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https://github.com/mollyim/webrtc.git
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c1e7878c76
Bug: webrtc:12419 Change-Id: I501b96865f69f15e49a813c5dcd6ccf44d67c2e7 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/205621 Commit-Queue: Artem Titov <titovartem@webrtc.org> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org> Cr-Commit-Position: refs/heads/master@{#33157}
121 lines
3.6 KiB
C++
121 lines
3.6 KiB
C++
/*
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* Copyright 2019 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_SEQUENCE_CHECKER_H_
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#define RTC_BASE_SYNCHRONIZATION_SEQUENCE_CHECKER_H_
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#include <type_traits>
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#include "rtc_base/checks.h"
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#include "rtc_base/deprecation.h"
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#include "rtc_base/synchronization/sequence_checker_internal.h"
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#include "rtc_base/thread_annotations.h"
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namespace webrtc {
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// SequenceChecker is a helper class used to help verify that some methods
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// of a class are called on the same task queue or thread. A
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// SequenceChecker is bound to a a task queue if the object is
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// created on a task queue, or a thread otherwise.
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//
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//
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// Example:
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// class MyClass {
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// public:
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// void Foo() {
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// RTC_DCHECK_RUN_ON(sequence_checker_);
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// ... (do stuff) ...
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// }
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//
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// private:
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// SequenceChecker sequence_checker_;
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// }
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//
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// In Release mode, IsCurrent will always return true.
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#if RTC_DCHECK_IS_ON
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class RTC_LOCKABLE SequenceChecker
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: public webrtc_sequence_checker_internal::SequenceCheckerImpl {};
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#else
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class RTC_LOCKABLE SequenceChecker
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: public webrtc_sequence_checker_internal::SequenceCheckerDoNothing {};
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#endif // RTC_ENABLE_THREAD_CHECKER
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} // namespace webrtc
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// RTC_RUN_ON/RTC_GUARDED_BY/RTC_DCHECK_RUN_ON macros allows to annotate
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// variables are accessed from same thread/task queue.
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// Using tools designed to check mutexes, it checks at compile time everywhere
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// variable is access, there is a run-time dcheck thread/task queue is correct.
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//
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// class ThreadExample {
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// public:
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// void NeedVar1() {
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// RTC_DCHECK_RUN_ON(network_thread_);
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// transport_->Send();
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// }
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//
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// private:
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// rtc::Thread* network_thread_;
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// int transport_ RTC_GUARDED_BY(network_thread_);
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// };
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//
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// class SequenceCheckerExample {
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// public:
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// int CalledFromPacer() RTC_RUN_ON(pacer_sequence_checker_) {
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// return var2_;
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// }
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//
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// void CallMeFromPacer() {
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// RTC_DCHECK_RUN_ON(&pacer_sequence_checker_)
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// << "Should be called from pacer";
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// CalledFromPacer();
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// }
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//
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// private:
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// int pacer_var_ RTC_GUARDED_BY(pacer_sequence_checker_);
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// SequenceChecker pacer_sequence_checker_;
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// };
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//
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// class TaskQueueExample {
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// public:
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// class Encoder {
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// public:
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// rtc::TaskQueue* Queue() { return encoder_queue_; }
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// void Encode() {
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// RTC_DCHECK_RUN_ON(encoder_queue_);
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// DoSomething(var_);
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// }
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//
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// private:
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// rtc::TaskQueue* const encoder_queue_;
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// Frame var_ RTC_GUARDED_BY(encoder_queue_);
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// };
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//
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// void Encode() {
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// // Will fail at runtime when DCHECK is enabled:
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// // encoder_->Encode();
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// // Will work:
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// rtc::scoped_refptr<Encoder> encoder = encoder_;
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// encoder_->Queue()->PostTask([encoder] { encoder->Encode(); });
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// }
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//
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// private:
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// rtc::scoped_refptr<Encoder> encoder_;
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// }
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// Document if a function expected to be called from same thread/task queue.
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#define RTC_RUN_ON(x) \
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RTC_THREAD_ANNOTATION_ATTRIBUTE__(exclusive_locks_required(x))
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#define RTC_DCHECK_RUN_ON(x) \
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webrtc::webrtc_sequence_checker_internal::SequenceCheckerScope scope(x); \
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RTC_DCHECK((x)->IsCurrent()) \
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<< webrtc::webrtc_sequence_checker_internal::ExpectationToString(x)
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#endif // RTC_BASE_SYNCHRONIZATION_SEQUENCE_CHECKER_H_
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