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6e7c2685e3
instead of using Lock/Unlock attributes, use Assert attribute to annotate code is running on certain task queue or thread. Such check better matches what is checked, in particular allows to recheck (and thus better document) currently used task queue Bug: None Change-Id: I5bc1c397efbc8342cf7915093b578bb015c85651 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/269381 Commit-Queue: Danil Chapovalov <danilchap@webrtc.org> Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org> Cr-Commit-Position: refs/heads/main@{#37619}
115 lines
3.7 KiB
C++
115 lines
3.7 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 API_SEQUENCE_CHECKER_H_
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#define API_SEQUENCE_CHECKER_H_
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#include "rtc_base/checks.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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class RTC_LOCKABLE SequenceChecker
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#if RTC_DCHECK_IS_ON
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: public webrtc_sequence_checker_internal::SequenceCheckerImpl {
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using Impl = webrtc_sequence_checker_internal::SequenceCheckerImpl;
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#else
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: public webrtc_sequence_checker_internal::SequenceCheckerDoNothing {
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using Impl = webrtc_sequence_checker_internal::SequenceCheckerDoNothing;
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#endif
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public:
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// Returns true if sequence checker is attached to the current sequence.
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bool IsCurrent() const { return Impl::IsCurrent(); }
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// Detaches checker from sequence to which it is attached. Next attempt
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// to do a check with this checker will result in attaching this checker
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// to the sequence on which check was performed.
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void Detach() { Impl::Detach(); }
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};
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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 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::TaskQueueBase& 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::TaskQueueBase& 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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RTC_DCHECK((x)->IsCurrent()) \
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<< webrtc::webrtc_sequence_checker_internal::ExpectationToString(x); \
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webrtc::webrtc_sequence_checker_internal::AssertHeld(x)
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#endif // API_SEQUENCE_CHECKER_H_
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