blob: 8a7cc89d6bc04c0c893e0f9e1c08711ac81dbe9d (
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
|
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>io_context::strand</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="../../boost_asio.html" title="Boost.Asio">
<link rel="up" href="../reference.html" title="Reference">
<link rel="prev" href="io_context__service/_service.html" title="io_context::service::~service">
<link rel="next" href="io_context__strand/context.html" title="io_context::strand::context">
</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="io_context__service/_service.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="io_context__strand/context.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="boost_asio.reference.io_context__strand"></a><a class="link" href="io_context__strand.html" title="io_context::strand">io_context::strand</a>
</h3></div></div></div>
<p>
Provides serialised handler execution.
</p>
<pre class="programlisting">class strand
</pre>
<h5>
<a name="boost_asio.reference.io_context__strand.h0"></a>
<span class="phrase"><a name="boost_asio.reference.io_context__strand.member_functions"></a></span><a class="link" href="io_context__strand.html#boost_asio.reference.io_context__strand.member_functions">Member
Functions</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Name
</p>
</th>
<th>
<p>
Description
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/context.html" title="io_context::strand::context"><span class="bold"><strong>context</strong></span></a>
</p>
</td>
<td>
<p>
Obtain the underlying execution context.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/defer.html" title="io_context::strand::defer"><span class="bold"><strong>defer</strong></span></a>
</p>
</td>
<td>
<p>
Request the strand to invoke the given function object.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/dispatch.html" title="io_context::strand::dispatch"><span class="bold"><strong>dispatch</strong></span></a>
</p>
</td>
<td>
<p>
Request the strand to invoke the given function object. <br>
<span class="silver"> —</span><br> (Deprecated: Use boost::asio::dispatch().) Request the strand
to invoke the given handler.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/get_io_context.html" title="io_context::strand::get_io_context"><span class="bold"><strong>get_io_context</strong></span></a>
</p>
</td>
<td>
<p>
(Deprecated: Use context().) Get the io_context associated with
the strand.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/get_io_service.html" title="io_context::strand::get_io_service"><span class="bold"><strong>get_io_service</strong></span></a>
</p>
</td>
<td>
<p>
(Deprecated: Use context().) Get the io_context associated with
the strand.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/on_work_finished.html" title="io_context::strand::on_work_finished"><span class="bold"><strong>on_work_finished</strong></span></a>
</p>
</td>
<td>
<p>
Inform the strand that some work is no longer outstanding.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/on_work_started.html" title="io_context::strand::on_work_started"><span class="bold"><strong>on_work_started</strong></span></a>
</p>
</td>
<td>
<p>
Inform the strand that it has some outstanding work to do.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/post.html" title="io_context::strand::post"><span class="bold"><strong>post</strong></span></a>
</p>
</td>
<td>
<p>
Request the strand to invoke the given function object. <br>
<span class="silver"> —</span><br> (Deprecated: Use boost::asio::post().) Request the strand
to invoke the given handler and return immediately.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/running_in_this_thread.html" title="io_context::strand::running_in_this_thread"><span class="bold"><strong>running_in_this_thread</strong></span></a>
</p>
</td>
<td>
<p>
Determine whether the strand is running in the current thread.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/strand.html" title="io_context::strand::strand"><span class="bold"><strong>strand</strong></span></a>
</p>
</td>
<td>
<p>
Constructor.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/wrap.html" title="io_context::strand::wrap"><span class="bold"><strong>wrap</strong></span></a>
</p>
</td>
<td>
<p>
(Deprecated: Use boost::asio::bind_executor().) Create a new handler
that automatically dispatches the wrapped handler on the strand.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/_strand.html" title="io_context::strand::~strand"><span class="bold"><strong>~strand</strong></span></a>
</p>
</td>
<td>
<p>
Destructor.
</p>
</td>
</tr>
</tbody>
</table></div>
<h5>
<a name="boost_asio.reference.io_context__strand.h1"></a>
<span class="phrase"><a name="boost_asio.reference.io_context__strand.friends"></a></span><a class="link" href="io_context__strand.html#boost_asio.reference.io_context__strand.friends">Friends</a>
</h5>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Name
</p>
</th>
<th>
<p>
Description
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/operator_not__eq_.html" title="io_context::strand::operator!="><span class="bold"><strong>operator!=</strong></span></a>
</p>
</td>
<td>
<p>
Compare two strands for inequality.
</p>
</td>
</tr>
<tr>
<td>
<p>
<a class="link" href="io_context__strand/operator_eq__eq_.html" title="io_context::strand::operator=="><span class="bold"><strong>operator==</strong></span></a>
</p>
</td>
<td>
<p>
Compare two strands for equality.
</p>
</td>
</tr>
</tbody>
</table></div>
<p>
The <a class="link" href="io_context__strand.html" title="io_context::strand"><code class="computeroutput">io_context::strand</code></a>
class provides the ability to post and dispatch handlers with the guarantee
that none of those handlers will execute concurrently.
</p>
<h5>
<a name="boost_asio.reference.io_context__strand.h2"></a>
<span class="phrase"><a name="boost_asio.reference.io_context__strand.order_of_handler_invocation"></a></span><a class="link" href="io_context__strand.html#boost_asio.reference.io_context__strand.order_of_handler_invocation">Order
of handler invocation</a>
</h5>
<p>
Given:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
a strand object <code class="computeroutput">s</code>
</li>
<li class="listitem">
an object <code class="computeroutput">a</code> meeting completion handler requirements
</li>
<li class="listitem">
an object <code class="computeroutput">a1</code> which is an arbitrary copy of <code class="computeroutput">a</code>
made by the implementation
</li>
<li class="listitem">
an object <code class="computeroutput">b</code> meeting completion handler requirements
</li>
<li class="listitem">
an object <code class="computeroutput">b1</code> which is an arbitrary copy of <code class="computeroutput">b</code>
made by the implementation
</li>
</ul></div>
<p>
if any of the following conditions are true:
</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<code class="computeroutput">s.post(a)</code> happens-before <code class="computeroutput">s.post(b)</code>
</li>
<li class="listitem">
<code class="computeroutput">s.post(a)</code> happens-before <code class="computeroutput">s.dispatch(b)</code>, where
the latter is performed outside the strand
</li>
<li class="listitem">
<code class="computeroutput">s.dispatch(a)</code> happens-before <code class="computeroutput">s.post(b)</code>, where
the former is performed outside the strand
</li>
<li class="listitem">
<code class="computeroutput">s.dispatch(a)</code> happens-before <code class="computeroutput">s.dispatch(b)</code>,
where both are performed outside the strand
</li>
</ul></div>
<p>
then <code class="computeroutput">asio_handler_invoke(a1, &a1)</code> happens-before <code class="computeroutput">asio_handler_invoke(b1,
&b1)</code>.
</p>
<p>
Note that in the following case:
</p>
<pre class="programlisting">async_op_1(..., s.wrap(a));
async_op_2(..., s.wrap(b));
</pre>
<p>
the completion of the first async operation will perform <code class="computeroutput">s.dispatch(a)</code>,
and the second will perform <code class="computeroutput">s.dispatch(b)</code>, but the order in
which those are performed is unspecified. That is, you cannot state whether
one happens-before the other. Therefore none of the above conditions are
met and no ordering guarantee is made.
</p>
<h5>
<a name="boost_asio.reference.io_context__strand.h3"></a>
<span class="phrase"><a name="boost_asio.reference.io_context__strand.remarks"></a></span><a class="link" href="io_context__strand.html#boost_asio.reference.io_context__strand.remarks">Remarks</a>
</h5>
<p>
The implementation makes no guarantee that handlers posted or dispatched
through different <code class="computeroutput">strand</code> objects will be invoked concurrently.
</p>
<h5>
<a name="boost_asio.reference.io_context__strand.h4"></a>
<span class="phrase"><a name="boost_asio.reference.io_context__strand.thread_safety"></a></span><a class="link" href="io_context__strand.html#boost_asio.reference.io_context__strand.thread_safety">Thread Safety</a>
</h5>
<p>
<span class="emphasis"><em>Distinct</em></span> <span class="emphasis"><em>objects:</em></span> Safe.
</p>
<p>
<span class="emphasis"><em>Shared</em></span> <span class="emphasis"><em>objects:</em></span> Safe.
</p>
<h5>
<a name="boost_asio.reference.io_context__strand.h5"></a>
<span class="phrase"><a name="boost_asio.reference.io_context__strand.requirements"></a></span><a class="link" href="io_context__strand.html#boost_asio.reference.io_context__strand.requirements">Requirements</a>
</h5>
<p>
<span class="emphasis"><em>Header: </em></span><code class="literal">boost/asio/io_context_strand.hpp</code>
</p>
<p>
<span class="emphasis"><em>Convenience header: </em></span><code class="literal">boost/asio.hpp</code>
</p>
</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 © 2003-2018 Christopher M. Kohlhoff<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="io_context__service/_service.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../reference.html"><img src="../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../boost_asio.html"><img src="../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="io_context__strand/context.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a>
</div>
</body>
</html>
|
