bug 1161892 use separate thread pool for platform decoder task queues r=bholley

so that platform decoder tasks will run when their readers wait and block
their thread pool.

--HG--
extra : rebase_source : 6d2e3f1c1937991d746ea9754f39add4d184e413

dom/media/MediaDecoderReader.cpp

@@ -344,7 +344,7 @@ MediaDecoderReader::EnsureTaskQueue()
 {
   if (!mTaskQueue) {
     MOZ_ASSERT(!mTaskQueueIsBorrowed);
-    RefPtr<SharedThreadPool> pool(GetMediaThreadPool());
+    RefPtr<SharedThreadPool> pool(GetMediaThreadPool(MediaThreadType::PLAYBACK));
     MOZ_DIAGNOSTIC_ASSERT(pool);
     mTaskQueue = new MediaTaskQueue(pool.forget());
   }

dom/media/MediaDecoderStateMachine.cpp

@@ -202,7 +202,8 @@ MediaDecoderStateMachine::MediaDecoderStateMachine(MediaDecoder* aDecoder,
                                                    MediaDecoderReader* aReader,
                                                    bool aRealTime) :
   mDecoder(aDecoder),
-  mTaskQueue(new MediaTaskQueue(GetMediaThreadPool(), /* aAssertTailDispatch = */ true)),
+  mTaskQueue(new MediaTaskQueue(GetMediaThreadPool(MediaThreadType::PLAYBACK),
+                                /* aAssertTailDispatch = */ true)),
   mWatchManager(this, mTaskQueue),
   mRealTime(aRealTime),
   mDispatchedStateMachine(false),

dom/media/VideoUtils.cpp

@@ -197,10 +197,22 @@ IsValidVideoRegion(const nsIntSize& aFrame, const nsIntRect& aPicture,
     aDisplay.width * aDisplay.height != 0;
 }
 
-TemporaryRef<SharedThreadPool> GetMediaThreadPool()
+TemporaryRef<SharedThreadPool> GetMediaThreadPool(MediaThreadType aType)
 {
-  return SharedThreadPool::Get(NS_LITERAL_CSTRING("Media Playback"),
-                               Preferences::GetUint("media.num-decode-threads", 25));
+  const char *name;
+  switch (aType) {
+    case MediaThreadType::PLATFORM_DECODER:
+      name = "MediaPDecoder";
+      break;
+    default:
+      MOZ_ASSERT(false);
+    case MediaThreadType::PLAYBACK:
+      name = "MediaPlayback";
+      break;
+  }
+  return SharedThreadPool::
+    Get(nsDependentCString(name),
+        Preferences::GetUint("media.num-decode-threads", 12));
 }
 
 bool
@@ -304,7 +316,8 @@ class CreateTaskQueueTask : public nsRunnable {
 public:
   NS_IMETHOD Run() {
     MOZ_ASSERT(NS_IsMainThread());
-    mTaskQueue = new MediaTaskQueue(GetMediaThreadPool());
+    mTaskQueue =
+      new MediaTaskQueue(GetMediaThreadPool(MediaThreadType::PLATFORM_DECODER));
     return NS_OK;
   }
   nsRefPtr<MediaTaskQueue> mTaskQueue;
@@ -314,7 +327,8 @@ class CreateFlushableTaskQueueTask : public nsRunnable {
 public:
   NS_IMETHOD Run() {
     MOZ_ASSERT(NS_IsMainThread());
-    mTaskQueue = new FlushableMediaTaskQueue(GetMediaThreadPool());
+    mTaskQueue =
+      new FlushableMediaTaskQueue(GetMediaThreadPool(MediaThreadType::PLATFORM_DECODER));
     return NS_OK;
   }
   nsRefPtr<FlushableMediaTaskQueue> mTaskQueue;

dom/media/VideoUtils.h

@@ -216,9 +216,22 @@ private:
 
 class SharedThreadPool;
 
+// The MediaDataDecoder API blocks, with implementations waiting on platform
+// decoder tasks.  These platform decoder tasks are queued on a separate
+// thread pool to ensure they can run when the MediaDataDecoder clients'
+// thread pool is blocked.  Tasks on the PLATFORM_DECODER thread pool must not
+// wait on tasks in the PLAYBACK thread pool.
+//
+// No new dependencies on this mechanism should be added, as methods are being
+// made async supported by MediaPromise, making this unnecessary and
+// permitting unifying the pool.
+enum class MediaThreadType {
+  PLAYBACK, // MediaDecoderStateMachine and MediaDecoderReader
+  PLATFORM_DECODER
+};
 // Returns the thread pool that is shared amongst all decoder state machines
 // for decoding streams.
-TemporaryRef<SharedThreadPool> GetMediaThreadPool();
+TemporaryRef<SharedThreadPool> GetMediaThreadPool(MediaThreadType aType);
 
 enum H264_PROFILE {
   H264_PROFILE_UNKNOWN                     = 0,

dom/media/fmp4/MP4Reader.cpp

@@ -289,10 +289,12 @@ MP4Reader::Init(MediaDecoderReader* aCloneDonor)
 
   InitLayersBackendType();
 
-  mAudio.mTaskQueue = new FlushableMediaTaskQueue(GetMediaThreadPool());
+  mAudio.mTaskQueue =
+    new FlushableMediaTaskQueue(GetMediaThreadPool(MediaThreadType::PLATFORM_DECODER));
   NS_ENSURE_TRUE(mAudio.mTaskQueue, NS_ERROR_FAILURE);
 
-  mVideo.mTaskQueue = new FlushableMediaTaskQueue(GetMediaThreadPool());
+  mVideo.mTaskQueue =
+    new FlushableMediaTaskQueue(GetMediaThreadPool(MediaThreadType::PLATFORM_DECODER));
   NS_ENSURE_TRUE(mVideo.mTaskQueue, NS_ERROR_FAILURE);
 
   static bool sSetupPrefCache = false;

dom/media/fmp4/SharedDecoderManager.cpp

@@ -77,7 +77,7 @@ private:
 };
 
 SharedDecoderManager::SharedDecoderManager()
-  : mTaskQueue(new FlushableMediaTaskQueue(GetMediaThreadPool()))
+  : mTaskQueue(new FlushableMediaTaskQueue(GetMediaThreadPool(MediaThreadType::PLATFORM_DECODER)))
   , mActiveProxy(nullptr)
   , mActiveCallback(nullptr)
   , mWaitForInternalDrain(false)

dom/media/mediasource/TrackBuffer.cpp

@@ -53,7 +53,8 @@ TrackBuffer::TrackBuffer(MediaSourceDecoder* aParentDecoder, const nsACString& a
 {
   MOZ_COUNT_CTOR(TrackBuffer);
   mParser = ContainerParser::CreateForMIMEType(aType);
-  mTaskQueue = new MediaTaskQueue(GetMediaThreadPool());
+  mTaskQueue =
+    new MediaTaskQueue(GetMediaThreadPool(MediaThreadType::PLAYBACK));
   aParentDecoder->AddTrackBuffer(this);
   mDecoderPerSegment = Preferences::GetBool("media.mediasource.decoder-per-segment", false);
   MSE_DEBUG("TrackBuffer created for parent decoder %p", aParentDecoder);