Bug 995065 - Backout bug 947227 for causing WebGL performances regressions. r=jgilbert

gfx/gl/SurfaceStream.cpp

@@ -22,7 +22,7 @@ SurfaceStream::ChooseGLStreamType(SurfaceStream::OMTC omtc,
         if (preserveBuffer)
             return SurfaceStreamType::TripleBuffer_Copy;
         else
-            return SurfaceStreamType::TripleBuffer;
+            return SurfaceStreamType::TripleBuffer_Async;
     } else {
         if (preserveBuffer)
             return SurfaceStreamType::SingleBuffer;
@@ -43,6 +43,9 @@ SurfaceStream::CreateForType(SurfaceStreamType type, mozilla::gl::GLContext* glC
         case SurfaceStreamType::TripleBuffer_Copy:
             result = new SurfaceStream_TripleBuffer_Copy(prevStream);
             break;
+        case SurfaceStreamType::TripleBuffer_Async:
+            result = new SurfaceStream_TripleBuffer_Async(prevStream);
+            break;
         case SurfaceStreamType::TripleBuffer:
             result = new SurfaceStream_TripleBuffer(prevStream);
             break;
@@ -429,7 +432,9 @@ SurfaceStream_TripleBuffer::SwapProducer(SurfaceFactory* factory,
     if (mProducer) {
         RecycleScraps(factory);
 
-        if (mStaging)
+        // If WaitForCompositor succeeds, mStaging has moved to mConsumer.
+        // If it failed, we might have to scrap it.
+        if (mStaging && !WaitForCompositor())
             Scrap(mStaging);
 
         MOZ_ASSERT(!mStaging);
@@ -456,5 +461,26 @@ SurfaceStream_TripleBuffer::SwapConsumer_NoWait()
     return mConsumer;
 }
 
+SurfaceStream_TripleBuffer_Async::SurfaceStream_TripleBuffer_Async(SurfaceStream* prevStream)
+    : SurfaceStream_TripleBuffer(SurfaceStreamType::TripleBuffer_Async, prevStream)
+{
+}
+
+SurfaceStream_TripleBuffer_Async::~SurfaceStream_TripleBuffer_Async()
+{
+}
+
+bool
+SurfaceStream_TripleBuffer_Async::WaitForCompositor()
+{
+    PROFILER_LABEL("SurfaceStream_TripleBuffer_Async", "WaitForCompositor");
+
+    // We are assumed to be locked
+    while (mStaging)
+        mMonitor.Wait();
+
+    return true;
+}
+
 } /* namespace gfx */
 } /* namespace mozilla */

gfx/gl/SurfaceStream.h

@@ -191,6 +191,9 @@ protected:
     SharedSurface* mStaging;
     SharedSurface* mConsumer;
 
+    // Returns true if we were able to wait, false if not
+    virtual bool WaitForCompositor() { return false; }
+
     // To support subclasses initializing the mType.
     SurfaceStream_TripleBuffer(SurfaceStreamType type, SurfaceStream* prevStream);
 
@@ -214,6 +217,18 @@ public:
     virtual void SurrenderSurfaces(SharedSurface*& producer, SharedSurface*& consumer);
 };
 
+class SurfaceStream_TripleBuffer_Async
+    : public SurfaceStream_TripleBuffer
+{
+protected:
+    virtual bool WaitForCompositor() MOZ_OVERRIDE;
+
+public:
+    SurfaceStream_TripleBuffer_Async(SurfaceStream* prevStream);
+    virtual ~SurfaceStream_TripleBuffer_Async();
+};
+
+
 } /* namespace gfx */
 } /* namespace mozilla */
 

gfx/gl/SurfaceTypes.h

@@ -87,6 +87,7 @@ MOZ_END_ENUM_CLASS(SharedSurfaceType)
 MOZ_BEGIN_ENUM_CLASS(SurfaceStreamType, uint8_t)
     SingleBuffer,
     TripleBuffer_Copy,
+    TripleBuffer_Async,
     TripleBuffer,
     Max
 MOZ_END_ENUM_CLASS(SurfaceStreamType)