Implement suspend() and resume() for OfflineAudioContext

Source/modules/webaudio/OfflineAudioContext.h

Index: Source/modules/webaudio/OfflineAudioContext.h
diff --git a/Source/modules/webaudio/OfflineAudioContext.h b/Source/modules/webaudio/OfflineAudioContext.h
index 99276e7cbb5e19dc7edf2934b67a726f2eed8d2a..b1db612069c09d532d456f8a76d471eb587305c7 100644
--- a/Source/modules/webaudio/OfflineAudioContext.h
+++ b/Source/modules/webaudio/OfflineAudioContext.h
@@ -27,10 +27,14 @@
 
 #include "modules/ModulesExport.h"
 #include "modules/webaudio/AudioContext.h"
+#include "wtf/HashMap.h"
 
 namespace blink {
 
 class ExceptionState;
+class ScheduledSuspendContainer;
+
+using SuspendContainerMap = HashMap<size_t, RefPtr<ScheduledSuspendContainer>>;

[hongchan, 2015/06/24 21:14:12]

I changed the vector to HashMap. I didn't use HeapHashMap since we decided to
ditch the oilpan on this variable.

 
 class MODULES_EXPORT OfflineAudioContext final : public AudioContext {
     DEFINE_WRAPPERTYPEINFO();
@@ -39,9 +43,94 @@ public:
 
     virtual ~OfflineAudioContext();
 
+    DECLARE_VIRTUAL_TRACE();
+
+    // Fire completion event when the rendering is finished.
+    void fireCompletionEvent() override;
+
+    // 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() override;
+
+    // Clear suspensions marked as 'resolved' in the list.
+    void resolvePendingSuspendPromises() override;
+
+    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);
+
+    // Validate a suspend with various criteria on the render thread.
+    void checkDuplicateSuspend(ScheduledSuspendContainer*);
+
+    // Reject a suspend on the main thread after the validation fails.
+    void rejectSuspendPromiseOnMainThread(ScheduledSuspendContainer*);
+
+    // Resolve pending suspend promises and removes them from the list.
+    void resolvePendingSuspendPromisesOnMainThread(ScheduledSuspendContainer*);
+
+    // Vector<RefPtr<ScheduledSuspendContainer>> m_scheduledSuspends;
+    SuspendContainerMap m_scheduledSuspends;

[hongchan, 2015/06/24 21:14:12]

This is HashMap of <size_t suspendFrame, RefPtr<SchduledSuspendContainer>>.

+    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;
+
+    bool m_isResolvingSuspendPromise;
+
+    // Total render sample length.
+    size_t m_totalRenderFrames;
+};
+
+// A container class for a pair of time information and the suspend promise
+// resolver.
+// TODO: This class is |ThreadSafeRefCounted| because it needs to be accessed by
+// the offline render thread which is not oilpan-enabled. This is a short-term
+// solution until the offline render thread gets oilpan coverage.
+class ScheduledSuspendContainer : public ThreadSafeRefCounted<ScheduledSuspendContainer> {
+public:
+    static ScheduledSuspendContainer* create(double suspendTime, size_t suspendFrame, PassRefPtrWillBeRawPtr<ScriptPromiseResolver>);

[yhirano, 2015/06/25 04:00:53]

static PassRefPtr<ScheduledSuspendContainer> create(...) {...}

[hongchan, 2015/06/25 23:34:13]

Done.

+    ~ScheduledSuspendContainer();
+
+    DECLARE_TRACE();

[yhirano, 2015/06/25 04:00:53]

No TRACE is needed.

[hongchan, 2015/06/25 23:34:13]

Removed.

+
+    PassRefPtrWillBeRawPtr<ScriptPromiseResolver> resolver() { return m_resolver; }
+
+    double suspendTime() const { return m_suspendTime; }
+
+    size_t suspendFrame() const { return m_suspendFrame; }
+
+    // Query if the rendering should be suspended at |whenFrame|.
+    bool shouldSuspendAtFrame(size_t whenFrame) const;
+
+    // Query if the suspend is pending for the promise resolution.
+    bool isPending() const;
+
+    // Mark the suspend as pending. Containers with 'pending' flag will
+    // be collectively resolved when the actual suspension happens.
+    void markAsPending();
+
+private:
+    ScheduledSuspendContainer(double suspendTime, size_t suspendFrame, PassRefPtrWillBeRawPtr<ScriptPromiseResolver>);
+
+    // Actual suspend time before the quantization by render quantum frame.
+    double m_suspendTime;
+
+    // Suspend time in samples.
+    size_t m_suspendFrame;
+
+    // Associated promise resolver.
+    RefPtrWillBeMember<ScriptPromiseResolver> m_resolver;

[yhirano, 2015/06/25 04:00:53]

RefPtrWillBePersistent

[hongchan, 2015/06/25 23:34:13]

Done.

+
+    // A pending marker for the safe batch removal.
+    bool m_isPending;
 };
 
 } // namespace blink