769629e02f
This header landed recently but it was not built, so this wasn't caught. Bug: webrtc:12336 Change-Id: Ie566d4fe22d1c9f17488ac1cf94068e606c0378b Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/216381 Commit-Queue: Markus Handell <handellm@webrtc.org> Reviewed-by: Markus Handell <handellm@webrtc.org> Cr-Commit-Position: refs/heads/master@{#33859}
66 lines
2.4 KiB
C++
66 lines
2.4 KiB
C++
/*
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* Copyright 2020 The WebRTC Project Authors. All rights reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef RTC_BASE_SYNCHRONIZATION_MUTEX_RACE_CHECK_H_
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#define RTC_BASE_SYNCHRONIZATION_MUTEX_RACE_CHECK_H_
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#include <atomic>
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#include "absl/base/attributes.h"
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#include "rtc_base/checks.h"
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#include "rtc_base/system/unused.h"
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#include "rtc_base/thread_annotations.h"
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namespace webrtc {
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// This implementation class is useful when a consuming project can guarantee
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// that all WebRTC invocation is happening serially. Additionally, the consuming
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// project cannot use WebRTC code that spawn threads or task queues.
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//
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// The class internally check fails on Lock() if it finds the consumer actually
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// invokes WebRTC concurrently.
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//
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// To use the race check mutex, define WEBRTC_RACE_CHECK_MUTEX globally. This
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// also adds a dependency to absl::Mutex from logging.cc because even though
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// objects are invoked serially, the logging is static and invoked concurrently
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// and hence needs protection.
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class RTC_LOCKABLE MutexImpl final {
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public:
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MutexImpl() = default;
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MutexImpl(const MutexImpl&) = delete;
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MutexImpl& operator=(const MutexImpl&) = delete;
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void Lock() RTC_EXCLUSIVE_LOCK_FUNCTION() {
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bool was_free = free_.exchange(false, std::memory_order_acquire);
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RTC_CHECK(was_free)
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<< "WEBRTC_RACE_CHECK_MUTEX: mutex locked concurrently.";
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}
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ABSL_MUST_USE_RESULT bool TryLock() RTC_EXCLUSIVE_TRYLOCK_FUNCTION(true) {
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bool was_free = free_.exchange(false, std::memory_order_acquire);
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return was_free;
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}
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void Unlock() RTC_UNLOCK_FUNCTION() {
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free_.store(true, std::memory_order_release);
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}
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private:
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// Release-acquire ordering is used.
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// - In the Lock methods we're guaranteeing that reads and writes happening
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// after the (Try)Lock don't appear to have happened before the Lock (acquire
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// ordering).
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// - In the Unlock method we're guaranteeing that reads and writes happening
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// before the Unlock don't appear to happen after it (release ordering).
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std::atomic<bool> free_{true};
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};
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} // namespace webrtc
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#endif // RTC_BASE_SYNCHRONIZATION_MUTEX_RACE_CHECK_H_
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