Bug 1087944 - Implement the promise version of OfflineAudioContext. r=ehsan,smaug

--HG--
extra : rebase_source : 1ede286a68f592038320ed5b82051bb9dd3cc0db

dom/media/webaudio/AudioContext.cpp

@@ -632,17 +632,21 @@ AudioContext::GetGlobalJSObject() const
   return parentObject->GetGlobalJSObject();
 }
 
-void
+already_AddRefed<Promise>
 AudioContext::StartRendering(ErrorResult& aRv)
 {
+  nsCOMPtr<nsIGlobalObject> parentObject = do_QueryInterface(GetParentObject());
+
   MOZ_ASSERT(mIsOffline, "This should only be called on OfflineAudioContext");
   if (mIsStarted) {
     aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
-    return;
+    return nullptr;
   }
 
   mIsStarted = true;
-  mDestination->StartRendering();
+  nsRefPtr<Promise> promise = Promise::Create(parentObject, aRv);
+  mDestination->StartRendering(promise);
+  return promise.forget();
 }
 
 void

dom/media/webaudio/AudioContext.h

@@ -191,7 +191,7 @@ public:
                   const Optional<OwningNonNull<DecodeErrorCallback> >& aFailureCallback);
 
   // OfflineAudioContext methods
-  void StartRendering(ErrorResult& aRv);
+  already_AddRefed<Promise> StartRendering(ErrorResult& aRv);
   IMPL_EVENT_HANDLER(complete)
 
   bool IsOffline() const { return mIsOffline; }

dom/media/webaudio/AudioDestinationNode.cpp

@@ -22,6 +22,7 @@
 #include "nsServiceManagerUtils.h"
 #include "nsIAppShell.h"
 #include "nsWidgetsCID.h"
+#include "mozilla/dom/Promise.h"
 
 namespace mozilla {
 namespace dom {
@@ -126,6 +127,28 @@ public:
     }
   }
 
+  class OnCompleteTask MOZ_FINAL : public nsRunnable
+  {
+  public:
+    OnCompleteTask(AudioContext* aAudioContext, AudioBuffer* aRenderedBuffer)
+      : mAudioContext(aAudioContext)
+      , mRenderedBuffer(aRenderedBuffer)
+    {}
+
+    NS_IMETHOD Run()
+    {
+      nsRefPtr<OfflineAudioCompletionEvent> event =
+          new OfflineAudioCompletionEvent(mAudioContext, nullptr, nullptr);
+      event->InitEvent(mRenderedBuffer);
+      mAudioContext->DispatchTrustedEvent(event);
+
+      return NS_OK;
+    }
+  private:
+    nsRefPtr<AudioContext> mAudioContext;
+    nsRefPtr<AudioBuffer> mRenderedBuffer;
+  };
+
   void FireOfflineCompletionEvent(AudioDestinationNode* aNode)
   {
     AudioContext* context = aNode->Context();
@@ -152,10 +175,11 @@ public:
       renderedBuffer->SetRawChannelContents(i, mInputChannels[i]);
     }
 
-    nsRefPtr<OfflineAudioCompletionEvent> event =
-        new OfflineAudioCompletionEvent(context, nullptr, nullptr);
-    event->InitEvent(renderedBuffer);
-    context->DispatchTrustedEvent(event);
+    aNode->ResolvePromise(renderedBuffer);
+
+    nsRefPtr<OnCompleteTask> task =
+      new OnCompleteTask(context, renderedBuffer);
+    NS_DispatchToMainThread(task);
   }
 
   virtual size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const MOZ_OVERRIDE
@@ -301,7 +325,8 @@ private:
 NS_IMPL_ISUPPORTS(EventProxyHandler, nsIDOMEventListener)
 
 NS_IMPL_CYCLE_COLLECTION_INHERITED(AudioDestinationNode, AudioNode,
-                                   mAudioChannelAgent, mEventProxyHelper)
+                                   mAudioChannelAgent, mEventProxyHelper,
+                                   mOfflineRenderingPromise)
 
 NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(AudioDestinationNode)
   NS_INTERFACE_MAP_ENTRY(nsIDOMEventListener)
@@ -415,6 +440,14 @@ AudioDestinationNode::FireOfflineCompletionEvent()
   engine->FireOfflineCompletionEvent(this);
 }
 
+void
+AudioDestinationNode::ResolvePromise(AudioBuffer* aRenderedBuffer)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  MOZ_ASSERT(mIsOffline);
+  mOfflineRenderingPromise->MaybeResolve(aRenderedBuffer);
+}
+
 uint32_t
 AudioDestinationNode::MaxChannelCount() const
 {
@@ -463,8 +496,9 @@ AudioDestinationNode::WrapObject(JSContext* aCx)
 }
 
 void
-AudioDestinationNode::StartRendering()
+AudioDestinationNode::StartRendering(Promise* aPromise)
 {
+  mOfflineRenderingPromise = aPromise;
   mOfflineRenderingRef.Take(this);
   mStream->Graph()->StartNonRealtimeProcessing(mFramesToProduce);
 }

dom/media/webaudio/AudioDestinationNode.h

@@ -54,7 +54,7 @@ public:
   void Mute();
   void Unmute();
 
-  void StartRendering();
+  void StartRendering(Promise* aPromise);
 
   void OfflineShutdown();
 
@@ -85,6 +85,7 @@ public:
   virtual size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const MOZ_OVERRIDE;
 
   void InputMuted(bool aInputMuted);
+  void ResolvePromise(AudioBuffer* aRenderedBuffer);
 
 protected:
   virtual ~AudioDestinationNode();
@@ -103,6 +104,7 @@ private:
   nsCOMPtr<nsIAudioChannelAgent> mAudioChannelAgent;
 
   nsRefPtr<EventProxyHandler> mEventProxyHelper;
+  nsRefPtr<Promise> mOfflineRenderingPromise;
 
   // Audio Channel Type.
   AudioChannel mAudioChannel;

dom/webidl/OfflineAudioContext.webidl

@@ -16,7 +16,7 @@ callback OfflineRenderSuccessCallback = void (AudioBuffer renderedData);
 interface OfflineAudioContext : AudioContext {
 
     [Throws]
-    void startRendering();
+    Promise<AudioBuffer> startRendering();
 
     attribute EventHandler oncomplete;