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// 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_COMPLETION_EVENT_H_
#define CC_COMPLETION_EVENT_H_
#include "base/synchronization/waitable_event.h"
#include "base/threading/thread_restrictions.h"
#include "base/logging.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()
: m_event(false /* manual_reset */, false /* initially_signaled */)
{
#ifndef NDEBUG
m_waited = false;
m_signaled = false;
#endif
}
~CompletionEvent()
{
#ifndef NDEBUG
DCHECK(m_waited);
DCHECK(m_signaled);
#endif
}
void wait()
{
#ifndef NDEBUG
DCHECK(!m_waited);
m_waited = true;
#endif
base::ThreadRestrictions::ScopedAllowWait allow_wait;
m_event.Wait();
}
void signal()
{
#ifndef NDEBUG
DCHECK(!m_signaled);
m_signaled = true;
#endif
m_event.Signal();
}
private:
base::WaitableEvent m_event;
#ifndef NDEBUG
// Used to assert that wait() and signal() are each called exactly once.
bool m_waited;
bool m_signaled;
#endif
};
}
#endif // CC_COMPLETION_EVENT_H_
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