Implement suspend() and resume() for OfflineAudioContext

Source/modules/webaudio/OfflineAudioContext.h

 /*
  * 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 21 matching lines @@
 
 class ExceptionState;
 
 class MODULES_EXPORT OfflineAudioContext final : public AudioContext {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static OfflineAudioContext* create(ExecutionContext*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate, ExceptionState&);
 
     virtual ~OfflineAudioContext();
 
+    // Check all the scheduled suspends if the context should suspend at
+    // currentTime(). Then post tasks to resolve promises on the main thread
+    // if necessary.
+    bool shouldSuspendNow();
+
+    // Clear suspensions marked as 'resolved' in the list.
+    void resolvePendingSuspendPromises();
+
+    // Fire completion event when the rendering is finished.
+    void fireCompletionEvent();
+
+    DEFINE_ATTRIBUTE_EVENT_LISTENER(complete);
+
     ScriptPromise startOfflineRendering(ScriptState*);
+    ScriptPromise suspendOfflineRendering(ScriptState*, double);
+    ScriptPromise resumeOfflineRendering(ScriptState*);
+
 private:
     OfflineAudioContext(Document*, unsigned numberOfChannels, size_t numberOfFrames, float sampleRate);
+
+    // A container class for a pair of time information and the suspend promise
+    // resolver.
+    class ScheduledSuspendContainer
+    : public NoBaseWillBeGarbageCollected<ScheduledSuspendContainer> {
+    public:
+        static PassOwnPtr<ScheduledSuspendContainer> create(size_t suspendFrame, PassRefPtrWillBeRawPtr<ScriptPromiseResolver>);
+        ~ScheduledSuspendContainer();
+        PassRefPtrWillBeRawPtr<ScriptPromiseResolver> resolver() { return m_resolver; }
+
+        // Query if the rendering should be suspended at |whenFrame|.
+        bool shouldSuspendAt(size_t whenFrame) const;
+
+        // Query if the suspend is pending for the promise resolution.
+        bool isPending() const;
+
+        // Mark the suspend as 'pending'.

[Raymond Toy, 2015/06/12 21:11:37]

Describe better what pending means.

[hongchan, 2015/06/15 18:40:46]

Done.

+        void markAsPending();
+
+        DECLARE_TRACE();
+
+    private:
+        ScheduledSuspendContainer(size_t suspendFrame, PassRefPtrWillBeRawPtr<ScriptPromiseResolver>);
+
+        // Suspend time in samples.
+        size_t m_suspendFrame;
+
+        // Associated promise resolver.
+        RefPtrWillBeMember<ScriptPromiseResolver> m_resolver;
+
+        // A pending marker for the safe batch removal.
+        bool m_isPending;
+    };
+
+    // Resolve pending suspend promises and removes it from the list.
+    void resolvePendingSuspendPromisesOnMainThread();
+
+    WillBeHeapVector<OwnPtrWillBeMember<ScheduledSuspendContainer>> m_scheduledSuspends;
+    RefPtrWillBeMember<ScriptPromiseResolver> m_completeResolver;
+
+    // This flag is necessary to indicate the rendering has actually started.
+    // Note that initial state of context is 'Suspended', which is the same
+    // state when the context is suspended.
+    bool m_isRenderingStarted;
+
+    // Total render sample length.
+    size_t m_totalRenderFrames;
 };
 
 } // namespace blink
 
 #endif // OfflineAudioContext_h