Use audio thread for the fake input audio stream.

media/audio/fake_audio_input_stream.cc

 // 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.
 
 #include "media/audio/fake_audio_input_stream.h"
 
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "media/audio/audio_manager_base.h"
 #include "media/base/audio_bus.h"
 
 using base::TimeTicks;
 using base::TimeDelta;
 
 namespace media {
 
 namespace {
 
 // These values are based on experiments for local-to-local
 // PeerConnection to demonstrate audio/video synchronization.
 const int kBeepDurationMilliseconds = 20;
 const int kBeepFrequency = 400;
 
 // Intervals between two automatic beeps.
 const int kAutomaticBeepIntervalInMs = 500;
 
 // Automatic beep will be triggered every |kAutomaticBeepIntervalInMs| unless
 // users explicitly call BeepOnce(), which will disable the automatic beep.
-struct BeepContext {
-  BeepContext() : beep_once(false), automatic(true) {}
-  base::Lock beep_lock;
-  bool beep_once;
-  bool automatic;
+class BeepContext {

[henrika (OOO until Aug 14), 2014/07/17 11:21:59]

How are the changes related to this CL?

[no longer working on chromium, 2014/07/17 11:31:15]

Comment was addressed offline, this is a better way than using a global lock.

+ public:
+  BeepContext() : beep_once_(false), automatic_beep_(true) {}
+
+  void SetBeepOnce(bool enable) {
+    base::AutoLock auto_lock(lock_);
+    beep_once_ = enable;
+
+    // Disable the automatic beep if users explicit set |beep_once_| to true.
+    if (enable)
+      automatic_beep_ = false;
+  }
+  bool beep_once() const {
+    base::AutoLock auto_lock(lock_);
+    return beep_once_;
+  }
+  bool automatic_beep() const {
+    base::AutoLock auto_lock(lock_);
+    return automatic_beep_;
+  }
+
+ private:
+  mutable base::Lock lock_;
+  bool beep_once_;
+  bool automatic_beep_;
 };
 
 static base::LazyInstance<BeepContext> g_beep_context =
     LAZY_INSTANCE_INITIALIZER;
 
 }  // namespace
 
 AudioInputStream* FakeAudioInputStream::MakeFakeStream(
     AudioManagerBase* manager,
     const AudioParameters& params) {
   return new FakeAudioInputStream(manager, params);
 }
 
 FakeAudioInputStream::FakeAudioInputStream(AudioManagerBase* manager,
                                            const AudioParameters& params)
     : audio_manager_(manager),
       callback_(NULL),
       buffer_size_((params.channels() * params.bits_per_sample() *
                     params.frames_per_buffer()) /
                    8),
       params_(params),
-      thread_("FakeAudioRecordingThread"),
+      task_runner_(manager->GetWorkerTaskRunner()),
       callback_interval_(base::TimeDelta::FromMilliseconds(
           (params.frames_per_buffer() * 1000) / params.sample_rate())),
       beep_duration_in_buffers_(kBeepDurationMilliseconds *
                                 params.sample_rate() /
                                 params.frames_per_buffer() /
                                 1000),
       beep_generated_in_buffers_(0),
       beep_period_in_frames_(params.sample_rate() / kBeepFrequency),
       frames_elapsed_(0),
-      audio_bus_(AudioBus::Create(params)) {
+      audio_bus_(AudioBus::Create(params)),
+      weak_factory_(this) {
+  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
 }
 
 FakeAudioInputStream::~FakeAudioInputStream() {}
 
 bool FakeAudioInputStream::Open() {
+  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
   buffer_.reset(new uint8[buffer_size_]);
   memset(buffer_.get(), 0, buffer_size_);
   audio_bus_->Zero();
   return true;
 }
 
 void FakeAudioInputStream::Start(AudioInputCallback* callback)  {
-  DCHECK(!thread_.IsRunning());
+  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
   DCHECK(!callback_);
   callback_ = callback;
   last_callback_time_ = TimeTicks::Now();
-  thread_.Start();
-  thread_.message_loop()->PostDelayedTask(
+  task_runner_->PostDelayedTask(
       FROM_HERE,
-      base::Bind(&FakeAudioInputStream::DoCallback, base::Unretained(this)),
+      base::Bind(&FakeAudioInputStream::DoCallback, weak_factory_.GetWeakPtr()),

[henrika (OOO until Aug 14), 2014/07/17 11:21:21]

Why do you need a weak pointer here?

[no longer working on chromium, 2014/07/17 11:22:48]

If Stop() is called before the task is executed, then the task will never be
executed, otherwise it will crash.

       callback_interval_);
 }
 
 void FakeAudioInputStream::DoCallback() {
   DCHECK(callback_);
 
   const TimeTicks now = TimeTicks::Now();
   base::TimeDelta next_callback_time =
       last_callback_time_ + callback_interval_ * 2 - now;
 
   // If we are falling behind, try to catch up as much as we can in the next
   // callback.
   if (next_callback_time < base::TimeDelta())
     next_callback_time = base::TimeDelta();
 
   // Accumulate the time from the last beep.
   interval_from_last_beep_ += now - last_callback_time_;
 
   last_callback_time_ = now;
 
   memset(buffer_.get(), 0, buffer_size_);
 
   bool should_beep = false;
   {
     BeepContext* beep_context = g_beep_context.Pointer();
-    base::AutoLock auto_lock(beep_context->beep_lock);
-    if (beep_context->automatic) {
+    if (beep_context->automatic_beep()) {
       base::TimeDelta delta = interval_from_last_beep_ -
           TimeDelta::FromMilliseconds(kAutomaticBeepIntervalInMs);
       if (delta > base::TimeDelta()) {
         should_beep = true;
         interval_from_last_beep_ = delta;
       }
     } else {
-      should_beep = beep_context->beep_once;
-      beep_context->beep_once = false;
+      should_beep = beep_context->beep_once();
+      beep_context->SetBeepOnce(false);
     }
   }
 
   // If this object was instructed to generate a beep or has started to
   // generate a beep sound.
   if (should_beep || beep_generated_in_buffers_) {
     // Compute the number of frames to output high value. Then compute the
     // number of bytes based on channels and bits per channel.
     int high_frames = beep_period_in_frames_ / 2;
     int high_bytes = high_frames * params_.bits_per_sample() *
@@ skipping 12 matching lines @@
     ++beep_generated_in_buffers_;
     if (beep_generated_in_buffers_ >= beep_duration_in_buffers_)
       beep_generated_in_buffers_ = 0;
   }
 
   audio_bus_->FromInterleaved(
       buffer_.get(), audio_bus_->frames(), params_.bits_per_sample() / 8);
   callback_->OnData(this, audio_bus_.get(), buffer_size_, 1.0);
   frames_elapsed_ += params_.frames_per_buffer();
 
-  thread_.message_loop()->PostDelayedTask(
+  task_runner_->PostDelayedTask(
       FROM_HERE,
-      base::Bind(&FakeAudioInputStream::DoCallback, base::Unretained(this)),
+      base::Bind(&FakeAudioInputStream::DoCallback, weak_factory_.GetWeakPtr()),
       next_callback_time);
 }
 
 void FakeAudioInputStream::Stop() {
-  thread_.Stop();
+  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
+  weak_factory_.InvalidateWeakPtrs();
   callback_ = NULL;
 }
 
 void FakeAudioInputStream::Close() {
+  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
   audio_manager_->ReleaseInputStream(this);
 }
 
 double FakeAudioInputStream::GetMaxVolume() {
+  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
   return 1.0;
 }
 
 void FakeAudioInputStream::SetVolume(double volume) {
+  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
 }
 
 double FakeAudioInputStream::GetVolume() {
+  DCHECK(audio_manager_->GetTaskRunner()->BelongsToCurrentThread());
   return 1.0;
 }
 
 void FakeAudioInputStream::SetAutomaticGainControl(bool enabled) {}
 
 bool FakeAudioInputStream::GetAutomaticGainControl() {
   return true;
 }
 
 // static
 void FakeAudioInputStream::BeepOnce() {
   BeepContext* beep_context = g_beep_context.Pointer();
-  base::AutoLock auto_lock(beep_context->beep_lock);
-  beep_context->beep_once = true;
-  beep_context->automatic = false;
+  beep_context->SetBeepOnce(true);
 }
 
 }  // namespace media