Bug 848954 - Part 15 - Allow an AudioCallbackDriver to sleep to save power. r=roc

content/media/GraphDriver.cpp

@@ -331,7 +331,6 @@ SystemClockDriver::WaitForNextIteration()
     mWaitState = WAITSTATE_WAITING_FOR_NEXT_ITERATION;
   } else {
     mWaitState = WAITSTATE_WAITING_INDEFINITELY;
-    mGraphImpl->PausedIndefinitly();
   }
   if (timeout > 0) {
     mGraphImpl->GetMonitor().Wait(timeout);
@@ -340,7 +339,6 @@ SystemClockDriver::WaitForNextIteration()
           (TimeStamp::Now() - now).ToSeconds()));
   }
 
-  mGraphImpl->ResumedFromPaused();
   mWaitState = WAITSTATE_RUNNING;
   mNeedAnotherIteration = false;
 }
@@ -445,6 +443,13 @@ AsyncCubebTask::Run()
       mDriver->Stop();
       mDriver = nullptr;
       break;
+    case AsyncCubebOperation::SLEEP: {
+      MonitorAutoLock mon(mDriver->mGraphImpl->GetMonitor());
+      mDriver->Stop();
+      mDriver->mGraphImpl->GetMonitor().Wait(PR_INTERVAL_NO_TIMEOUT);
+      STREAM_LOG(PR_LOG_DEBUG, ("Restarting audio stream from sleep."));
+      mDriver->Start();
+    }
     default:
       MOZ_CRASH("Operation not implemented.");
   }
@@ -602,6 +607,19 @@ AudioCallbackDriver::GetCurrentTime()
   return mSampleRate * position;
 }
 
+void AudioCallbackDriver::WaitForNextIteration()
+{
+  // We can't block on the monitor in the audio callback, so we kick off a new
+  // thread that will pause the audio stream, and restart it when unblocked.
+  if (!mNeedAnotherIteration) {
+    mWaitState = WAITSTATE_WAITING_INDEFINITELY;
+    STREAM_LOG(PR_LOG_DEBUG+1, ("AudioCallbackDriver going to sleep"));
+    nsRefPtr<AsyncCubebTask> sleepEvent =
+      new AsyncCubebTask(this, AsyncCubebTask::SLEEP);
+    sleepEvent->Dispatch();
+  }
+}
+
 void
 AudioCallbackDriver::WakeUp()
 {
@@ -720,6 +738,7 @@ AudioCallbackDriver::DataCallback(AudioDataValue* aBuffer, long aFrames)
     mBuffer.BufferFilled();
   }
 
+  WaitForNextIteration();
 
   if (mNextDriver && stillProcessing) {
     {

content/media/GraphDriver.h

@@ -340,7 +340,8 @@ class AsyncCubebTask : public nsRunnable
 public:
   enum AsyncCubebOperation {
     INIT,
-    SHUTDOWN
+    SHUTDOWN,
+    SLEEP
   };
 
 
@@ -406,7 +407,7 @@ public:
   virtual void GetIntervalForIteration(GraphTime& aFrom,
                                        GraphTime& aTo) MOZ_OVERRIDE;
   virtual GraphTime GetCurrentTime() MOZ_OVERRIDE;
-  virtual void WaitForNextIteration() MOZ_OVERRIDE { }
+  virtual void WaitForNextIteration() MOZ_OVERRIDE;
   virtual void WakeUp() MOZ_OVERRIDE;
 
   /* Static wrapper function cubeb calls back. */

content/media/MediaStreamGraph.cpp

@@ -1227,42 +1227,6 @@ MediaStreamGraphImpl::AllFinishedStreamsNotified()
   return true;
 }
 
-void MediaStreamGraphImpl::PausedIndefinitly()
-{
-  PauseAllAudioOutputs();
-}
-
-void MediaStreamGraphImpl::ResumedFromPaused()
-{
-  ResumeAllAudioOutputs();
-}
-
-void
-MediaStreamGraphImpl::PauseAllAudioOutputs()
-{
-  if (mAudioOutputsPaused) {
-    return;
-  }
-  if (mMixedAudioStream) {
-    mMixedAudioStream->Pause();
-  }
-  mAudioOutputsPaused = true;
-}
-
-void
-MediaStreamGraphImpl::ResumeAllAudioOutputs()
-{
-  if (!mAudioOutputsPaused) {
-    return;
-  }
-
-  if (mMixedAudioStream) {
-    mMixedAudioStream->Resume();
-  }
-
-  mAudioOutputsPaused = false;
-}
-
 void
 MediaStreamGraphImpl::UpdateGraph(GraphTime aEndBlockingDecision)
 {
@@ -2698,7 +2662,6 @@ MediaStreamGraphImpl::MediaStreamGraphImpl(bool aRealtime,
   , mSelfRef(MOZ_THIS_IN_INITIALIZER_LIST())
   , mAudioStreamSizes()
   , mNeedsMemoryReport(false)
-  , mAudioOutputsPaused(false)
 #ifdef DEBUG
   , mCanRunMessagesSynchronously(false)
 #endif

content/media/MediaStreamGraphImpl.h

@@ -371,14 +371,6 @@ public:
   {
     mStreamOrderDirty = true;
   }
-  /**
-   * Pause all AudioStreams being written to by MediaStreams
-   */
-  void PauseAllAudioOutputs();
-  /**
-   * Resume all AudioStreams being written to by MediaStreams
-   */
-  void ResumeAllAudioOutputs();
 
   TrackRate AudioSampleRate() const { return mSampleRate; }
   TrackRate GraphRate() const { return mSampleRate; }
@@ -634,12 +626,6 @@ private:
    */
   bool mNeedsMemoryReport;
 
-  /**
-   * True if the audio outputs are paused because they would output silence
-   * anyway.
-   */
-  bool mAudioOutputsPaused;
-
 #ifdef DEBUG
   /**
    * Used to assert when AppendMessage() runs ControlMessages synchronously.