gpu: reference target surfaces through a globally unique surface id.

content/browser/gpu/gpu_surface_tracker.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 CONTENT_BROWSER_GPU_GPU_SURFACE_TRACKER_H_
+#define CONTENT_BROWSER_GPU_GPU_SURFACE_TRACKER_H_
+
+#include <map>
+
+#include "base/basictypes.h"
+#include "base/memory/singleton.h"
+#include "base/synchronization/lock.h"
+#include "ui/gfx/native_widget_types.h"
+
+// This class is responsible for managing rendering surfaces exposed to the
+// GPU process. Every surface gets registered to this class, and gets an ID.
+// All calls to and from the GPU process, with the exception of
+// CreateViewCommandBuffer, refer to the rendering surface by its ID.
+// This class is thread safe.
+//
+// Note: The ID can exist before the actual native handle for the surface is
+// created, for example to allow giving a reference to it to a renderer, so that
+// it is unamibiguously identified.
+class GpuSurfaceTracker {
+ public:
+  static GpuSurfaceTracker* GetInstance();
+  static GpuSurfaceTracker* Get() { return GetInstance(); }

[jonathan.backer, 2012/01/16 19:47:26]

Why both Get() and GetInstance()?

[piman, 2012/01/17 19:40:54]

I added a comment, it's just syntactic sugar. Singleton (implementation detail)
want GetInstance. For call site clarity, having it named "Get" helps a lot
(wrapping). But they're identical.

+
+  // Adds a surface for a given RenderWidgetHost. |renderer_id| is the renderer
+  // process ID, |render_widget_id| is the RenderWidgetHost route id within that
+  // renderer. Returns the surface ID.
+  int AddSurfaceForRenderer(int renderer_id, int render_widget_id);
+
+  // Looks up a surface for a given RenderWidgetHost. Returns the surface
+  // ID, or 0 if not found.
+  // Note: This is an O(N) lookup.
+  int LookupSurfaceForRenderer(int renderer_id, int render_widget_id);

[jonathan.backer, 2012/01/16 19:47:26]

Not sure it matters (this isn't performance critical code), but it'd be
straightforward to have a map from pair<renderer_id,render_widget_id> ->
surface_id to make this a fast lookup.

[piman, 2012/01/17 19:40:54]

Yeah, I figured it's not worth the extra space, plus the added complexity of
maintaining that other map (needs to be done in at the call sites).

+
+  // Removes a given existing surface.
+  void RemoveSurface(int surface_id);
+
+  // Gets the renderer process ID and RenderWidgetHost route id for a given
+  // surface, returning true if the surface is found (and corresponds to a
+  // RenderWidgetHost), or false if not.
+  bool GetRenderWidgetIDForSurface(int surface_id,
+                                   int* renderer_id,
+                                   int* render_widget_id);
+
+  // Sets the native handle for the given surface.
+  // Note: This is an O(log N) lookup.
+  void SetSurfaceHandle(int surface_id, gfx::PluginWindowHandle handle);
+
+  // Gets the native handle for the given surface.
+  // Note: This is an O(log N) lookup.
+  gfx::PluginWindowHandle GetSurfaceHandle(int surface_id);
+
+ private:
+  struct SurfaceInfo {
+    int renderer_id;
+    int render_widget_id;
+    gfx::PluginWindowHandle handle;
+  };
+  typedef std::map<int, SurfaceInfo> SurfaceMap;
+
+  friend class DefaultSingletonTraits<GpuSurfaceTracker>;
+
+  GpuSurfaceTracker();
+  ~GpuSurfaceTracker();
+
+  base::Lock lock_;
+  SurfaceMap surface_map_;
+  int next_surface_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(GpuSurfaceTracker);
+};
+
+#endif  // CONTENT_BROWSER_GPU_GPU_SURFACE_TRACKER_H_