b=752368; [android] random black screen when opening links from other apps; r=bgirard,ajuma

gfx/layers/ipc/CompositorParent.cpp

@@ -1,4 +1,4 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set sw=2 ts=2 et tw=80 : */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
@@ -71,6 +71,7 @@ CompositorParent::CompositorParent(nsIWidget* aWidget, MessageLoop* aMsgLoop,
   , mThreadID(aThreadID)
   , mRenderToEGLSurface(aRenderToEGLSurface)
   , mEGLSurfaceSize(aSurfaceWidth, aSurfaceHeight)
+  , mPauseCompositionMonitor("PauseCompositionMonitor")
 {
   MOZ_COUNT_CTOR(CompositorParent);
 }
@@ -146,6 +147,9 @@ CompositorParent::PauseComposition()
 {
   NS_ABORT_IF_FALSE(CompositorThreadID() == PlatformThread::CurrentId(),
                     "PauseComposition() can only be called on the compositor thread");
+
+  mozilla::MonitorAutoLock lock(mPauseCompositionMonitor);
+
   if (!mPaused) {
     mPaused = true;
 
@@ -153,6 +157,9 @@ CompositorParent::PauseComposition()
     static_cast<LayerManagerOGL*>(mLayerManager.get())->gl()->ReleaseSurface();
 #endif
   }
+
+  // if anyone's waiting to make sure that composition really got paused, tell them
+  lock.NotifyAll();
 }
 
 void
@@ -184,12 +191,21 @@ CompositorParent::ResumeCompositionAndResize(int width, int height)
   ResumeComposition();
 }
 
+/*
+ * This will execute a pause synchronously, waiting to make sure that the compositor
+ * really is paused.
+ */
 void
 CompositorParent::SchedulePauseOnCompositorThread()
 {
+  mozilla::MonitorAutoLock lock(mPauseCompositionMonitor);
+
   CancelableTask *pauseTask = NewRunnableMethod(this,
                                                 &CompositorParent::PauseComposition);
   CompositorLoop()->PostTask(FROM_HERE, pauseTask);
+
+  // Wait until the pause has actually been processed by the compositor thread
+  lock.Wait();
 }
 
 void

gfx/layers/ipc/CompositorParent.h

@@ -1,4 +1,4 @@
-/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set sw=4 ts=8 et tw=80 : */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
@@ -52,6 +52,7 @@
 #include "mozilla/layers/PCompositorParent.h"
 #include "mozilla/layers/PLayersParent.h"
 #include "base/thread.h"
+#include "mozilla/Monitor.h"
 #include "ShadowLayersManager.h"
 
 class nsIWidget;
@@ -170,6 +171,8 @@ private:
   bool mRenderToEGLSurface;
   nsIntSize mEGLSurfaceSize;
 
+  mozilla::Monitor mPauseCompositionMonitor;
+
   DISALLOW_EVIL_CONSTRUCTORS(CompositorParent);
 };
 

mobile/android/base/gfx/GeckoLayerClient.java

@@ -466,7 +466,13 @@ public class GeckoLayerClient implements GeckoEventResponder,
     public void compositionPauseRequested() {
         // We need to coordinate with Gecko when pausing composition, to ensure
         // that Gecko never executes a draw event while the compositor is paused.
-        GeckoAppShell.sendEventToGecko(GeckoEvent.createCompositorPauseEvent());
+        // This is sent synchronously to make sure that we don't attempt to use
+        // any outstanding Surfaces after we call this (such as from a
+        // surfaceDestroyed notification), and to make sure that any in-flight
+        // Gecko draw events have been processed.  When this returns, composition is
+        // definitely paused -- it'll synchronize with the Gecko event loop, which
+        // in turn will synchronize with the compositor thread.
+        GeckoAppShell.sendEventToGeckoSync(GeckoEvent.createCompositorPauseEvent());
     }
 
     /** Implementation of LayerView.Listener */