Bug 952893. Part 1: Block the AudioDestinationNode when it's the only node in the AudioContext. r=padenot

content/media/AudioNodeStream.cpp

@@ -10,6 +10,7 @@
 #include "ThreeDPoint.h"
 #include "AudioChannelFormat.h"
 #include "AudioParamTimeline.h"
+#include "AudioContext.h"
 
 using namespace mozilla::dom;
 
@@ -30,7 +31,7 @@ AudioNodeStream::~AudioNodeStream()
 }
 
 void
-AudioNodeStream::SetStreamTimeParameter(uint32_t aIndex, MediaStream* aRelativeToStream,
+AudioNodeStream::SetStreamTimeParameter(uint32_t aIndex, AudioContext* aContext,
                                         double aStreamTime)
 {
   class Message : public ControlMessage {
@@ -50,7 +51,9 @@ AudioNodeStream::SetStreamTimeParameter(uint32_t aIndex, MediaStream* aRelativeT
   };
 
   MOZ_ASSERT(this);
-  GraphImpl()->AppendMessage(new Message(this, aIndex, aRelativeToStream, aStreamTime));
+  GraphImpl()->AppendMessage(new Message(this, aIndex,
+      aContext->DestinationStream(),
+      aStreamTime - aContext->ExtraCurrentTime()));
 }
 
 void

content/media/AudioNodeStream.h

@@ -16,6 +16,7 @@ namespace dom {
 struct ThreeDPoint;
 class AudioParamTimeline;
 class DelayNodeEngine;
+class AudioContext;
 }
 
 class ThreadSharedFloatArrayBufferList;
@@ -33,6 +34,8 @@ class AudioNodeEngine;
  */
 class AudioNodeStream : public ProcessedMediaStream {
 public:
+  typedef mozilla::dom::AudioContext AudioContext;
+
   enum { AUDIO_TRACK = 1 };
 
   typedef nsAutoTArray<AudioChunk, 1> OutputChunks;
@@ -66,7 +69,7 @@ public:
    * Sets a parameter that's a time relative to some stream's played time.
    * This time is converted to a time relative to this stream when it's set.
    */
-  void SetStreamTimeParameter(uint32_t aIndex, MediaStream* aRelativeToStream,
+  void SetStreamTimeParameter(uint32_t aIndex, AudioContext* aContext,
                               double aStreamTime);
   void SetDoubleParameter(uint32_t aIndex, double aValue);
   void SetInt32Parameter(uint32_t aIndex, int32_t aValue);

content/media/webaudio/AudioBufferSourceNode.cpp

@@ -532,7 +532,7 @@ AudioBufferSourceNode::Start(double aWhen, double aOffset,
 
   // Don't set parameter unnecessarily
   if (aWhen > 0.0) {
-    ns->SetStreamTimeParameter(START, Context()->DestinationStream(), aWhen);
+    ns->SetStreamTimeParameter(START, Context(), aWhen);
   }
 
   MarkActive();
@@ -616,8 +616,7 @@ AudioBufferSourceNode::Stop(double aWhen, ErrorResult& aRv)
     return;
   }
 
-  ns->SetStreamTimeParameter(STOP, Context()->DestinationStream(),
-                             std::max(0.0, aWhen));
+  ns->SetStreamTimeParameter(STOP, Context(), std::max(0.0, aWhen));
 }
 
 void

content/media/webaudio/AudioContext.cpp

@@ -84,6 +84,7 @@ AudioContext::AudioContext(nsPIDOMWindow* aWindow,
   : nsDOMEventTargetHelper(aWindow)
   , mSampleRate(GetSampleRateForAudioContext(aIsOffline, aSampleRate))
   , mNumberOfChannels(aNumberOfChannels)
+  , mNodeCount(0)
   , mIsOffline(aIsOffline)
   , mIsStarted(!aIsOffline)
   , mIsShutDown(false)
@@ -95,6 +96,10 @@ AudioContext::AudioContext(nsPIDOMWindow* aWindow,
   mDestination = new AudioDestinationNode(this, aIsOffline, aNumberOfChannels,
                                           aLength, aSampleRate);
   mDestination->Stream()->AddAudioOutput(&gWebAudioOutputKey);
+  // We skip calling SetIsOnlyNodeForContext during mDestination's constructor,
+  // because we can only call SetIsOnlyNodeForContext after mDestination has
+  // been set up.
+  mDestination->SetIsOnlyNodeForContext(true);
 }
 
 AudioContext::~AudioContext()
@@ -543,7 +548,8 @@ AudioContext::DestinationStream() const
 double
 AudioContext::CurrentTime() const
 {
-  return MediaTimeToSeconds(Destination()->Stream()->GetCurrentTime());
+  return MediaTimeToSeconds(Destination()->Stream()->GetCurrentTime()) +
+      Destination()->ExtraCurrentTime();
 }
 
 void
@@ -589,6 +595,18 @@ AudioContext::Resume()
   }
 }
 
+void
+AudioContext::UpdateNodeCount(int32_t aDelta)
+{
+  bool firstNode = mNodeCount == 0;
+  mNodeCount += aDelta;
+  MOZ_ASSERT(mNodeCount >= 0);
+  // mDestinationNode may be null when we're destroying nodes unlinked by CC
+  if (!firstNode && mDestination) {
+    mDestination->SetIsOnlyNodeForContext(mNodeCount == 1);
+  }
+}
+
 JSContext*
 AudioContext::GetJSContext() const
 {
@@ -679,5 +697,11 @@ AudioContext::CollectReports(nsIHandleReportCallback* aHandleReport,
                             amount, "Memory used by AudioContext objects (Web Audio).");
 }
 
+double
+AudioContext::ExtraCurrentTime() const
+{
+  return mDestination->ExtraCurrentTime();
+}
+
 }
 }

content/media/webaudio/AudioContext.h

@@ -246,6 +246,12 @@ public:
   AudioChannel MozAudioChannelType() const;
   void SetMozAudioChannelType(AudioChannel aValue, ErrorResult& aRv);
 
+  void UpdateNodeCount(int32_t aDelta);
+
+  // Returns the difference between CurrentTime() and the current time of the
+  // AudioDestinationNode's MediaStream.
+  double ExtraCurrentTime() const;
+
 private:
   void RemoveFromDecodeQueue(WebAudioDecodeJob* aDecodeJob);
   void ShutdownDecoder();
@@ -272,6 +278,8 @@ private:
   nsTHashtable<nsPtrHashKey<PannerNode> > mPannerNodes;
   // Number of channels passed in the OfflineAudioContext ctor.
   uint32_t mNumberOfChannels;
+  // Number of nodes that currently exist for this AudioContext
+  int32_t mNodeCount;
   bool mIsOffline;
   bool mIsStarted;
   bool mIsShutDown;

content/media/webaudio/AudioDestinationNode.cpp

@@ -17,6 +17,8 @@
 #include "nsIPermissionManager.h"
 #include "nsIScriptObjectPrincipal.h"
 #include "nsServiceManagerUtils.h"
+#include "nsIAppShell.h"
+#include "nsWidgetsCID.h"
 
 namespace mozilla {
 namespace dom {
@@ -217,6 +219,8 @@ AudioDestinationNode::AudioDestinationNode(AudioContext* aContext,
   , mAudioChannel(AudioChannel::Normal)
   , mIsOffline(aIsOffline)
   , mHasFinished(false)
+  , mExtraCurrentTime(0)
+  , mExtraCurrentTimeUpdatedSinceLastStableState(false)
 {
   MediaStreamGraph* graph = aIsOffline ?
                             MediaStreamGraph::CreateNonRealtimeInstance() :
@@ -486,6 +490,62 @@ AudioDestinationNode::CreateAudioChannelAgent()
   mAudioChannelAgent->StartPlaying(&state);
   SetCanPlay(state == AudioChannelState::AUDIO_CHANNEL_STATE_NORMAL);
 }
+
+void
+AudioDestinationNode::NotifyStableState()
+{
+  mExtraCurrentTimeUpdatedSinceLastStableState = false;
+}
+
+static NS_DEFINE_CID(kAppShellCID, NS_APPSHELL_CID);
+
+void
+AudioDestinationNode::ScheduleStableStateNotification()
+{
+  nsCOMPtr<nsIAppShell> appShell = do_GetService(kAppShellCID);
+  if (appShell) {
+    nsCOMPtr<nsIRunnable> event =
+      NS_NewRunnableMethod(this, &AudioDestinationNode::NotifyStableState);
+    appShell->RunInStableState(event);
+  }
+}
+
+double
+AudioDestinationNode::ExtraCurrentTime()
+{
+  if (!mStartedBlockingDueToBeingOnlyNode.IsNull() &&
+      !mExtraCurrentTimeUpdatedSinceLastStableState) {
+    mExtraCurrentTimeUpdatedSinceLastStableState = true;
+    mExtraCurrentTimeSinceLastStartedBlocking =
+      (TimeStamp::Now() - mStartedBlockingDueToBeingOnlyNode).ToSeconds();
+    ScheduleStableStateNotification();
+  }
+  return mExtraCurrentTime + mExtraCurrentTimeSinceLastStartedBlocking;
+}
+
+void
+AudioDestinationNode::SetIsOnlyNodeForContext(bool aIsOnlyNode)
+{
+  if (!mStartedBlockingDueToBeingOnlyNode.IsNull() == aIsOnlyNode) {
+    return;
+  }
+
+  if (aIsOnlyNode) {
+    mStream->ChangeExplicitBlockerCount(1);
+    mStartedBlockingDueToBeingOnlyNode = TimeStamp::Now();
+    mExtraCurrentTimeSinceLastStartedBlocking = 0;
+    // Don't do an update of mExtraCurrentTimeSinceLastStartedBlocking until the next stable state.
+    mExtraCurrentTimeUpdatedSinceLastStableState = true;
+    ScheduleStableStateNotification();
+  } else {
+    // Force update of mExtraCurrentTimeSinceLastStartedBlocking if necessary
+    ExtraCurrentTime();
+    mExtraCurrentTime += mExtraCurrentTimeSinceLastStartedBlocking;
+    mStream->ChangeExplicitBlockerCount(-1);
+    mStartedBlockingDueToBeingOnlyNode = TimeStamp();
+  }
+}
+
 }
 
 }

content/media/webaudio/AudioDestinationNode.h

@@ -70,12 +70,22 @@ public:
   virtual void NotifyMainThreadStateChanged() MOZ_OVERRIDE;
   void FireOfflineCompletionEvent();
 
+  // An amount that should be added to the MediaStream's current time to
+  // get the AudioContext.currentTime.
+  double ExtraCurrentTime();
+
+  // When aIsOnlyNode is true, this is the only node for the AudioContext.
+  void SetIsOnlyNodeForContext(bool aIsOnlyNode);
+
 private:
   bool CheckAudioChannelPermissions(AudioChannel aValue);
   void CreateAudioChannelAgent();
 
   void SetCanPlay(bool aCanPlay);
 
+  void NotifyStableState();
+  void ScheduleStableStateNotification();
+
   SelfReference<AudioDestinationNode> mOfflineRenderingRef;
   uint32_t mFramesToProduce;
 
@@ -83,8 +93,16 @@ private:
 
   // Audio Channel Type.
   AudioChannel mAudioChannel;
+<<<<<<< /home/roc/mozilla-central/content/media/webaudio/AudioDestinationNode.h
   bool mIsOffline;
   bool mHasFinished;
+=======
+
+  TimeStamp mStartedBlockingDueToBeingOnlyNode;
+  double mExtraCurrentTime;
+  double mExtraCurrentTimeSinceLastStartedBlocking;
+  bool mExtraCurrentTimeUpdatedSinceLastStableState;
+>>>>>>> /tmp/AudioDestinationNode.h~other.MvuUBx
 };
 
 }

content/media/webaudio/AudioNode.cpp

@@ -19,6 +19,7 @@ NS_IMPL_CYCLE_COLLECTION_CLASS(AudioNode)
 
 NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(AudioNode, nsDOMEventTargetHelper)
   tmp->DisconnectFromGraph();
+  tmp->mContext->UpdateNodeCount(-1);
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mContext)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mOutputNodes)
   NS_IMPL_CYCLE_COLLECTION_UNLINK(mOutputParams)
@@ -58,6 +59,9 @@ AudioNode::AudioNode(AudioContext* aContext,
   , mChannelInterpretation(aChannelInterpretation)
 {
   MOZ_ASSERT(aContext);
+  nsDOMEventTargetHelper::BindToOwner(aContext->GetParentObject());
+  SetIsDOMBinding();
+  aContext->UpdateNodeCount(1);
 }
 
 AudioNode::~AudioNode()
@@ -65,6 +69,9 @@ AudioNode::~AudioNode()
   MOZ_ASSERT(mInputNodes.IsEmpty());
   MOZ_ASSERT(mOutputNodes.IsEmpty());
   MOZ_ASSERT(mOutputParams.IsEmpty());
+  if (mContext) {
+    mContext->UpdateNodeCount(-1);
+  }
 }
 
 template <class InputNode>

content/media/webaudio/OscillatorNode.cpp

@@ -578,8 +578,7 @@ OscillatorNode::Start(double aWhen, ErrorResult& aRv)
 
   // TODO: Perhaps we need to do more here.
   ns->SetStreamTimeParameter(OscillatorNodeEngine::START,
-                             Context()->DestinationStream(),
-                             aWhen);
+                             Context(), aWhen);
 
   MarkActive();
 }
@@ -605,8 +604,7 @@ OscillatorNode::Stop(double aWhen, ErrorResult& aRv)
 
   // TODO: Perhaps we need to do more here.
   ns->SetStreamTimeParameter(OscillatorNodeEngine::STOP,
-                             Context()->DestinationStream(),
-                             std::max(0.0, aWhen));
+                             Context(), std::max(0.0, aWhen));
 }
 
 void

content/media/webaudio/moz.build

@@ -9,6 +9,7 @@ PARALLEL_DIRS += ['blink', 'test']
 TEST_TOOL_DIRS += ['compiledtest']
 
 EXPORTS += [
+    'AudioContext.h',
     'AudioParamTimeline.h',
     'MediaBufferDecoder.h',
     'ThreeDPoint.h',