[Android WebView] Clean up global GL resource pt.1

content/browser/android/in_process/synchronous_compositor_impl.cc

Index: content/browser/android/in_process/synchronous_compositor_impl.cc
diff --git a/content/browser/android/in_process/synchronous_compositor_impl.cc b/content/browser/android/in_process/synchronous_compositor_impl.cc
index d2246a504dcb3ab7fff34dccd44124115437d192..6833947d5cafc2a9fcb8b933a8e1925cc84de9ed 100644
--- a/content/browser/android/in_process/synchronous_compositor_impl.cc
+++ b/content/browser/android/in_process/synchronous_compositor_impl.cc
@@ -76,7 +76,8 @@ class VideoContextProvider
 class SynchronousCompositorFactoryImpl : public SynchronousCompositorFactory {
  public:
   SynchronousCompositorFactoryImpl()
-      : wrapped_gl_context_for_main_thread_(NULL) {
+      : wrapped_gl_context_for_main_thread_(NULL),
+        num_hardware_compositor_(0) {
     SynchronousCompositorFactory::SetInstance(this);
   }
 
@@ -137,16 +138,20 @@ class SynchronousCompositorFactoryImpl : public SynchronousCompositorFactory {
 
   virtual scoped_refptr<cc::ContextProvider>
   GetOffscreenContextProviderForMainThread() OVERRIDE {
-    if (!offscreen_context_for_main_thread_.get() ||
-        offscreen_context_for_main_thread_->DestroyedOnMainThread()) {
+    bool can_create_context = CanCreateMainThreadContext();
+    if (can_create_context &&
+        (!offscreen_context_for_main_thread_.get() ||
+         offscreen_context_for_main_thread_->DestroyedOnMainThread())) {
       offscreen_context_for_main_thread_ =
           webkit::gpu::ContextProviderInProcess::Create(
               CreateOffscreenContext());
-      if (offscreen_context_for_main_thread_.get() &&
-          !offscreen_context_for_main_thread_->BindToCurrentThread()) {
-        offscreen_context_for_main_thread_ = NULL;
-        wrapped_gl_context_for_main_thread_ = NULL;
-      }
+    }
+
+    if (!can_create_context ||
+        (offscreen_context_for_main_thread_.get() &&
+         !offscreen_context_for_main_thread_->BindToCurrentThread())) {
+      offscreen_context_for_main_thread_ = NULL;
+      wrapped_gl_context_for_main_thread_ = NULL;
     }
     return offscreen_context_for_main_thread_;
   }
@@ -159,7 +164,7 @@ class SynchronousCompositorFactoryImpl : public SynchronousCompositorFactory {
   // any thread and is lightweight.
   virtual scoped_refptr<cc::ContextProvider>
       GetOffscreenContextProviderForCompositorThread() OVERRIDE {
-    base::AutoLock lock(offscreen_context_for_compositor_thread_creation_lock_);
+    base::AutoLock lock(offscreen_context_for_compositor_thread_lock_);

[no sievers, 2013/09/04 22:27:09]

Does this also need to check if we actually have a shared context, i.e.
num_hardware_compositors > 0?
Or should it at least DCHECK()?

[boliu, 2013/09/04 23:05:57]

Aha, yes, I did give this some thought. cc should never ask for the unless
hardware is initialized (ie has gl_renderer), by that time, we must already have
a compositor context, so it's fine.

I would have added DCHECK except we also call this from InitializeHwDraw, where
we need to call this before knowing if initialization is going to be successful,
so for the first initialization, num_hardware_compositor will be 0. Didn't want
to change things too much for merging to m30...

     if (!offscreen_context_for_compositor_thread_.get() ||
         offscreen_context_for_compositor_thread_->DestroyedOnMainThread()) {
       offscreen_context_for_compositor_thread_ =
@@ -178,19 +183,62 @@ class SynchronousCompositorFactoryImpl : public SynchronousCompositorFactory {
         .PassAs<StreamTextureFactory>();
   }
 
+  void CompositorInitializedHardwareDraw(SynchronousCompositorImpl* compositor);
+  void CompositorReleasedHardwareDraw(SynchronousCompositorImpl* compositor);
+
  private:
+  void ReleaseGlobalHardwareResources();
+  bool CanCreateMainThreadContext();
+
   SynchronousInputEventFilter synchronous_input_event_filter_;
 
-  // Only guards construction of |offscreen_context_for_compositor_thread_|,
-  // not usage.
-  base::Lock offscreen_context_for_compositor_thread_creation_lock_;
+  // Only guards construction and destruction of
+  // |offscreen_context_for_compositor_thread_|, not usage.
+  base::Lock offscreen_context_for_compositor_thread_lock_;
   scoped_refptr<cc::ContextProvider> offscreen_context_for_main_thread_;
   // This is a pointer to the context owned by
   // |offscreen_context_for_main_thread_|.
   gpu::GLInProcessContext* wrapped_gl_context_for_main_thread_;
   scoped_refptr<cc::ContextProvider> offscreen_context_for_compositor_thread_;
+
+  base::Lock num_hardware_compositor_lock_;
+  unsigned int num_hardware_compositor_;

[no sievers, 2013/09/04 22:27:09]

nit: num_hardware_compositors

[boliu, 2013/09/04 23:05:57]

Done.

 };
 
+void SynchronousCompositorFactoryImpl::CompositorInitializedHardwareDraw(
+    SynchronousCompositorImpl* compositor) {
+  base::AutoLock lock(num_hardware_compositor_lock_);
+  num_hardware_compositor_++;
+}
+
+void SynchronousCompositorFactoryImpl::CompositorReleasedHardwareDraw(
+    SynchronousCompositorImpl* compositor) {
+  bool should_release_resources = false;
+  {
+    base::AutoLock lock(num_hardware_compositor_lock_);
+    DCHECK_GT(num_hardware_compositor_, 0u);
+    num_hardware_compositor_--;
+    should_release_resources = num_hardware_compositor_ == 0u;
+  }
+  if (should_release_resources)
+    ReleaseGlobalHardwareResources();
+}
+
+void SynchronousCompositorFactoryImpl::ReleaseGlobalHardwareResources() {
+  {
+    base::AutoLock lock(offscreen_context_for_compositor_thread_lock_);
+    offscreen_context_for_compositor_thread_ = NULL;
+  }
+
+  // TODO(boliu): Properly clean up command buffer server of main thread
+  // context here.
+}
+
+bool SynchronousCompositorFactoryImpl::CanCreateMainThreadContext() {
+  base::AutoLock lock(num_hardware_compositor_lock_);
+  return num_hardware_compositor_ > 0;
+}
+
 base::LazyInstance<SynchronousCompositorFactoryImpl>::Leaky g_factory =
     LAZY_INSTANCE_INITIALIZER;
 
@@ -241,15 +289,19 @@ bool SynchronousCompositorImpl::InitializeHwDraw(
     scoped_refptr<gfx::GLSurface> surface) {
   DCHECK(CalledOnValidThread());
   DCHECK(output_surface_);
-  return output_surface_->InitializeHwDraw(
+  bool success = output_surface_->InitializeHwDraw(
       surface,
       g_factory.Get().GetOffscreenContextProviderForCompositorThread());
+  if (success)
+    g_factory.Get().CompositorInitializedHardwareDraw(this);
+  return success;
 }
 
 void SynchronousCompositorImpl::ReleaseHwDraw() {
   DCHECK(CalledOnValidThread());
   DCHECK(output_surface_);
-  return output_surface_->ReleaseHwDraw();
+  output_surface_->ReleaseHwDraw();
+  g_factory.Get().CompositorReleasedHardwareDraw(this);
 }
 
 bool SynchronousCompositorImpl::DemandDrawHw(