Bug 748649 - Allow layer transactions that don't require a buffer swap to be perform asynchronously. r=cjones

--HG--
extra : rebase_source : b0d11710119eb87cef8f461ece44baaba88f7477

gfx/layers/ipc/PLayers.ipdl

@@ -244,6 +244,10 @@ parent:
   sync Update(Edit[] cset, bool isFirstPaint)
     returns (EditReply[] reply);
 
+  // We don't need to send a sync transaction if
+  // no transaction operate require a swap.
+  async UpdateNoSwap(Edit[] cset, bool isFirstPaint);
+
   async __delete__();
 };
 

gfx/layers/ipc/ShadowLayers.cpp

@@ -66,7 +66,10 @@ typedef std::set<ShadowableLayer*> ShadowableLayerSet;
 class Transaction
 {
 public:
-  Transaction() : mOpen(false) {}
+  Transaction()
+    : mOpen(false)
+    , mSwapRequired(false)
+  {}
 
   void Begin() { mOpen = true; }
 
@@ -76,6 +79,11 @@ public:
     mCset.push_back(aEdit);
   }
   void AddPaint(const Edit& aPaint)
+  {
+    AddNoSwapPaint(aPaint);
+    mSwapRequired = true;
+  }
+  void AddNoSwapPaint(const Edit& aPaint)
   {
     NS_ABORT_IF_FALSE(!Finished(), "forgot BeginTransaction?");
     mPaints.push_back(aPaint);
@@ -102,6 +110,7 @@ public:
     mDyingBuffers.Clear();
     mMutants.clear();
     mOpen = false;
+    mSwapRequired = false;
   }
 
   bool Empty() const {
@@ -113,6 +122,7 @@ public:
   EditVector mPaints;
   BufferArray mDyingBuffers;
   ShadowableLayerSet mMutants;
+  bool mSwapRequired;
 
 private:
   bool mOpen;
@@ -247,7 +257,7 @@ ShadowLayerForwarder::PaintedTiledLayerBuffer(ShadowableLayer* aLayer,
 {
   if (XRE_GetProcessType() != GeckoProcessType_Default)
     NS_RUNTIMEABORT("PaintedTiledLayerBuffer must be made IPC safe (not share pointers)");
-  mTxn->AddPaint(OpPaintTiledLayerBuffer(NULL, Shadow(aLayer),
+  mTxn->AddNoSwapPaint(OpPaintTiledLayerBuffer(NULL, Shadow(aLayer),
                                          uintptr_t(aTiledLayerBuffer)));
 }
 
@@ -341,11 +351,22 @@ ShadowLayerForwarder::EndTransaction(InfallibleTArray<EditReply>* aReplies)
   MOZ_LAYERS_LOG(("[LayersForwarder] syncing before send..."));
   PlatformSyncBeforeUpdate();
 
-  MOZ_LAYERS_LOG(("[LayersForwarder] sending transaction..."));
-  RenderTraceScope rendertrace3("Foward Transaction", "000093");
-  if (!mShadowManager->SendUpdate(cset, mIsFirstPaint, aReplies)) {
-    MOZ_LAYERS_LOG(("[LayersForwarder] WARNING: sending transaction failed!"));
-    return false;
+  if (mTxn->mSwapRequired) {
+    MOZ_LAYERS_LOG(("[LayersForwarder] sending transaction..."));
+    RenderTraceScope rendertrace3("Forward Transaction", "000093");
+    if (!mShadowManager->SendUpdate(cset, mIsFirstPaint, aReplies)) {
+      MOZ_LAYERS_LOG(("[LayersForwarder] WARNING: sending transaction failed!"));
+      return false;
+    }
+  } else {
+    // If we don't require a swap we can call SendUpdateNoSwap which
+    // assumes that aReplies is empty (DEBUG assertion)
+    MOZ_LAYERS_LOG(("[LayersForwarder] sending no swap transaction..."));
+    RenderTraceScope rendertrace3("Forward NoSwap Transaction", "000093");
+    if (!mShadowManager->SendUpdateNoSwap(cset, mIsFirstPaint)) {
+      MOZ_LAYERS_LOG(("[LayersForwarder] WARNING: sending transaction failed!"));
+      return false;
+    }
   }
 
   mIsFirstPaint = false;

gfx/layers/ipc/ShadowLayersParent.cpp

@@ -147,6 +147,17 @@ ShadowLayersParent::Destroy()
   }
 }
 
+/* virtual */
+bool
+ShadowLayersParent::RecvUpdateNoSwap(const InfallibleTArray<Edit>& cset,
+                 const bool& isFirstPaint)
+{
+  InfallibleTArray<EditReply> noReplies;
+  bool success = RecvUpdate(cset, isFirstPaint, &noReplies);
+  NS_ABORT_IF_FALSE(noReplies.Length() == 0, "RecvUpdateNoSwap requires a sync Update to carry Edits");
+  return success;
+}
+
 bool
 ShadowLayersParent::RecvUpdate(const InfallibleTArray<Edit>& cset,
                                const bool& isFirstPaint,

gfx/layers/ipc/ShadowLayersParent.h

@@ -81,6 +81,9 @@ protected:
                                       const bool& isFirstPaint,
                                       EditReplyArray* reply);
 
+  NS_OVERRIDE virtual bool RecvUpdateNoSwap(const EditArray& cset,
+                                            const bool& isFirstPaint);
+
   NS_OVERRIDE virtual PLayerParent* AllocPLayer();
   NS_OVERRIDE virtual bool DeallocPLayer(PLayerParent* actor);