Ensures that audio tasks cannot run after AudioManager is deleted.

media/audio/audio_manager.h

 // Copyright (c) 2012 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_MANAGER_H_
 #define MEDIA_AUDIO_AUDIO_MANAGER_H_
 
 #include <memory>
 #include <string>
 
 #include "base/callback_forward.h"
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequenced_task_runner_helpers.h"
 #include "base/strings/string16.h"
+#include "base/threading/thread_checker.h"
 #include "build/build_config.h"
 #include "media/audio/audio_device_description.h"
 #include "media/audio/audio_logging.h"
+#include "media/audio/audio_thread.h"
 #include "media/base/audio_parameters.h"
 
 namespace base {
 class FilePath;
 class SingleThreadTaskRunner;
 }
 
 namespace media {
 
 class AudioInputStream;
 class AudioManager;
 class AudioOutputStream;
 
-class MEDIA_EXPORT AudioManagerDeleter {
- public:
-  void operator()(const AudioManager* instance) const;
-};
-using ScopedAudioManagerPtr =
-    std::unique_ptr<AudioManager, AudioManagerDeleter>;
-
 // Manages all audio resources.  Provides some convenience functions that avoid
 // the need to provide iterators over the existing streams.
 //
 // Except on OSX, a hang monitor for the audio thread is always created. When a
 // thread hang is detected, it is reported to UMA.
 class MEDIA_EXPORT AudioManager {
  public:
+  virtual ~AudioManager();
+
   // Construct the audio manager; only one instance is allowed.
-  // The returned instance must be deleted on AudioManager::GetTaskRunnner().
   //
   // The manager will forward CreateAudioLog() calls to the provided
   // AudioLogFactory; as such |audio_log_factory| must outlive the AudioManager.
   //
-  // The manager will use |task_runner| for audio IO. This same task runner
-  // is returned by GetTaskRunner().
-  // On OS_MACOSX, CoreAudio requires that |task_runner| must belong to the
-  // main thread of the process, which in our case is sadly the browser UI
-  // thread. Failure to execute calls on the right thread leads to crashes and
-  // odd behavior. See http://crbug.com/158170.
+  // The manager will use |audio_thread->GetTaskRunner()| for audio IO.
+  // On OS_MACOSX, CoreAudio requires that |audio_thread->GetTaskRunner()|
+  // must belong to the main thread of the process, which in our case is sadly
+  // the browser UI thread. Failure to execute calls on the right thread leads
+  // to crashes and odd behavior. See http://crbug.com/158170.
   //
-  // The manager will use |worker_task_runner| for heavyweight tasks.
-  // The |worker_task_runner| may be the same as |task_runner|. This same
-  // task runner is returned by GetWorkerTaskRunner.
+  // The manager will use |audio_thread->GetWorkerTaskRunner()| for heavyweight
+  // tasks. The |audio_thread->GetWorkerTaskRunner()| may be the same as
+  // |audio_thread->GetTaskRunner()|.
   //
   // |file_task_runner| is used for audio debug recordings and is the task
   // runner to do file output operations on.
-  static ScopedAudioManagerPtr Create(
-      scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-      scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
+  static std::unique_ptr<AudioManager> Create(
+      std::unique_ptr<AudioThread> audio_thread,
       scoped_refptr<base::SingleThreadTaskRunner> file_task_runner,
       AudioLogFactory* audio_log_factory);
 
   // A convenience wrapper of AudioManager::Create for testing.
-  // The given |task_runner| is shared for both audio io and heavyweight tasks.
-  static ScopedAudioManagerPtr CreateForTesting(
-      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
+  static std::unique_ptr<AudioManager> CreateForTesting(
+      std::unique_ptr<AudioThread> audio_thread);
 
   // Starts monitoring AudioManager task runner for hangs.
   // Runs the monitor on the given |task_runner|, which must be different from
   // AudioManager::GetTaskRunner to be meaningful.
   // This must be called only after an AudioManager instance is created.
   static void StartHangMonitorIfNeeded(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
 #if defined(OS_LINUX)
   // Sets the name of the audio source as seen by external apps. Only actually
   // used with PulseAudio as of this writing.
   static void SetGlobalAppName(const std::string& app_name);
 
   // Returns the app name or an empty string if it is not set.
   static const std::string& GetGlobalAppName();
 #endif
 
   // Returns the pointer to the last created instance, or NULL if not yet
   // created. This is a utility method for the code outside of media directory,
   // like src/chrome.
   static AudioManager* Get();
 
+  // Releases all audio resources.
+  // Must be called before deletion and on the same thread as AudioManager
+  // was created.
+  void Shutdown();
+
   // Log callback used for sending log messages from a stream to the object
   // that manages the stream.
   using LogCallback = base::Callback<void(const std::string&)>;
 
   // Factory for all the supported stream formats. |params| defines parameters
   // of the audio stream to be created.
   //
   // |params.sample_per_packet| is the requested buffer allocation which the
   // audio source thinks it can usually fill without blocking. Internally two
   // or three buffers are created, one will be locked for playback and one will
@@ skipping 36 matching lines @@
   // we have reached some other platform specific limit.
   //
   // Do not free the returned AudioInputStream. It is owned by AudioManager.
   // When you are done with it, call |Stop()| and |Close()| to release it.
   virtual AudioInputStream* MakeAudioInputStream(
       const AudioParameters& params,
       const std::string& device_id,
       const LogCallback& log_callback) = 0;
 
   // Returns the task runner used for audio IO.
-  // TODO(alokp): Rename to task_runner().
   base::SingleThreadTaskRunner* GetTaskRunner() const {
-    return task_runner_.get();
+    return audio_thread_->GetTaskRunner();
   }
 
   // Heavyweight tasks should use GetWorkerTaskRunner() instead of
   // GetTaskRunner(). On most platforms they are the same, but some share the
   // UI loop with the audio IO loop.
-  // TODO(alokp): Rename to worker_task_runner().
   base::SingleThreadTaskRunner* GetWorkerTaskRunner() const {
-    return worker_task_runner_.get();
+    return audio_thread_->GetWorkerTaskRunner();
   }
 
   // Allows clients to listen for device state changes; e.g. preferred sample
   // rate or channel layout changes.  The typical response to receiving this
   // callback is to recreate the stream.
   class AudioDeviceListener {
    public:
     virtual void OnDeviceChange() = 0;
   };
 
@@ skipping 18 matching lines @@
   // Gets the name of the audio manager (e.g., Windows, Mac, PulseAudio).
   virtual const char* GetName() = 0;
 
   // Limits the number of streams that can be created for testing purposes.
   virtual void SetMaxStreamCountForTesting(int max_input, int max_output);
 
  protected:
   FRIEND_TEST_ALL_PREFIXES(AudioManagerTest, AudioDebugRecording);
   friend class AudioDeviceInfoAccessorForTests;
 
-  AudioManager(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-               scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner);
-  virtual ~AudioManager();
+  explicit AudioManager(std::unique_ptr<AudioThread> audio_thread);
+
+  virtual void ShutdownOnAudioThread() = 0;
 
   // Initializes output debug recording. Can be called on any thread; will post
   // to the audio thread if not called on it.
   virtual void InitializeOutputDebugRecording(
       scoped_refptr<base::SingleThreadTaskRunner> file_task_runner) = 0;
 
   // Returns true if the OS reports existence of audio devices. This does not
   // guarantee that the existing devices support all formats and sample rates.
   virtual bool HasAudioOutputDevices() = 0;
 
@@ skipping 55 matching lines @@
   // an empty string. Must be called on the audio worker thread (see
   // GetTaskRunner()).
   virtual std::string GetAssociatedOutputDeviceID(
       const std::string& input_device_id) = 0;
 
  private:
   friend class base::DeleteHelper<AudioManager>;
   friend class AudioManagerDeleter;
   friend class AudioSystemImpl;
 
-  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
-  scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner_;
+  base::ThreadChecker thread_checker_;
+  std::unique_ptr<AudioThread> audio_thread_;
+  bool shutdown_;  // True after |this| has been shutdown.

[o1ka, 2017/05/10 15:57:57]

= false?

[alokp, 2017/05/10 18:04:03]

Done.

+
   DISALLOW_COPY_AND_ASSIGN(AudioManager);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_MANAGER_H_