Implement proper synchronization between HW video decode IPC and CommandBuffer.

content/common/gpu/media/gpu_video_decode_accelerator.h

 // Copyright (c) 2011 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_COMMON_GPU_MEDIA_GPU_VIDEO_DECODE_ACCELERATOR_H_
 #define CONTENT_COMMON_GPU_MEDIA_GPU_VIDEO_DECODE_ACCELERATOR_H_
 
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/shared_memory.h"
 #include "ipc/ipc_channel.h"
 #include "ipc/ipc_message.h"
 #include "media/video/video_decode_accelerator.h"
 
+namespace gpu {
+class ReadWriteTokens;
+}
+
+class GpuCommandBufferStub;
+
 class GpuVideoDecodeAccelerator
     : public base::RefCountedThreadSafe<GpuVideoDecodeAccelerator>,
       public IPC::Channel::Listener,
       public IPC::Message::Sender,
       public media::VideoDecodeAccelerator::Client {
  public:
-  GpuVideoDecodeAccelerator(IPC::Message::Sender* sender, int32 host_route_id);
+  GpuVideoDecodeAccelerator(IPC::Message::Sender* sender,
+                            int32 host_route_id,
+                            int32 decoder_route_id,
+                            GpuCommandBufferStub* stub);
   virtual ~GpuVideoDecodeAccelerator();
 
   // IPC::Channel::Listener implementation.
   virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE;
   virtual void OnChannelConnected(int32 peer_pid) OVERRIDE;
   virtual void OnChannelError() OVERRIDE;
 
   // media::VideoDecodeAccelerator::Client implementation.
   virtual void ProvidePictureBuffers(
       uint32 requested_num_of_buffers,
@@ skipping 12 matching lines @@
   virtual bool Send(IPC::Message* message);
 
   void set_video_decode_accelerator(
       media::VideoDecodeAccelerator* accelerator) {
     DCHECK(!video_decode_accelerator_.get());
     video_decode_accelerator_.reset(accelerator);
   }
 
   void AssignGLESBuffers(const std::vector<media::GLESBuffer>& buffers);
 
+  // Callback to be fired when the underlying stub receives a new token.
+  void OnSetToken(int32 token);
+
  private:
+  // Defers |msg| for later processing if it specifies a write token that hasn't
+  // come to pass yet, and set |*deferred| to true.  Return false if the message
+  // failed to parse.
+  bool DeferMessageIfNeeded(const IPC::Message& msg, bool* deferred);
+
   // Handlers for IPC messages.
-  void OnGetConfigs(const std::vector<uint32>& config,
-                    std::vector<uint32>* configs);
-  void OnInitialize(const std::vector<uint32>& configs);
-  void OnDecode(int32 id, base::SharedMemoryHandle handle, int32 size);
-  void OnAssignSysmemBuffers(const std::vector<int32>& buffer_ids,
-                             const std::vector<base::SharedMemoryHandle>& data,
-                             const std::vector<gfx::Size>& sizes);
-  void OnReusePictureBuffer(int32 picture_buffer_id);
-  void OnFlush();
-  void OnAbort();
+  void OnGetConfigs(
+      const gpu::ReadWriteTokens& /* tokens */,

[scherkus (not reviewing), 2011/06/28 22:02:07]

do you still need all the /* tokens */ or can we just have tokens sans-comment?

I was under the impression you had the /* tokens */ because we had
std::pair<int,int> but if that wasn't the case then ignore

[Ami GONE FROM CHROMIUM, 2011/06/28 22:25:06]

I put the param name as comment when the param is not used inside the method. 
Same convention as _ignored suffix, but less vulnerable to bitrot.

+      const std::vector<uint32>& config,
+      std::vector<uint32>* configs);
+  void OnInitialize(
+      const gpu::ReadWriteTokens& /* tokens */,
+      const std::vector<uint32>& configs);
+  void OnDecode(
+      const gpu::ReadWriteTokens& /* tokens */,
+      base::SharedMemoryHandle handle, int32 id, int32 size);
+  void OnAssignTextures(
+      const gpu::ReadWriteTokens& /* tokens */,
+      const std::vector<int32>& buffer_ids,
+      const std::vector<uint32>& texture_ids,
+      const std::vector<gfx::Size>& sizes);
+  void OnAssignSysmemBuffers(
+      const gpu::ReadWriteTokens& /* tokens */,
+      const std::vector<int32> buffer_ids,
+      const std::vector<base::SharedMemoryHandle> data,
+      const std::vector<gfx::Size> sizes);
+  void OnReusePictureBuffer(
+      const gpu::ReadWriteTokens& /* tokens */,
+      int32 picture_buffer_id);
+  void OnFlush(const gpu::ReadWriteTokens& /* tokens */);
+  void OnAbort(const gpu::ReadWriteTokens& /* tokens */);
 
   // Pointer to the IPC message sender.
   IPC::Message::Sender* sender_;
 
   // Route ID to communicate with the host.
-  int32 route_id_;
+  int32 host_route_id_;
+
+  // Route ID of the decoder.
+  int32 decoder_route_id_;
+
+  // Messages deferred for later processing when their tokens have come to pass.
+  std::vector<IPC::Message*> deferred_messages_;
+
+  // Unowned pointer to the underlying GpuCommandBufferStub.
+  GpuCommandBufferStub* stub_;
 
   // Pointer to the underlying VideoDecodeAccelerator.
   scoped_ptr<media::VideoDecodeAccelerator> video_decode_accelerator_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(GpuVideoDecodeAccelerator);
 };
 
 #endif  // CONTENT_COMMON_GPU_MEDIA_GPU_VIDEO_DECODE_ACCELERATOR_H_