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/*
* Copyright 2020 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef RTC_BASE_SYNCHRONIZATION_MUTEX_H_
#define RTC_BASE_SYNCHRONIZATION_MUTEX_H_
#include <atomic>
#include "absl/base/attributes.h"
#include "absl/base/const_init.h"
#include "rtc_base/checks.h"
#include "rtc_base/thread_annotations.h"
#if defined(WEBRTC_ABSL_MUTEX)
#include "rtc_base/synchronization/mutex_abseil.h" // nogncheck
#elif defined(WEBRTC_WIN)
#include "rtc_base/synchronization/mutex_critical_section.h"
#elif defined(WEBRTC_POSIX)
#include "rtc_base/synchronization/mutex_pthread.h"
#else
#error Unsupported platform.
#endif
namespace webrtc {
// The Mutex guarantees exclusive access and aims to follow Abseil semantics
// (i.e. non-reentrant etc).
class RTC_LOCKABLE Mutex final {
public:
Mutex() = default;
Mutex(const Mutex&) = delete;
Mutex& operator=(const Mutex&) = delete;
void Lock() RTC_EXCLUSIVE_LOCK_FUNCTION() { impl_.Lock(); }
ABSL_MUST_USE_RESULT bool TryLock() RTC_EXCLUSIVE_TRYLOCK_FUNCTION(true) {
return impl_.TryLock();
}
// Return immediately if this thread holds the mutex, or RTC_DCHECK_IS_ON==0.
// Otherwise, may report an error (typically by crashing with a diagnostic),
// or may return immediately.
void AssertHeld() const RTC_ASSERT_EXCLUSIVE_LOCK() { impl_.AssertHeld(); }
void Unlock() RTC_UNLOCK_FUNCTION() { impl_.Unlock(); }
private:
MutexImpl impl_;
};
// MutexLock, for serializing execution through a scope.
class RTC_SCOPED_LOCKABLE MutexLock final {
public:
MutexLock(const MutexLock&) = delete;
MutexLock& operator=(const MutexLock&) = delete;
explicit MutexLock(Mutex* mutex) RTC_EXCLUSIVE_LOCK_FUNCTION(mutex)
: mutex_(mutex) {
mutex->Lock();
}
~MutexLock() RTC_UNLOCK_FUNCTION() { mutex_->Unlock(); }
private:
Mutex* mutex_;
};
} // namespace webrtc
#endif // RTC_BASE_SYNCHRONIZATION_MUTEX_H_
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