blob: a23ac08885ec88cf6dad56e0350e1d49a75992d1 [file] [log] [blame]
* 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.
#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 {
explicit SequenceCheckerImpl(bool attach_to_current_thread);
explicit SequenceCheckerImpl(TaskQueueBase* attached_queue);
~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;
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_);
// 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 {
explicit SequenceCheckerDoNothing(bool attach_to_current_thread) {}
explicit SequenceCheckerDoNothing(TaskQueueBase* attached_queue) {}
bool IsCurrent() const { return true; }
void Detach() {}
template <typename ThreadLikeObject>
std::enable_if_t<std::is_base_of_v<SequenceCheckerImpl, ThreadLikeObject>,
ExpectationToString(const ThreadLikeObject* checker) {
return checker->ExpectationToString();
return std::string();
// Catch-all implementation for types other than explicitly supported above.
template <typename ThreadLikeObject>
std::enable_if_t<!std::is_base_of_v<SequenceCheckerImpl, ThreadLikeObject>,
ExpectationToString(const ThreadLikeObject*) {
return std::string();
} // namespace webrtc_sequence_checker_internal
} // namespace webrtc