Bug 1425453 - Move some WebRender api calls into transactions. r=kats

gfx/layers/wr/AsyncImagePipelineManager.cpp

@@ -276,16 +276,26 @@ AsyncImagePipelineManager::ApplyAsyncImages()
   ++mAsyncImageEpoch; // Update webrender epoch
   wr::Epoch epoch = wr::NewEpoch(mAsyncImageEpoch);
 
+  // TODO: We can improve upon this by using two transactions: one for everything that
+  // doesn't change the display list (in other words does not cause the scene to be
+  // re-built), and one for the rest. This way, if an async pipeline needs to re-build
+  // its display list, other async pipelines can still be rendered while the scene is
+  // building.
+  wr::TransactionBuilder txn;
+
   // We use a pipeline with a very small display list for each video element.
   // Update each of them if needed.
   for (auto iter = mAsyncImagePipelines.Iter(); !iter.Done(); iter.Next()) {
     wr::ResourceUpdateQueue resourceUpdates;
+
     wr::PipelineId pipelineId = wr::AsPipelineId(iter.Key());
     AsyncImagePipeline* pipeline = iter.Data();
 
     nsTArray<wr::ImageKey> keys;
     auto op = UpdateImageKeys(resourceUpdates, pipeline, keys);
 
+    txn.UpdateResources(resourceUpdates);
+
     bool updateDisplayList = pipeline->mInitialised &&
                              (pipeline->mIsChanged || op == Some(TextureHost::ADD_IMAGE)) &&
                              !!pipeline->mCurrentTexture;
@@ -299,7 +309,7 @@ AsyncImagePipelineManager::ApplyAsyncImages()
       // We don't need to update the display list, either because we can't or because
       // the previous one is still up to date.
       // We may, however, have updated some resources.
-      mApi->UpdatePipelineResources(resourceUpdates, pipelineId, epoch);
+      txn.UpdateEpoch(pipelineId, epoch);
       if (pipeline->mCurrentTexture) {
         HoldExternalImage(pipelineId, epoch, pipeline->mCurrentTexture->AsWebRenderTextureHost());
       }
@@ -351,11 +361,14 @@ AsyncImagePipelineManager::ApplyAsyncImages()
     wr::BuiltDisplayList dl;
     wr::LayoutSize builderContentSize;
     builder.Finalize(builderContentSize, dl);
-    mApi->SetDisplayList(gfx::Color(0.f, 0.f, 0.f, 0.f), epoch, LayerSize(pipeline->mScBounds.Width(), pipeline->mScBounds.Height()),
-                         pipelineId, builderContentSize,
-                         dl.dl_desc, dl.dl,
-                         resourceUpdates);
+    txn.SetDisplayList(gfx::Color(0.f, 0.f, 0.f, 0.f),
+                       epoch,
+                       LayerSize(pipeline->mScBounds.Width(), pipeline->mScBounds.Height()),
+                       pipelineId, builderContentSize,
+                       dl.dl_desc, dl.dl);
   }
+
+  mApi->SendTransaction(txn);
 }
 
 void

gfx/layers/wr/WebRenderBridgeParent.cpp

@@ -603,6 +603,7 @@ WebRenderBridgeParent::RecvSetDisplayList(const gfx::IntSize& aSize,
   uint32_t wrEpoch = GetNextWrEpoch();
 
   mAsyncImageManager->SetCompositionTime(TimeStamp::Now());
+
   ProcessWebRenderParentCommands(aCommands);
 
   wr::ResourceUpdateQueue resources;
@@ -610,6 +611,8 @@ WebRenderBridgeParent::RecvSetDisplayList(const gfx::IntSize& aSize,
     return IPC_FAIL(this, "Failed to deserialize resource updates");
   }
 
+  wr::TransactionBuilder txn;
+  txn.UpdateResources(resources);
 
   wr::Vec<uint8_t> dlData(Move(dl));
 
@@ -619,13 +622,14 @@ WebRenderBridgeParent::RecvSetDisplayList(const gfx::IntSize& aSize,
   if (mIdNamespace == aIdNamespace) {
     if (mWidget) {
       LayoutDeviceIntSize size = mWidget->GetClientSize();
-      mApi->SetWindowParameters(size);
+      txn.SetWindowParameters(size);
     }
     gfx::Color clearColor(0.f, 0.f, 0.f, 0.f);
-    mApi->SetDisplayList(clearColor, wr::NewEpoch(wrEpoch), LayerSize(aSize.width, aSize.height),
-                        mPipelineId, aContentSize,
-                        dlDesc, dlData,
-                        resources);
+    txn.SetDisplayList(clearColor, wr::NewEpoch(wrEpoch), LayerSize(aSize.width, aSize.height),
+                       mPipelineId, aContentSize,
+                       dlDesc, dlData);
+
+    mApi->SendTransaction(txn);
 
     ScheduleGenerateFrame();
 
@@ -686,12 +690,11 @@ WebRenderBridgeParent::RecvEmptyTransaction(const FocusTarget& aFocusTarget,
   UpdateAPZ(false);
 
   if (!aCommands.IsEmpty()) {
+    wr::TransactionBuilder txn;
     uint32_t wrEpoch = GetNextWrEpoch();
-    // Send empty UpdatePipelineResources to WebRender just to notify a new epoch.
-    // The epoch is used to know a timing of calling DidComposite().
-    // This is much simpler than tracking an epoch of AsyncImagePipeline.
-    wr::ResourceUpdateQueue resourceUpdates;
-    mApi->UpdatePipelineResources(resourceUpdates, mPipelineId, wr::NewEpoch(wrEpoch));
+    txn.UpdateEpoch(mPipelineId, wr::NewEpoch(wrEpoch));
+    mApi->SendTransaction(txn);
+
     HoldPendingTransactionId(wrEpoch, aTransactionId, aTxnStartTime, aFwdTime);
   } else {
     bool sendDidComposite = false;
@@ -706,6 +709,7 @@ WebRenderBridgeParent::RecvEmptyTransaction(const FocusTarget& aFocusTarget,
       mCompositorBridge->DidComposite(wr::AsUint64(mPipelineId), now, now);
     }
   }
+
   return IPC_OK();
 }
 
@@ -1243,11 +1247,15 @@ WebRenderBridgeParent::CompositeToTarget(gfx::DrawTarget* aTarget, const gfx::In
   mApi->SetFrameStartTime(startTime);
 #endif
 
+  wr::TransactionBuilder txn;
+
   if (!transformArray.IsEmpty() || !opacityArray.IsEmpty()) {
-    mApi->GenerateFrame(opacityArray, transformArray);
-  } else {
-    mApi->GenerateFrame();
+    txn.UpdateDynamicProperties(opacityArray, transformArray);
   }
+
+  txn.GenerateFrame();
+
+  mApi->SendTransaction(txn);
 }
 
 void

gfx/webrender_bindings/src/bindings.rs

@@ -1072,6 +1072,9 @@ pub extern "C" fn wr_api_send_transaction(
     dh: &mut DocumentHandle,
     transaction: &mut Transaction
 ) {
+    if transaction.is_empty() {
+        return;
+    }
     let txn = mem::replace(transaction, Transaction::new());
     dh.api.send_transaction(dh.document_id, txn);
 }