webrtc/rtc_base/synchronization/sequence_checker_internal.h
Tommi 3da04a93cd Allow SequenceChecker to be initialized detached.
The motivation for this is to not have to implement this pattern:

foo.h:

class Foo {
 public:
  Foo();
 private:
  SequenceChecker checker_;
};

foo.cc:

Foo::Foo() {
  checker_.Detach();
}

And instead be able to do this inline in the .h file:

class Foo {
 public:
  Foo();
 private:
  SequenceChecker checker_{SequenceChecker::kDetached};
};

Bug: none
Change-Id: Idd7ca82d15c2f77f3aaccf26f1943a49f4b40661
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/298445
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Commit-Queue: Tomas Gunnarsson <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#39616}
2023-03-21 12:34:15 +00:00

89 lines
3.1 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_SEQUENCE_CHECKER_INTERNAL_H_
#define RTC_BASE_SYNCHRONIZATION_SEQUENCE_CHECKER_INTERNAL_H_
#include <string>
#include <type_traits>
#include "api/task_queue/task_queue_base.h"
#include "rtc_base/platform_thread_types.h"
#include "rtc_base/synchronization/mutex.h"
#include "rtc_base/system/rtc_export.h"
#include "rtc_base/thread_annotations.h"
namespace webrtc {
namespace webrtc_sequence_checker_internal {
// Real implementation of SequenceChecker, for use in debug mode, or
// for temporary use in release mode (e.g. to RTC_CHECK on a threading issue
// seen only in the wild).
//
// Note: You should almost always use the SequenceChecker class to get the
// right version for your build configuration.
class RTC_EXPORT SequenceCheckerImpl {
public:
explicit SequenceCheckerImpl(bool attach_to_current_thread);
~SequenceCheckerImpl() = default;
bool IsCurrent() const;
// Changes the task queue or thread that is checked for in IsCurrent. This can
// be useful when an object may be created on one task queue / thread and then
// used exclusively on another thread.
void Detach();
// Returns a string that is formatted to match with the error string printed
// by RTC_CHECK() when a condition is not met.
// This is used in conjunction with the RTC_DCHECK_RUN_ON() macro.
std::string ExpectationToString() const;
private:
mutable Mutex lock_;
// These are mutable so that IsCurrent can set them.
mutable bool attached_ RTC_GUARDED_BY(lock_);
mutable rtc::PlatformThreadRef valid_thread_ RTC_GUARDED_BY(lock_);
mutable const TaskQueueBase* valid_queue_ RTC_GUARDED_BY(lock_);
mutable const void* valid_system_queue_ RTC_GUARDED_BY(lock_);
};
// Do nothing implementation, for use in release mode.
//
// Note: You should almost always use the SequenceChecker class to get the
// right version for your build configuration.
class SequenceCheckerDoNothing {
public:
explicit SequenceCheckerDoNothing(bool attach_to_current_thread) {}
bool IsCurrent() const { return true; }
void Detach() {}
};
template <typename ThreadLikeObject>
std::enable_if_t<std::is_base_of_v<SequenceCheckerImpl, ThreadLikeObject>,
std::string>
ExpectationToString(const ThreadLikeObject* checker) {
#if RTC_DCHECK_IS_ON
return checker->ExpectationToString();
#else
return std::string();
#endif
}
// Catch-all implementation for types other than explicitly supported above.
template <typename ThreadLikeObject>
std::enable_if_t<!std::is_base_of_v<SequenceCheckerImpl, ThreadLikeObject>,
std::string>
ExpectationToString(const ThreadLikeObject*) {
return std::string();
}
} // namespace webrtc_sequence_checker_internal
} // namespace webrtc
#endif // RTC_BASE_SYNCHRONIZATION_SEQUENCE_CHECKER_INTERNAL_H_