Implement suspend() and resume() for OfflineAudioContext

Source/modules/webaudio/AudioContext.cpp

 /*
  * Copyright (C) 2010, 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 81 matching lines @@
     }
 
     AudioContext* audioContext = new AudioContext(&document);
     audioContext->suspendIfNeeded();
     return audioContext;
 }
 
 // Constructor for rendering to the audio hardware.
 AudioContext::AudioContext(Document* document)
     : ActiveDOMObject(document)
+    , m_destinationNode(nullptr)
+    , m_didInitializeContextGraphMutex(false)
+    , m_contextState(Suspended)
     , m_isStopScheduled(false)
     , m_isCleared(false)
     , m_isInitialized(false)
-    , m_destinationNode(nullptr)
     , m_isResolvingResumePromises(false)
     , m_connectionCount(0)
-    , m_didInitializeContextGraphMutex(false)
     , m_deferredTaskHandler(DeferredTaskHandler::create())
     , m_isOfflineContext(false)
-    , m_contextState(Suspended)
     , m_cachedSampleFrame(0)
 {
     m_didInitializeContextGraphMutex = true;
     m_destinationNode = DefaultAudioDestinationNode::create(this);
 
     initialize();
 }
 
 // Constructor for offline (non-realtime) rendering.
 AudioContext::AudioContext(Document* document, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate)
     : ActiveDOMObject(document)
+    , m_destinationNode(nullptr)
+    , m_didInitializeContextGraphMutex(false)
+    , m_contextState(Suspended)
     , m_isStopScheduled(false)
     , m_isCleared(false)
     , m_isInitialized(false)
-    , m_destinationNode(nullptr)
     , m_isResolvingResumePromises(false)
     , m_connectionCount(0)
-    , m_didInitializeContextGraphMutex(false)
     , m_deferredTaskHandler(DeferredTaskHandler::create())
     , m_isOfflineContext(true)
-    , m_contextState(Suspended)
     , m_cachedSampleFrame(0)
 {
     m_didInitializeContextGraphMutex = true;
+
     // Create a new destination for offline rendering.
     m_renderTarget = AudioBuffer::create(numberOfChannels, numberOfFrames, sampleRate);
     if (m_renderTarget.get())
         m_destinationNode = OfflineAudioDestinationNode::create(this, m_renderTarget.get());
 
     initialize();
 }
 
 AudioContext::~AudioContext()
 {
@@ skipping 580 matching lines @@
     }
 
     if (newState == m_contextState) {
         // ASSERTs above failed; just return.
         return;
     }
 
     m_contextState = newState;
 
     // Notify context that state changed
-    if (executionContext())
-        executionContext()->postTask(FROM_HERE, createSameThreadTask(&AudioContext::notifyStateChange, this));
+    if (executionContext()) {
+        executionContext()->postTask(FROM_HERE,
+            createSameThreadTask(&AudioContext::notifyStateChange, this));
+    }

[Raymond Toy, 2015/05/13 17:16:08]

Why?

[hongchan, 2015/05/13 17:30:53]

Added some line breaks to make the code read better.

 }
 
 void AudioContext::notifyStateChange()
 {
     dispatchEvent(Event::create(EventTypeNames::statechange));
 }
 
 ScriptPromise AudioContext::suspendContext(ScriptState* scriptState)
 {
     ASSERT(isMainThread());
@@ skipping 268 matching lines @@
     ASSERT(m_destinationNode);
     ASSERT(!isOfflineContext());
 
     if (m_contextState == Running) {
         destination()->audioDestinationHandler().stopRendering();
         setContextState(Suspended);
         deferredTaskHandler().clearHandlersToBeDeleted();
     }
 }
 
+void AudioContext::fireSuspendEvent()
+{
+    ASSERT(isMainThread());
+    if (!isMainThread())
+        return;
+
+    // AudioBuffer* renderedBuffer = m_renderTarget.get();
+
+    setContextState(Suspended);
+
+    // ASSERT(renderedBuffer);
+    // if (!renderedBuffer)
+    //     return;
+
+    // Avoid firing the event if the document has already gone away.
+    // if (executionContext()) {
+    //     dispatchEvent(Event::create(EventTypeNames::statechange));
+    //     // m_offlineResolver->resolve(renderedBuffer);
+    // }
+}
+
 void AudioContext::fireCompletionEvent()
 {
     ASSERT(isMainThread());
     if (!isMainThread())
         return;
 
     AudioBuffer* renderedBuffer = m_renderTarget.get();
 
     // For an offline context, we set the state to closed here so that the oncomplete handler sees
     // that the context has been closed.
@@ skipping 62 matching lines @@
 
     // Stop the audio context. This will stop the destination node from pulling audio anymore. And
     // since we have disconnected the destination from the audio graph, and thus has no references,
     // the destination node can GCed if JS has no references. stop() will also resolve the Promise
     // created here.
     stop();
 
     return promise;
 }
 
+bool AudioContext::suspendIfNecessary()
+{
+    ASSERT_WITH_MESSAGE(1, "suspendIfNecessary() only valid for offline audio context");
+    return false;
+}
+
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)