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
|
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
#include "common.h"
#include "eventpipe.h"
#include "eventpipeconfiguration.h"
#include "eventpipebuffer.h"
#include "eventpipebuffermanager.h"
#ifdef FEATURE_PERFTRACING
#ifndef __llvm__
__declspec(thread) ThreadEventBufferList ThreadEventBufferList::gCurrentThreadEventBufferList;
#else // !__llvm__
thread_local ThreadEventBufferList ThreadEventBufferList::gCurrentThreadEventBufferList;
#endif // !__llvm__
EventPipeBufferManager::EventPipeBufferManager()
{
CONTRACTL
{
THROWS;
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;
m_pPerThreadBufferList = new SList<SListElem<EventPipeBufferList*>>();
m_sizeOfAllBuffers = 0;
m_lock.Init(LOCK_TYPE_DEFAULT);
#ifdef _DEBUG
m_numBuffersAllocated = 0;
m_numBuffersStolen = 0;
m_numBuffersLeaked = 0;
m_numEventsStored = 0;
m_numEventsDropped = 0;
m_numEventsWritten = 0;
#endif // _DEBUG
}
EventPipeBufferManager::~EventPipeBufferManager()
{
CONTRACTL
{
NOTHROW;
GC_TRIGGERS;
MODE_ANY;
}
CONTRACTL_END;
if(m_pPerThreadBufferList != NULL)
{
SListElem<EventPipeBufferList*> *pElem = m_pPerThreadBufferList->GetHead();
while(pElem != NULL)
{
SListElem<EventPipeBufferList*> *pCurElem = pElem;
EventPipeBufferList *pThreadBufferList = pCurElem->GetValue();
if (!pThreadBufferList->OwnedByThread())
{
// We don't delete buffers themself because they can be in-use
delete(pThreadBufferList);
}
pElem = m_pPerThreadBufferList->GetNext(pElem);
delete(pCurElem);
}
delete(m_pPerThreadBufferList);
m_pPerThreadBufferList = NULL;
}
}
EventPipeBuffer* EventPipeBufferManager::AllocateBufferForThread(EventPipeSession &session, unsigned int requestSize)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
PRECONDITION(requestSize > 0);
}
CONTRACTL_END;
// Allocating a buffer requires us to take the lock.
SpinLockHolder _slh(&m_lock);
// Determine if the requesting thread has at least one buffer.
// If not, we guarantee that each thread gets at least one (to prevent thrashing when the circular buffer size is too small).
bool allocateNewBuffer = false;
EventPipeBufferList *pThreadBufferList = ThreadEventBufferList::Get();
if(pThreadBufferList == NULL)
{
pThreadBufferList = new (nothrow) EventPipeBufferList(this);
if (pThreadBufferList == NULL)
{
return NULL;
}
SListElem<EventPipeBufferList*> *pElem = new (nothrow) SListElem<EventPipeBufferList*>(pThreadBufferList);
if (pElem == NULL)
{
return NULL;
}
m_pPerThreadBufferList->InsertTail(pElem);
ThreadEventBufferList::Set(pThreadBufferList);
allocateNewBuffer = true;
}
// Determine if policy allows us to allocate another buffer, or if we need to steal one
// from another thread.
if(!allocateNewBuffer)
{
EventPipeConfiguration *pConfig = EventPipe::GetConfiguration();
if(pConfig == NULL)
{
return NULL;
}
size_t circularBufferSizeInBytes = pConfig->GetCircularBufferSize();
if(m_sizeOfAllBuffers < circularBufferSizeInBytes)
{
// We don't worry about the fact that a new buffer could put us over the circular buffer size.
// This is OK, and we won't do it again if we actually go over.
allocateNewBuffer = true;
}
}
// Only steal buffers from other threads if the session being written to is a
// file-based session. Streaming sessions will simply drop events.
// TODO: Add dropped events telemetry here.
EventPipeBuffer *pNewBuffer = NULL;
if(!allocateNewBuffer && (session.GetSessionType() == EventPipeSessionType::File))
{
// We can't allocate a new buffer.
// Find the oldest buffer, de-allocate it, and re-purpose it for this thread.
// Find the thread that contains the oldest stealable buffer, and get its list of buffers.
EventPipeBufferList *pListToStealFrom = FindThreadToStealFrom();
if(pListToStealFrom != NULL)
{
// Assert that the buffer we're stealing is not the only buffer in the list.
// This invariant is enforced by FindThreadToStealFrom.
_ASSERTE((pListToStealFrom->GetHead() != NULL) && (pListToStealFrom->GetHead()->GetNext() != NULL));
// Remove the oldest buffer from the list.
pNewBuffer = pListToStealFrom->GetAndRemoveHead();
// De-allocate the buffer. We do this because buffers are variable sized
// based on how much volume is coming from the thread.
DeAllocateBuffer(pNewBuffer);
pNewBuffer = NULL;
// Set that we want to allocate a new buffer.
allocateNewBuffer = true;
#ifdef _DEBUG
m_numBuffersStolen++;
#endif // _DEBUG
}
else
{
// This only happens when # of threads == # of buffers.
// We'll allocate one more buffer, and then this won't happen again.
allocateNewBuffer = true;
}
}
if(allocateNewBuffer)
{
// Pick a buffer size by multiplying the base buffer size by the number of buffers already allocated for this thread.
unsigned int sizeMultiplier = pThreadBufferList->GetCount() + 1;
// Pick the base buffer size based. Debug builds have a smaller size to stress the allocate/steal path more.
unsigned int baseBufferSize =
#ifdef _DEBUG
30 * 1024; // 30K
#else
100 * 1024; // 100K
#endif
unsigned int bufferSize = baseBufferSize * sizeMultiplier;
// Make sure that buffer size >= request size so that the buffer size does not
// determine the max event size.
if(bufferSize < requestSize)
{
bufferSize = requestSize;
}
// Don't allow the buffer size to exceed 1MB.
const unsigned int maxBufferSize = 1024 * 1024;
if(bufferSize > maxBufferSize)
{
bufferSize = maxBufferSize;
}
// EX_TRY is used here as opposed to new (nothrow) because
// the constructor also allocates a private buffer, which
// could throw, and cannot be easily checked
EX_TRY
{
pNewBuffer = new EventPipeBuffer(bufferSize);
}
EX_CATCH
{
pNewBuffer = NULL;
}
EX_END_CATCH(SwallowAllExceptions);
if (pNewBuffer == NULL)
{
return NULL;
}
m_sizeOfAllBuffers += bufferSize;
#ifdef _DEBUG
m_numBuffersAllocated++;
#endif // _DEBUG
}
// Set the buffer on the thread.
if(pNewBuffer != NULL)
{
pThreadBufferList->InsertTail(pNewBuffer);
return pNewBuffer;
}
return NULL;
}
EventPipeBufferList* EventPipeBufferManager::FindThreadToStealFrom()
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
PRECONDITION(m_lock.OwnedByCurrentThread());
}
CONTRACTL_END;
// Find the thread buffer list containing the buffer whose most recent event is the oldest as long as the buffer is not
// the current buffer for the thread (e.g. it's next pointer is non-NULL).
// This means that the thread must also have multiple buffers, so that we don't steal its only buffer.
EventPipeBufferList *pOldestContainingList = NULL;
SListElem<EventPipeBufferList*> *pElem = m_pPerThreadBufferList->GetHead();
while(pElem != NULL)
{
EventPipeBufferList *pCandidate = pElem->GetValue();
// The current candidate has more than one buffer (otherwise it is disqualified).
if(pCandidate->GetHead()->GetNext() != NULL)
{
// If we haven't seen any candidates, this one automatically becomes the oldest candidate.
if(pOldestContainingList == NULL)
{
pOldestContainingList = pCandidate;
}
// Otherwise, to replace the existing candidate, this candidate must have an older timestamp in its oldest buffer.
else if((pOldestContainingList->GetHead()->GetMostRecentTimeStamp().QuadPart) >
(pCandidate->GetHead()->GetMostRecentTimeStamp().QuadPart))
{
pOldestContainingList = pCandidate;
}
}
pElem = m_pPerThreadBufferList->GetNext(pElem);
}
return pOldestContainingList;
}
void EventPipeBufferManager::DeAllocateBuffer(EventPipeBuffer *pBuffer)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;
if(pBuffer != NULL)
{
m_sizeOfAllBuffers -= pBuffer->GetSize();
delete(pBuffer);
#ifdef _DEBUG
m_numBuffersAllocated--;
#endif // _DEBUG
}
}
bool EventPipeBufferManager::WriteEvent(Thread *pThread, EventPipeSession &session, EventPipeEvent &event, EventPipeEventPayload &payload, LPCGUID pActivityId, LPCGUID pRelatedActivityId, Thread *pEventThread, StackContents *pStack)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
// The input thread must match the current thread because no lock is taken on the buffer.
PRECONDITION(pThread == GetThread());
}
CONTRACTL_END;
_ASSERTE(pThread == GetThread());
// Check to see an event thread was specified. If not, then use the current thread.
if(pEventThread == NULL)
{
pEventThread = pThread;
}
// Before we pick a buffer, make sure the event is enabled.
if(!event.IsEnabled())
{
return false;
}
// Check one more time to make sure that the event is still enabled.
// We do this because we might be trying to disable tracing and free buffers, so we
// must make sure that the event is enabled after we mark that we're writing to avoid
// races with the destructing thread.
if(!event.IsEnabled())
{
return false;
}
// See if the thread already has a buffer to try.
bool allocNewBuffer = false;
EventPipeBuffer *pBuffer = NULL;
EventPipeBufferList *pThreadBufferList = ThreadEventBufferList::Get();
if(pThreadBufferList == NULL)
{
allocNewBuffer = true;
}
else
{
// The thread already has a buffer list. Select the newest buffer and attempt to write into it.
pBuffer = pThreadBufferList->GetTail();
if(pBuffer == NULL)
{
// This should never happen. If the buffer list exists, it must contain at least one entry.
_ASSERT(!"Thread buffer list with zero entries encountered.");
return false;
}
else
{
// The event is still enabled. Mark that the thread is now writing an event.
pThreadBufferList->SetThreadEventWriteInProgress(true);
// Attempt to write the event to the buffer. If this fails, we should allocate a new buffer.
allocNewBuffer = !pBuffer->WriteEvent(pEventThread, session, event, payload, pActivityId, pRelatedActivityId, pStack);
// Mark that the thread is no longer writing an event.
pThreadBufferList->SetThreadEventWriteInProgress(false);
}
}
// Check to see if we need to allocate a new buffer, and if so, do it here.
if(allocNewBuffer)
{
// We previously switched to preemptive mode here, however, this is not safe and can cause deadlocks.
// When a GC is started, and background threads are created (for the first BGC), a thread creation event is fired.
// When control gets here the buffer is allocated, but then the thread hangs waiting for the GC to complete
// (it was marked as started before creating threads) so that it can switch back to cooperative mode.
// However, the GC is waiting on this call to return so that it can make forward progress. Thus it is not safe
// to switch to preemptive mode here.
unsigned int requestSize = sizeof(EventPipeEventInstance) + payload.GetSize();
pBuffer = AllocateBufferForThread(session, requestSize);
}
// Try to write the event after we allocated (or stole) a buffer.
// This is the first time if the thread had no buffers before the call to this function.
// This is the second time if this thread did have one or more buffers, but they were full.
if(allocNewBuffer && pBuffer != NULL)
{
// By this point, a new buffer list has been allocated so we should fetch it again before using it.
pThreadBufferList = ThreadEventBufferList::Get();
// The event is still enabled. Mark that the thread is now writing an event.
pThreadBufferList->SetThreadEventWriteInProgress(true);
allocNewBuffer = !pBuffer->WriteEvent(pEventThread, session, event, payload, pActivityId, pRelatedActivityId, pStack);
// Mark that the thread is no longer writing an event.
pThreadBufferList->SetThreadEventWriteInProgress(false);
}
#ifdef _DEBUG
if(!allocNewBuffer)
{
InterlockedIncrement(&m_numEventsStored);
}
else
{
InterlockedIncrement(&m_numEventsDropped);
}
#endif // _DEBUG
return !allocNewBuffer;
}
void EventPipeBufferManager::WriteAllBuffersToFile(EventPipeFile *pFile, LARGE_INTEGER stopTimeStamp)
{
CONTRACTL
{
THROWS;
GC_NOTRIGGER;
MODE_ANY;
PRECONDITION(pFile != NULL);
}
CONTRACTL_END;
// TODO: Better version of merge sort.
// 1. Iterate through all of the threads, adding each buffer to a temporary list.
// 2. While iterating, get the lowest most recent timestamp. This is the timestamp that we want to process up to.
// 3. Process up to the lowest most recent timestamp for the set of buffers.
// 4. When we get NULLs from each of the buffers on PopNext(), we're done.
// 5. While iterating if PopNext() == NULL && Empty() == NULL, remove the buffer from the list. It's empty.
// 6. While iterating, grab the next lowest most recent timestamp.
// 7. Walk through the list again and look for any buffers that have a lower most recent timestamp than the next most recent timestamp.
// 8. If we find one, add it to the list and select its most recent timestamp as the lowest.
// 9. Process again (go to 3).
// 10. Continue until there are no more buffers to process.
// Take the lock before walking the buffer list.
SpinLockHolder _slh(&m_lock);
// Naively walk the circular buffer, writing the event stream in timestamp order.
while(true)
{
EventPipeEventInstance *pOldestInstance = NULL;
EventPipeBuffer *pOldestContainingBuffer = NULL;
EventPipeBufferList *pOldestContainingList = NULL;
SListElem<EventPipeBufferList*> *pElem = m_pPerThreadBufferList->GetHead();
while(pElem != NULL)
{
EventPipeBufferList *pBufferList = pElem->GetValue();
// Peek the next event out of the list.
EventPipeBuffer *pContainingBuffer = NULL;
EventPipeEventInstance *pNext = pBufferList->PeekNextEvent(stopTimeStamp, &pContainingBuffer);
if(pNext != NULL)
{
// If it's the oldest event we've seen, then save it.
if((pOldestInstance == NULL) ||
(pOldestInstance->GetTimeStamp()->QuadPart > pNext->GetTimeStamp()->QuadPart))
{
pOldestInstance = pNext;
pOldestContainingBuffer = pContainingBuffer;
pOldestContainingList = pBufferList;
}
}
pElem = m_pPerThreadBufferList->GetNext(pElem);
}
if(pOldestInstance == NULL)
{
// We're done. There are no more events.
break;
}
// Write the oldest event.
pFile->WriteEvent(*pOldestInstance);
#ifdef _DEBUG
m_numEventsWritten++;
#endif // _DEBUG
// Pop the event from the buffer.
pOldestContainingList->PopNextEvent(stopTimeStamp);
}
}
EventPipeEventInstance* EventPipeBufferManager::GetNextEvent()
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;
// Take the lock before walking the buffer list.
SpinLockHolder _slh(&m_lock);
// Naively walk the circular buffer, getting the event stream in timestamp order.
LARGE_INTEGER stopTimeStamp;
QueryPerformanceCounter(&stopTimeStamp);
while (true)
{
EventPipeEventInstance *pOldestInstance = NULL;
EventPipeBuffer *pOldestContainingBuffer = NULL;
EventPipeBufferList *pOldestContainingList = NULL;
SListElem<EventPipeBufferList*> *pElem = m_pPerThreadBufferList->GetHead();
while (pElem != NULL)
{
EventPipeBufferList *pBufferList = pElem->GetValue();
// Peek the next event out of the list.
EventPipeBuffer *pContainingBuffer = NULL;
EventPipeEventInstance *pNext = pBufferList->PeekNextEvent(stopTimeStamp, &pContainingBuffer);
if (pNext != NULL)
{
// If it's the oldest event we've seen, then save it.
if ((pOldestInstance == NULL) ||
(pOldestInstance->GetTimeStamp()->QuadPart > pNext->GetTimeStamp()->QuadPart))
{
pOldestInstance = pNext;
pOldestContainingBuffer = pContainingBuffer;
pOldestContainingList = pBufferList;
}
}
pElem = m_pPerThreadBufferList->GetNext(pElem);
}
if (pOldestInstance == NULL)
{
// We're done. There are no more events.
return NULL;
}
// Pop the event from the buffer.
pOldestContainingList->PopNextEvent(stopTimeStamp);
// Return the oldest event that hasn't yet been processed.
return pOldestInstance;
}
}
void EventPipeBufferManager::DeAllocateBuffers()
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;
_ASSERTE(EnsureConsistency());
// Take the buffer manager manipulation lock
SpinLockHolder _slh(&m_lock);
SListElem<EventPipeBufferList*> *pElem = m_pPerThreadBufferList->GetHead();
while(pElem != NULL)
{
// Get the list and determine if we can free it.
EventPipeBufferList *pBufferList = pElem->GetValue();
if(!pBufferList->OwnedByThread())
{
// Iterate over all nodes in the list and de-allocate them.
EventPipeBuffer *pBuffer = pBufferList->GetAndRemoveHead();
while(pBuffer != NULL)
{
DeAllocateBuffer(pBuffer);
pBuffer = pBufferList->GetAndRemoveHead();
}
// Remove the buffer list from the per-thread buffer list.
pElem = m_pPerThreadBufferList->FindAndRemove(pElem);
_ASSERTE(pElem != NULL);
SListElem<EventPipeBufferList*> *pCurElem = pElem;
pElem = m_pPerThreadBufferList->GetNext(pElem);
delete(pCurElem);
// Now that all of the list elements have been freed, free the list itself.
delete(pBufferList);
pBufferList = NULL;
}
else
{
pElem = m_pPerThreadBufferList->GetNext(pElem);
}
}
}
#ifdef _DEBUG
bool EventPipeBufferManager::EnsureConsistency()
{
LIMITED_METHOD_CONTRACT;
SListElem<EventPipeBufferList*> *pElem = m_pPerThreadBufferList->GetHead();
while(pElem != NULL)
{
EventPipeBufferList *pBufferList = pElem->GetValue();
_ASSERTE(pBufferList->EnsureConsistency());
pElem = m_pPerThreadBufferList->GetNext(pElem);
}
return true;
}
#endif // _DEBUG
EventPipeBufferList::EventPipeBufferList(EventPipeBufferManager *pManager)
{
LIMITED_METHOD_CONTRACT;
m_pManager = pManager;
m_pHeadBuffer = NULL;
m_pTailBuffer = NULL;
m_bufferCount = 0;
m_pReadBuffer = NULL;
m_ownedByThread = true;
m_threadEventWriteInProgress = false;
#ifdef _DEBUG
m_pCreatingThread = GetThread();
#endif // _DEBUG
}
EventPipeBuffer* EventPipeBufferList::GetHead()
{
LIMITED_METHOD_CONTRACT;
return m_pHeadBuffer;
}
EventPipeBuffer* EventPipeBufferList::GetTail()
{
LIMITED_METHOD_CONTRACT;
return m_pTailBuffer;
}
void EventPipeBufferList::InsertTail(EventPipeBuffer *pBuffer)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
PRECONDITION(pBuffer != NULL);
}
CONTRACTL_END;
_ASSERTE(EnsureConsistency());
// Ensure that the input buffer didn't come from another list that was improperly cleaned up.
_ASSERTE((pBuffer->GetNext() == NULL) && (pBuffer->GetPrevious() == NULL));
// First node in the list.
if(m_pTailBuffer == NULL)
{
m_pHeadBuffer = m_pTailBuffer = pBuffer;
}
else
{
// Set links between the old and new tail nodes.
m_pTailBuffer->SetNext(pBuffer);
pBuffer->SetPrevious(m_pTailBuffer);
// Set the new tail node.
m_pTailBuffer = pBuffer;
}
m_bufferCount++;
_ASSERTE(EnsureConsistency());
}
EventPipeBuffer* EventPipeBufferList::GetAndRemoveHead()
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;
_ASSERTE(EnsureConsistency());
EventPipeBuffer *pRetBuffer = NULL;
if(m_pHeadBuffer != NULL)
{
// Save the head node.
pRetBuffer = m_pHeadBuffer;
// Set the new head node.
m_pHeadBuffer = m_pHeadBuffer->GetNext();
// Update the head node's previous pointer.
if(m_pHeadBuffer != NULL)
{
m_pHeadBuffer->SetPrevious(NULL);
}
else
{
// We just removed the last buffer from the list.
// Make sure both head and tail pointers are NULL.
m_pTailBuffer = NULL;
}
// Clear the next pointer of the old head node.
pRetBuffer->SetNext(NULL);
// Ensure that the old head node has no dangling references.
_ASSERTE((pRetBuffer->GetNext() == NULL) && (pRetBuffer->GetPrevious() == NULL));
// Decrement the count of buffers in the list.
m_bufferCount--;
}
_ASSERTE(EnsureConsistency());
return pRetBuffer;
}
unsigned int EventPipeBufferList::GetCount() const
{
LIMITED_METHOD_CONTRACT;
return m_bufferCount;
}
EventPipeEventInstance* EventPipeBufferList::PeekNextEvent(LARGE_INTEGER beforeTimeStamp, EventPipeBuffer **pContainingBuffer)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;
// Get the current read buffer.
// If it's not set, start with the head buffer.
if(m_pReadBuffer == NULL)
{
m_pReadBuffer = m_pHeadBuffer;
}
// If the read buffer is still NULL, then this list contains no buffers.
if(m_pReadBuffer == NULL)
{
return NULL;
}
// Get the next event in the buffer.
EventPipeEventInstance *pNext = m_pReadBuffer->PeekNext(beforeTimeStamp);
// If the next event is NULL, then go to the next buffer.
if(pNext == NULL)
{
m_pReadBuffer = m_pReadBuffer->GetNext();
if(m_pReadBuffer != NULL)
{
pNext = m_pReadBuffer->PeekNext(beforeTimeStamp);
}
}
// Set the containing buffer.
if(pNext != NULL && pContainingBuffer != NULL)
{
*pContainingBuffer = m_pReadBuffer;
}
// Make sure pContainingBuffer is properly set.
_ASSERTE((pNext == NULL) || (pNext != NULL && pContainingBuffer == NULL) || (pNext != NULL && *pContainingBuffer == m_pReadBuffer));
return pNext;
}
EventPipeEventInstance* EventPipeBufferList::PopNextEvent(LARGE_INTEGER beforeTimeStamp)
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;
// Get the next event.
EventPipeBuffer *pContainingBuffer = NULL;
EventPipeEventInstance *pNext = PeekNextEvent(beforeTimeStamp, &pContainingBuffer);
// Check to see if we need to clean-up the buffer that contained the previously popped event.
if(pContainingBuffer->GetPrevious() != NULL)
{
// Remove the previous node. The previous node should always be the head node.
EventPipeBuffer *pRemoved = GetAndRemoveHead();
_ASSERTE(pRemoved != pContainingBuffer);
_ASSERTE(pContainingBuffer == GetHead());
// De-allocate the buffer.
m_pManager->DeAllocateBuffer(pRemoved);
}
// If the event is non-NULL, pop it.
if(pNext != NULL && pContainingBuffer != NULL)
{
pContainingBuffer->PopNext(beforeTimeStamp);
}
return pNext;
}
#ifdef _DEBUG
Thread* EventPipeBufferList::GetThread()
{
LIMITED_METHOD_CONTRACT;
return m_pCreatingThread;
}
bool EventPipeBufferList::EnsureConsistency()
{
CONTRACTL
{
NOTHROW;
GC_NOTRIGGER;
MODE_ANY;
}
CONTRACTL_END;
// Either the head and tail nodes are both NULL or both are non-NULL.
_ASSERTE((m_pHeadBuffer == NULL && m_pTailBuffer == NULL) || (m_pHeadBuffer != NULL && m_pTailBuffer != NULL));
// If the list is NULL, check the count and return.
if(m_pHeadBuffer == NULL)
{
_ASSERTE(m_bufferCount == 0);
return true;
}
// If the list is non-NULL, walk the list forward until we get to the end.
unsigned int nodeCount = (m_pHeadBuffer != NULL) ? 1 : 0;
EventPipeBuffer *pIter = m_pHeadBuffer;
while(pIter->GetNext() != NULL)
{
pIter = pIter->GetNext();
nodeCount++;
// Check for consistency of the buffer itself.
// NOTE: We can't check the last buffer because the owning thread could
// be writing to it, which could result in false asserts.
if(pIter->GetNext() != NULL)
{
_ASSERTE(pIter->EnsureConsistency());
}
// Check for cycles.
_ASSERTE(nodeCount <= m_bufferCount);
}
// When we're done with the walk, pIter must point to the tail node.
_ASSERTE(pIter == m_pTailBuffer);
// Node count must equal the buffer count.
_ASSERTE(nodeCount == m_bufferCount);
// Now, walk the list in reverse.
pIter = m_pTailBuffer;
nodeCount = (m_pTailBuffer != NULL) ? 1 : 0;
while(pIter->GetPrevious() != NULL)
{
pIter = pIter->GetPrevious();
nodeCount++;
// Check for cycles.
_ASSERTE(nodeCount <= m_bufferCount);
}
// When we're done with the reverse walk, pIter must point to the head node.
_ASSERTE(pIter == m_pHeadBuffer);
// Node count must equal the buffer count.
_ASSERTE(nodeCount == m_bufferCount);
// We're done.
return true;
}
#endif // _DEBUG
ThreadEventBufferList::~ThreadEventBufferList()
{
// Before the thread dies, mark its buffers as no longer owned
// so that they can be cleaned up after the thread dies.
// EventPipeBufferList *pList = GetThreadEventBufferList();
if (m_pThreadEventBufferList != NULL)
m_pThreadEventBufferList->SetOwnedByThread(false);
}
#endif // FEATURE_PERFTRACING
|