Bug 1381095 - Fallback correctly to non-WebRender if the GPU process/WebRender are disabled when creating a remote compositor session. r=dvander

gfx/ipc/GPUProcessManager.cpp

@@ -187,6 +187,11 @@ GPUProcessManager::DisableGPUProcess(const char* aMessage)
   // correctly. We cannot re-enter DisableGPUProcess from this call because we
   // know that it is disabled in the config above.
   EnsureProtocolsReady();
+
+  // If we disable the GPU process during reinitialization after a previous
+  // crash, then we need to tell the content processes again, because they
+  // need to rebind to the UI process.
+  HandleProcessLost();
 }
 
 bool
@@ -481,12 +486,12 @@ GPUProcessManager::OnProcessUnexpectedShutdown(GPUProcessHost* aHost)
     mDecodeVideoOnGpuProcess = false;
     Telemetry::Accumulate(Telemetry::GPU_PROCESS_CRASH_FALLBACKS,
                                      uint32_t(FallbackType::DECODINGDISABLED));
+    HandleProcessLost();
   } else {
     Telemetry::Accumulate(Telemetry::GPU_PROCESS_CRASH_FALLBACKS,
                                      uint32_t(FallbackType::NONE));
+    HandleProcessLost();
   }
-
-  HandleProcessLost();
 }
 
 void
@@ -666,14 +671,17 @@ GPUProcessManager::DestroyProcess()
 #endif
 }
 
-RefPtr<CompositorSession>
+already_AddRefed<CompositorSession>
 GPUProcessManager::CreateTopLevelCompositor(nsBaseWidget* aWidget,
                                             LayerManager* aLayerManager,
                                             CSSToLayoutDeviceScale aScale,
                                             const CompositorOptions& aOptions,
                                             bool aUseExternalSurfaceSize,
-                                            const gfx::IntSize& aSurfaceSize)
+                                            const gfx::IntSize& aSurfaceSize,
+                                            bool* aRetryOut)
 {
+  MOZ_ASSERT(aRetryOut);
+
   uint64_t layerTreeId = AllocateLayerTreeId();
 
   EnsureProtocolsReady();
@@ -692,10 +700,10 @@ GPUProcessManager::CreateTopLevelCompositor(nsBaseWidget* aWidget,
     if (!session) {
       // We couldn't create a remote compositor, so abort the process.
       DisableGPUProcess("Failed to create remote compositor");
+      *aRetryOut = true;
+      return nullptr;
     }
-  }
-
-  if (!session) {
+  } else {
     session = InProcessCompositorSession::Create(
       aWidget,
       aLayerManager,
@@ -715,7 +723,8 @@ GPUProcessManager::CreateTopLevelCompositor(nsBaseWidget* aWidget,
   }
 #endif // defined(MOZ_WIDGET_ANDROID)
 
-  return session;
+  *aRetryOut = false;
+  return session.forget();
 }
 
 RefPtr<CompositorSession>

gfx/ipc/GPUProcessManager.h

@@ -89,13 +89,14 @@ public:
   // Otherwise it blocks until the GPU process has finished launching.
   bool EnsureGPUReady();
 
-  RefPtr<CompositorSession> CreateTopLevelCompositor(
+  already_AddRefed<CompositorSession> CreateTopLevelCompositor(
     nsBaseWidget* aWidget,
     LayerManager* aLayerManager,
     CSSToLayoutDeviceScale aScale,
     const CompositorOptions& aOptions,
     bool aUseExternalSurfaceSize,
-    const gfx::IntSize& aSurfaceSize);
+    const gfx::IntSize& aSurfaceSize,
+    bool* aRetry);
 
   bool CreateContentBridges(
     base::ProcessId aOtherProcess,

widget/nsBaseWidget.cpp

@@ -1247,6 +1247,56 @@ nsBaseWidget::GetCompositorVsyncDispatcher()
   return mCompositorVsyncDispatcher;
 }
 
+already_AddRefed<LayerManager>
+nsBaseWidget::CreateCompositorSession(int aWidth,
+                                      int aHeight,
+                                      CompositorOptions* aOptionsOut)
+{
+  MOZ_ASSERT(aOptionsOut);
+
+  do {
+    CreateCompositorVsyncDispatcher();
+
+    bool enableWR = gfx::gfxVars::UseWebRender();
+    if (enableWR && !WidgetTypeSupportsAcceleration()) {
+      // fall back to basic
+      break;
+    }
+    bool enableAPZ = UseAPZ();
+    CompositorOptions options(enableAPZ, enableWR);
+
+    bool enableAL = gfx::gfxConfig::IsEnabled(gfx::Feature::ADVANCED_LAYERS);
+    options.SetUseAdvancedLayers(enableAL);
+
+    RefPtr<LayerManager> lm;
+    if (options.UseWebRender()) {
+      lm = new WebRenderLayerManager(this);
+    } else {
+      lm = new ClientLayerManager(this);
+    }
+
+    bool retry = false;
+    gfx::GPUProcessManager* gpu = gfx::GPUProcessManager::Get();
+    mCompositorSession = gpu->CreateTopLevelCompositor(
+      this,
+      lm,
+      GetDefaultScale(),
+      options,
+      UseExternalCompositingSurface(),
+      gfx::IntSize(aWidth, aHeight),
+      &retry);
+
+    // We need to retry in a loop because the act of failing to create the
+    // compositor can change our state (e.g. disable WebRender).
+    if (mCompositorSession || !retry) {
+      *aOptionsOut = options;
+      return lm.forget();
+    }
+  } while (true);
+
+  return nullptr;
+}
+
 void nsBaseWidget::CreateCompositor(int aWidth, int aHeight)
 {
   // This makes sure that gfxPlatforms gets initialized if it hasn't by now.
@@ -1271,34 +1321,14 @@ void nsBaseWidget::CreateCompositor(int aWidth, int aHeight)
     return;
   }
 
-  CreateCompositorVsyncDispatcher();
-
-  bool enableWR = gfx::gfxVars::UseWebRender();
-  if (enableWR && !WidgetTypeSupportsAcceleration()) {
-    // fall back to basic
+  CompositorOptions options;
+  RefPtr<LayerManager> lm =
+    CreateCompositorSession(aWidth, aHeight, &options);
+  if (!lm) {
     return;
   }
-  bool enableAPZ = UseAPZ();
-  CompositorOptions options(enableAPZ, enableWR);
 
-  bool enableAL = gfx::gfxConfig::IsEnabled(gfx::Feature::ADVANCED_LAYERS);
-  options.SetUseAdvancedLayers(enableAL);
-
-  RefPtr<LayerManager> lm;
-  if (options.UseWebRender()) {
-    lm = new WebRenderLayerManager(this);
-  } else {
-    lm = new ClientLayerManager(this);
-  }
-
-  gfx::GPUProcessManager* gpu = gfx::GPUProcessManager::Get();
-  mCompositorSession = gpu->CreateTopLevelCompositor(
-    this,
-    lm,
-    GetDefaultScale(),
-    options,
-    UseExternalCompositingSurface(),
-    gfx::IntSize(aWidth, aHeight));
+  MOZ_ASSERT(mCompositorSession);
   mCompositorBridgeChild = mCompositorSession->GetCompositorBridgeChild();
   mCompositorWidgetDelegate = mCompositorSession->GetCompositorWidgetDelegate();
 

widget/nsBaseWidget.h

@@ -11,6 +11,7 @@
 #include "mozilla/UniquePtr.h"
 #include "mozilla/WidgetUtils.h"
 #include "mozilla/layers/APZCCallbackHelper.h"
+#include "mozilla/layers/CompositorOptions.h"
 #include "nsRect.h"
 #include "nsIWidget.h"
 #include "nsWidgetsCID.h"
@@ -743,6 +744,11 @@ protected:
 
   static bool debug_GetCachedBoolPref(const char* aPrefName);
 #endif
+
+private:
+  already_AddRefed<LayerManager>
+  CreateCompositorSession(int aWidth, int aHeight,
+                          mozilla::layers::CompositorOptions* aOptionsOut);
 };
 
 #endif // nsBaseWidget_h__