gpu: Allow fences to check whether a flush has occurred

ui/gl/gl_context.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GL_GL_CONTEXT_H_
 #define UI_GL_GL_CONTEXT_H_
 
 #include <string>
+#include <vector>
 
+#include "base/atomicops.h"
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/gl/gl_share_group.h"
 #include "ui/gl/gl_state_restorer.h"
 #include "ui/gl/gpu_preference.h"
 
 namespace gfx {
 
 class GLSurface;
 class VirtualGLApi;
 struct GLVersionInfo;
 
 // Encapsulates an OpenGL context, hiding platform specific management.
 class GL_EXPORT GLContext : public base::RefCounted<GLContext> {
  public:
   explicit GLContext(GLShareGroup* share_group);
 
   // Initializes the GL context to be compatible with the given surface. The GL
   // context can be made with other surface's of the same type. The compatible
   // surface is only needed for certain platforms like WGL, OSMesa and GLX. It
   // should be specific for all platforms though.
   virtual bool Initialize(
       GLSurface* compatible_surface, GpuPreference gpu_preference) = 0;
 
+  class FlushEvent : public base::RefCountedThreadSafe<FlushEvent> {
+    public:
+      bool IsSignaled();
+
+    private:
+      friend class base::RefCountedThreadSafe<FlushEvent>;
+      friend class GLContext;
+      FlushEvent();
+      virtual ~FlushEvent();
+      void Signal();
+
+      base::subtle::Atomic32 state_;
+  };
+
+  scoped_refptr<FlushEvent> SignalFlush();
+
   // Destroys the GL context.
   virtual void Destroy() = 0;
 
   // Makes the GL context and a surface current on the current thread.
   virtual bool MakeCurrent(GLSurface* surface) = 0;
 
   // Releases this GL context and surface as current on the current thread.
   virtual void ReleaseCurrent(GLSurface* surface) = 0;
 
   // Returns true if this context and surface is current. Pass a null surface
@@ skipping 62 matching lines @@
   // Notify this context that |virtual_context|, that was using us, is
   // being released or destroyed.
   void OnReleaseVirtuallyCurrent(GLContext* virtual_context);
 
   // Returns the GL version string. The context must be current.
   virtual std::string GetGLVersion();
 
   // Returns the GL renderer string. The context must be current.
   virtual std::string GetGLRenderer();
 
+  // Called when glFlush()/glFinish() is called with this context current.
+  void OnFlush();
+
  protected:
   virtual ~GLContext();
 
   // Sets the GL api to the real hardware API (vs the VirtualAPI)
   static void SetRealGLApi();
   virtual void SetCurrent(GLSurface* surface);
 
   // Initialize function pointers to functions where the bound version depends
   // on GL version or supported extensions. Should be called immediately after
   // this context is made current.
   bool InitializeDynamicBindings();
 
   // Returns the last real (non-virtual) GLContext made current.
   static GLContext* GetRealCurrent();
 
  private:
   friend class base::RefCounted<GLContext>;
 
   // For GetRealCurrent.
   friend class VirtualGLApi;
 
   scoped_refptr<GLShareGroup> share_group_;
   scoped_ptr<VirtualGLApi> virtual_gl_api_;
   scoped_ptr<GLStateRestorer> state_restorer_;
   scoped_ptr<GLVersionInfo> version_info_;
 
+  std::vector<scoped_refptr<FlushEvent> > flush_events_;
+
   DISALLOW_COPY_AND_ASSIGN(GLContext);
 };
 
 class GL_EXPORT GLContextReal : public GLContext {
  public:
   explicit GLContextReal(GLShareGroup* share_group);
 
  protected:
   virtual ~GLContextReal();
 
   virtual void SetCurrent(GLSurface* surface) OVERRIDE;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(GLContextReal);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_CONTEXT_H_