Oilpan: WebAudio: Apply the weak HashMap pattern to remove an entry from AudioContext::m_dirtyAudio…

Source/modules/webaudio/AudioSummingJunction.cpp

 /*
  * Copyright (C) 2012, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 20 matching lines @@
 #include "modules/webaudio/AudioContext.h"
 #include "modules/webaudio/AudioNodeOutput.h"
 #include <algorithm>
 
 namespace WebCore {
 
 AudioSummingJunction::AudioSummingJunction(AudioContext* context)
     : m_context(context)
     , m_renderingStateNeedUpdating(false)
 {
+    ASSERT(context);
+#if ENABLE(OILPAN)
+    m_context->registerLiveAudioSummingJunction(*this);

[haraken, 2014/07/18 10:01:01]

Instead of registering an AudioSummingJunction when it's created, would it be
possible to only register the AudioSummingJunction when
markSummingJunctionDirty() is called?

What m_liveAudioSummingJunctions has to manage is a list of
AudioSummingJunctions that are in m_dirtySummingJunctions (not a list of all
AudioSummingJunctions).

[tkent, 2014/07/18 13:43:09]

We can't do it.  markSummingJunctionDirty can be called in audio thread, we want
to avoid multi-thread access to m_liveAudioSummingJunctions.

[haraken, 2014/07/18 13:49:01]

Makes sense. Probably we can add a comment and mention that.
m_liveAudioSummingJunctions can contain AudioSummingJunctions that are not in
m_dirtySummingJunctions. Thus we can m_dirtySummingJunctions.remove() for
AudioSummingJunctions that are not contained in the m_dirtySummingJunctions, but
that's no problem.

+#endif
 }
 
 AudioSummingJunction::~AudioSummingJunction()
 {
-    // Oilpan: m_context is null if AudioContext and this object die
-    // together. It's non-null if this object dies before AudioContext.
+#if !ENABLE(OILPAN)
     if (m_renderingStateNeedUpdating && m_context.get())
         m_context->removeMarkedSummingJunction(this);
+#endif
 }
 
 void AudioSummingJunction::trace(Visitor* visitor)
 {
     visitor->trace(m_context);
 }
 
 void AudioSummingJunction::changedOutputs()
 {
     ASSERT(context()->isGraphOwner());
@@ skipping 19 matching lines @@
 
         didUpdate();
 
         m_renderingStateNeedUpdating = false;
     }
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)