1 /*
2 * Copyright 2004 The WebRTC Project Authors. All rights reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include "rtc_base/thread.h"
12
13 #if defined(WEBRTC_WIN)
14 #include <comdef.h>
15 #elif defined(WEBRTC_POSIX)
16 #include <time.h>
17 #else
18 #error "Either WEBRTC_WIN or WEBRTC_POSIX needs to be defined."
19 #endif
20
21 #if defined(WEBRTC_WIN)
22 // Disable warning that we don't care about:
23 // warning C4722: destructor never returns, potential memory leak
24 #pragma warning(disable : 4722)
25 #endif
26
27 #include <stdio.h>
28
29 #include <utility>
30
31 #include "absl/algorithm/container.h"
32 #include "rtc_base/atomic_ops.h"
33 #include "rtc_base/checks.h"
34 #include "rtc_base/deprecated/recursive_critical_section.h"
35 #include "rtc_base/logging.h"
36 #include "rtc_base/null_socket_server.h"
37 #include "rtc_base/synchronization/sequence_checker.h"
38 #include "rtc_base/task_utils/to_queued_task.h"
39 #include "rtc_base/time_utils.h"
40 #include "rtc_base/trace_event.h"
41
42 #if defined(WEBRTC_MAC)
43 #include "rtc_base/system/cocoa_threading.h"
44
45 /*
46 * These are forward-declarations for methods that are part of the
47 * ObjC runtime. They are declared in the private header objc-internal.h.
48 * These calls are what clang inserts when using @autoreleasepool in ObjC,
49 * but here they are used directly in order to keep this file C++.
50 * https://clang.llvm.org/docs/AutomaticReferenceCounting.html#runtime-support
51 */
52 extern "C" {
53 void* objc_autoreleasePoolPush(void);
54 void objc_autoreleasePoolPop(void* pool);
55 }
56
57 namespace {
58 class ScopedAutoReleasePool {
59 public:
ScopedAutoReleasePool()60 ScopedAutoReleasePool() : pool_(objc_autoreleasePoolPush()) {}
~ScopedAutoReleasePool()61 ~ScopedAutoReleasePool() { objc_autoreleasePoolPop(pool_); }
62
63 private:
64 void* const pool_;
65 };
66 } // namespace
67 #endif
68
69 namespace rtc {
70 namespace {
71
72 const int kSlowDispatchLoggingThreshold = 50; // 50 ms
73
74 class MessageHandlerWithTask final : public MessageHandler {
75 public:
76 MessageHandlerWithTask() = default;
77
OnMessage(Message * msg)78 void OnMessage(Message* msg) override {
79 static_cast<rtc_thread_internal::MessageLikeTask*>(msg->pdata)->Run();
80 delete msg->pdata;
81 }
82
83 private:
~MessageHandlerWithTask()84 ~MessageHandlerWithTask() override {}
85
86 RTC_DISALLOW_COPY_AND_ASSIGN(MessageHandlerWithTask);
87 };
88
89 class RTC_SCOPED_LOCKABLE MarkProcessingCritScope {
90 public:
MarkProcessingCritScope(const RecursiveCriticalSection * cs,size_t * processing)91 MarkProcessingCritScope(const RecursiveCriticalSection* cs,
92 size_t* processing) RTC_EXCLUSIVE_LOCK_FUNCTION(cs)
93 : cs_(cs), processing_(processing) {
94 cs_->Enter();
95 *processing_ += 1;
96 }
97
RTC_UNLOCK_FUNCTION()98 ~MarkProcessingCritScope() RTC_UNLOCK_FUNCTION() {
99 *processing_ -= 1;
100 cs_->Leave();
101 }
102
103 private:
104 const RecursiveCriticalSection* const cs_;
105 size_t* processing_;
106
107 RTC_DISALLOW_COPY_AND_ASSIGN(MarkProcessingCritScope);
108 };
109
110 } // namespace
111
Instance()112 ThreadManager* ThreadManager::Instance() {
113 static ThreadManager* const thread_manager = new ThreadManager();
114 return thread_manager;
115 }
116
~ThreadManager()117 ThreadManager::~ThreadManager() {
118 // By above RTC_DEFINE_STATIC_LOCAL.
119 RTC_NOTREACHED() << "ThreadManager should never be destructed.";
120 }
121
122 // static
Add(Thread * message_queue)123 void ThreadManager::Add(Thread* message_queue) {
124 return Instance()->AddInternal(message_queue);
125 }
AddInternal(Thread * message_queue)126 void ThreadManager::AddInternal(Thread* message_queue) {
127 CritScope cs(&crit_);
128 // Prevent changes while the list of message queues is processed.
129 RTC_DCHECK_EQ(processing_, 0);
130 message_queues_.push_back(message_queue);
131 }
132
133 // static
Remove(Thread * message_queue)134 void ThreadManager::Remove(Thread* message_queue) {
135 return Instance()->RemoveInternal(message_queue);
136 }
RemoveInternal(Thread * message_queue)137 void ThreadManager::RemoveInternal(Thread* message_queue) {
138 {
139 CritScope cs(&crit_);
140 // Prevent changes while the list of message queues is processed.
141 RTC_DCHECK_EQ(processing_, 0);
142 std::vector<Thread*>::iterator iter;
143 iter = absl::c_find(message_queues_, message_queue);
144 if (iter != message_queues_.end()) {
145 message_queues_.erase(iter);
146 }
147 #if RTC_DCHECK_IS_ON
148 RemoveFromSendGraph(message_queue);
149 #endif
150 }
151 }
152
153 #if RTC_DCHECK_IS_ON
RemoveFromSendGraph(Thread * thread)154 void ThreadManager::RemoveFromSendGraph(Thread* thread) {
155 for (auto it = send_graph_.begin(); it != send_graph_.end();) {
156 if (it->first == thread) {
157 it = send_graph_.erase(it);
158 } else {
159 it->second.erase(thread);
160 ++it;
161 }
162 }
163 }
164
RegisterSendAndCheckForCycles(Thread * source,Thread * target)165 void ThreadManager::RegisterSendAndCheckForCycles(Thread* source,
166 Thread* target) {
167 CritScope cs(&crit_);
168 std::deque<Thread*> all_targets({target});
169 // We check the pre-existing who-sends-to-who graph for any path from target
170 // to source. This loop is guaranteed to terminate because per the send graph
171 // invariant, there are no cycles in the graph.
172 for (size_t i = 0; i < all_targets.size(); i++) {
173 const auto& targets = send_graph_[all_targets[i]];
174 all_targets.insert(all_targets.end(), targets.begin(), targets.end());
175 }
176 RTC_CHECK_EQ(absl::c_count(all_targets, source), 0)
177 << " send loop between " << source->name() << " and " << target->name();
178
179 // We may now insert source -> target without creating a cycle, since there
180 // was no path from target to source per the prior CHECK.
181 send_graph_[source].insert(target);
182 }
183 #endif
184
185 // static
Clear(MessageHandler * handler)186 void ThreadManager::Clear(MessageHandler* handler) {
187 return Instance()->ClearInternal(handler);
188 }
ClearInternal(MessageHandler * handler)189 void ThreadManager::ClearInternal(MessageHandler* handler) {
190 // Deleted objects may cause re-entrant calls to ClearInternal. This is
191 // allowed as the list of message queues does not change while queues are
192 // cleared.
193 MarkProcessingCritScope cs(&crit_, &processing_);
194 for (Thread* queue : message_queues_) {
195 queue->Clear(handler);
196 }
197 }
198
199 // static
ProcessAllMessageQueuesForTesting()200 void ThreadManager::ProcessAllMessageQueuesForTesting() {
201 return Instance()->ProcessAllMessageQueuesInternal();
202 }
203
ProcessAllMessageQueuesInternal()204 void ThreadManager::ProcessAllMessageQueuesInternal() {
205 // This works by posting a delayed message at the current time and waiting
206 // for it to be dispatched on all queues, which will ensure that all messages
207 // that came before it were also dispatched.
208 volatile int queues_not_done = 0;
209
210 // This class is used so that whether the posted message is processed, or the
211 // message queue is simply cleared, queues_not_done gets decremented.
212 class ScopedIncrement : public MessageData {
213 public:
214 ScopedIncrement(volatile int* value) : value_(value) {
215 AtomicOps::Increment(value_);
216 }
217 ~ScopedIncrement() override { AtomicOps::Decrement(value_); }
218
219 private:
220 volatile int* value_;
221 };
222
223 {
224 MarkProcessingCritScope cs(&crit_, &processing_);
225 for (Thread* queue : message_queues_) {
226 if (!queue->IsProcessingMessagesForTesting()) {
227 // If the queue is not processing messages, it can
228 // be ignored. If we tried to post a message to it, it would be dropped
229 // or ignored.
230 continue;
231 }
232 queue->PostDelayed(RTC_FROM_HERE, 0, nullptr, MQID_DISPOSE,
233 new ScopedIncrement(&queues_not_done));
234 }
235 }
236
237 rtc::Thread* current = rtc::Thread::Current();
238 // Note: One of the message queues may have been on this thread, which is
239 // why we can't synchronously wait for queues_not_done to go to 0; we need
240 // to process messages as well.
241 while (AtomicOps::AcquireLoad(&queues_not_done) > 0) {
242 if (current) {
243 current->ProcessMessages(0);
244 }
245 }
246 }
247
248 // static
Current()249 Thread* Thread::Current() {
250 ThreadManager* manager = ThreadManager::Instance();
251 Thread* thread = manager->CurrentThread();
252
253 #ifndef NO_MAIN_THREAD_WRAPPING
254 // Only autowrap the thread which instantiated the ThreadManager.
255 if (!thread && manager->IsMainThread()) {
256 thread = new Thread(SocketServer::CreateDefault());
257 thread->WrapCurrentWithThreadManager(manager, true);
258 }
259 #endif
260
261 return thread;
262 }
263
264 #if defined(WEBRTC_POSIX)
ThreadManager()265 ThreadManager::ThreadManager() : main_thread_ref_(CurrentThreadRef()) {
266 #if defined(WEBRTC_MAC)
267 InitCocoaMultiThreading();
268 #endif
269 pthread_key_create(&key_, nullptr);
270 }
271
CurrentThread()272 Thread* ThreadManager::CurrentThread() {
273 return static_cast<Thread*>(pthread_getspecific(key_));
274 }
275
SetCurrentThreadInternal(Thread * thread)276 void ThreadManager::SetCurrentThreadInternal(Thread* thread) {
277 pthread_setspecific(key_, thread);
278 }
279 #endif
280
281 #if defined(WEBRTC_WIN)
ThreadManager()282 ThreadManager::ThreadManager()
283 : key_(TlsAlloc()), main_thread_ref_(CurrentThreadRef()) {}
284
CurrentThread()285 Thread* ThreadManager::CurrentThread() {
286 return static_cast<Thread*>(TlsGetValue(key_));
287 }
288
SetCurrentThreadInternal(Thread * thread)289 void ThreadManager::SetCurrentThreadInternal(Thread* thread) {
290 TlsSetValue(key_, thread);
291 }
292 #endif
293
SetCurrentThread(Thread * thread)294 void ThreadManager::SetCurrentThread(Thread* thread) {
295 #if RTC_DLOG_IS_ON
296 if (CurrentThread() && thread) {
297 RTC_DLOG(LS_ERROR) << "SetCurrentThread: Overwriting an existing value?";
298 }
299 #endif // RTC_DLOG_IS_ON
300
301 if (thread) {
302 thread->EnsureIsCurrentTaskQueue();
303 } else {
304 Thread* current = CurrentThread();
305 if (current) {
306 // The current thread is being cleared, e.g. as a result of
307 // UnwrapCurrent() being called or when a thread is being stopped
308 // (see PreRun()). This signals that the Thread instance is being detached
309 // from the thread, which also means that TaskQueue::Current() must not
310 // return a pointer to the Thread instance.
311 current->ClearCurrentTaskQueue();
312 }
313 }
314
315 SetCurrentThreadInternal(thread);
316 }
317
ChangeCurrentThreadForTest(rtc::Thread * thread)318 void rtc::ThreadManager::ChangeCurrentThreadForTest(rtc::Thread* thread) {
319 SetCurrentThreadInternal(thread);
320 }
321
WrapCurrentThread()322 Thread* ThreadManager::WrapCurrentThread() {
323 Thread* result = CurrentThread();
324 if (nullptr == result) {
325 result = new Thread(SocketServer::CreateDefault());
326 result->WrapCurrentWithThreadManager(this, true);
327 }
328 return result;
329 }
330
UnwrapCurrentThread()331 void ThreadManager::UnwrapCurrentThread() {
332 Thread* t = CurrentThread();
333 if (t && !(t->IsOwned())) {
334 t->UnwrapCurrent();
335 delete t;
336 }
337 }
338
IsMainThread()339 bool ThreadManager::IsMainThread() {
340 return IsThreadRefEqual(CurrentThreadRef(), main_thread_ref_);
341 }
342
ScopedDisallowBlockingCalls()343 Thread::ScopedDisallowBlockingCalls::ScopedDisallowBlockingCalls()
344 : thread_(Thread::Current()),
345 previous_state_(thread_->SetAllowBlockingCalls(false)) {}
346
~ScopedDisallowBlockingCalls()347 Thread::ScopedDisallowBlockingCalls::~ScopedDisallowBlockingCalls() {
348 RTC_DCHECK(thread_->IsCurrent());
349 thread_->SetAllowBlockingCalls(previous_state_);
350 }
351
Thread(SocketServer * ss)352 Thread::Thread(SocketServer* ss) : Thread(ss, /*do_init=*/true) {}
353
Thread(std::unique_ptr<SocketServer> ss)354 Thread::Thread(std::unique_ptr<SocketServer> ss)
355 : Thread(std::move(ss), /*do_init=*/true) {}
356
Thread(SocketServer * ss,bool do_init)357 Thread::Thread(SocketServer* ss, bool do_init)
358 : fPeekKeep_(false),
359 delayed_next_num_(0),
360 fInitialized_(false),
361 fDestroyed_(false),
362 stop_(0),
363 ss_(ss) {
364 RTC_DCHECK(ss);
365 ss_->SetMessageQueue(this);
366 SetName("Thread", this); // default name
367 if (do_init) {
368 DoInit();
369 }
370 }
371
Thread(std::unique_ptr<SocketServer> ss,bool do_init)372 Thread::Thread(std::unique_ptr<SocketServer> ss, bool do_init)
373 : Thread(ss.get(), do_init) {
374 own_ss_ = std::move(ss);
375 }
376
~Thread()377 Thread::~Thread() {
378 Stop();
379 DoDestroy();
380 }
381
DoInit()382 void Thread::DoInit() {
383 if (fInitialized_) {
384 return;
385 }
386
387 fInitialized_ = true;
388 ThreadManager::Add(this);
389 }
390
DoDestroy()391 void Thread::DoDestroy() {
392 if (fDestroyed_) {
393 return;
394 }
395
396 fDestroyed_ = true;
397 // The signal is done from here to ensure
398 // that it always gets called when the queue
399 // is going away.
400 SignalQueueDestroyed();
401 ThreadManager::Remove(this);
402 ClearInternal(nullptr, MQID_ANY, nullptr);
403
404 if (ss_) {
405 ss_->SetMessageQueue(nullptr);
406 }
407 }
408
socketserver()409 SocketServer* Thread::socketserver() {
410 return ss_;
411 }
412
WakeUpSocketServer()413 void Thread::WakeUpSocketServer() {
414 ss_->WakeUp();
415 }
416
Quit()417 void Thread::Quit() {
418 AtomicOps::ReleaseStore(&stop_, 1);
419 WakeUpSocketServer();
420 }
421
IsQuitting()422 bool Thread::IsQuitting() {
423 return AtomicOps::AcquireLoad(&stop_) != 0;
424 }
425
Restart()426 void Thread::Restart() {
427 AtomicOps::ReleaseStore(&stop_, 0);
428 }
429
Peek(Message * pmsg,int cmsWait)430 bool Thread::Peek(Message* pmsg, int cmsWait) {
431 if (fPeekKeep_) {
432 *pmsg = msgPeek_;
433 return true;
434 }
435 if (!Get(pmsg, cmsWait))
436 return false;
437 msgPeek_ = *pmsg;
438 fPeekKeep_ = true;
439 return true;
440 }
441
Get(Message * pmsg,int cmsWait,bool process_io)442 bool Thread::Get(Message* pmsg, int cmsWait, bool process_io) {
443 // Return and clear peek if present
444 // Always return the peek if it exists so there is Peek/Get symmetry
445
446 if (fPeekKeep_) {
447 *pmsg = msgPeek_;
448 fPeekKeep_ = false;
449 return true;
450 }
451
452 // Get w/wait + timer scan / dispatch + socket / event multiplexer dispatch
453
454 int64_t cmsTotal = cmsWait;
455 int64_t cmsElapsed = 0;
456 int64_t msStart = TimeMillis();
457 int64_t msCurrent = msStart;
458 while (true) {
459 // Check for posted events
460 int64_t cmsDelayNext = kForever;
461 bool first_pass = true;
462 while (true) {
463 // All queue operations need to be locked, but nothing else in this loop
464 // (specifically handling disposed message) can happen inside the crit.
465 // Otherwise, disposed MessageHandlers will cause deadlocks.
466 {
467 CritScope cs(&crit_);
468 // On the first pass, check for delayed messages that have been
469 // triggered and calculate the next trigger time.
470 if (first_pass) {
471 first_pass = false;
472 while (!delayed_messages_.empty()) {
473 if (msCurrent < delayed_messages_.top().run_time_ms_) {
474 cmsDelayNext =
475 TimeDiff(delayed_messages_.top().run_time_ms_, msCurrent);
476 break;
477 }
478 messages_.push_back(delayed_messages_.top().msg_);
479 delayed_messages_.pop();
480 }
481 }
482 // Pull a message off the message queue, if available.
483 if (messages_.empty()) {
484 break;
485 } else {
486 *pmsg = messages_.front();
487 messages_.pop_front();
488 }
489 } // crit_ is released here.
490
491 // If this was a dispose message, delete it and skip it.
492 if (MQID_DISPOSE == pmsg->message_id) {
493 RTC_DCHECK(nullptr == pmsg->phandler);
494 delete pmsg->pdata;
495 *pmsg = Message();
496 continue;
497 }
498 return true;
499 }
500
501 if (IsQuitting())
502 break;
503
504 // Which is shorter, the delay wait or the asked wait?
505
506 int64_t cmsNext;
507 if (cmsWait == kForever) {
508 cmsNext = cmsDelayNext;
509 } else {
510 cmsNext = std::max<int64_t>(0, cmsTotal - cmsElapsed);
511 if ((cmsDelayNext != kForever) && (cmsDelayNext < cmsNext))
512 cmsNext = cmsDelayNext;
513 }
514
515 {
516 // Wait and multiplex in the meantime
517 if (!ss_->Wait(static_cast<int>(cmsNext), process_io))
518 return false;
519 }
520
521 // If the specified timeout expired, return
522
523 msCurrent = TimeMillis();
524 cmsElapsed = TimeDiff(msCurrent, msStart);
525 if (cmsWait != kForever) {
526 if (cmsElapsed >= cmsWait)
527 return false;
528 }
529 }
530 return false;
531 }
532
Post(const Location & posted_from,MessageHandler * phandler,uint32_t id,MessageData * pdata,bool time_sensitive)533 void Thread::Post(const Location& posted_from,
534 MessageHandler* phandler,
535 uint32_t id,
536 MessageData* pdata,
537 bool time_sensitive) {
538 RTC_DCHECK(!time_sensitive);
539 if (IsQuitting()) {
540 delete pdata;
541 return;
542 }
543
544 // Keep thread safe
545 // Add the message to the end of the queue
546 // Signal for the multiplexer to return
547
548 {
549 CritScope cs(&crit_);
550 Message msg;
551 msg.posted_from = posted_from;
552 msg.phandler = phandler;
553 msg.message_id = id;
554 msg.pdata = pdata;
555 messages_.push_back(msg);
556 }
557 WakeUpSocketServer();
558 }
559
PostDelayed(const Location & posted_from,int delay_ms,MessageHandler * phandler,uint32_t id,MessageData * pdata)560 void Thread::PostDelayed(const Location& posted_from,
561 int delay_ms,
562 MessageHandler* phandler,
563 uint32_t id,
564 MessageData* pdata) {
565 return DoDelayPost(posted_from, delay_ms, TimeAfter(delay_ms), phandler, id,
566 pdata);
567 }
568
PostAt(const Location & posted_from,int64_t run_at_ms,MessageHandler * phandler,uint32_t id,MessageData * pdata)569 void Thread::PostAt(const Location& posted_from,
570 int64_t run_at_ms,
571 MessageHandler* phandler,
572 uint32_t id,
573 MessageData* pdata) {
574 return DoDelayPost(posted_from, TimeUntil(run_at_ms), run_at_ms, phandler, id,
575 pdata);
576 }
577
DoDelayPost(const Location & posted_from,int64_t delay_ms,int64_t run_at_ms,MessageHandler * phandler,uint32_t id,MessageData * pdata)578 void Thread::DoDelayPost(const Location& posted_from,
579 int64_t delay_ms,
580 int64_t run_at_ms,
581 MessageHandler* phandler,
582 uint32_t id,
583 MessageData* pdata) {
584 if (IsQuitting()) {
585 delete pdata;
586 return;
587 }
588
589 // Keep thread safe
590 // Add to the priority queue. Gets sorted soonest first.
591 // Signal for the multiplexer to return.
592
593 {
594 CritScope cs(&crit_);
595 Message msg;
596 msg.posted_from = posted_from;
597 msg.phandler = phandler;
598 msg.message_id = id;
599 msg.pdata = pdata;
600 DelayedMessage delayed(delay_ms, run_at_ms, delayed_next_num_, msg);
601 delayed_messages_.push(delayed);
602 // If this message queue processes 1 message every millisecond for 50 days,
603 // we will wrap this number. Even then, only messages with identical times
604 // will be misordered, and then only briefly. This is probably ok.
605 ++delayed_next_num_;
606 RTC_DCHECK_NE(0, delayed_next_num_);
607 }
608 WakeUpSocketServer();
609 }
610
GetDelay()611 int Thread::GetDelay() {
612 CritScope cs(&crit_);
613
614 if (!messages_.empty())
615 return 0;
616
617 if (!delayed_messages_.empty()) {
618 int delay = TimeUntil(delayed_messages_.top().run_time_ms_);
619 if (delay < 0)
620 delay = 0;
621 return delay;
622 }
623
624 return kForever;
625 }
626
ClearInternal(MessageHandler * phandler,uint32_t id,MessageList * removed)627 void Thread::ClearInternal(MessageHandler* phandler,
628 uint32_t id,
629 MessageList* removed) {
630 // Remove messages with phandler
631
632 if (fPeekKeep_ && msgPeek_.Match(phandler, id)) {
633 if (removed) {
634 removed->push_back(msgPeek_);
635 } else {
636 delete msgPeek_.pdata;
637 }
638 fPeekKeep_ = false;
639 }
640
641 // Remove from ordered message queue
642
643 for (auto it = messages_.begin(); it != messages_.end();) {
644 if (it->Match(phandler, id)) {
645 if (removed) {
646 removed->push_back(*it);
647 } else {
648 delete it->pdata;
649 }
650 it = messages_.erase(it);
651 } else {
652 ++it;
653 }
654 }
655
656 // Remove from priority queue. Not directly iterable, so use this approach
657
658 auto new_end = delayed_messages_.container().begin();
659 for (auto it = new_end; it != delayed_messages_.container().end(); ++it) {
660 if (it->msg_.Match(phandler, id)) {
661 if (removed) {
662 removed->push_back(it->msg_);
663 } else {
664 delete it->msg_.pdata;
665 }
666 } else {
667 *new_end++ = *it;
668 }
669 }
670 delayed_messages_.container().erase(new_end,
671 delayed_messages_.container().end());
672 delayed_messages_.reheap();
673 }
674
Dispatch(Message * pmsg)675 void Thread::Dispatch(Message* pmsg) {
676 TRACE_EVENT2("webrtc", "Thread::Dispatch", "src_file",
677 pmsg->posted_from.file_name(), "src_func",
678 pmsg->posted_from.function_name());
679 int64_t start_time = TimeMillis();
680 pmsg->phandler->OnMessage(pmsg);
681 int64_t end_time = TimeMillis();
682 int64_t diff = TimeDiff(end_time, start_time);
683 if (diff >= kSlowDispatchLoggingThreshold) {
684 RTC_LOG(LS_INFO) << "Message took " << diff
685 << "ms to dispatch. Posted from: "
686 << pmsg->posted_from.ToString();
687 }
688 }
689
IsCurrent() const690 bool Thread::IsCurrent() const {
691 return ThreadManager::Instance()->CurrentThread() == this;
692 }
693
CreateWithSocketServer()694 std::unique_ptr<Thread> Thread::CreateWithSocketServer() {
695 return std::unique_ptr<Thread>(new Thread(SocketServer::CreateDefault()));
696 }
697
Create()698 std::unique_ptr<Thread> Thread::Create() {
699 return std::unique_ptr<Thread>(
700 new Thread(std::unique_ptr<SocketServer>(new NullSocketServer())));
701 }
702
SleepMs(int milliseconds)703 bool Thread::SleepMs(int milliseconds) {
704 AssertBlockingIsAllowedOnCurrentThread();
705
706 #if defined(WEBRTC_WIN)
707 ::Sleep(milliseconds);
708 return true;
709 #else
710 // POSIX has both a usleep() and a nanosleep(), but the former is deprecated,
711 // so we use nanosleep() even though it has greater precision than necessary.
712 struct timespec ts;
713 ts.tv_sec = milliseconds / 1000;
714 ts.tv_nsec = (milliseconds % 1000) * 1000000;
715 int ret = nanosleep(&ts, nullptr);
716 if (ret != 0) {
717 RTC_LOG_ERR(LS_WARNING) << "nanosleep() returning early";
718 return false;
719 }
720 return true;
721 #endif
722 }
723
SetName(const std::string & name,const void * obj)724 bool Thread::SetName(const std::string& name, const void* obj) {
725 RTC_DCHECK(!IsRunning());
726
727 name_ = name;
728 if (obj) {
729 // The %p specifier typically produce at most 16 hex digits, possibly with a
730 // 0x prefix. But format is implementation defined, so add some margin.
731 char buf[30];
732 snprintf(buf, sizeof(buf), " 0x%p", obj);
733 name_ += buf;
734 }
735 return true;
736 }
737
Start()738 bool Thread::Start() {
739 RTC_DCHECK(!IsRunning());
740
741 if (IsRunning())
742 return false;
743
744 Restart(); // reset IsQuitting() if the thread is being restarted
745
746 // Make sure that ThreadManager is created on the main thread before
747 // we start a new thread.
748 ThreadManager::Instance();
749
750 owned_ = true;
751
752 #if defined(WEBRTC_WIN)
753 thread_ = CreateThread(nullptr, 0, PreRun, this, 0, &thread_id_);
754 if (!thread_) {
755 return false;
756 }
757 #elif defined(WEBRTC_POSIX)
758 pthread_attr_t attr;
759 pthread_attr_init(&attr);
760
761 int error_code = pthread_create(&thread_, &attr, PreRun, this);
762 if (0 != error_code) {
763 RTC_LOG(LS_ERROR) << "Unable to create pthread, error " << error_code;
764 thread_ = 0;
765 return false;
766 }
767 RTC_DCHECK(thread_);
768 #endif
769 return true;
770 }
771
WrapCurrent()772 bool Thread::WrapCurrent() {
773 return WrapCurrentWithThreadManager(ThreadManager::Instance(), true);
774 }
775
UnwrapCurrent()776 void Thread::UnwrapCurrent() {
777 // Clears the platform-specific thread-specific storage.
778 ThreadManager::Instance()->SetCurrentThread(nullptr);
779 #if defined(WEBRTC_WIN)
780 if (thread_ != nullptr) {
781 if (!CloseHandle(thread_)) {
782 RTC_LOG_GLE(LS_ERROR)
783 << "When unwrapping thread, failed to close handle.";
784 }
785 thread_ = nullptr;
786 thread_id_ = 0;
787 }
788 #elif defined(WEBRTC_POSIX)
789 thread_ = 0;
790 #endif
791 }
792
SafeWrapCurrent()793 void Thread::SafeWrapCurrent() {
794 WrapCurrentWithThreadManager(ThreadManager::Instance(), false);
795 }
796
Join()797 void Thread::Join() {
798 if (!IsRunning())
799 return;
800
801 RTC_DCHECK(!IsCurrent());
802 if (Current() && !Current()->blocking_calls_allowed_) {
803 RTC_LOG(LS_WARNING) << "Waiting for the thread to join, "
804 "but blocking calls have been disallowed";
805 }
806
807 #if defined(WEBRTC_WIN)
808 RTC_DCHECK(thread_ != nullptr);
809 WaitForSingleObject(thread_, INFINITE);
810 CloseHandle(thread_);
811 thread_ = nullptr;
812 thread_id_ = 0;
813 #elif defined(WEBRTC_POSIX)
814 pthread_join(thread_, nullptr);
815 thread_ = 0;
816 #endif
817 }
818
SetAllowBlockingCalls(bool allow)819 bool Thread::SetAllowBlockingCalls(bool allow) {
820 RTC_DCHECK(IsCurrent());
821 bool previous = blocking_calls_allowed_;
822 blocking_calls_allowed_ = allow;
823 return previous;
824 }
825
826 // static
AssertBlockingIsAllowedOnCurrentThread()827 void Thread::AssertBlockingIsAllowedOnCurrentThread() {
828 #if !defined(NDEBUG)
829 Thread* current = Thread::Current();
830 RTC_DCHECK(!current || current->blocking_calls_allowed_);
831 #endif
832 }
833
834 // static
835 #if defined(WEBRTC_WIN)
PreRun(LPVOID pv)836 DWORD WINAPI Thread::PreRun(LPVOID pv) {
837 #else
838 void* Thread::PreRun(void* pv) {
839 #endif
840 Thread* thread = static_cast<Thread*>(pv);
841 ThreadManager::Instance()->SetCurrentThread(thread);
842 rtc::SetCurrentThreadName(thread->name_.c_str());
843 #if defined(WEBRTC_MAC)
844 ScopedAutoReleasePool pool;
845 #endif
846 thread->Run();
847
848 ThreadManager::Instance()->SetCurrentThread(nullptr);
849 #ifdef WEBRTC_WIN
850 return 0;
851 #else
852 return nullptr;
853 #endif
854 } // namespace rtc
855
856 void Thread::Run() {
857 ProcessMessages(kForever);
858 }
859
860 bool Thread::IsOwned() {
861 RTC_DCHECK(IsRunning());
862 return owned_;
863 }
864
865 void Thread::Stop() {
866 Thread::Quit();
867 Join();
868 }
869
870 void Thread::Send(const Location& posted_from,
871 MessageHandler* phandler,
872 uint32_t id,
873 MessageData* pdata) {
874 RTC_DCHECK(!IsQuitting());
875 if (IsQuitting())
876 return;
877
878 // Sent messages are sent to the MessageHandler directly, in the context
879 // of "thread", like Win32 SendMessage. If in the right context,
880 // call the handler directly.
881 Message msg;
882 msg.posted_from = posted_from;
883 msg.phandler = phandler;
884 msg.message_id = id;
885 msg.pdata = pdata;
886 if (IsCurrent()) {
887 msg.phandler->OnMessage(&msg);
888 return;
889 }
890
891 AssertBlockingIsAllowedOnCurrentThread();
892
893 AutoThread thread;
894 Thread* current_thread = Thread::Current();
895 RTC_DCHECK(current_thread != nullptr); // AutoThread ensures this
896 RTC_DCHECK(current_thread->IsInvokeToThreadAllowed(this));
897 #if RTC_DCHECK_IS_ON
898 ThreadManager::Instance()->RegisterSendAndCheckForCycles(current_thread,
899 this);
900 #endif
901 bool ready = false;
902 PostTask(
903 webrtc::ToQueuedTask([msg]() mutable { msg.phandler->OnMessage(&msg); },
904 [this, &ready, current_thread] {
905 CritScope cs(&crit_);
906 ready = true;
907 current_thread->socketserver()->WakeUp();
908 }));
909
910 bool waited = false;
911 crit_.Enter();
912 while (!ready) {
913 crit_.Leave();
914 current_thread->socketserver()->Wait(kForever, false);
915 waited = true;
916 crit_.Enter();
917 }
918 crit_.Leave();
919
920 // Our Wait loop above may have consumed some WakeUp events for this
921 // Thread, that weren't relevant to this Send. Losing these WakeUps can
922 // cause problems for some SocketServers.
923 //
924 // Concrete example:
925 // Win32SocketServer on thread A calls Send on thread B. While processing the
926 // message, thread B Posts a message to A. We consume the wakeup for that
927 // Post while waiting for the Send to complete, which means that when we exit
928 // this loop, we need to issue another WakeUp, or else the Posted message
929 // won't be processed in a timely manner.
930
931 if (waited) {
932 current_thread->socketserver()->WakeUp();
933 }
934 }
935
936 void Thread::InvokeInternal(const Location& posted_from,
937 rtc::FunctionView<void()> functor) {
938 TRACE_EVENT2("webrtc", "Thread::Invoke", "src_file", posted_from.file_name(),
939 "src_func", posted_from.function_name());
940
941 class FunctorMessageHandler : public MessageHandler {
942 public:
943 explicit FunctorMessageHandler(rtc::FunctionView<void()> functor)
944 : functor_(functor) {}
945 void OnMessage(Message* msg) override { functor_(); }
946
947 private:
948 rtc::FunctionView<void()> functor_;
949 } handler(functor);
950
951 Send(posted_from, &handler);
952 }
953
954 // Called by the ThreadManager when being set as the current thread.
955 void Thread::EnsureIsCurrentTaskQueue() {
956 task_queue_registration_ =
957 std::make_unique<TaskQueueBase::CurrentTaskQueueSetter>(this);
958 }
959
960 // Called by the ThreadManager when being set as the current thread.
961 void Thread::ClearCurrentTaskQueue() {
962 task_queue_registration_.reset();
963 }
964
965 void Thread::QueuedTaskHandler::OnMessage(Message* msg) {
966 RTC_DCHECK(msg);
967 auto* data = static_cast<ScopedMessageData<webrtc::QueuedTask>*>(msg->pdata);
968 std::unique_ptr<webrtc::QueuedTask> task = std::move(data->data());
969 // Thread expects handler to own Message::pdata when OnMessage is called
970 // Since MessageData is no longer needed, delete it.
971 delete data;
972
973 // QueuedTask interface uses Run return value to communicate who owns the
974 // task. false means QueuedTask took the ownership.
975 if (!task->Run())
976 task.release();
977 }
978
979 void Thread::AllowInvokesToThread(Thread* thread) {
980 #if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
981 if (!IsCurrent()) {
982 PostTask(webrtc::ToQueuedTask(
983 [thread, this]() { AllowInvokesToThread(thread); }));
984 return;
985 }
986 RTC_DCHECK_RUN_ON(this);
987 allowed_threads_.push_back(thread);
988 invoke_policy_enabled_ = true;
989 #endif
990 }
991
992 void Thread::DisallowAllInvokes() {
993 #if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
994 if (!IsCurrent()) {
995 PostTask(webrtc::ToQueuedTask([this]() { DisallowAllInvokes(); }));
996 return;
997 }
998 RTC_DCHECK_RUN_ON(this);
999 allowed_threads_.clear();
1000 invoke_policy_enabled_ = true;
1001 #endif
1002 }
1003
1004 // Returns true if no policies added or if there is at least one policy
1005 // that permits invocation to |target| thread.
1006 bool Thread::IsInvokeToThreadAllowed(rtc::Thread* target) {
1007 #if (!defined(NDEBUG) || defined(DCHECK_ALWAYS_ON))
1008 RTC_DCHECK_RUN_ON(this);
1009 if (!invoke_policy_enabled_) {
1010 return true;
1011 }
1012 for (const auto* thread : allowed_threads_) {
1013 if (thread == target) {
1014 return true;
1015 }
1016 }
1017 return false;
1018 #else
1019 return true;
1020 #endif
1021 }
1022
1023 void Thread::PostTask(std::unique_ptr<webrtc::QueuedTask> task) {
1024 // Though Post takes MessageData by raw pointer (last parameter), it still
1025 // takes it with ownership.
1026 Post(RTC_FROM_HERE, &queued_task_handler_,
1027 /*id=*/0, new ScopedMessageData<webrtc::QueuedTask>(std::move(task)));
1028 }
1029
1030 void Thread::PostDelayedTask(std::unique_ptr<webrtc::QueuedTask> task,
1031 uint32_t milliseconds) {
1032 // Though PostDelayed takes MessageData by raw pointer (last parameter),
1033 // it still takes it with ownership.
1034 PostDelayed(RTC_FROM_HERE, milliseconds, &queued_task_handler_,
1035 /*id=*/0,
1036 new ScopedMessageData<webrtc::QueuedTask>(std::move(task)));
1037 }
1038
1039 void Thread::Delete() {
1040 Stop();
1041 delete this;
1042 }
1043
1044 bool Thread::IsProcessingMessagesForTesting() {
1045 return (owned_ || IsCurrent()) && !IsQuitting();
1046 }
1047
1048 void Thread::Clear(MessageHandler* phandler,
1049 uint32_t id,
1050 MessageList* removed) {
1051 CritScope cs(&crit_);
1052 ClearInternal(phandler, id, removed);
1053 }
1054
1055 bool Thread::ProcessMessages(int cmsLoop) {
1056 // Using ProcessMessages with a custom clock for testing and a time greater
1057 // than 0 doesn't work, since it's not guaranteed to advance the custom
1058 // clock's time, and may get stuck in an infinite loop.
1059 RTC_DCHECK(GetClockForTesting() == nullptr || cmsLoop == 0 ||
1060 cmsLoop == kForever);
1061 int64_t msEnd = (kForever == cmsLoop) ? 0 : TimeAfter(cmsLoop);
1062 int cmsNext = cmsLoop;
1063
1064 while (true) {
1065 #if defined(WEBRTC_MAC)
1066 ScopedAutoReleasePool pool;
1067 #endif
1068 Message msg;
1069 if (!Get(&msg, cmsNext))
1070 return !IsQuitting();
1071 Dispatch(&msg);
1072
1073 if (cmsLoop != kForever) {
1074 cmsNext = static_cast<int>(TimeUntil(msEnd));
1075 if (cmsNext < 0)
1076 return true;
1077 }
1078 }
1079 }
1080
1081 bool Thread::WrapCurrentWithThreadManager(ThreadManager* thread_manager,
1082 bool need_synchronize_access) {
1083 RTC_DCHECK(!IsRunning());
1084
1085 #if defined(WEBRTC_WIN)
1086 if (need_synchronize_access) {
1087 // We explicitly ask for no rights other than synchronization.
1088 // This gives us the best chance of succeeding.
1089 thread_ = OpenThread(SYNCHRONIZE, FALSE, GetCurrentThreadId());
1090 if (!thread_) {
1091 RTC_LOG_GLE(LS_ERROR) << "Unable to get handle to thread.";
1092 return false;
1093 }
1094 thread_id_ = GetCurrentThreadId();
1095 }
1096 #elif defined(WEBRTC_POSIX)
1097 thread_ = pthread_self();
1098 #endif
1099 owned_ = false;
1100 thread_manager->SetCurrentThread(this);
1101 return true;
1102 }
1103
1104 bool Thread::IsRunning() {
1105 #if defined(WEBRTC_WIN)
1106 return thread_ != nullptr;
1107 #elif defined(WEBRTC_POSIX)
1108 return thread_ != 0;
1109 #endif
1110 }
1111
1112 // static
1113 MessageHandler* Thread::GetPostTaskMessageHandler() {
1114 // Allocate at first call, never deallocate.
1115 static MessageHandler* handler = new MessageHandlerWithTask;
1116 return handler;
1117 }
1118
1119 AutoThread::AutoThread()
1120 : Thread(SocketServer::CreateDefault(), /*do_init=*/false) {
1121 if (!ThreadManager::Instance()->CurrentThread()) {
1122 // DoInit registers with ThreadManager. Do that only if we intend to
1123 // be rtc::Thread::Current(), otherwise ProcessAllMessageQueuesInternal will
1124 // post a message to a queue that no running thread is serving.
1125 DoInit();
1126 ThreadManager::Instance()->SetCurrentThread(this);
1127 }
1128 }
1129
1130 AutoThread::~AutoThread() {
1131 Stop();
1132 DoDestroy();
1133 if (ThreadManager::Instance()->CurrentThread() == this) {
1134 ThreadManager::Instance()->SetCurrentThread(nullptr);
1135 }
1136 }
1137
1138 AutoSocketServerThread::AutoSocketServerThread(SocketServer* ss)
1139 : Thread(ss, /*do_init=*/false) {
1140 DoInit();
1141 old_thread_ = ThreadManager::Instance()->CurrentThread();
1142 // Temporarily set the current thread to nullptr so that we can keep checks
1143 // around that catch unintentional pointer overwrites.
1144 rtc::ThreadManager::Instance()->SetCurrentThread(nullptr);
1145 rtc::ThreadManager::Instance()->SetCurrentThread(this);
1146 if (old_thread_) {
1147 ThreadManager::Remove(old_thread_);
1148 }
1149 }
1150
1151 AutoSocketServerThread::~AutoSocketServerThread() {
1152 RTC_DCHECK(ThreadManager::Instance()->CurrentThread() == this);
1153 // Some tests post destroy messages to this thread. To avoid memory
1154 // leaks, we have to process those messages. In particular
1155 // P2PTransportChannelPingTest, relying on the message posted in
1156 // cricket::Connection::Destroy.
1157 ProcessMessages(0);
1158 // Stop and destroy the thread before clearing it as the current thread.
1159 // Sometimes there are messages left in the Thread that will be
1160 // destroyed by DoDestroy, and sometimes the destructors of the message and/or
1161 // its contents rely on this thread still being set as the current thread.
1162 Stop();
1163 DoDestroy();
1164 rtc::ThreadManager::Instance()->SetCurrentThread(nullptr);
1165 rtc::ThreadManager::Instance()->SetCurrentThread(old_thread_);
1166 if (old_thread_) {
1167 ThreadManager::Add(old_thread_);
1168 }
1169 }
1170
1171 } // namespace rtc
1172