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_didInitializeContextGraphMutex(false)
+    , m_isOfflineContext(false)
+    , m_destinationNode(nullptr)
     , 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_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_didInitializeContextGraphMutex(false)
+    , m_isOfflineContext(true)
+    , m_destinationNode(nullptr)
     , 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_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 567 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, 2015/05/28 16:37:35]

This change isn't really necessary, is it?

[hongchan, 2015/06/09 20:49:59]

No, I am reverting this in PS6.

 }
 
 void AudioContext::notifyStateChange()
 {
     dispatchEvent(Event::create(EventTypeNames::statechange));
 }
 
 ScriptPromise AudioContext::suspendContext(ScriptState* scriptState)
 {
     ASSERT(isMainThread());
+    ASSERT(!isOfflineContext());
+
     AutoLocker locker(this);
 
-    if (isOfflineContext()) {
-        return ScriptPromise::rejectWithDOMException(
-            scriptState,
-            DOMException::create(
-                InvalidAccessError,
-                "cannot suspend an OfflineAudioContext"));
-    }
-
     RefPtrWillBeRawPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
     if (m_contextState == Closed) {
         resolver->reject(
             DOMException::create(InvalidStateError, "Cannot suspend a context that has been closed"));
     } else {
         // Stop rendering now.
         if (m_destinationNode)
             stopRendering();
@@ skipping 185 matching lines @@
     return EventTargetNames::AudioContext;
 }
 
 ExecutionContext* AudioContext::executionContext() const
 {
     return m_isStopScheduled ? 0 : ActiveDOMObject::executionContext();
 }
 
 void AudioContext::startRendering()
 {
-    // This is called for both online and offline contexts.
+    // This is only for the real-time context.

[Raymond Toy, 2015/05/28 16:37:35]

Add assert for !isOfflineContext()?

[hongchan, 2015/06/09 20:49:59]

Done.

     ASSERT(isMainThread());
     ASSERT(m_destinationNode);
 
     if (m_contextState == Suspended) {
         destination()->audioDestinationHandler().startRendering();
         setContextState(Running);
     }
 }
 
 void AudioContext::stopRendering()
 {
     ASSERT(isMainThread());
     ASSERT(m_destinationNode);
     ASSERT(!isOfflineContext());
 
     if (m_contextState == Running) {
         destination()->audioDestinationHandler().stopRendering();
         setContextState(Suspended);
         deferredTaskHandler().clearHandlersToBeDeleted();
     }
 }
 
+bool AudioContext::shouldSuspendNow()

[Raymond Toy, 2015/05/28 16:37:35]

Can't this be a method just on an OfflineAudioContext?

[hongchan, 2015/06/09 20:49:58]

The problem is OAC is a very thin wrapper for AC. So calling context() inside of
OfflineAudioDestintion always goes to AudioContext first. That's why I made this
as public/virtual so I can override in OfflineAudioContext. Does it make sense?

[Raymond Toy, 2015/06/09 22:34:59]

Why not make context() be virtual? I don't know which would be better.

+{
+    ASSERT_WITH_MESSAGE(1, "shouldSuspendNow() only valid for offline audio context");
+    return false;
+}
+
 void AudioContext::fireCompletionEvent()

[Raymond Toy, 2015/05/28 16:37:35]

Could this be moved to the OfflineAudioContext class?

[hongchan, 2015/06/09 20:49:59]

The same reason above.

 {
-    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.
-    setContextState(Closed);
-
-    ASSERT(renderedBuffer);
-    if (!renderedBuffer)
-        return;
-
-    // Avoid firing the event if the document has already gone away.
-    if (executionContext()) {
-        // Call the offline rendering completion event listener and resolve the promise too.
-        dispatchEvent(OfflineAudioCompletionEvent::create(renderedBuffer));
-        m_offlineResolver->resolve(renderedBuffer);
-    }
+    ASSERT_WITH_MESSAGE(1, "fireCompletionEvent() only valid for offline audio context");
 }
 
 DEFINE_TRACE(AudioContext)
 {
     visitor->trace(m_closeResolver);
-    visitor->trace(m_offlineResolver);
     visitor->trace(m_renderTarget);
     visitor->trace(m_destinationNode);
     visitor->trace(m_listener);
     // trace() can be called in AudioContext constructor, and
     // m_contextGraphMutex might be unavailable.
     if (m_didInitializeContextGraphMutex) {
         AutoLocker lock(this);
         visitor->trace(m_activeSourceNodes);
     } else {
         visitor->trace(m_activeSourceNodes);
@@ skipping 36 matching lines @@
     // the destination node can GCed if JS has no references. stop() will also resolve the Promise
     // created here.
     stop();
 
     return promise;
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)