Commit b78f6f27 authored by Karl Tomlinson's avatar Karl Tomlinson
Browse files

bug 1191648 don't create audioprocess event when there is no listener r=padenot 

Creating the event added a reference to the ScriptProcessorNode, which wasn't
released until the AudioProcessingEvent was destroyed in
nsCycleCollector::FreeSnowWhite().

If another event is dispatched before cycle collection considers the
ScriptProcessorNode, then the node will not be collected.

Also, the reference count of the ScriptProcessorNode is no longer toggled
because this seemed to interfere with the cycle collection process.

--HG--
extra : rebase_source : 41878e716fe3fcc8f46f518be2a50d050b8ed14c
parent d03299a5

dom/media/webaudio/ScriptProcessorNode.cpp

+38 −21
Original line number Diff line number Diff line
@@ -379,19 +379,42 @@ private: 


      NS_IMETHOD Run() override

      {

        nsRefPtr<ScriptProcessorNode> node = static_cast<ScriptProcessorNode*>

          (mStream->Engine()->NodeMainThread());

        nsRefPtr<ThreadSharedFloatArrayBufferList> output;



        auto engine =

          static_cast<ScriptProcessorNodeEngine*>(mStream->Engine());

        {

          auto node = static_cast<ScriptProcessorNode*>

            (engine->NodeMainThread());

          if (!node) {

            return NS_OK;

          }

        AudioContext* context = node->Context();

        if (!context) {



          if (node->HasListenersFor(nsGkAtoms::onaudioprocess)) {

            output = DispatchAudioProcessEvent(node);

          }

          // The node may have been destroyed during event dispatch.

        }



        // Append it to our output buffer queue

        engine->GetSharedBuffers()->

          FinishProducingOutputBuffer(output, engine->mBufferSize);



        return NS_OK;

      }



      // Returns the output buffers if set in event handlers.

      ThreadSharedFloatArrayBufferList*

        DispatchAudioProcessEvent(ScriptProcessorNode* aNode)

      {

        AudioContext* context = aNode->Context();

        if (!context) {

          return nullptr;

        }



        AutoJSAPI jsapi;

        if (NS_WARN_IF(!jsapi.Init(node->GetOwner()))) {

          return NS_OK;

        if (NS_WARN_IF(!jsapi.Init(aNode->GetOwner()))) {

          return nullptr;

        }

        JSContext* cx = jsapi.cx();
@@ -401,10 +424,10 @@ private: 
          ErrorResult rv;

          inputBuffer =

            AudioBuffer::Create(context, mInputChannels.Length(),

                                node->BufferSize(),

                                aNode->BufferSize(),

                                context->SampleRate(), cx, rv);

          if (rv.Failed()) {

            return NS_OK;

            return nullptr;

          }

          // Put the channel data inside it

          for (uint32_t i = 0; i < mInputChannels.Length(); ++i) {
@@ -417,33 +440,27 @@ private: 
        // avoid creating the input buffer as well.  The AudioProcessingEvent class

        // knows how to lazily create them if needed once the script tries to access

        // them.  Otherwise, we may be able to get away without creating them!

        nsRefPtr<AudioProcessingEvent> event = new AudioProcessingEvent(node, nullptr, nullptr);

        nsRefPtr<AudioProcessingEvent> event =

          new AudioProcessingEvent(aNode, nullptr, nullptr);

        event->InitEvent(inputBuffer,

                         mInputChannels.Length(),

                         context->StreamTimeToDOMTime(mPlaybackTime));

        node->DispatchTrustedEvent(event);

        aNode->DispatchTrustedEvent(event);



        // Steal the output buffers if they have been set.

        // Don't create a buffer if it hasn't been used to return output;

        // FinishProducingOutputBuffer() will optimize output = null.

        // GetThreadSharedChannelsForRate() may also return null after OOM.

        nsRefPtr<ThreadSharedFloatArrayBufferList> output;

        if (event->HasOutputBuffer()) {

          ErrorResult rv;

          AudioBuffer* buffer = event->GetOutputBuffer(rv);

          // HasOutputBuffer() returning true means that GetOutputBuffer()

          // will not fail.

          MOZ_ASSERT(!rv.Failed());

          output = buffer->GetThreadSharedChannelsForRate(cx);

          return buffer->GetThreadSharedChannelsForRate(cx);

        }



        // Append it to our output buffer queue

        auto engine =

          static_cast<ScriptProcessorNodeEngine*>(mStream->Engine());

        engine->GetSharedBuffers()->

          FinishProducingOutputBuffer(output, node->BufferSize());



        return NS_OK;

        return nullptr;

      }

    private:

      nsRefPtr<AudioNodeStream> mStream;