Bug 1091008 - Hoist stream pinning into the MediaDecoderReaders and make MediaDecoderStateMachine::GetBuffered just forward to them. r=cpearce

Whether or not we ping a stream depends a lot on what kind of decoder we're
dealing with. In particular, it doesn't really make sense for MSE.

dom/media/MediaDecoderReader.cpp

@@ -6,6 +6,7 @@
 
 #include "MediaDecoderReader.h"
 #include "AbstractMediaDecoder.h"
+#include "MediaResource.h"
 #include "VideoUtils.h"
 #include "ImageContainer.h"
 
@@ -131,7 +132,7 @@ MediaDecoderReader::SetStartTime(int64_t aStartTime)
 nsresult
 MediaDecoderReader::GetBuffered(mozilla::dom::TimeRanges* aBuffered)
 {
-  MediaResource* stream = mDecoder->GetResource();
+  AutoPinned<MediaResource> stream(mDecoder->GetResource());
   int64_t durationUs = 0;
   {
     ReentrantMonitorAutoEnter mon(mDecoder->GetReentrantMonitor());

dom/media/MediaDecoderStateMachine.cpp

@@ -2985,15 +2985,6 @@ void MediaDecoderStateMachine::StartBuffering()
 #endif
 }
 
-nsresult MediaDecoderStateMachine::GetBuffered(dom::TimeRanges* aBuffered) {
-  MediaResource* resource = mDecoder->GetResource();
-  NS_ENSURE_TRUE(resource, NS_ERROR_FAILURE);
-  resource->Pin();
-  nsresult res = mReader->GetBuffered(aBuffered);
-  resource->Unpin();
-  return res;
-}
-
 void MediaDecoderStateMachine::SetPlayStartTime(const TimeStamp& aTimeStamp)
 {
   AssertCurrentThreadInMonitor();

dom/media/MediaDecoderStateMachine.h

@@ -254,7 +254,9 @@ public:
     return mState == DECODER_STATE_SEEKING;
   }
 
-  nsresult GetBuffered(dom::TimeRanges* aBuffered);
+  nsresult GetBuffered(dom::TimeRanges* aBuffered) {
+    return mReader->GetBuffered(aBuffered);
+  }
 
   void SetPlaybackRate(double aPlaybackRate);
   void SetPreservesPitch(bool aPreservesPitch);

dom/media/MediaResource.h

@@ -718,6 +718,33 @@ protected:
   bool mIsTransportSeekable;
 };
 
+/**
+ * RAII class that handles pinning and unpinning for MediaResource and derived.
+ * This should be used when making calculations that involve potentially-cached
+ * MediaResource data, so that the state of the world can't change out from under
+ * us.
+ */
+template<class T>
+class MOZ_STACK_CLASS AutoPinned {
+ public:
+  explicit AutoPinned(T* aResource MOZ_GUARD_OBJECT_NOTIFIER_PARAM) : mResource(aResource) {
+    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+    MOZ_ASSERT(mResource);
+    mResource->Pin();
+  }
+
+  ~AutoPinned() {
+    mResource->Unpin();
+  }
+
+  operator T*() const { return mResource; }
+  T* operator->() const { return mResource; }
+
+private:
+  T* mResource;
+  MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+};
+
 } // namespace mozilla
 
 #endif

dom/media/fmp4/MP4Reader.cpp

@@ -800,13 +800,11 @@ MP4Reader::UpdateIndex()
     return;
   }
 
-  MediaResource* resource = mDecoder->GetResource();
-  resource->Pin();
+  AutoPinned<MediaResource> resource(mDecoder->GetResource());
   nsTArray<MediaByteRange> ranges;
   if (NS_SUCCEEDED(resource->GetCachedRanges(ranges))) {
     mDemuxer->UpdateIndex(ranges);
   }
-  resource->Unpin();
 }
 
 int64_t
@@ -829,11 +827,9 @@ MP4Reader::GetBuffered(dom::TimeRanges* aBuffered)
   }
   MOZ_ASSERT(mStartTime != -1, "Need to finish metadata decode first");
 
-  MediaResource* resource = mDecoder->GetResource();
+  AutoPinned<MediaResource> resource(mDecoder->GetResource());
   nsTArray<MediaByteRange> ranges;
-  resource->Pin();
   nsresult rv = resource->GetCachedRanges(ranges);
-  resource->Unpin();
 
   if (NS_SUCCEEDED(rv)) {
     nsTArray<Interval<Microseconds>> timeRanges;

dom/media/gstreamer/GStreamerReader.cpp

@@ -824,7 +824,7 @@ nsresult GStreamerReader::GetBuffered(dom::TimeRanges* aBuffered)
 #if GST_VERSION_MAJOR == 0
   GstFormat format = GST_FORMAT_TIME;
 #endif
-  MediaResource* resource = mDecoder->GetResource();
+  AutoPinned<MediaResource> resource(mDecoder->GetResource());
   nsTArray<MediaByteRange> ranges;
   resource->GetCachedRanges(ranges);
 

dom/media/ogg/OggReader.cpp

@@ -1900,7 +1900,7 @@ nsresult OggReader::GetBuffered(dom::TimeRanges* aBuffered)
     return NS_OK;
   }
 
-  MediaResource* resource = mDecoder->GetResource();
+  AutoPinned<MediaResource> resource(mDecoder->GetResource());
   nsTArray<MediaByteRange> ranges;
   nsresult res = resource->GetCachedRanges(ranges);
   NS_ENSURE_SUCCESS(res, res);

dom/media/wave/WaveReader.cpp

@@ -283,9 +283,10 @@ nsresult WaveReader::GetBuffered(dom::TimeRanges* aBuffered)
   if (!mInfo.HasAudio()) {
     return NS_OK;
   }
-  int64_t startOffset = mDecoder->GetResource()->GetNextCachedData(mWavePCMOffset);
+  AutoPinned<MediaResource> resource(mDecoder->GetResource());
+  int64_t startOffset = resource->GetNextCachedData(mWavePCMOffset);
   while (startOffset >= 0) {
-    int64_t endOffset = mDecoder->GetResource()->GetCachedDataEnd(startOffset);
+    int64_t endOffset = resource->GetCachedDataEnd(startOffset);
     // Bytes [startOffset..endOffset] are cached.
     NS_ASSERTION(startOffset >= mWavePCMOffset, "Integer underflow in GetBuffered");
     NS_ASSERTION(endOffset >= mWavePCMOffset, "Integer underflow in GetBuffered");
@@ -295,7 +296,7 @@ nsresult WaveReader::GetBuffered(dom::TimeRanges* aBuffered)
     // the media element.
     aBuffered->Add(RoundToUsecs(BytesToTime(startOffset - mWavePCMOffset)),
                    RoundToUsecs(BytesToTime(endOffset - mWavePCMOffset)));
-    startOffset = mDecoder->GetResource()->GetNextCachedData(endOffset);
+    startOffset = resource->GetNextCachedData(endOffset);
   }
   return NS_OK;
 }

dom/media/webm/WebMReader.cpp

@@ -1092,7 +1092,7 @@ nsresult WebMReader::GetBuffered(dom::TimeRanges* aBuffered)
     return NS_ERROR_FAILURE;
   }
 
-  MediaResource* resource = mDecoder->GetResource();
+  AutoPinned<MediaResource> resource(mDecoder->GetResource());
 
   // Special case completely cached files.  This also handles local files.
   if (mContext && resource->IsDataCachedToEndOfResource(0)) {