| // Copyright 2011 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef CC_BASE_COMPLETION_EVENT_H_ |
| #define CC_BASE_COMPLETION_EVENT_H_ |
| |
| #include "base/logging.h" |
| #include "base/synchronization/waitable_event.h" |
| #include "base/threading/thread_restrictions.h" |
| #include "base/time/time.h" |
| |
| namespace cc { |
| |
| // Used for making blocking calls from one thread to another. Use only when |
| // absolutely certain that doing-so will not lead to a deadlock. |
| // |
| // It is safe to destroy this object as soon as Wait() returns. |
| class CompletionEvent { |
| public: |
| CompletionEvent() |
| : event_(base::WaitableEvent::ResetPolicy::AUTOMATIC, |
| base::WaitableEvent::InitialState::NOT_SIGNALED) { |
| #if DCHECK_IS_ON() |
| waited_ = false; |
| signaled_ = false; |
| #endif |
| } |
| |
| ~CompletionEvent() { |
| #if DCHECK_IS_ON() |
| DCHECK(waited_); |
| DCHECK(signaled_); |
| #endif |
| } |
| |
| void Wait() { |
| #if DCHECK_IS_ON() |
| DCHECK(!waited_); |
| waited_ = true; |
| #endif |
| base::ThreadRestrictions::ScopedAllowWait allow_wait; |
| event_.Wait(); |
| } |
| |
| void TimedWait(const base::TimeDelta& max_time) { |
| #if DCHECK_IS_ON() |
| DCHECK(!waited_); |
| waited_ = true; |
| #endif |
| event_.TimedWait(max_time); |
| } |
| |
| bool IsSignaled() { return event_.IsSignaled(); } |
| |
| void Signal() { |
| #if DCHECK_IS_ON() |
| DCHECK(!signaled_); |
| signaled_ = true; |
| #endif |
| event_.Signal(); |
| } |
| |
| private: |
| base::WaitableEvent event_; |
| #if DCHECK_IS_ON() |
| // Used to assert that Wait() and Signal() are each called exactly once. |
| bool waited_; |
| bool signaled_; |
| #endif |
| }; |
| |
| } // namespace cc |
| |
| #endif // CC_BASE_COMPLETION_EVENT_H_ |