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 #ifndef NDEBUG 23 waited_ = false; 24 signaled_ = false; 25 #endif 26 } 27 28 ~CompletionEvent() { 29 #ifndef NDEBUG 30 DCHECK(waited_); 31 DCHECK(signaled_); 32 #endif 33 } 34 35 void Wait() { 36 #ifndef NDEBUG 37 DCHECK(!waited_); 38 waited_ = true; 39 #endif 40 base::ThreadRestrictions::ScopedAllowWait allow_wait; 41 event_.Wait(); 42 } 43 44 void Signal() { 45 #ifndef NDEBUG 46 DCHECK(!signaled_); 47 signaled_ = true; 48 #endif 49 event_.Signal(); 50 } 51 52 private: 53 base::WaitableEvent event_; 54 #ifndef NDEBUG 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_ 64
