| // Copyright 2018 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef MEDIA_AUDIO_AUDIO_THREAD_HANG_MONITOR_H_ |
| #define MEDIA_AUDIO_AUDIO_THREAD_HANG_MONITOR_H_ |
| |
| #include "media/audio/audio_manager.h" |
| |
| #include <atomic> |
| #include <memory> |
| |
| #include "base/macros.h" |
| #include "base/memory/ref_counted.h" |
| #include "base/memory/scoped_refptr.h" |
| #include "base/sequence_checker.h" |
| #include "base/sequenced_task_runner.h" |
| #include "base/time/time.h" |
| #include "base/timer/timer.h" |
| #include "media/base/media_export.h" |
| #include "media/base/media_switches.h" |
| |
| namespace base { |
| class TickClock; |
| class SingleThreadTaskRunner; |
| } // namespace base |
| |
| namespace media { |
| |
| // This class detects if the audio manager thread is hung. It logs a histogram, |
| // and can optionally (if |dump_on_hang| is set) upload a crash dump when a hang |
| // is detected. It runs on a task runner from the task scheduler. It works by |
| // posting a task to the audio thread every minute and checking that it was |
| // executed. If three consecutive such pings are missed, the thread is |
| // considered hung. |
| class MEDIA_EXPORT AudioThreadHangMonitor final { |
| public: |
| using Ptr = |
| std::unique_ptr<AudioThreadHangMonitor, base::OnTaskRunnerDeleter>; |
| |
| // These values are histogrammed over time; do not change their ordinal |
| // values. |
| enum class ThreadStatus { |
| // kNone = 0, obsolete. |
| kStarted = 1, |
| kHung, |
| kRecovered, |
| kMaxValue = kRecovered |
| }; |
| |
| // |monitor_task_runner| may be set explicitly by tests only. Other callers |
| // should use the default. |
| static Ptr Create( |
| bool dump_on_hang, |
| const base::TickClock* clock, |
| scoped_refptr<base::SingleThreadTaskRunner> audio_thread_task_runner, |
| scoped_refptr<base::SequencedTaskRunner> monitor_task_runner = nullptr); |
| |
| ~AudioThreadHangMonitor(); |
| |
| // Thread-safe. |
| bool IsAudioThreadHung() const; |
| |
| private: |
| class SharedAtomicFlag final |
| : public base::RefCountedThreadSafe<SharedAtomicFlag> { |
| public: |
| SharedAtomicFlag(); |
| |
| std::atomic_bool flag_ = {false}; |
| |
| private: |
| friend class base::RefCountedThreadSafe<SharedAtomicFlag>; |
| ~SharedAtomicFlag(); |
| }; |
| |
| AudioThreadHangMonitor( |
| bool dump_on_hang, |
| const base::TickClock* clock, |
| scoped_refptr<base::SingleThreadTaskRunner> audio_thread_task_runner); |
| |
| void StartTimer(); |
| |
| bool NeverLoggedThreadHung() const; |
| bool NeverLoggedThreadRecoveredAfterHung() const; |
| |
| // This function is run by the |timer_|. It checks if the audio thread has |
| // shown signs of life since the last time it was called (by checking the |
| // |alive_flag_|) and updates the value of |successful_pings_| and |
| // |failed_pings_| as appropriate. It also changes the thread status and logs |
| // its value to a histogram. |
| void CheckIfAudioThreadIsAlive(); |
| |
| // LogHistogramThreadStatus logs |thread_status_| to a histogram. |
| void LogHistogramThreadStatus(); |
| |
| const base::TickClock* const clock_; |
| |
| // This flag is set to false on the monitor sequence and then set to true on |
| // the audio thread to indicate that the audio thread is alive. |
| const scoped_refptr<SharedAtomicFlag> alive_flag_; |
| |
| // |audio_task_runner_| is the task runner of the audio thread. |
| const scoped_refptr<base::SingleThreadTaskRunner> audio_task_runner_; |
| |
| // If |dump_on_hang_| is set, a crash dump will be collected the first time |
| // the thread is detected as hung (note that no actual crashing is involved). |
| const bool dump_on_hang_; |
| |
| std::atomic<ThreadStatus> audio_thread_status_ = {ThreadStatus::kStarted}; |
| |
| // All fields below are accessed on |monitor_sequence|. |
| SEQUENCE_CHECKER(monitor_sequence_); |
| |
| // Timer to check |alive_flag_| regularly. |
| base::RepeatingTimer timer_; |
| |
| // This variable is used to check to detect suspend/resume cycles. |
| // If a long time has passed since the timer was last fired, it is likely due |
| // to the machine being suspended. In such a case, we want to avoid falsely |
| // detecting the audio thread as hung. |
| base::TimeTicks last_check_time_ = base::TimeTicks(); |
| |
| // |recent_ping_state_| tracks the recent life signs from the audio thread. If |
| // the most recent ping was successful, the number indicates the number of |
| // successive successful pings. If the most recent ping was failed, the number |
| // is the negative of the number of successive failed pings. |
| int recent_ping_state_ = 0; |
| |
| DISALLOW_COPY_AND_ASSIGN(AudioThreadHangMonitor); |
| }; |
| |
| } // namespace media |
| |
| #endif // MEDIA_AUDIO_AUDIO_THREAD_HANG_MONITOR_H_ |