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| 1 // Copyright 2011 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #ifndef CC_BASE_COMPLETION_EVENT_H_ | |
| 6 #define CC_BASE_COMPLETION_EVENT_H_ | |
| 7 | |
| 8 #include "base/logging.h" | |
| 9 #include "base/synchronization/waitable_event.h" | |
| 10 #include "base/threading/thread_restrictions.h" | |
| 11 | |
| 12 namespace cc { | |
| 13 | |
| 14 // Used for making blocking calls from one thread to another. Use only when | |
| 15 // absolutely certain that doing-so will not lead to a deadlock. | |
| 16 // | |
| 17 // It is safe to destroy this object as soon as Wait() returns. | |
| 18 class CompletionEvent { | |
| 19 public: | |
| 20 CompletionEvent() | |
| 21 : event_(false /* manual_reset */, false /* initially_signaled */) { | |
| 22 #if DCHECK_IS_ON() | |
| 23 waited_ = false; | |
| 24 signaled_ = false; | |
| 25 #endif | |
| 26 } | |
| 27 | |
| 28 ~CompletionEvent() { | |
| 29 #if DCHECK_IS_ON() | |
| 30 DCHECK(waited_); | |
| 31 DCHECK(signaled_); | |
| 32 #endif | |
| 33 } | |
| 34 | |
| 35 void Wait() { | |
| 36 #if DCHECK_IS_ON() | |
| 37 DCHECK(!waited_); | |
| 38 waited_ = true; | |
| 39 #endif | |
| 40 base::ThreadRestrictions::ScopedAllowWait allow_wait; | |
| 41 event_.Wait(); | |
| 42 } | |
| 43 | |
| 44 void Signal() { | |
| 45 #if DCHECK_IS_ON() | |
| 46 DCHECK(!signaled_); | |
| 47 signaled_ = true; | |
| 48 #endif | |
| 49 event_.Signal(); | |
| 50 } | |
| 51 | |
| 52 private: | |
| 53 base::WaitableEvent event_; | |
| 54 #if DCHECK_IS_ON() | |
| 55 // Used to assert that Wait() and Signal() are each called exactly once. | |
| 56 bool waited_; | |
| 57 bool signaled_; | |
| 58 #endif | |
| 59 }; | |
| 60 | |
| 61 } // namespace cc | |
| 62 | |
| 63 #endif // CC_BASE_COMPLETION_EVENT_H_ | |
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