bug 1205540 provide querying whether engines need to continue processing even without input r=padenot

--HG--
extra : rebase_source : 76545deae4cdc929f1b3ce4d10065f99f21a2ec3

dom/media/webaudio/AnalyserNode.cpp

@@ -83,6 +83,11 @@ public:
     NS_DispatchToMainThread(transfer);
   }
 
+  virtual bool IsActive() const override
+  {
+    return mChunksToProcess != 0;
+  }
+
   virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const override
   {
     return aMallocSizeOf(this) + SizeOfExcludingThis(aMallocSizeOf);

dom/media/webaudio/AudioBufferSourceNode.cpp

@@ -508,6 +508,12 @@ public:
     }
   }
 
+  virtual bool IsActive() const override
+  {
+    // Whether buffer has been set and start() has been called.
+    return mBufferSampleRate != 0;
+  }
+
   virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
   {
     // Not owned:

dom/media/webaudio/AudioDestinationNode.cpp

@@ -112,6 +112,14 @@ public:
     }
   }
 
+  virtual bool IsActive() const override
+  {
+    // Keep processing to track stream time, which is used for all timelines
+    // associated with the same AudioContext.
+    return true;
+  }
+
+
   class OnCompleteTask final : public nsRunnable
   {
   public:
@@ -255,6 +263,16 @@ public:
     }
   }
 
+  virtual bool IsActive() const override
+  {
+    // Keep processing to track stream time, which is used for all timelines
+    // associated with the same AudioContext.  If there are no other engines
+    // for the AudioContext, then this could return false to suspend the
+    // stream, but the stream is blocked anyway through
+    // AudioDestinationNode::SetIsOnlyNodeForContext().
+    return true;
+  }
+
   virtual void SetDoubleParameter(uint32_t aIndex, double aParam) override
   {
     if (aIndex == VOLUME) {

dom/media/webaudio/AudioNodeEngine.h

@@ -346,6 +346,12 @@ public:
                                     OutputChunks& aOutput,
                                     bool* aFinished);
 
+  // IsActive() returns true if the engine needs to continue processing an
+  // unfinished stream even when it has silent or no input connections.  This
+  // includes tail-times and when sources have been scheduled to start.  If
+  // returning false, then the stream can be suspended.
+  virtual bool IsActive() const { return false; }
+
   bool HasNode() const
   {
     MOZ_ASSERT(NS_IsMainThread());

dom/media/webaudio/BiquadFilterNode.cpp

@@ -211,6 +211,11 @@ public:
     }
   }
 
+  virtual bool IsActive() const override
+  {
+    return !mBiquads.IsEmpty();
+  }
+
   virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
   {
     // Not owned:

dom/media/webaudio/ConvolverNode.cpp

@@ -154,6 +154,11 @@ public:
     mReverb->process(&input, aOutput, WEBAUDIO_BLOCK_SIZE);
   }
 
+  virtual bool IsActive() const override
+  {
+    return mLeftOverData != INT32_MIN;
+  }
+
   virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
   {
     size_t amount = AudioNodeEngine::SizeOfExcludingThis(aMallocSizeOf);

dom/media/webaudio/DelayNode.cpp

@@ -161,6 +161,11 @@ public:
     mHaveProducedBeforeInput = true;
   }
 
+  virtual bool IsActive() const override
+  {
+    return mLeftOverData != INT32_MIN;
+  }
+
   virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
   {
     size_t amount = AudioNodeEngine::SizeOfExcludingThis(aMallocSizeOf);

dom/media/webaudio/OscillatorNode.cpp

@@ -330,6 +330,12 @@ public:
 
   }
 
+  virtual bool IsActive() const override
+  {
+    // start() has been called.
+    return mStart != -1;
+  }
+
   virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
   {
     size_t amount = AudioNodeEngine::SizeOfExcludingThis(aMallocSizeOf);

dom/media/webaudio/PannerNode.cpp

@@ -172,6 +172,11 @@ public:
     (this->*mPanningModelFunction)(aInput, aOutput);
   }
 
+  virtual bool IsActive() const override
+  {
+    return mLeftOverData != INT_MIN;
+  }
+
   void ComputeAzimuthAndElevation(float& aAzimuth, float& aElevation);
   float ComputeConeGain();
   // Compute how much the distance contributes to the gain reduction.

dom/media/webaudio/ScriptProcessorNode.cpp

@@ -333,6 +333,14 @@ public:
     }
   }
 
+  virtual bool IsActive() const override
+  {
+    // Could return false when !mIsConnected after all output chunks produced
+    // by main thread events calling
+    // SharedBuffers::FinishProducingOutputBuffer() have been processed.
+    return true;
+  }
+
   virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const override
   {
     // Not owned: