</table></div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
                These functions are based on the <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3634.pdf" target="_top"><span class="bold"><strong>N3634 - Improvements to std::future&lt;T&gt; and related
                APIs</strong></span></a> C++1y proposal by N. Gustafsson, A. Laksberg,
                H. Sutter, S. Mithani.
              </p></td></tr>
</table></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    The three functions differ only by input parameters. The first
                    only takes a callable object which accepts a shared_future object
                    as a parameter. The second function takes an executor as the
                    first parameter and a callable object as the second parameter.
                    The third function takes a launch policy as the first parameter
                    and a callable object as the second parameter.
                  </p></dd>
<dt><span class="term">Requires:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">INVOKE</span><span class="special">(</span><span class="identifier">DECAY_COPY</span> <span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">func</span><span class="special">)),</span>
                    <span class="special">*</span><span class="keyword">this</span><span class="special">)</span></code> shall be a valid expression.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                    All the functions create a shared state that is associated with
                    the returned future object. Additionally,
                  </p>
<p>
                    - When the object's shared state is ready, the continuation
                    <code class="computeroutput"><span class="identifier">INVOKE</span><span class="special">(</span><span class="identifier">DECAY_COPY</span><span class="special">(</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">func</span><span class="special">)),</span>
                    <span class="special">*</span><span class="keyword">this</span><span class="special">)</span></code> is called depending on the overload
                    (see below) with the call to DECAY_COPY() being evaluated in
                    the thread that called then.
                  </p>
<p>
                    - Any value returned from the continuation is stored as the result
                    in the shared state of the resulting <code class="computeroutput"><span class="identifier">future</span></code>.
                    Any exception propagated from the execution of the continuation
                    is stored as the exceptional result in the shared state of the
                    resulting <code class="computeroutput"><span class="identifier">future</span></code>.
                  </p>
<p>
                    The continuation launches according to the specified policy or
                    executor or noting.
                  </p>
<p>
                    - When the launch policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">none</span></code>
                    the continuation is called on an unspecified thread of execution.
                  </p>
<p>
                    - When the launch policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code>
                    the continuation is called on a new thread of execution.
                  </p>
<p>
                    - When the launch policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>
                    the continuation is called on demand.
                  </p>
<p>
                    - When the launch policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">executor</span></code>
                    the continuation is called on one of the thread of execution
                    of the executor.
                  </p>
<p>
                    - When the launch policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">inherit</span></code>
                    the continuation inherits the parent's launch policy or executor.
                  </p>
<p>
                    - When the executor or launch policy is not provided (first overload)
                    is if as if launch::none was specified.
                  </p>
<p>
                    - When the executor is provided (second overload) the continuation
                    is called on one of the thread of execution of the executor.
                  </p>
<p>
                    - If the parent has a policy of <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>
                    and the continuation does not have a specified launch policy
                    executor, then the parent is filled by immediately calling <code class="computeroutput"><span class="special">.</span><span class="identifier">wait</span><span class="special">()</span></code>, and the policy of the antecedent
                    is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>.
                  </p>
</dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                    An object of type <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">result_of</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">(</span><span class="identifier">shared_future</span><span class="special">)&gt;</span></code> that refers to the shared
                    state created by the continuation.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd>
<p>
                    - Note that nested futures are not implicitly unwrapped yet.
                    This could be subject to change in future versions.
                  </p>
<p>
                    - The returned futures behave as the ones returned from boost::async,
                    the destructor of the future object returned from then will block.
                    This could be subject to change in future versions.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd>
<p>
                    - The future object is moved to the parameter of the continuation
                    function .
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span>
                    <span class="special">==</span> <span class="keyword">true</span></code>
                    on original <code class="computeroutput"><span class="identifier">shared_future</span></code>;
                    <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span>
                    <span class="special">==</span> <span class="keyword">true</span></code>
                    on the <code class="computeroutput"><span class="identifier">future</span></code>
                    returned from then.
                  </p>
</dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.promise"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">promise</span></code> class template</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">R</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">promise</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
  <span class="keyword">typedef</span> <span class="identifier">R</span> <span class="identifier">value_type</span><span class="special">;</span>  <span class="comment">// EXTENSION</span>

  <span class="identifier">promise</span><span class="special">();</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Allocator</span><span class="special">&gt;</span>
  <span class="identifier">promise</span><span class="special">(</span><span class="identifier">allocator_arg_t</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="identifier">a</span><span class="special">);</span>
  <span class="identifier">promise</span> <span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">promise</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
  <span class="identifier">promise</span><span class="special">(</span><span class="identifier">promise</span> <span class="keyword">const</span><span class="special">&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
  <span class="special">~</span><span class="identifier">promise</span><span class="special">();</span>

  <span class="comment">// Move support</span>
  <span class="identifier">promise</span><span class="special">(</span><span class="identifier">promise</span> <span class="special">&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;;</span>
  <span class="identifier">promise</span> <span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">promise</span><span class="special">&amp;&amp;</span> <span class="identifier">rhs</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;;</span>

  <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">promise</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="comment">// Result retrieval</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span> <span class="identifier">get_future</span><span class="special">();</span>

  <span class="comment">// Set the value</span>
  <span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">(</span><span class="identifier">see</span> <span class="identifier">below</span><span class="special">);</span>
  <span class="keyword">void</span> <span class="identifier">set_exception</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">exception_ptr</span> <span class="identifier">e</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">E</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">set_exception</span><span class="special">(</span><span class="identifier">E</span> <span class="identifier">e</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

  <span class="comment">// setting the result with deferred notification</span>
  <span class="keyword">void</span> <span class="identifier">set_value_at_thread_exit</span><span class="special">(</span><span class="identifier">see</span> <span class="identifier">below</span><span class="special">);</span>
  <span class="keyword">void</span> <span class="identifier">set_exception_at_thread_exit</span><span class="special">(</span><span class="identifier">exception_ptr</span> <span class="identifier">p</span><span class="special">);</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">E</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">set_exception_at_thread_exit</span><span class="special">(</span><span class="identifier">E</span> <span class="identifier">p</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>

  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">set_wait_callback</span><span class="special">(</span><span class="identifier">F</span> <span class="identifier">f</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
<span class="special">};</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.default_constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.default_constructor" title="Default Constructor">Default
            Constructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">promise</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a new <a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code></a> with no associated
                    result.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.alloc_constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.alloc_constructor" title="Allocator Constructor">Allocator
            Constructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Allocator</span><span class="special">&gt;</span>
<span class="identifier">promise</span><span class="special">(</span><span class="identifier">allocator_arg_t</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="identifier">a</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a new <a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code></a> with no associated
                    result using the allocator <code class="computeroutput"><span class="identifier">a</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    Available only if BOOST_THREAD_FUTURE_USES_ALLOCATORS is defined.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.move_constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.move_constructor" title="Move Constructor">Move
            Constructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">promise</span><span class="special">(</span><span class="identifier">promise</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a new <a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code></a>, and transfers
                    ownership of the result associated with <code class="computeroutput"><span class="identifier">other</span></code>
                    to <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                    leaving <code class="computeroutput"><span class="identifier">other</span></code>
                    with no associated result.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    If the compiler does not support rvalue-references, this is implemented
                    using the boost.thread move emulation.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.move_assignment"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.move_assignment" title="Move Assignment Operator">Move
            Assignment Operator</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">promise</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">promise</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Transfers ownership of the result associated with <code class="computeroutput"><span class="identifier">other</span></code> to <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>, leaving <code class="computeroutput"><span class="identifier">other</span></code>
                    with no associated result. If there was already a result associated
                    with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                    and that result was not <span class="emphasis"><em>ready</em></span>, sets any
                    futures associated with that result to <span class="emphasis"><em>ready</em></span>
                    with a <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">broken_promise</span></code>
                    exception as the result.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    If the compiler does not support rvalue-references, this is implemented
                    using the boost.thread move emulation.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.destructor" title="Destructor">Destructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">promise</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                    If there was a result associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>, and that result is not
                    <span class="emphasis"><em>ready</em></span>, sets any futures associated with
                    that task to <span class="emphasis"><em>ready</em></span> with a <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">broken_promise</span></code> exception as
                    the result.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.get_future"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.get_future" title="Member Function get_future()">Member
            Function <code class="computeroutput"><span class="identifier">get_future</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span> <span class="identifier">get_future</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    If <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    was not associated with a result, allocate storage for a new
                    shared state and associate it with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>. Returns a <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> associated with
                    the result associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_already_retrieved</span></code> if
                    the future associated with the task has already been retrieved.
                    <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_alloc</span></code> if any memory necessary
                    could not be allocated.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.set_value"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.set_value" title="Member Function set_value()">Member
            Function <code class="computeroutput"><span class="identifier">set_value</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">(</span><span class="identifier">R</span><span class="special">&amp;&amp;</span> <span class="identifier">r</span><span class="special">);</span>
<span class="keyword">void</span> <span class="identifier">set_value</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">R</span><span class="special">&amp;</span> <span class="identifier">r</span><span class="special">);</span>
<span class="keyword">void</span> <span class="identifier">promise</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&amp;&gt;::</span><span class="identifier">set_value</span><span class="special">(</span><span class="identifier">R</span><span class="special">&amp;</span> <span class="identifier">r</span><span class="special">);</span>
<span class="keyword">void</span> <span class="identifier">promise</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;::</span><span class="identifier">set_value</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                    - If BOOST_THREAD_PROVIDES_PROMISE_LAZY is defined and if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    was not associated with a result, allocate storage for a new
                    shared state and associate it with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                  </p>
<p>
                    - Store the value <code class="computeroutput"><span class="identifier">r</span></code>
                    in the shared state associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>. Any threads blocked waiting
                    for the asynchronous result are woken.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    All futures waiting on the shared state are <span class="emphasis"><em>ready</em></span>
                    and <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.has_value" title="Member function has_value() EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">has_value</span><span class="special">()</span></code></a>
                    or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.has_value" title="Member function has_value() EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">has_value</span><span class="special">()</span></code></a>
                    for those futures shall return <code class="computeroutput"><span class="keyword">true</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise_already_satisfied</span></code> if
                    the result associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is already <span class="emphasis"><em>ready</em></span>.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">broken_promise</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    has no shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_alloc</span></code> if the memory required
                    for storage of the result cannot be allocated.
                  </p>
<p>
                    - Any exception thrown by the copy or move-constructor of <code class="computeroutput"><span class="identifier">R</span></code>.
                  </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.set_exception"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.set_exception" title="Member Function set_exception()">Member
            Function <code class="computeroutput"><span class="identifier">set_exception</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">set_exception</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">exception_ptr</span> <span class="identifier">e</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">E</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">set_exception</span><span class="special">(</span><span class="identifier">E</span> <span class="identifier">e</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                    - If BOOST_THREAD_PROVIDES_PROMISE_LAZY is defined and if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    was not associated with a result, allocate storage for a new
                    shared state and associate it with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                  </p>
<p>
                    - Store the exception <code class="computeroutput"><span class="identifier">e</span></code>
                    in the shared state associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>. Any threads blocked waiting
                    for the asynchronous result are woken.
                  </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    All futures waiting on the shared state are <span class="emphasis"><em>ready</em></span>
                    and <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.has_exception" title="Member function has_exception() EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">has_exception</span><span class="special">()</span></code></a>
                    or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.has_exception" title="Member function has_exception() EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">has_exception</span><span class="special">()</span></code></a>
                    for those futures shall return <code class="computeroutput"><span class="keyword">true</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise_already_satisfied</span></code> if
                    the result associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is already <span class="emphasis"><em>ready</em></span>.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">broken_promise</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    has no shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_alloc</span></code> if the memory required
                    for storage of the result cannot be allocated.
                  </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.set_value_at_thread_exit"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.set_value_at_thread_exit" title="Member Function set_value_at_thread_exit()">Member
            Function <code class="computeroutput"><span class="identifier">set_value_at_thread_exit</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">set_value_at_thread_exit</span><span class="special">(</span><span class="identifier">R</span><span class="special">&amp;&amp;</span> <span class="identifier">r</span><span class="special">);</span>
<span class="keyword">void</span> <span class="identifier">set_value_at_thread_exit</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">R</span><span class="special">&amp;</span> <span class="identifier">r</span><span class="special">);</span>
<span class="keyword">void</span> <span class="identifier">promise</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&amp;&gt;::</span><span class="identifier">set_value_at_thread_exit</span><span class="special">(</span><span class="identifier">R</span><span class="special">&amp;</span> <span class="identifier">r</span><span class="special">);</span>
<span class="keyword">void</span> <span class="identifier">promise</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;::</span><span class="identifier">set_value_at_thread_exit</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Stores the value r in the shared state without making that state
                    ready immediately. Schedules that state to be made ready when
                    the current thread exits, after all objects of thread storage
                    duration associated with the current thread have been destroyed.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise_already_satisfied</span></code> if
                    the result associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is already <span class="emphasis"><em>ready</em></span>.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">broken_promise</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    has no shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_alloc</span></code> if the memory required
                    for storage of the result cannot be allocated.
                  </p>
<p>
                    - Any exception thrown by the copy or move-constructor of <code class="computeroutput"><span class="identifier">R</span></code>.
                  </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.set_exception_at_thread_exit"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.set_exception_at_thread_exit" title="Member Function set_exception_at_thread_exit()">Member
            Function <code class="computeroutput"><span class="identifier">set_exception_at_thread_exit</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">set_exception_at_thread_exit</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">exception_ptr</span> <span class="identifier">e</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">E</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">set_exception_at_thread_exit</span><span class="special">(</span><span class="identifier">E</span> <span class="identifier">p</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Stores the exception pointer p in the shared state without making
                    that state ready immediately. Schedules that state to be made
                    ready when the current thread exits, after all objects of thread
                    storage duration associated with the current thread have been
                    destroyed.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    All futures waiting on the shared state are <span class="emphasis"><em>ready</em></span>
                    and <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future.has_exception" title="Member function has_exception() EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">has_exception</span><span class="special">()</span></code></a>
                    or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future.has_exception" title="Member function has_exception() EXTENSION"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;::</span><span class="identifier">has_exception</span><span class="special">()</span></code></a>
                    for those futures shall return <code class="computeroutput"><span class="keyword">true</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise_already_satisfied</span></code> if
                    the result associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> is already <span class="emphasis"><em>ready</em></span>.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">broken_promise</span></code> if <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>
                    has no shared state.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_alloc</span></code> if the memory required
                    for storage of the result cannot be allocated.
                  </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.promise.set_wait_callback"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise.set_wait_callback" title="Member Function set_wait_callback() EXTENSION">Member
            Function <code class="computeroutput"><span class="identifier">set_wait_callback</span><span class="special">()</span></code> EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">set_wait_callback</span><span class="special">(</span><span class="identifier">F</span> <span class="identifier">f</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Preconditions:</span></dt>
<dd><p>
                    The expression <code class="computeroutput"><span class="identifier">f</span><span class="special">(</span><span class="identifier">t</span><span class="special">)</span></code> where <code class="computeroutput"><span class="identifier">t</span></code>
                    is a lvalue of type <a class="link" href="synchronization.html#thread.synchronization.futures.reference.promise" title="promise class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">promise</span></code></a> shall be well-formed.
                    Invoking a copy of <code class="computeroutput"><span class="identifier">f</span></code>
                    shall have the same effect as invoking <code class="computeroutput"><span class="identifier">f</span></code>
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Store a copy of <code class="computeroutput"><span class="identifier">f</span></code>
                    with the shared state associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> as a <span class="emphasis"><em>wait callback</em></span>.
                    This will replace any existing wait callback store alongside
                    that result. If a thread subsequently calls one of the wait functions
                    on a <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a> associated
                    with this result, and the result is not <span class="emphasis"><em>ready</em></span>,
                    <code class="computeroutput"><span class="identifier">f</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span></code>
                    shall be invoked.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_alloc</span></code> if memory cannot
                    be allocated for the required storage.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.packaged_task"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">packaged_task</span></code> class template</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">S</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">packaged_task</span><span class="special">;</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">R</span>
  <span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">ArgTypes</span>
<span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">packaged_task</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">(</span><span class="identifier">ArgTypes</span><span class="special">)&gt;</span>
<span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
  <span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">packaged_task</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>
  <span class="identifier">packaged_task</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">packaged_task</span> <span class="keyword">const</span><span class="special">&amp;)</span> <span class="special">=</span> <span class="keyword">delete</span><span class="special">;</span>

  <span class="comment">// construction and destruction</span>
  <span class="identifier">packaged_task</span><span class="special">()</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="keyword">explicit</span> <span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">R</span><span class="special">(*</span><span class="identifier">f</span><span class="special">)(</span><span class="identifier">ArgTypes</span><span class="special">...));</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">&gt;</span>
  <span class="keyword">explicit</span> <span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">);</span>

  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Allocator</span><span class="special">&gt;</span>
  <span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">allocator_arg_t</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="identifier">a</span><span class="special">,</span> <span class="identifier">R</span><span class="special">(*</span><span class="identifier">f</span><span class="special">)(</span><span class="identifier">ArgTypes</span><span class="special">...));</span>
  <span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Allocator</span><span class="special">&gt;</span>
  <span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">allocator_arg_t</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="identifier">a</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">);</span>

  <span class="special">~</span><span class="identifier">packaged_task</span><span class="special">()</span>
  <span class="special">{}</span>

  <span class="comment">// move support</span>
  <span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">packaged_task</span><span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="identifier">packaged_task</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">packaged_task</span><span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="keyword">void</span> <span class="identifier">swap</span><span class="special">(</span><span class="identifier">packaged_task</span><span class="special">&amp;</span> <span class="identifier">other</span><span class="special">)</span> <span class="keyword">noexcept</span><span class="special">;</span>

  <span class="keyword">bool</span> <span class="identifier">valid</span><span class="special">()</span> <span class="keyword">const</span> <span class="keyword">noexcept</span><span class="special">;</span>
  <span class="comment">// result retrieval</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span> <span class="identifier">get_future</span><span class="special">();</span>

  <span class="comment">// execution</span>
  <span class="keyword">void</span> <span class="keyword">operator</span><span class="special">()(</span><span class="identifier">ArgTypes</span><span class="special">...</span> <span class="special">);</span>
  <span class="keyword">void</span> <span class="identifier">make_ready_at_thread_exit</span><span class="special">(</span><span class="identifier">ArgTypes</span><span class="special">...);</span>

  <span class="keyword">void</span> <span class="identifier">reset</span><span class="special">();</span>
  <span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">set_wait_callback</span><span class="special">(</span><span class="identifier">F</span> <span class="identifier">f</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
<span class="special">};</span>
</pre>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.packaged_task.task_constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task.task_constructor" title="Task Constructor">Task
            Constructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">R</span><span class="special">(*</span><span class="identifier">f</span><span class="special">)(</span><span class="identifier">ArgTypes</span><span class="special">...));</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
<span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">F</span><span class="special">&amp;&amp;</span><span class="identifier">f</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Preconditions:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">f</span><span class="special">()</span></code>
                    is a valid expression with a return type convertible to <code class="computeroutput"><span class="identifier">R</span></code>. Invoking a copy of <code class="computeroutput"><span class="identifier">f</span></code> must behave the same as invoking
                    <code class="computeroutput"><span class="identifier">f</span></code>.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a new <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a> with
                    <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">)</span></code>
                    stored as the associated task.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - Any exceptions thrown by the copy (or move) constructor of
                    <code class="computeroutput"><span class="identifier">f</span></code>.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_alloc</span></code> if memory for the
                    internal data structures could not be allocated.
                  </p>
</dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    The R(*f)(ArgTypes...)) overload to allow passing a function
                    without needing to use <code class="computeroutput"><span class="special">&amp;</span></code>.
                  </p></dd>
<dt><span class="term">Remark:</span></dt>
<dd><p>
                    This constructor doesn't participate in overload resolution if
                    decay&lt;F&gt;::type is the same type as boost::packaged_task&lt;R&gt;.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.packaged_task.alloc_constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task.alloc_constructor" title="Allocator Constructor">Allocator
            Constructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Allocator</span><span class="special">&gt;</span>
<span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">allocator_arg_t</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="identifier">a</span><span class="special">,</span> <span class="identifier">R</span><span class="special">(*</span><span class="identifier">f</span><span class="special">)(</span><span class="identifier">ArgTypes</span><span class="special">...));</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Allocator</span><span class="special">&gt;</span>
<span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">allocator_arg_t</span><span class="special">,</span> <span class="identifier">Allocator</span> <span class="identifier">a</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Preconditions:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">f</span><span class="special">()</span></code>
                    is a valid expression with a return type convertible to <code class="computeroutput"><span class="identifier">R</span></code>. Invoking a copy of <code class="computeroutput"><span class="identifier">f</span></code> shall behave the same as
                    invoking <code class="computeroutput"><span class="identifier">f</span></code>.
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a new <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a> with
                    <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">)</span></code>
                    stored as the associated task using the allocator <code class="computeroutput"><span class="identifier">a</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Any exceptions thrown by the copy (or move) constructor of <code class="computeroutput"><span class="identifier">f</span></code>. <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_alloc</span></code>
                    if memory for the internal data structures could not be allocated.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    Available only if BOOST_THREAD_FUTURE_USES_ALLOCATORS is defined.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    The R(*f)(ArgTypes...)) overload to allow passing a function
                    without needing to use <code class="computeroutput"><span class="special">&amp;</span></code>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.packaged_task.move_constructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task.move_constructor" title="Move Constructor">Move
            Constructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">packaged_task</span><span class="special">(</span><span class="identifier">packaged_task</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Constructs a new <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a>, and transfers
                    ownership of the task associated with <code class="computeroutput"><span class="identifier">other</span></code>
                    to <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                    leaving <code class="computeroutput"><span class="identifier">other</span></code>
                    with no associated task.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    If the compiler does not support rvalue-references, this is implemented
                    using the boost.thread move emulation.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.packaged_task.move_assignment"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task.move_assignment" title="Move Assignment Operator">Move
            Assignment Operator</a>
</h6></div></div></div>
<pre class="programlisting"><span class="identifier">packaged_task</span><span class="special">&amp;</span> <span class="keyword">operator</span><span class="special">=(</span><span class="identifier">packaged_task</span> <span class="special">&amp;&amp;</span> <span class="identifier">other</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Transfers ownership of the task associated with <code class="computeroutput"><span class="identifier">other</span></code> to <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>, leaving <code class="computeroutput"><span class="identifier">other</span></code>
                    with no associated task. If there was already a task associated
                    with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>,
                    and that task has not been invoked, sets any futures associated
                    with that task to <span class="emphasis"><em>ready</em></span> with a <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">broken_promise</span></code> exception as
                    the result.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                    If the compiler does not support rvalue-references, this is implemented
                    using the boost.thread move emulation.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.packaged_task.destructor"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task.destructor" title="Destructor">Destructor</a>
</h6></div></div></div>
<pre class="programlisting"><span class="special">~</span><span class="identifier">packaged_task</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Destroys <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                    If there was a task associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>, and that task has not been
                    invoked, sets any futures associated with that task to <span class="emphasis"><em>ready</em></span>
                    with a <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">broken_promise</span></code>
                    exception as the result.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    Nothing.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.packaged_task.get_future"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task.get_future" title="Member Function get_future()">Member
            Function <code class="computeroutput"><span class="identifier">get_future</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span> <span class="identifier">get_future</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Returns a <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> associated with
                    the result of the task associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code>.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">task_moved</span></code> if ownership of
                    the task associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> has been moved to another
                    instance of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a>. <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">future_already_retrieved</span></code> if
                    the future associated with the task has already been retrieved.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.packaged_task.call_operator"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task.call_operator" title="Member Function operator()()">Member
            Function <code class="computeroutput"><span class="keyword">operator</span><span class="special">()()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="keyword">operator</span><span class="special">()();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Invoke the task associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> and store the result in the
                    corresponding future. If the task returns normally, the return
                    value is stored as the shared state, otherwise the exception
                    thrown is stored. Any threads blocked waiting for the shared
                    state associated with this task are woken.
                  </p></dd>
<dt><span class="term">Postconditions:</span></dt>
<dd><p>
                    All futures waiting on the shared state are <span class="emphasis"><em>ready</em></span>
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">task_moved</span></code> if ownership of
                    the task associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> has been moved to another
                    instance of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a>.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">task_already_started</span></code> if the
                    task has already been invoked.
                  </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.packaged_task.make_ready_at_thread_exit"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task.make_ready_at_thread_exit" title="Member Function make_ready_at_thread_exit()">Member
            Function <code class="computeroutput"><span class="identifier">make_ready_at_thread_exit</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">make_ready_at_thread_exit</span><span class="special">(</span><span class="identifier">ArgTypes</span><span class="special">...);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Invoke the task associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> and store the result in the
                    corresponding future. If the task returns normally, the return
                    value is stored as the shared state, otherwise the exception
                    thrown is stored. In either case, this is done without making
                    that state ready immediately. Schedules the shared state to be
                    made ready when the current thread exits, after all objects of
                    thread storage duration associated with the current thread have
                    been destroyed.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">task_moved</span></code> if ownership of
                    the task associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> has been moved to another
                    instance of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a>.
                  </p>
<p>
                    - <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">task_already_started</span></code> if the
                    task has already been invoked.
                  </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.packaged_task.reset"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task.reset" title="Member Function reset()">Member
            Function <code class="computeroutput"><span class="identifier">reset</span><span class="special">()</span></code></a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">reset</span><span class="special">();</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Reset the state of the packaged_task so that it can be called
                    again.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">task_moved</span></code> if ownership of
                    the task associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> has been moved to another
                    instance of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a>.
                  </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h6 class="title">
<a name="thread.synchronization.futures.reference.packaged_task.set_wait_callback"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task.set_wait_callback" title="Member Function set_wait_callback() EXTENSION">Member
            Function <code class="computeroutput"><span class="identifier">set_wait_callback</span><span class="special">()</span></code> EXTENSION</a>
</h6></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F</span><span class="special">&gt;</span>
<span class="keyword">void</span> <span class="identifier">set_wait_callback</span><span class="special">(</span><span class="identifier">F</span> <span class="identifier">f</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Preconditions:</span></dt>
<dd><p>
                    The expression <code class="computeroutput"><span class="identifier">f</span><span class="special">(</span><span class="identifier">t</span><span class="special">)</span></code> where <code class="computeroutput"><span class="identifier">t</span></code>
                    is a lvalue of type <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a> shall
                    be well-formed. Invoking a copy of <code class="computeroutput"><span class="identifier">f</span></code>
                    shall have the same effect as invoking <code class="computeroutput"><span class="identifier">f</span></code>
                  </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                    Store a copy of <code class="computeroutput"><span class="identifier">f</span></code>
                    with the task associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> as a <span class="emphasis"><em>wait callback</em></span>.
                    This will replace any existing wait callback store alongside
                    that task. If a thread subsequently calls one of the wait functions
                    on a <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a> associated
                    with this task, and the result of the task is not <span class="emphasis"><em>ready</em></span>,
                    <code class="computeroutput"><span class="identifier">f</span><span class="special">(*</span><span class="keyword">this</span><span class="special">)</span></code>
                    shall be invoked.
                  </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                    <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">task_moved</span></code> if ownership of
                    the task associated with <code class="computeroutput"><span class="special">*</span><span class="keyword">this</span></code> has been moved to another
                    instance of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.packaged_task" title="packaged_task class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">packaged_task</span></code></a>.
                  </p></dd>
</dl>
</div>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.decay_copy"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.decay_copy" title="Non-member function decay_copy()">Non-member
          function <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">()</span></code></a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span> <span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="identifier">v</span><span class="special">)</span>
<span class="special">{</span>
  <span class="keyword">return</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;(</span><span class="identifier">v</span><span class="special">);</span>
<span class="special">}</span>
</pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.async"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.async" title="Non-member function async()">Non-member
          function <code class="computeroutput"><span class="identifier">async</span><span class="special">()</span></code></a>
</h5></div></div></div>
<p>
            The function template async provides a mechanism to launch a function
            potentially in a new thread and provides the result of the function in
            a future object with which it shares a shared state.
          </p>
<h6>
<a name="thread.synchronization.futures.reference.async.h0"></a>
            <span class="phrase"><a name="thread.synchronization.futures.reference.async.non_variadic_variant"></a></span><a class="link" href="synchronization.html#thread.synchronization.futures.reference.async.non_variadic_variant">Non-Variadic
            variant</a>
          </h6>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">()&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">async</span><span class="special">(</span><span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">()&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">async</span><span class="special">(</span><span class="identifier">launch</span> <span class="identifier">policy</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">F</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">...)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">async</span><span class="special">(</span><span class="identifier">Executor</span> <span class="special">&amp;</span><span class="identifier">ex</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">Args</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd>
<p>
</p>
<pre class="programlisting"><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">))()</span>
</pre>
<p>
                </p>
<p>
                  shall be a valid expression.
                </p>
</dd>
<dt><span class="term">Effects</span></dt>
<dd>
<p>
                  The first function behaves the same as a call to the second function
                  with a policy argument of <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span>
                  <span class="special">|</span> <span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>
                  and the same arguments for <code class="computeroutput"><span class="identifier">F</span></code>.
                </p>
<p>
                  The second and third functions create a shared state that is associated
                  with the returned future object.
                </p>
<p>
                  The further behavior of the second function depends on the policy
                  argument as follows (if more than one of these conditions applies,
                  the implementation may choose any of the corresponding policies):
                </p>
<p>
                  - if <code class="computeroutput"><span class="identifier">policy</span> <span class="special">&amp;</span>
                  <span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code> is non-zero - calls <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">))()</span></code>
                  as if in a new thread of execution represented by a thread object
                  with the calls to <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">()</span></code> being evaluated in the thread
                  that called <code class="computeroutput"><span class="identifier">async</span></code>.
                  Any return value is stored as the result in the shared state. Any
                  exception propagated from the execution of <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">))()</span></code> is stored as the exceptional
                  result in the shared state. The thread object is stored in the
                  shared state and affects the behavior of any asynchronous return
                  objects that reference that state.
                </p>
<p>
                  - if <code class="computeroutput"><span class="identifier">policy</span> <span class="special">&amp;</span>
                  <span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code> is non-zero - Stores
                  <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">))</span></code>
                  in the shared state. This copy of <code class="computeroutput"><span class="identifier">f</span></code>
                  constitute a deferred function. Invocation of the deferred function
                  evaluates <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">g</span><span class="special">)()</span></code> where <code class="computeroutput"><span class="identifier">g</span></code>
                  is the stored value of <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">))</span></code>. The shared state is not made
                  ready until the function has completed. The first call to a non-timed
                  waiting function on an asynchronous return object referring to
                  this shared state shall invoke the deferred function in the thread
                  that called the waiting function. Once evaluation of <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">g</span><span class="special">)()</span></code>
                  begins, the function is no longer considered deferred. (Note: If
                  this policy is specified together with other policies, such as
                  when using a policy value of <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span>
                  <span class="special">|</span> <span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>,
                  implementations should defer invocation or the selection of the
                  policy when no more concurrency can be effectively exploited.)
                </p>
<p>
                  - if no valid launch policy is provided the behavior is undefined.
                </p>
<p>
                  The further behavior of the third function is as follows:
                </p>
<p>
                  - The Executor::submit() function is given a function&lt;void ()&gt;
                  which calls `INVOKE (DECAY_COPY (std::forward&lt;F&gt;(f)), DECAY_COPY
                  (std::forward&lt;Args&gt;(args))...). The implementation of the
                  executor is decided by the programmer.
                </p>
</dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  An object of type <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span>
                  <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">()&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span></code>
                  that refers to the shared state created by this call to <code class="computeroutput"><span class="identifier">async</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd>
<p>
                  Regardless of the provided policy argument,
                </p>
<p>
                  - the invocation of <code class="computeroutput"><span class="identifier">async</span></code>
                  synchronizes with the invocation of <code class="computeroutput"><span class="identifier">f</span></code>.
                  (Note: This statement applies even when the corresponding future
                  object is moved to another thread.); and
                </p>
<p>
                  - the completion of the function <code class="computeroutput"><span class="identifier">f</span></code>
                  is sequenced before the shared state is made ready. (Note: <code class="computeroutput"><span class="identifier">f</span></code> might not be called at all,
                  so its completion might never happen.)
                </p>
<p>
                  If the implementation chooses the <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code>
                  policy,
                </p>
<p>
                  - a call to a non-timed waiting function on an asynchronous return
                  object that shares the shared state created by this async call
                  shall block until the associated thread has completed, as if joined,
                  or else time out;
                </p>
<p>
                  - the associated thread completion synchronizes with the return
                  from the first function that successfully detects the ready status
                  of the shared state or with the return from the last function that
                  releases the shared state, whichever happens first.
                </p>
</dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">system_error</span></code> if
                  policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code>
                  and the implementation is unable to start a new thread.
                </p></dd>
<dt><span class="term">Error conditions:</span></dt>
<dd><p>
                  - <code class="computeroutput"><span class="identifier">resource_unavailable_try_again</span></code>
                  - if policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code>
                  and the system is unable to start a new thread.
                </p></dd>
<dt><span class="term">Remarks::</span></dt>
<dd><p>
                  The first signature shall not participate in overload resolution
                  if <code class="computeroutput"><span class="identifier">decay_t</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;</span>
                  <span class="identifier">is</span> </code>boost:: launch<code class="computeroutput">
                  <span class="keyword">or</span> </code>boost::is_executor&lt;F&gt;<code class="computeroutput">
                  <span class="identifier">is</span> </code>true_type`.
                </p></dd>
</dl>
</div>
<h6>
<a name="thread.synchronization.futures.reference.async.h1"></a>
            <span class="phrase"><a name="thread.synchronization.futures.reference.async.variadic_variant"></a></span><a class="link" href="synchronization.html#thread.synchronization.futures.reference.async.variadic_variant">Variadic
            variant</a>
          </h6>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Args</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">...)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">async</span><span class="special">(</span><span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">Args</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Args</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">...)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">async</span><span class="special">(</span><span class="identifier">launch</span> <span class="identifier">policy</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">Args</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span><span class="special">);</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">Executor</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">F</span><span class="special">,</span> <span class="keyword">class</span><span class="special">...</span> <span class="identifier">Args</span><span class="special">&gt;</span>
   <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">...)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span>
  <span class="identifier">async</span><span class="special">(</span><span class="identifier">Executor</span> <span class="special">&amp;</span><span class="identifier">ex</span><span class="special">,</span> <span class="identifier">F</span><span class="special">&amp;&amp;</span> <span class="identifier">f</span><span class="special">,</span> <span class="identifier">Args</span><span class="special">&amp;&amp;...</span> <span class="identifier">args</span><span class="special">);</span>
</pre>
<div class="warning"><table border="0" summary="Warning">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
<th align="left">Warning</th>
</tr>
<tr><td align="left" valign="top"><p>
              the variadic prototype is provided only on C++11 compilers supporting
              rvalue references, variadic templates, decltype and a standard library
              providing &lt;tuple&gt; (waiting for a boost::tuple that is move aware),
              and BOOST_THREAD_PROVIDES_SIGNATURE_PACKAGED_TASK is defined.
            </p></td></tr>
</table></div>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd>
<p>
                  <code class="computeroutput"><span class="identifier">F</span></code> and each <code class="computeroutput"><span class="identifier">Ti</span></code> in <code class="computeroutput"><span class="identifier">Args</span></code>
                  shall satisfy the <code class="computeroutput"><span class="identifier">MoveConstructible</span></code>
                  requirements.
                </p>
<p>
                  invoke (decay_copy (boost::forward&lt;F&gt;(f)), decay_copy (boost::forward&lt;Args&gt;(args))...)
                </p>
<p>
                  shall be a valid expression.
                </p>
</dd>
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  - The first function behaves the same as a call to the second function
                  with a policy argument of <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span>
                  <span class="special">|</span> <span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>
                  and the same arguments for <code class="computeroutput"><span class="identifier">F</span></code>
                  and <code class="computeroutput"><span class="identifier">Args</span></code>.
                </p>
<p>
                  - The second function creates a shared state that is associated
                  with the returned future object. The further behavior of the second
                  function depends on the policy argument as follows (if more than
                  one of these conditions applies, the implementation may choose
                  any of the corresponding policies):
                </p>
<p>
                  - if <code class="computeroutput"><span class="identifier">policy</span> <span class="special">&amp;</span>
                  <span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code> is non-zero - calls <code class="computeroutput"><span class="identifier">invoke</span><span class="special">(</span><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">)),</span>
                  <span class="identifier">decay_copy</span> <span class="special">(</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">))...)</span></code>
                  as if in a new thread of execution represented by a thread object
                  with the calls to <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">()</span></code> being evaluated in the thread
                  that called <code class="computeroutput"><span class="identifier">async</span></code>.
                  Any return value is stored as the result in the shared state. Any
                  exception propagated from the execution of <code class="computeroutput"><span class="identifier">invoke</span><span class="special">(</span><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">)),</span> <span class="identifier">decay_copy</span>
                  <span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">))...)</span></code> is stored as the exceptional
                  result in the shared state. The thread object is stored in the
                  shared state and affects the behavior of any asynchronous return
                  objects that reference that state.
                </p>
<p>
                  - if <code class="computeroutput"><span class="identifier">policy</span> <span class="special">&amp;</span>
                  <span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code> is non-zero - Stores
                  <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">))</span></code>
                  and <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">))...</span></code> in the shared state. These
                  copies of <code class="computeroutput"><span class="identifier">f</span></code> and
                  <code class="computeroutput"><span class="identifier">args</span></code> constitute
                  a deferred function. Invocation of the deferred function evaluates
                  <code class="computeroutput"><span class="identifier">invoke</span><span class="special">(</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">g</span><span class="special">),</span>
                  <span class="identifier">move</span><span class="special">(</span><span class="identifier">xyz</span><span class="special">))</span></code>
                  where <code class="computeroutput"><span class="identifier">g</span></code> is the
                  stored value of <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;(</span><span class="identifier">f</span><span class="special">))</span></code> and <code class="computeroutput"><span class="identifier">xyz</span></code>
                  is the stored copy of <code class="computeroutput"><span class="identifier">decay_copy</span><span class="special">(</span><span class="identifier">forward</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;(</span><span class="identifier">args</span><span class="special">))...</span></code>. The shared state is not made
                  ready until the function has completed. The first call to a non-timed
                  waiting function on an asynchronous return object referring to
                  this shared state shall invoke the deferred function in the thread
                  that called the waiting function. Once evaluation of <code class="computeroutput"><span class="identifier">invoke</span><span class="special">(</span><span class="identifier">move</span><span class="special">(</span><span class="identifier">g</span><span class="special">),</span>
                  <span class="identifier">move</span><span class="special">(</span><span class="identifier">xyz</span><span class="special">))</span></code>
                  begins, the function is no longer considered deferred.
                </p>
<p>
                  - if no valid launch policy is provided the behaviour is undefined.
                </p>
</dd>
<dt><span class="term">Note:</span></dt>
<dd><p>
                  If this policy is specified together with other policies, such
                  as when using a policy value of <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span>
                  <span class="special">|</span> <span class="identifier">launch</span><span class="special">::</span><span class="identifier">deferred</span></code>,
                  implementations should defer invocation or the selection of the
                  policy when no more concurrency can be effectively exploited.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  An object of type <code class="computeroutput"> <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">result_of</span><span class="special">&lt;</span><span class="keyword">typename</span>
                  <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">F</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">(</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">Args</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">...)&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span></code> that refers to the shared state
                  created by this call to <code class="computeroutput"><span class="identifier">async</span></code>.
                </p></dd>
<dt><span class="term">Synchronization:</span></dt>
<dd>
<p>
                  Regardless of the provided policy argument,
                </p>
<p>
                  - the invocation of async synchronizes with the invocation of
                  <code class="computeroutput"><span class="identifier">f</span></code>. (Note: This
                  statement applies even when the corresponding future object is
                  moved to another thread.); and
                </p>
<p>
                  - the completion of the function <code class="computeroutput"><span class="identifier">f</span></code>
                  is sequenced before the shared state is made ready. (Note: f might
                  not be called at all, so its completion might never happen.)
                </p>
<p>
                  If the implementation chooses the <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code>
                  policy,
                </p>
<p>
                  - a call to a waiting function on an asynchronous return object
                  that shares the shared state created by this async call shall block
                  until the associated thread has completed, as if joined, or else
                  time out;
                </p>
<p>
                  - the associated thread completion synchronizes with the return
                  from the first function that successfully detects the ready status
                  of the shared state or with the return from the last function that
                  releases the shared state, whichever happens first.
                </p>
</dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">system_error</span></code> if
                  policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code>
                  and the implementation is unable to start a new thread.
                </p></dd>
<dt><span class="term">Error conditions:</span></dt>
<dd><p>
                  - <code class="computeroutput"><span class="identifier">resource_unavailable_try_again</span></code>
                  - if policy is <code class="computeroutput"><span class="identifier">launch</span><span class="special">::</span><span class="identifier">async</span></code>
                  and the system is unable to start a new thread.
                </p></dd>
<dt><span class="term">Remarks:</span></dt>
<dd><p>
                  The first signature shall not participate in overload resolution
                  if decay&lt;F&gt;::type is boost::launch.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.wait_for_any"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.wait_for_any" title="Non-member function wait_for_any() - EXTENSION">Non-member
          function <code class="computeroutput"><span class="identifier">wait_for_any</span><span class="special">()</span></code>
          - EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">&gt;</span>
  <span class="identifier">Iterator</span> <span class="identifier">wait_for_any</span><span class="special">(</span><span class="identifier">Iterator</span> <span class="identifier">begin</span><span class="special">,</span><span class="identifier">Iterator</span> <span class="identifier">end</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F2</span><span class="special">&gt;</span>
  <span class="keyword">unsigned</span> <span class="identifier">wait_for_any</span><span class="special">(</span><span class="identifier">F1</span><span class="special">&amp;</span> <span class="identifier">f1</span><span class="special">,</span><span class="identifier">F2</span><span class="special">&amp;</span> <span class="identifier">f2</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F3</span><span class="special">&gt;</span>
  <span class="keyword">unsigned</span> <span class="identifier">wait_for_any</span><span class="special">(</span><span class="identifier">F1</span><span class="special">&amp;</span> <span class="identifier">f1</span><span class="special">,</span><span class="identifier">F2</span><span class="special">&amp;</span> <span class="identifier">f2</span><span class="special">,</span><span class="identifier">F3</span><span class="special">&amp;</span> <span class="identifier">f3</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F3</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F4</span><span class="special">&gt;</span>
  <span class="keyword">unsigned</span> <span class="identifier">wait_for_any</span><span class="special">(</span><span class="identifier">F1</span><span class="special">&amp;</span> <span class="identifier">f1</span><span class="special">,</span><span class="identifier">F2</span><span class="special">&amp;</span> <span class="identifier">f2</span><span class="special">,</span><span class="identifier">F3</span><span class="special">&amp;</span> <span class="identifier">f3</span><span class="special">,</span><span class="identifier">F4</span><span class="special">&amp;</span> <span class="identifier">f4</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F3</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F4</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F5</span><span class="special">&gt;</span>
  <span class="keyword">unsigned</span> <span class="identifier">wait_for_any</span><span class="special">(</span><span class="identifier">F1</span><span class="special">&amp;</span> <span class="identifier">f1</span><span class="special">,</span><span class="identifier">F2</span><span class="special">&amp;</span> <span class="identifier">f2</span><span class="special">,</span><span class="identifier">F3</span><span class="special">&amp;</span> <span class="identifier">f3</span><span class="special">,</span><span class="identifier">F4</span><span class="special">&amp;</span> <span class="identifier">f4</span><span class="special">,</span><span class="identifier">F5</span><span class="special">&amp;</span> <span class="identifier">f5</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Preconditions:</span></dt>
<dd><p>
                  The types <code class="computeroutput"><span class="identifier">Fn</span></code> shall
                  be specializations of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a>, and <code class="computeroutput"><span class="identifier">Iterator</span></code> shall be a forward iterator
                  with a <code class="computeroutput"><span class="identifier">value_type</span></code>
                  which is a specialization of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Waits until at least one of the specified futures is <span class="emphasis"><em>ready</em></span>.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  The range-based overload returns an <code class="computeroutput"><span class="identifier">Iterator</span></code>
                  identifying the first future in the range that was detected as
                  <span class="emphasis"><em>ready</em></span>. The remaining overloads return the
                  zero-based index of the first future that was detected as <span class="emphasis"><em>ready</em></span>
                  (first parameter =&gt; 0, second parameter =&gt; 1, etc.).
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">thread_interrupted</span></code> if the current
                  thread is interrupted. Any exception thrown by the <span class="emphasis"><em>wait
                  callback</em></span> associated with any of the futures being waited
                  for. <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">bad_alloc</span></code> if memory could not
                  be allocated for the internal wait structures.
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">wait_for_any</span><span class="special">()</span></code>
                  is an <span class="emphasis"><em>interruption point</em></span>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.wait_for_all"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.wait_for_all" title="Non-member function wait_for_all() - EXTENSION">Non-member
          function <code class="computeroutput"><span class="identifier">wait_for_all</span><span class="special">()</span></code>
          - EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Iterator</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">wait_for_all</span><span class="special">(</span><span class="identifier">Iterator</span> <span class="identifier">begin</span><span class="special">,</span><span class="identifier">Iterator</span> <span class="identifier">end</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F2</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">wait_for_all</span><span class="special">(</span><span class="identifier">F1</span><span class="special">&amp;</span> <span class="identifier">f1</span><span class="special">,</span><span class="identifier">F2</span><span class="special">&amp;</span> <span class="identifier">f2</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F3</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">wait_for_all</span><span class="special">(</span><span class="identifier">F1</span><span class="special">&amp;</span> <span class="identifier">f1</span><span class="special">,</span><span class="identifier">F2</span><span class="special">&amp;</span> <span class="identifier">f2</span><span class="special">,</span><span class="identifier">F3</span><span class="special">&amp;</span> <span class="identifier">f3</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F3</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F4</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">wait_for_all</span><span class="special">(</span><span class="identifier">F1</span><span class="special">&amp;</span> <span class="identifier">f1</span><span class="special">,</span><span class="identifier">F2</span><span class="special">&amp;</span> <span class="identifier">f2</span><span class="special">,</span><span class="identifier">F3</span><span class="special">&amp;</span> <span class="identifier">f3</span><span class="special">,</span><span class="identifier">F4</span><span class="special">&amp;</span> <span class="identifier">f4</span><span class="special">);</span> <span class="comment">// EXTENSION</span>

<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">F1</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F2</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F3</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F4</span><span class="special">,</span><span class="keyword">typename</span> <span class="identifier">F5</span><span class="special">&gt;</span>
  <span class="keyword">void</span> <span class="identifier">wait_for_all</span><span class="special">(</span><span class="identifier">F1</span><span class="special">&amp;</span> <span class="identifier">f1</span><span class="special">,</span><span class="identifier">F2</span><span class="special">&amp;</span> <span class="identifier">f2</span><span class="special">,</span><span class="identifier">F3</span><span class="special">&amp;</span> <span class="identifier">f3</span><span class="special">,</span><span class="identifier">F4</span><span class="special">&amp;</span> <span class="identifier">f4</span><span class="special">,</span><span class="identifier">F5</span><span class="special">&amp;</span> <span class="identifier">f5</span><span class="special">);</span> <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Preconditions:</span></dt>
<dd><p>
                  The types <code class="computeroutput"><span class="identifier">Fn</span></code> shall
                  be specializations of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a>, and <code class="computeroutput"><span class="identifier">Iterator</span></code> shall be a forward iterator
                  with a <code class="computeroutput"><span class="identifier">value_type</span></code>
                  which is a specialization of <a class="link" href="synchronization.html#thread.synchronization.futures.reference.unique_future" title="future class template"><code class="computeroutput"><span class="identifier">future</span></code></a> or <a class="link" href="synchronization.html#thread.synchronization.futures.reference.shared_future" title="shared_future class template"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">shared_future</span></code></a>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  Waits until all of the specified futures are <span class="emphasis"><em>ready</em></span>.
                </p></dd>
<dt><span class="term">Throws:</span></dt>
<dd><p>
                  Any exceptions thrown by a call to <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code> on the specified futures.
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">wait_for_all</span><span class="special">()</span></code>
                  is an <span class="emphasis"><em>interruption point</em></span>.
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.when_all"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.when_all" title="Non-member function when_all() - EXTENSION">Non-member
          function <code class="computeroutput"><span class="identifier">when_all</span><span class="special">()</span></code>
          - EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">InputIterator</span><span class="special">&gt;</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">InputIterator</span><span class="special">::</span><span class="identifier">value_type</span><span class="special">::</span><span class="identifier">value_type</span><span class="special">&gt;&gt;</span>
  <span class="identifier">when_all</span><span class="special">(</span><span class="identifier">InputIterator</span> <span class="identifier">first</span><span class="special">,</span> <span class="identifier">InputIterator</span> <span class="identifier">last</span><span class="special">);</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span><span class="special">...</span> <span class="identifier">FutTypes</span><span class="special">&gt;</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="identifier">decay_t</span><span class="special">&lt;</span><span class="identifier">FutTypes</span><span class="special">&gt;...&gt;</span> <span class="identifier">when_all</span><span class="special">(</span><span class="identifier">FutTypes</span><span class="special">&amp;&amp;...</span> <span class="identifier">futures</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  - For the first overload, <code class="computeroutput"><span class="identifier">InputIterator</span></code>'s
                  value type shall be convertible to <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code> or <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>. All <code class="computeroutput"><span class="identifier">R</span></code>
                  types must be the same. If any of the <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code> or <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code> objects are in invalid state
                  (i.e. <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span>
                  <span class="special">==</span> <span class="keyword">false</span></code>),
                  the behavior is undefined. - For the second overload, <code class="computeroutput"><span class="identifier">FutTypes</span></code> is of type <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>
                  or <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>. The effect of calling <code class="computeroutput"><span class="identifier">when_all</span></code> on a <code class="computeroutput"><span class="identifier">future</span></code>
                  or a <code class="computeroutput"><span class="identifier">shared_future</span></code>
                  object for which <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span> <span class="special">==</span>
                  <span class="keyword">false</span></code> is undefined.
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd>
<p>
                  - There are two variations of <code class="computeroutput"><span class="identifier">when_all</span></code>.
                  The first version takes a pair of <code class="computeroutput"><span class="identifier">InputIterators</span></code>.
                  The second takes any arbitrary number of <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R0</span><span class="special">&gt;</span></code> and <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R1</span><span class="special">&gt;</span></code> objects, where <code class="computeroutput"><span class="identifier">R0</span></code> and <code class="computeroutput"><span class="identifier">R1</span></code>
                  need not be the same type.
                </p>
<p>
                  - Calling the first signature of <code class="computeroutput"><span class="identifier">when_all</span></code>
                  where <code class="computeroutput"><span class="identifier">InputIterator</span></code>
                  first equals last, returns a future with an empty <code class="computeroutput"><span class="identifier">vector</span></code> that is immediately ready.
                </p>
<p>
                  - Calling the second signature of <code class="computeroutput"><span class="identifier">when_all</span></code>
                  with no arguments returns a future&lt;tuple&lt;&gt;&gt; that is
                  immediately ready.
                </p>
</dd>
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  - If any of the futures supplied to a call to <code class="computeroutput"><span class="identifier">when_all</span></code>
                  refer to deferred tasks that have not started execution, those
                  tasks are executed before the call to <code class="computeroutput"><span class="identifier">when_all</span></code>
                  returns. Once all such tasks have been executed, the call to <code class="computeroutput"><span class="identifier">when_all</span></code> returns immediately.
                </p>
<p>
                  - The call to <code class="computeroutput"><span class="identifier">when_all</span></code>
                  does not wait for non-deferred tasks, or deferred tasks that have
                  already started executing elsewhere, to complete before returning.
                </p>
<p>
                  - Once all the <code class="computeroutput"><span class="identifier">future</span></code>s/<code class="computeroutput"><span class="identifier">shared_future</span></code>s supplied to the
                  call to <code class="computeroutput"><span class="identifier">when_all</span></code>
                  are ready, the <code class="computeroutput"><span class="identifier">future</span></code>s/<code class="computeroutput"><span class="identifier">shared_future</span></code>s are moved/copied
                  into the associated state of the future returned from the call
                  to <code class="computeroutput"><span class="identifier">when_all</span></code>, preserving
                  the order of the futures supplied to <code class="computeroutput"><span class="identifier">when_all</span></code>.
                </p>
<p>
                  - The collection is then stored as the result in a newly created
                  shared state.
                </p>
<p>
                  - A new future object that refers to the shared state is created.
                  The exact type of the future is further described below.
                </p>
<p>
                  - The <code class="computeroutput"><span class="identifier">future</span></code> returned
                  by <code class="computeroutput"><span class="identifier">when_all</span></code> will
                  not throw an exception when calling <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code>, but the futures held in the
                  output collection may.
                </p>
</dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                  - <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">tuple</span><span class="special">&lt;&gt;&gt;</span></code>
                  if <code class="computeroutput"><span class="identifier">when_all</span></code> is
                  called with zero arguments.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;&gt;&gt;</span></code>
                  if the input cardinality is unknown at compile and the iterator
                  pair yields <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>. The order of the futures in
                  the output vector will be the same as given by the input iterator.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;&gt;&gt;</span></code>
                  if the input cardinality is unknown at compile time and the iterator
                  pair yields <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>. The order of the futures in
                  the output vector will be the same as given by the input iterator.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="identifier">decay_t</span><span class="special">&lt;</span><span class="identifier">FutTypes</span><span class="special">&gt;...&gt;&gt;</span></code>
                  if inputs are fixed in number.
                </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd>
<p>
                  - All input futures valid() == false.
                </p>
<p>
                  - All input shared future valid() == true.
                </p>
<p>
                  - valid() == true.
                </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.when_any"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.when_any" title="Non-member function when_any() - EXTENSION">Non-member
          function <code class="computeroutput"><span class="identifier">when_any</span><span class="special">()</span></code>
          - EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">class</span> <span class="identifier">InputIterator</span><span class="special">&gt;</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">InputIterator</span><span class="special">::</span><span class="identifier">value_type</span><span class="special">::</span><span class="identifier">value_type</span><span class="special">&gt;&gt;</span>
  <span class="identifier">when_any</span><span class="special">(</span><span class="identifier">InputIterator</span> <span class="identifier">first</span><span class="special">,</span> <span class="identifier">InputIterator</span> <span class="identifier">last</span><span class="special">);</span>

<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span><span class="special">...</span> <span class="identifier">FutTypes</span><span class="special">&gt;</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">std</span><span class="special">::</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="identifier">decay_t</span><span class="special">&lt;</span><span class="identifier">FutTypes</span><span class="special">&gt;...&gt;</span>
  <span class="identifier">when_any</span><span class="special">(</span><span class="identifier">FutTypes</span><span class="special">&amp;&amp;...</span> <span class="identifier">futures</span><span class="special">);</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Requires:</span></dt>
<dd><p>
                  - For the first overload, <code class="computeroutput"><span class="identifier">InputIterator</span></code>'s
                  value type shall be convertible to <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code> or <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>. All <code class="computeroutput"><span class="identifier">R</span></code>
                  types must be the same. If any of the <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code> or <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code> objects are in invalid state
                  (i.e. <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span>
                  <span class="special">==</span> <span class="keyword">false</span></code>),
                  the behavior is undefined. - For the second overload, <code class="computeroutput"><span class="identifier">FutTypes</span></code> is of type <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>
                  or <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>. The effect of calling <code class="computeroutput"><span class="identifier">when_any</span></code> on a <code class="computeroutput"><span class="identifier">future</span></code>
                  or a <code class="computeroutput"><span class="identifier">shared_future</span></code>
                  object for which <code class="computeroutput"><span class="identifier">valid</span><span class="special">()</span> <span class="special">==</span>
                  <span class="keyword">false</span> <span class="identifier">is</span>
                  <span class="identifier">undefined</span></code>.
                </p></dd>
<dt><span class="term">Notes:</span></dt>
<dd>
<p>
                  - There are two variations of <code class="computeroutput"><span class="identifier">when_any</span>
                  </code>. The first version takes a pair of <code class="computeroutput"><span class="identifier">InputIterators</span></code>.
                  The second takes any arbitrary number of <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R0</span><span class="special">&gt;</span></code> and <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R1</span><span class="special">&gt;</span></code> objects, where <code class="computeroutput"><span class="identifier">R0</span></code> and <code class="computeroutput"><span class="identifier">R1</span></code>
                  need not be the same type.
                </p>
<p>
                  - Calling the first signature of <code class="computeroutput"><span class="identifier">when_any</span>
                  </code> where <code class="computeroutput"><span class="identifier">InputIterator</span></code>
                  first equals last, returns a future with an empty <code class="computeroutput"><span class="identifier">vector</span></code> that is immediately ready.
                </p>
<p>
                  - Calling the second signature of <code class="computeroutput"><span class="identifier">when_any</span></code>
                  with no arguments returns a future&lt;tuple&lt;&gt;&gt; that is
                  immediately ready.
                </p>
</dd>
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  - Each of the futures supplied to <code class="computeroutput"><span class="identifier">when_any</span></code>
                  is checked in the order supplied. If a given future is ready, then
                  no further futures are checked, and the call to <code class="computeroutput"><span class="identifier">when_any</span></code>
                  returns immediately. If a given future refers to a deferred task
                  that has not yet started execution, then no further futures are
                  checked, that task is executed, and the call to <code class="computeroutput"><span class="identifier">when_any</span></code>
                  then returns immediately.
                </p>
<p>
                  - The call to <code class="computeroutput"><span class="identifier">when_any</span></code>
                  does not wait for non-deferred tasks, or deferred tasks that have
                  already started executing elsewhere, to complete before returning.
                </p>
<p>
                  - Once at least one of the futures supplied to the call to <code class="computeroutput"><span class="identifier">when_any</span></code> are ready, the futures
                  are moved into the associated state of the future returned from
                  the call to <code class="computeroutput"><span class="identifier">when_any</span></code>,
                  preserving the order of the futures supplied to <code class="computeroutput"><span class="identifier">when_any</span></code>.
                  That future is then ready.
                </p>
<p>
                  - The collection is then stored as the result in a newly created
                  shared state.
                </p>
<p>
                  - A new future object that refers to the shared state is created.
                  The exact type of the future is further described below.
                </p>
<p>
                  - The future returned by <code class="computeroutput"><span class="identifier">when_any</span></code>
                  will not throw an exception when calling <code class="computeroutput"><span class="identifier">wait</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">get</span><span class="special">()</span></code>, but the futures held in the
                  output collection may.
                </p>
</dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                  - <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">tuple</span><span class="special">&lt;&gt;&gt;</span></code>
                  if <code class="computeroutput"><span class="identifier">when_any</span> </code> is
                  called with zero arguments.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;&gt;&gt;</span></code>
                  if the input cardinality is unknown at compile and the iterator
                  pair yields <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>. The order of the futures in
                  the output vector will be the same as given by the input iterator.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;&gt;&gt;</span></code>
                  if the input cardinality is unknown at compile time and the iterator
                  pair yields <code class="computeroutput"><span class="identifier">shared_future</span><span class="special">&lt;</span><span class="identifier">R</span><span class="special">&gt;</span></code>. The order of the futures in
                  the output vector will be the same as given by the input iterator.
                </p>
<p>
                  - <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">tuple</span><span class="special">&lt;</span><span class="identifier">decat_t</span><span class="special">&lt;</span><span class="identifier">FutTypes</span><span class="special">&gt;...&gt;&gt;</span></code>
                  if inputs are fixed in number.
                </p>
</dd>
<dt><span class="term">Postconditions:</span></dt>
<dd>
<p>
                  - All input futures valid() == false.
                </p>
<p>
                  - All input shared_futures valid() == true.
                </p>
<p>
                  - valid() == true.
                </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.make_ready_future"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.make_ready_future" title="Non-member function make_ready_future() EXTENSION">Non-member
          function <code class="computeroutput"><span class="identifier">make_ready_future</span><span class="special">()</span></code> EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">V</span><span class="special">&gt;</span> <span class="identifier">make_ready_future</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="identifier">value</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
<span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;</span> <span class="identifier">make_ready_future</span><span class="special">();</span>  <span class="comment">// EXTENSION</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">make_ready_future</span><span class="special">(</span><span class="identifier">exception_ptr</span> <span class="identifier">ex</span><span class="special">);</span>  <span class="comment">// DEPRECATED</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">E</span><span class="special">&gt;</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span> <span class="identifier">make_ready_future</span><span class="special">(</span><span class="identifier">E</span> <span class="identifier">ex</span><span class="special">);</span>  <span class="comment">// DEPRECATED</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Remark:</span></dt>
<dd><p>
                  where <code class="computeroutput"><span class="identifier">V</span></code> is determined
                  as follows: Let <code class="computeroutput"><span class="identifier">U</span></code>
                  be <code class="computeroutput"><span class="identifier">decay_t</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;</span></code>.
                  Then <code class="computeroutput"><span class="identifier">V</span></code> is <code class="computeroutput"><span class="identifier">X</span><span class="special">&amp;</span></code>
                  if <code class="computeroutput"><span class="identifier">U</span></code> equals <code class="computeroutput"><span class="identifier">reference_wrapper</span><span class="special">&lt;</span><span class="identifier">X</span><span class="special">&gt;</span></code>,
                  otherwise <code class="computeroutput"><span class="identifier">V</span></code> is
                  <code class="computeroutput"><span class="identifier">U</span></code>.
                </p></dd>
<dt><span class="term">Effects:</span></dt>
<dd>
<p>
                  - value prototype: The value that is passed into the function is
                  moved to the shared state of the returned future if it is an rvalue.
                  Otherwise the value is copied to the shared state of the returned
                  future.
                </p>
<p>
                  - exception: The exception that is passed into the function is
                  copied to the shared state of the returned future.
                </p>
<p>
                  .
                </p>
</dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                  - a ready future with the value set with <code class="computeroutput"><span class="identifier">value</span></code>
                </p>
<p>
                  - a ready future with the exception set with <code class="computeroutput"><span class="identifier">ex</span></code>
                </p>
<p>
                  - a ready future&lt;void&gt; with the value set (void).
                </p>
</dd>
<dt><span class="term">Postcondition:</span></dt>
<dd>
<p>
                  - Returned future, valid() == true
                </p>
<p>
                  - Returned future, is_ready() = true
                </p>
<p>
                  - Returned future, has_value() = true or has_exception() depending
                  on the prototype.
                </p>
</dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.make_exceptional_future"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.make_exceptional_future" title="Non-member function make_exceptional_future() EXTENSION">Non-member
          function <code class="computeroutput"><span class="identifier">make_exceptional_future</span><span class="special">()</span></code> EXTENSION</a>
</h5></div></div></div>
<pre class="programlisting"><span class="identifier">exceptional_ptr</span> <span class="identifier">make_exceptional_future</span><span class="special">(</span><span class="identifier">exception_ptr</span> <span class="identifier">ex</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
<span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">E</span><span class="special">&gt;</span>
  <span class="identifier">exceptional_ptr</span> <span class="identifier">make_exceptional_future</span><span class="special">(</span><span class="identifier">E</span> <span class="identifier">ex</span><span class="special">);</span>  <span class="comment">// EXTENSION</span>
<span class="identifier">exceptional_ptr</span> <span class="identifier">make_exceptional_future</span><span class="special">();</span>  <span class="comment">// EXTENSION</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The exception that is passed in to the function or the current
                  exception if no parameter is given is moved into the returned
                  <code class="computeroutput"><span class="identifier">exceptional_ptr</span></code>
                  if it is an rvalue. Otherwise the exception is copied into the
                  returned <code class="computeroutput"><span class="identifier">exceptional_ptr</span></code>.
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd><p>
                  An exceptional_ptr instance implicitly convertible to a future&lt;T&gt;
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.make_future"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.make_future" title="Non-member function make_future() DEPRECATED">Non-member
          function <code class="computeroutput"><span class="identifier">make_future</span><span class="special">()</span></code>
          DEPRECATED</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
  <span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span> <span class="identifier">make_future</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="identifier">value</span><span class="special">);</span>  <span class="comment">// DEPRECATED</span>
<span class="identifier">future</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;</span> <span class="identifier">make_future</span><span class="special">();</span>  <span class="comment">// DEPRECATED</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The value that is passed into the function is moved to the shared
                  state of the returned function if it is an rvalue. Otherwise the
                  value is copied to the shared state of the returned function. .
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                  - future&lt;T&gt;, if function is given a value of type T
                </p>
<p>
                  - future&lt;void&gt;, if the function is not given any inputs.
                </p>
</dd>
<dt><span class="term">Postcondition:</span></dt>
<dd>
<p>
                  - Returned future&lt;T&gt;, valid() == true
                </p>
<p>
                  - Returned future&lt;T&gt;, is_ready() = true
                </p>
</dd>
<dt><span class="term">See:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">make_ready_future</span><span class="special">()</span></code>
                </p></dd>
</dl>
</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="thread.synchronization.futures.reference.make_shared_future"></a><a class="link" href="synchronization.html#thread.synchronization.futures.reference.make_shared_future" title="Non-member function make_shared_future() DEPRECATED">Non-member
          function <code class="computeroutput"><span class="identifier">make_shared_future</span><span class="special">()</span></code> DEPRECATED</a>
</h5></div></div></div>
<pre class="programlisting"><span class="keyword">template</span> <span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
  <span class="identifier">shared_future</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">decay</span><span class="special">&lt;</span><span class="identifier">T</span><span class="special">&gt;::</span><span class="identifier">type</span><span class="special">&gt;</span> <span class="identifier">make_shared_future</span><span class="special">(</span><span class="identifier">T</span><span class="special">&amp;&amp;</span> <span class="identifier">value</span><span class="special">);</span>  <span class="comment">// DEPRECATED</span>
<span class="identifier">shared_future</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">&gt;</span> <span class="identifier">make_shared_future</span><span class="special">();</span>  <span class="comment">// DEPRECATED</span>
</pre>
<div class="variablelist">
<p class="title"><b></b></p>
<dl class="variablelist">
<dt><span class="term">Effects:</span></dt>
<dd><p>
                  The value that is passed in to the function is moved to the shared
                  state of the returned function if it is an rvalue. Otherwise the
                  value is copied to the shared state of the returned function. .
                </p></dd>
<dt><span class="term">Returns:</span></dt>
<dd>
<p>
                  - shared_future&lt;T&gt;, if function is given a value of type
                  T
                </p>
<p>
                  - shared_future&lt;void&gt;, if the function is not given any inputs.
                </p>
</dd>
<dt><span class="term">Postcondition:</span></dt>
<dd>
<p>
                  - Returned shared_future&lt;T&gt;, valid() == true
                </p>
<p>
                  - Returned shared_future&lt;T&gt;, is_ready() = true
                </p>
</dd>
<dt><span class="term">See:</span></dt>
<dd><p>
                  <code class="computeroutput"><span class="identifier">make_ready_future</span><span class="special">()</span></code> and <code class="computeroutput"><span class="identifier">future</span><span class="special">&lt;&gt;::</span><span class="identifier">share</span><span class="special">()</span></code>
                </p></dd>
</dl>
</div>
</div>
</div>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright &#169; 2007 -11 Anthony Williams<br>Copyright &#169; 2011 -16 Vicente J. Botet Escriba<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="ScopedThreads.html"><img src="../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../thread.html"><img src="../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../index.html"><img src="../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="thread_local_storage.html"><img src="../../../doc/src/images/next.png" alt="Next"></a>
</div>
</body>
</html>
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-14 20:42:41 +0000