Bug 1144486 - Use state watching machinery for mReadyState updates. r…

…=jww

dom/html/HTMLMediaElement.cpp

@@ -636,7 +636,7 @@ void HTMLMediaElement::ShutdownDecoder()
   RemoveMediaElementFromURITable();
   NS_ASSERTION(mDecoder, "Must have decoder to shut down");
   mDecoder->Shutdown();
-  mDecoder = nullptr;
+  SetDecoder(nullptr);
 }
 
 void HTMLMediaElement::AbortExistingLoads()
@@ -700,7 +700,7 @@ void HTMLMediaElement::AbortExistingLoads()
   mPendingEncryptedInitData.mInitDatas.Clear();
 #endif // MOZ_EME
   mSourcePointer = nullptr;
-  mLastNextFrameStatus = NEXT_FRAME_UNINITIALIZED;
+  mNextFrameStatus = NEXT_FRAME_UNINITIALIZED;
 
   mTags = nullptr;
 
@@ -941,13 +941,13 @@ void HTMLMediaElement::NotifyMediaStreamTracksAvailable(DOMMediaStream* aStream)
 
   bool videoHasChanged = IsVideo() && HasVideo() != !VideoTracks()->IsEmpty();
 
-  UpdateReadyStateForData(mLastNextFrameStatus);
-
   if (videoHasChanged) {
     // We are a video element and HasVideo() changed so update the screen
     // wakelock
     NotifyOwnerDocumentActivityChanged();
   }
+
+  mReadyStateUpdater->Notify();
 }
 
 void HTMLMediaElement::LoadFromSourceChildren()
@@ -2045,8 +2045,9 @@ HTMLMediaElement::HTMLMediaElement(already_AddRefed<mozilla::dom::NodeInfo>& aNo
   : nsGenericHTMLElement(aNodeInfo),
     mCurrentLoadID(0),
     mNetworkState(nsIDOMHTMLMediaElement::NETWORK_EMPTY),
-    mReadyState(nsIDOMHTMLMediaElement::HAVE_NOTHING),
-    mLastNextFrameStatus(NEXT_FRAME_UNINITIALIZED),
+    mReadyState(nsIDOMHTMLMediaElement::HAVE_NOTHING, "HTMLMediaElement::mReadyState"),
+    mReadyStateUpdater("HTMLMediaElement::mReadyStateUpdater"),
+    mNextFrameStatus(NEXT_FRAME_UNINITIALIZED, "HTMLMediaElement::mNextFrameStatus"),
     mLoadWaitStatus(NOT_WAITING),
     mVolume(1.0),
     mPreloadAction(PRELOAD_UNDEFINED),
@@ -2087,7 +2088,7 @@ HTMLMediaElement::HTMLMediaElement(already_AddRefed<mozilla::dom::NodeInfo>& aNo
     mMediaSecurityVerified(false),
     mCORSMode(CORS_NONE),
     mIsEncrypted(false),
-    mDownloadSuspendedByCache(false),
+    mDownloadSuspendedByCache(false, "HTMLMediaElement::mDownloadSuspendedByCache"),
     mAudioChannelFaded(false),
     mPlayingThroughTheAudioChannel(false),
     mDisableVideo(false),
@@ -2100,6 +2101,7 @@ HTMLMediaElement::HTMLMediaElement(already_AddRefed<mozilla::dom::NodeInfo>& aNo
   if (!gMediaElementEventsLog) {
     gMediaElementEventsLog = PR_NewLogModule("nsMediaElementEvents");
   }
+  EnsureStateWatchingLog();
 #endif
 
   mAudioChannel = AudioChannelService::GetDefaultAudioChannel();
@@ -2108,6 +2110,14 @@ HTMLMediaElement::HTMLMediaElement(already_AddRefed<mozilla::dom::NodeInfo>& aNo
 
   RegisterActivityObserver();
   NotifyOwnerDocumentActivityChanged();
+
+  MOZ_ASSERT(NS_IsMainThread());
+  mReadyStateUpdater->AddWeakCallback(this, &HTMLMediaElement::UpdateReadyStateInternal);
+  mReadyStateUpdater->Watch(mNextFrameStatus);
+  mReadyStateUpdater->Watch(mDownloadSuspendedByCache);
+  // Paradoxically, there is a self-edge whereby UpdateReadyStateInternal refuses
+  // to run until mReadyState reaches at least HAVE_METADATA by some other means.
+  mReadyStateUpdater->Watch(mReadyState);
 }
 
 HTMLMediaElement::~HTMLMediaElement()
@@ -2604,8 +2614,8 @@ HTMLMediaElement::ReportMSETelemetry()
     ErrorResult ignore;
     stalled = index != TimeRanges::NoIndex &&
               (ranges->End(index, ignore) - t) < errorMargin;
-    stalled |= mLastNextFrameStatus == MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE_BUFFERING &&
-                                       mReadyState == HTMLMediaElement::HAVE_CURRENT_DATA;
+    stalled |= mNextFrameStatus == MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE_BUFFERING &&
+                                   mReadyState == HTMLMediaElement::HAVE_CURRENT_DATA;
     if (stalled) {
       state = STALLED;
     }
@@ -2751,7 +2761,7 @@ nsresult HTMLMediaElement::InitializeDecoderForChannel(nsIChannel* aChannel,
   // RtspMediaResource.
   if (DecoderTraits::DecoderWaitsForOnConnected(mimeType)) {
     decoder->SetResource(resource);
-    mDecoder = decoder;
+    SetDecoder(decoder);
     if (aListener) {
       *aListener = nullptr;
     }
@@ -2777,7 +2787,7 @@ nsresult HTMLMediaElement::FinishDecoderSetup(MediaDecoder* aDecoder,
   mPendingEvents.Clear();
   // Set mDecoder now so if methods like GetCurrentSrc get called between
   // here and Load(), they work.
-  mDecoder = aDecoder;
+  SetDecoder(aDecoder);
 
   // Tell the decoder about its MediaResource now so things like principals are
   // available immediately.
@@ -2802,7 +2812,7 @@ nsresult HTMLMediaElement::FinishDecoderSetup(MediaDecoder* aDecoder,
 
   nsresult rv = aDecoder->Load(aListener, aCloneDonor);
   if (NS_FAILED(rv)) {
-    mDecoder = nullptr;
+    SetDecoder(nullptr);
     LOG(PR_LOG_DEBUG, ("%p Failed to load for decoder %p", this, aDecoder));
     return rv;
   }
@@ -3213,7 +3223,7 @@ void HTMLMediaElement::MetadataLoaded(const MediaInfo* aInfo,
   if (!aInfo->HasVideo()) {
     ResetState();
   } else {
-    UpdateReadyStateForData(mLastNextFrameStatus);
+    mReadyStateUpdater->Notify();
   }
 
   if (IsVideo() && aInfo->HasVideo()) {
@@ -3496,7 +3506,16 @@ bool HTMLMediaElement::IsCORSSameOrigin()
 
 void HTMLMediaElement::UpdateReadyStateForData(MediaDecoderOwner::NextFrameStatus aNextFrame)
 {
-  mLastNextFrameStatus = aNextFrame;
+  mNextFrameStatus = aNextFrame;
+}
+
+void
+HTMLMediaElement::UpdateReadyStateInternal()
+{
+  if (!mDecoder && !mSrcStream) {
+    // Not initialized - bail out.
+    return;
+  }
 
   if (mDecoder && mReadyState < nsIDOMHTMLMediaElement::HAVE_METADATA) {
     // aNextFrame might have a next frame because the decoder can advance
@@ -3520,7 +3539,7 @@ void HTMLMediaElement::UpdateReadyStateForData(MediaDecoderOwner::NextFrameStatu
     MetadataLoaded(&mediaInfo, nsAutoPtr<const MetadataTags>(nullptr));
   }
 
-  if (aNextFrame == MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE_SEEKING) {
+  if (mNextFrameStatus == MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE_SEEKING) {
     ChangeReadyState(nsIDOMHTMLMediaElement::HAVE_METADATA);
     return;
   }
@@ -3549,9 +3568,9 @@ void HTMLMediaElement::UpdateReadyStateForData(MediaDecoderOwner::NextFrameStatu
     return;
   }
 
-  if (aNextFrame != MediaDecoderOwner::NEXT_FRAME_AVAILABLE) {
+  if (mNextFrameStatus != MediaDecoderOwner::NEXT_FRAME_AVAILABLE) {
     ChangeReadyState(nsIDOMHTMLMediaElement::HAVE_CURRENT_DATA);
-    if (!mWaitingFired && aNextFrame == MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE_BUFFERING) {
+    if (!mWaitingFired && mNextFrameStatus == MediaDecoderOwner::NEXT_FRAME_UNAVAILABLE_BUFFERING) {
       FireTimeUpdate(false);
       DispatchAsyncEvent(NS_LITERAL_STRING("waiting"));
       mWaitingFired = true;
@@ -3870,7 +3889,7 @@ void HTMLMediaElement::UpdateMediaSize(const nsIntSize& aSize)
   }
 
   mMediaInfo.mVideo.mDisplay = aSize;
-  UpdateReadyStateForData(mLastNextFrameStatus);
+  mReadyStateUpdater->Notify();
 }
 
 void HTMLMediaElement::UpdateInitialMediaSize(const nsIntSize& aSize)

dom/html/HTMLMediaElement.h

@@ -23,6 +23,7 @@
 #ifdef MOZ_EME
 #include "mozilla/dom/MediaKeys.h"
 #endif
+#include "StateWatching.h"
 #include "nsGkAtoms.h"
 
 // X.h on Linux #defines CurrentTime as 0L, so we have to #undef it here.
@@ -647,6 +648,17 @@ class HTMLMediaElement : public nsGenericHTMLElement,
   class StreamListener;
   class StreamSizeListener;
 
+  void SetDecoder(MediaDecoder* aDecoder)
+  {
+    if (mDecoder) {
+      mReadyStateUpdater->Unwatch(mDecoder->ReadyStateWatchTarget());
+    }
+    mDecoder = aDecoder;
+    if (mDecoder) {
+      mReadyStateUpdater->Watch(mDecoder->ReadyStateWatchTarget());
+    }
+  }
+
   virtual void GetItemValueText(DOMString& text) override;
   virtual void SetItemValueText(const nsAString& text) override;
 
@@ -1013,6 +1025,9 @@ class HTMLMediaElement : public nsGenericHTMLElement,
   // MediaElement doesn't yet have one then it will create it.
   TextTrackManager* GetOrCreateTextTrackManager();
 
+  // Recomputes ready state and fires events as necessary based on current state.
+  void UpdateReadyStateInternal();
+
   class nsAsyncEventRunner;
   using nsGenericHTMLElement::DispatchEvent;
   // For nsAsyncEventRunner.
@@ -1090,10 +1105,12 @@ class HTMLMediaElement : public nsGenericHTMLElement,
   // Media loading flags. See:
   //   http://www.whatwg.org/specs/web-apps/current-work/#video)
   nsMediaNetworkState mNetworkState;
-  nsMediaReadyState mReadyState;
+  Watchable<nsMediaReadyState> mReadyState;
+
+  WatcherHolder mReadyStateUpdater;
 
   // Last value passed from codec or stream source to UpdateReadyStateForData.
-  NextFrameStatus mLastNextFrameStatus;
+  Watchable<NextFrameStatus> mNextFrameStatus;
 
   enum LoadAlgorithmState {
     // No load algorithm instance is waiting for a source to be added to the
@@ -1328,7 +1345,7 @@ class HTMLMediaElement : public nsGenericHTMLElement,
 #endif // MOZ_EME
 
   // True if the media's channel's download has been suspended.
-  bool mDownloadSuspendedByCache;
+  Watchable<bool> mDownloadSuspendedByCache;
 
   // Audio Channel.
   AudioChannel mAudioChannel;

dom/media/MediaDecoder.cpp

@@ -585,6 +585,7 @@ bool MediaDecoder::IsInfinite()
 }
 
 MediaDecoder::MediaDecoder() :
+  mReadyStateWatchTarget("MediaDecoder::mReadyStateWatchTarget"),
   mDecoderPosition(0),
   mPlaybackPosition(0),
   mCurrentTime(0.0),
@@ -595,7 +596,7 @@ MediaDecoder::MediaDecoder() :
   mMediaSeekable(true),
   mSameOriginMedia(false),
   mReentrantMonitor("media.decoder"),
-  mPlayState(PLAY_STATE_LOADING),
+  mPlayState(PLAY_STATE_LOADING, "MediaDecoder::mPlayState"),
   mNextState(PLAY_STATE_PAUSED),
   mIgnoreProgressData(false),
   mInfiniteStream(false),
@@ -622,8 +623,11 @@ MediaDecoder::MediaDecoder() :
   if (!gMediaDecoderLog) {
     gMediaDecoderLog = PR_NewLogModule("MediaDecoder");
   }
+  EnsureStateWatchingLog();
 #endif
   mAudioChannel = AudioChannelService::GetDefaultAudioChannel();
+
+  mReadyStateWatchTarget->Watch(mPlayState);
 }
 
 bool MediaDecoder::Init(MediaDecoderOwner* aOwner)
@@ -1140,7 +1144,6 @@ void MediaDecoder::NotifySuspendedStatusChanged()
   if (mResource && mOwner) {
     bool suspended = mResource->IsSuspendedByCache();
     mOwner->NotifySuspendedByCache(suspended);
-    UpdateReadyStateForData();
   }
 }
 
@@ -1704,8 +1707,8 @@ void MediaDecoder::UnpinForSeek()
 bool MediaDecoder::CanPlayThrough()
 {
   Statistics stats = GetStatistics();
+  NS_ENSURE_TRUE(mDecoderStateMachine, false);
 
-  NS_ASSERTION(mDecoderStateMachine, "CanPlayThrough should have state machine!");
   if (mDecoderStateMachine->IsRealTime() ||
       (stats.mTotalBytes < 0 && stats.mDownloadRateReliable) ||
       (stats.mTotalBytes >= 0 && stats.mTotalBytes == stats.mDownloadPosition)) {

dom/media/MediaDecoder.h

@@ -196,6 +196,7 @@ destroying the MediaDecoder object.
 #include "mozilla/ReentrantMonitor.h"
 #include "MediaStreamGraph.h"
 #include "AbstractMediaDecoder.h"
+#include "StateWatching.h"
 #include "necko-config.h"
 #ifdef MOZ_EME
 #include "mozilla/CDMProxy.h"
@@ -1040,6 +1041,8 @@ class MediaDecoder : public nsIObserver,
     GetFrameStatistics().NotifyDecodedFrames(aParsed, aDecoded, aDropped);
   }
 
+  WatchTarget& ReadyStateWatchTarget() { return *mReadyStateWatchTarget; }
+
 protected:
   virtual ~MediaDecoder();
   void SetStateMachineParameters();
@@ -1055,6 +1058,8 @@ class MediaDecoder : public nsIObserver,
   // Return true if the decoder has reached the end of playback
   bool IsEnded() const;
 
+  WatcherHolder mReadyStateWatchTarget;
+
   /******
    * The following members should be accessed with the decoder lock held.
    ******/
@@ -1137,7 +1142,7 @@ class MediaDecoder : public nsIObserver,
   // OR on the main thread.
   // Any change to the state on the main thread must call NotifyAll on the
   // monitor so the decode thread can wake up.
-  PlayState mPlayState;
+  Watchable<PlayState> mPlayState;
 
   // The state to change to after a seek or load operation.
   // This can only be changed on the main thread while holding the decoder