Bug 1126465 - Cancel sample requests when seeks start, disallow them while seeks are happening, and assert against seeks when samples arrive. r=mattwoodrow

The duplication of the IsSeeking() checks before all the Request{Audio,Video}Data
callsites is ugly. We'll fix this in the next patch by applying the same disconnect
treatment to the seek promise.

dom/media/mediasource/MediaSourceReader.cpp

@@ -119,7 +119,7 @@ MediaSourceReader::RequestAudioData()
     mAudioPromise.Reject(DECODE_ERROR, __func__);
     return p;
   }
-  if (mAudioIsSeeking) {
+  if (IsSeeking()) {
     MSE_DEBUG("MediaSourceReader(%p)::RequestAudioData called mid-seek. Rejecting.", this);
     mAudioPromise.Reject(CANCELED, __func__);
     return p;
@@ -148,6 +148,12 @@ MediaSourceReader::RequestAudioData()
 void
 MediaSourceReader::RequestAudioDataComplete(int64_t aTime)
 {
+  if (IsSeeking()) {
+    MSE_DEBUG("MediaSourceReader(%p)::RequestAudioDataComplete called mid-seek. Rejecting.", this);
+    MOZ_RELEASE_ASSERT(mAudioPromise.IsEmpty()); // Already rejected in ::Seek().
+    return;
+  }
+
   mAudioRequest.Begin(mAudioReader->RequestAudioData()
                       ->RefableThen(GetTaskQueue(), __func__, this,
                                     &MediaSourceReader::OnAudioDecoded,
@@ -163,6 +169,7 @@ MediaSourceReader::RequestAudioDataFailed(nsresult aResult)
 void
 MediaSourceReader::OnAudioDecoded(AudioData* aSample)
 {
+  MOZ_RELEASE_ASSERT(!IsSeeking());
   mAudioRequest.Complete();
 
   MSE_DEBUGV("MediaSourceReader(%p)::OnAudioDecoded [mTime=%lld mDuration=%lld mDiscontinuity=%d]",
@@ -180,12 +187,7 @@ MediaSourceReader::OnAudioDecoded(AudioData* aSample)
     mDropAudioBeforeThreshold = false;
   }
 
-  // Any OnAudioDecoded callbacks received while mAudioIsSeeking must be not
-  // update our last used timestamp, as these are emitted by the reader we're
-  // switching away from.
-  if (!mAudioIsSeeking) {
-    mLastAudioTime = aSample->mTime + aSample->mDuration;
-  }
+  mLastAudioTime = aSample->mTime + aSample->mDuration;
 
   mAudioPromise.Resolve(aSample, __func__);
 }
@@ -219,6 +221,7 @@ AdjustEndTime(int64_t* aEndTime, MediaDecoderReader* aReader)
 void
 MediaSourceReader::OnAudioNotDecoded(NotDecodedReason aReason)
 {
+  MOZ_RELEASE_ASSERT(!IsSeeking());
   mAudioRequest.Complete();
 
   MSE_DEBUG("MediaSourceReader(%p)::OnAudioNotDecoded aReason=%u IsEnded: %d", this, aReason, IsEnded());
@@ -265,7 +268,7 @@ MediaSourceReader::RequestVideoData(bool aSkipToNextKeyframe, int64_t aTimeThres
     mDropAudioBeforeThreshold = true;
     mDropVideoBeforeThreshold = true;
   }
-  if (mVideoIsSeeking) {
+  if (IsSeeking()) {
     MSE_DEBUG("MediaSourceReader(%p)::RequestVideoData called mid-seek. Rejecting.", this);
     mVideoPromise.Reject(CANCELED, __func__);
     return p;
@@ -298,6 +301,11 @@ MediaSourceReader::RequestVideoData(bool aSkipToNextKeyframe, int64_t aTimeThres
 void
 MediaSourceReader::RequestVideoDataComplete(int64_t aTime)
 {
+  if (IsSeeking()) {
+    MSE_DEBUG("MediaSourceReader(%p)::RequestVideoDataComplete called mid-seek. Rejecting.", this);
+    MOZ_ASSERT(mVideoPromise.IsEmpty()); // Already rejected in ::Seek().
+    return;
+  }
   mVideoRequest.Begin(mVideoReader->RequestVideoData(false, 0)
                       ->RefableThen(GetTaskQueue(), __func__, this,
                                     &MediaSourceReader::OnVideoDecoded,
@@ -313,6 +321,7 @@ MediaSourceReader::RequestVideoDataFailed(nsresult aResult)
 void
 MediaSourceReader::OnVideoDecoded(VideoData* aSample)
 {
+  MOZ_RELEASE_ASSERT(!IsSeeking());
   mVideoRequest.Complete();
 
   MSE_DEBUGV("MediaSourceReader(%p)::OnVideoDecoded [mTime=%lld mDuration=%lld mDiscontinuity=%d]",
@@ -330,12 +339,7 @@ MediaSourceReader::OnVideoDecoded(VideoData* aSample)
     mDropVideoBeforeThreshold = false;
   }
 
-  // Any OnVideoDecoded callbacks received while mVideoIsSeeking must be not
-  // update our last used timestamp, as these are emitted by the reader we're
-  // switching away from.
-  if (!mVideoIsSeeking) {
-    mLastVideoTime = aSample->mTime + aSample->mDuration;
-  }
+  mLastVideoTime = aSample->mTime + aSample->mDuration;
 
   mVideoPromise.Resolve(aSample, __func__);
 }
@@ -343,6 +347,7 @@ MediaSourceReader::OnVideoDecoded(VideoData* aSample)
 void
 MediaSourceReader::OnVideoNotDecoded(NotDecodedReason aReason)
 {
+  MOZ_RELEASE_ASSERT(!IsSeeking());
   mVideoRequest.Complete();
 
   MSE_DEBUG("MediaSourceReader(%p)::OnVideoNotDecoded aReason=%u IsEnded: %d", this, aReason, IsEnded());
@@ -683,6 +688,15 @@ MediaSourceReader::Seek(int64_t aTime, int64_t aIgnored /* Used only for ogg whi
     return p;
   }
 
+  // Any previous requests we've been waiting on are now unwanted.
+  mAudioRequest.DisconnectIfExists();
+  mVideoRequest.DisconnectIfExists();
+
+  // Additionally, reject any outstanding promises _we_ made that we might have
+  // been waiting on the above to fulfill.
+  mAudioPromise.RejectIfExists(CANCELED, __func__);
+  mVideoPromise.RejectIfExists(CANCELED, __func__);
+
   // Store pending seek target in case the track buffers don't contain
   // the desired time and we delay doing the seek.
   mPendingSeekTime = aTime;
@@ -858,11 +872,11 @@ MediaSourceReader::MaybeNotifyHaveData()
 {
   ReentrantMonitorAutoEnter mon(mDecoder->GetReentrantMonitor());
   bool haveAudio = false, haveVideo = false;
-  if (!mAudioIsSeeking && mAudioTrack && HaveData(mLastAudioTime, MediaData::AUDIO_DATA)) {
+  if (!IsSeeking() && mAudioTrack && HaveData(mLastAudioTime, MediaData::AUDIO_DATA)) {
     haveAudio = true;
     WaitPromise(MediaData::AUDIO_DATA).ResolveIfExists(MediaData::AUDIO_DATA, __func__);
   }
-  if (!mVideoIsSeeking && mVideoTrack && HaveData(mLastVideoTime, MediaData::VIDEO_DATA)) {
+  if (!IsSeeking() && mVideoTrack && HaveData(mLastVideoTime, MediaData::VIDEO_DATA)) {
     haveVideo = true;
     WaitPromise(MediaData::VIDEO_DATA).ResolveIfExists(MediaData::VIDEO_DATA, __func__);
   }

dom/media/mediasource/MediaSourceReader.h

@@ -173,6 +173,7 @@ private:
   bool HaveData(int64_t aTarget, MediaData::Type aType);
 
   void AttemptSeek();
+  bool IsSeeking() { return mPendingSeekTime != -1; }
 
   nsRefPtr<MediaDecoderReader> mAudioReader;
   nsRefPtr<MediaDecoderReader> mVideoReader;