Bug 902929. Be explicit about re-attaching async video compositable hosts. r=nical

content/media/plugins/MediaPluginReader.cpp

@@ -366,6 +366,11 @@ MediaPluginReader::ImageBufferCallback::operator()(size_t aWidth, size_t aHeight
       rgbImage = mozilla::layers::CreateSharedRGBImage(mImageContainer,
                                                        nsIntSize(aWidth, aHeight),
                                                        gfxASurface::ImageFormatRGB16_565);
+      if (!rgbImage) {
+        NS_WARNING("Could not create rgb image");
+        return nullptr;
+      }
+
       mImage = rgbImage;
       return rgbImage->AsSharedImage()->GetBuffer();
     case MPAPI::YCbCr:

gfx/layers/composite/CanvasLayerComposite.cpp

@@ -119,7 +119,7 @@ void
 CanvasLayerComposite::CleanupResources()
 {
   if (mImageHost) {
-    mImageHost->Detach();
+    mImageHost->Detach(this);
   }
   mImageHost = nullptr;
 }

gfx/layers/composite/CompositableHost.cpp

@@ -28,6 +28,7 @@ CompositableHost::CompositableHost(const TextureInfo& aTextureInfo)
   , mCompositor(nullptr)
   , mLayer(nullptr)
   , mAttached(false)
+  , mKeepAttached(false)
 {
   MOZ_COUNT_CTOR(CompositableHost);
 }

gfx/layers/composite/CompositableHost.h

@@ -210,19 +210,39 @@ public:
 
   virtual TiledLayerComposer* AsTiledLayerComposer() { return nullptr; }
 
-  virtual void Attach(Layer* aLayer, Compositor* aCompositor)
+  typedef uint32_t AttachFlags;
+  static const AttachFlags NO_FLAGS = 0;
+  static const AttachFlags ALLOW_REATTACH = 1;
+  static const AttachFlags KEEP_ATTACHED = 2;
+
+  virtual void Attach(Layer* aLayer,
+                      Compositor* aCompositor,
+                      AttachFlags aFlags = NO_FLAGS)
   {
     MOZ_ASSERT(aCompositor, "Compositor is required");
-    MOZ_ASSERT(!IsAttached());
+    NS_ASSERTION(aFlags & ALLOW_REATTACH || !mAttached,
+                 "Re-attaching compositables must be explicitly authorised");
     SetCompositor(aCompositor);
     SetLayer(aLayer);
     mAttached = true;
+    mKeepAttached = aFlags & KEEP_ATTACHED;
   }
-  void Detach()
+  // Detach this compositable host from its layer.
+  // If we are used for async video, then it is not safe to blindly detach since
+  // we might be re-attached to a different layer. aLayer is the layer which the
+  // caller expects us to be attached to, we will only detach if we are in fact
+  // attached to that layer. If we are part of a normal layer, then we will be
+  // detached in any case. if aLayer is null, then we will only detach if we are
+  // not async.
+  void Detach(Layer* aLayer = nullptr)
   {
-    SetLayer(nullptr);
-    SetCompositor(nullptr);
-    mAttached = false;
+    if (!mKeepAttached ||
+        aLayer == mLayer) {
+      SetLayer(nullptr);
+      SetCompositor(nullptr);
+      mAttached = false;
+      mKeepAttached = false;
+    }
   }
   bool IsAttached() { return mAttached; }
 
@@ -251,6 +271,7 @@ protected:
   Layer* mLayer;
   RefPtr<TextureHost> mFirstTexture;
   bool mAttached;
+  bool mKeepAttached;
 };
 
 class CompositableParentManager;

gfx/layers/composite/ThebesLayerComposite.cpp

@@ -169,7 +169,7 @@ void
 ThebesLayerComposite::CleanupResources()
 {
   if (mBuffer) {
-    mBuffer->Detach();
+    mBuffer->Detach(this);
   }
   mBuffer = nullptr;
 }

gfx/layers/composite/TiledContentHost.cpp

@@ -67,9 +67,11 @@ TiledLayerBufferComposite::ValidateTile(TiledTexture aTile,
 }
 
 void
-TiledContentHost::Attach(Layer* aLayer, Compositor* aCompositor)
+TiledContentHost::Attach(Layer* aLayer,
+                         Compositor* aCompositor,
+                         AttachFlags aFlags /* = NO_FLAGS */)
 {
-  CompositableHost::Attach(aLayer, aCompositor);
+  CompositableHost::Attach(aLayer, aCompositor, aFlags);
   static_cast<ThebesLayerComposite*>(aLayer)->EnsureTiled();
 }
 

gfx/layers/composite/TiledContentHost.h

@@ -237,7 +237,9 @@ public:
     mLowPrecisionVideoMemoryTiledBuffer.SetCompositor(aCompositor);
   }
 
-  virtual void Attach(Layer* aLayer, Compositor* aCompositor) MOZ_OVERRIDE;
+  virtual void Attach(Layer* aLayer,
+                      Compositor* aCompositor,
+                      AttachFlags aFlags = NO_FLAGS) MOZ_OVERRIDE;
 
 #ifdef MOZ_DUMP_PAINTING
   virtual void Dump(FILE* aFile=nullptr,

gfx/layers/ipc/LayerTransactionParent.cpp

@@ -405,7 +405,7 @@ LayerTransactionParent::RecvUpdate(const InfallibleTArray<Edit>& cset,
     }
     case Edit::TOpAttachCompositable: {
       const OpAttachCompositable& op = edit.get_OpAttachCompositable();
-      Attach(cast(op.layerParent()), cast(op.compositableParent()));
+      Attach(cast(op.layerParent()), cast(op.compositableParent()), false);
       cast(op.compositableParent())->SetCompositorID(
         mLayerManager->GetCompositor()->GetCompositorID());
       break;
@@ -414,7 +414,7 @@ LayerTransactionParent::RecvUpdate(const InfallibleTArray<Edit>& cset,
       const OpAttachAsyncCompositable& op = edit.get_OpAttachAsyncCompositable();
       CompositableParent* compositableParent = CompositableMap::Get(op.containerID());
       MOZ_ASSERT(compositableParent, "CompositableParent not found in the map");
-      Attach(cast(op.layerParent()), compositableParent);
+      Attach(cast(op.layerParent()), compositableParent, true);
       compositableParent->SetCompositorID(mLayerManager->GetCompositor()->GetCompositorID());
       break;
     }
@@ -501,7 +501,9 @@ LayerTransactionParent::RecvGetTransform(PLayerParent* aParent,
 }
 
 void
-LayerTransactionParent::Attach(ShadowLayerParent* aLayerParent, CompositableParent* aCompositable)
+LayerTransactionParent::Attach(ShadowLayerParent* aLayerParent,
+                               CompositableParent* aCompositable,
+                               bool aIsAsyncVideo)
 {
   LayerComposite* layer = aLayerParent->AsLayer()->AsLayerComposite();
   MOZ_ASSERT(layer);
@@ -512,7 +514,12 @@ LayerTransactionParent::Attach(ShadowLayerParent* aLayerParent, CompositablePare
   CompositableHost* compositable = aCompositable->GetCompositableHost();
   MOZ_ASSERT(compositable);
   layer->SetCompositableHost(compositable);
-  compositable->Attach(aLayerParent->AsLayer(), compositor);
+  compositable->Attach(aLayerParent->AsLayer(),
+                       compositor,
+                       aIsAsyncVideo
+                         ? CompositableHost::ALLOW_REATTACH
+                           | CompositableHost::KEEP_ATTACHED
+                         : CompositableHost::NO_FLAGS);
 }
 
 bool

gfx/layers/ipc/LayerTransactionParent.h

@@ -106,7 +106,9 @@ protected:
   virtual PCompositableParent* AllocPCompositableParent(const TextureInfo& aInfo) MOZ_OVERRIDE;
   virtual bool DeallocPCompositableParent(PCompositableParent* actor) MOZ_OVERRIDE;
 
-  void Attach(ShadowLayerParent* aLayerParent, CompositableParent* aCompositable);
+  void Attach(ShadowLayerParent* aLayerParent,
+              CompositableParent* aCompositable,
+              bool aIsAsyncVideo);
 
 private:
   nsRefPtr<LayerManagerComposite> mLayerManager;