webrtc/rtc_base/synchronization/mutex.h
Markus Handell 8e75bd40e0 Mutex: remove Abseil static initializer.
The change adds conditional inclusion of mutex_abseil.h from mutex.h
and conditional referencing of
//third_party/abseil-cpp/absl/synchronization
which introduces a static initializer.

https://webrtc-review.googlesource.com/c/src/+/176230 introduced a
static initializer which broke the Chromium autoroll,
https://chromium-review.googlesource.com/c/chromium/src/+/2230887.
Example failure:
https://ci.chromium.org/p/chromium/builders/try/android-lollipop-arm-rel/34133

TBR=karl@webrtc.org

No-Try: True
Bug: webrtc:11567
Change-Id: Id78af798f34d5d6beaf9f6e0150e6b3ddd31ff4f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/176513
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Olga Sharonova <olka@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31451}
2020-06-05 10:26:28 +00:00

103 lines
2.9 KiB
C++

/*
* 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/const_init.h"
#include "rtc_base/checks.h"
#include "rtc_base/system/unused.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(); }
RTC_WARN_UNUSED_RESULT bool TryLock() RTC_EXCLUSIVE_TRYLOCK_FUNCTION(true) {
return impl_.TryLock();
}
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_;
};
// A mutex used to protect global variables. Do NOT use for other purposes.
#if defined(WEBRTC_ABSL_MUTEX)
using GlobalMutex = absl::Mutex;
using GlobalMutexLock = absl::MutexLock;
#else
class RTC_LOCKABLE GlobalMutex final {
public:
GlobalMutex(const GlobalMutex&) = delete;
GlobalMutex& operator=(const GlobalMutex&) = delete;
constexpr explicit GlobalMutex(absl::ConstInitType /*unused*/)
: mutex_locked_(0) {}
void Lock() RTC_EXCLUSIVE_LOCK_FUNCTION();
void Unlock() RTC_UNLOCK_FUNCTION();
private:
std::atomic<int> mutex_locked_; // 0 means lock not taken, 1 means taken.
};
// GlobalMutexLock, for serializing execution through a scope.
class RTC_SCOPED_LOCKABLE GlobalMutexLock final {
public:
GlobalMutexLock(const GlobalMutexLock&) = delete;
GlobalMutexLock& operator=(const GlobalMutexLock&) = delete;
explicit GlobalMutexLock(GlobalMutex* mutex) RTC_EXCLUSIVE_LOCK_FUNCTION();
~GlobalMutexLock() RTC_UNLOCK_FUNCTION();
private:
GlobalMutex* mutex_;
};
#endif // if defined(WEBRTC_ABSL_MUTEX)
} // namespace webrtc
#endif // RTC_BASE_SYNCHRONIZATION_MUTEX_H_