GLInProcessContext: support async flushes and dedicated GPU thread

gpu/command_buffer/service/in_process_command_buffer.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 GPU_COMMAND_BUFFER_SERVICE_IN_PROCESS_COMMAND_BUFFER_H_
+#define GPU_COMMAND_BUFFER_SERVICE_IN_PROCESS_COMMAND_BUFFER_H_
+
+#include "base/callback.h"
+#include "base/compiler_specific.h"
+#include "base/synchronization/lock.h"
+#include "gpu/command_buffer/common/command_buffer.h"
+#include "gpu/gpu_export.h"
+#include "ui/gfx/native_widget_types.h"
+#include "ui/gl/gpu_preference.h"
+
+namespace gfx {
+class GLContext;
+class GLImage;
+class GLSurface;
+class Size;
+}
+
+namespace gpu {
+
+namespace gles2 {
+class GLES2Decoder;
+}
+
+class GpuScheduler;
+class TransferBufferManagerInterface;
+
+// This class provides a thread-safe interface to the global GPU service (for
+// example GPU thread) when being run in single process mode.
+// However, the behavior for accessing one context (i.e. one instance of this
+// class) from different client threads is undefined.
+class GPU_EXPORT InProcessCommandBuffer : public CommandBuffer {
+ public:
+  InProcessCommandBuffer();
+  virtual ~InProcessCommandBuffer();
+
+  // Used to override the GPU thread with explicit scheduling.
+  // (By default an internal GPU thread will be spawned to handle all GL work
+  // and the two functions are unused.)
+  // The callback will be called from different client threads. After the
+  // callback is issued, the client is expected to eventually call
+  // ProcessGpuWorkOnCurrentThread(). The latter cannot be called from different
+  // threads.
+  static void SetScheduleCallback(const base::Closure& callback);
+  static void ProcessGpuWorkOnCurrentThread();
+
+  static void EnableVirtualizedContext();
+
+  bool Initialize(bool is_offscreen,
+                  bool share_resources,
+                  gfx::AcceleratedWidget window,
+                  const gfx::Size& size,
+                  const char* allowed_extensions,
+                  const std::vector<int32>& attribs,
+                  gfx::GpuPreference gpu_preference,
+                  const base::Closure& context_lost_callback);
+  void Destroy();
+  void SignalSyncPoint(unsigned sync_point,
+                       const base::Closure& callback);
+  unsigned int AddImage(scoped_refptr<gfx::GLImage> image);
+  void RemoveImage(unsigned int image_id);
+
+  // CommandBuffer implementation:
+  virtual bool Initialize() OVERRIDE;
+  virtual State GetState() OVERRIDE;
+  virtual State GetLastState() OVERRIDE;
+  virtual int32 GetLastToken() OVERRIDE;
+  virtual void Flush(int32 put_offset) OVERRIDE;
+  virtual State FlushSync(int32 put_offset, int32 last_known_get) OVERRIDE;
+  virtual void SetGetBuffer(int32 shm_id) OVERRIDE;
+  virtual void SetGetOffset(int32 get_offset) OVERRIDE;
+  virtual gpu::Buffer CreateTransferBuffer(size_t size, int32* id) OVERRIDE;
+  virtual void DestroyTransferBuffer(int32 id) OVERRIDE;
+  virtual gpu::Buffer GetTransferBuffer(int32 id) OVERRIDE;
+  virtual void SetToken(int32 token) OVERRIDE;
+  virtual void SetParseError(gpu::error::Error error) OVERRIDE;
+  virtual void SetContextLostReason(
+      gpu::error::ContextLostReason reason) OVERRIDE;
+  virtual uint32 InsertSyncPoint() OVERRIDE;
+  virtual gpu::error::Error GetLastError() OVERRIDE;
+
+ private:
+  bool InitializeOnGpuThread(bool is_offscreen,
+                             gfx::AcceleratedWidget window,
+                             const gfx::Size& size,
+                             const char* allowed_extensions,
+                             const std::vector<int32>& attribs,
+                             gfx::GpuPreference gpu_preference);
+  bool DestroyOnGpuThread();
+  bool MakeCurrent();
+  bool IsContextLost();
+  base::Closure WrapCallback(const base::Closure& callback);
+  State GetStateFast();
+
+  // Callbacks:
+  void OnContextLost();
+  void OnResizeView(gfx::Size size, float scale_factor);
+  bool GetBufferChanged(int32 transfer_buffer_id);
+  void PumpCommands();
+
+  bool context_lost_;
+  bool share_resources_;
+  scoped_ptr<TransferBufferManagerInterface> transfer_buffer_manager_;
+  scoped_ptr<CommandBuffer> command_buffer_;
+  scoped_ptr<GpuScheduler> gpu_scheduler_;
+  scoped_ptr<gles2::GLES2Decoder> decoder_;
+  scoped_refptr<gfx::GLContext> context_;
+  scoped_refptr<gfx::GLSurface> surface_;
+  base::Closure context_lost_callback_;
+  State last_state_;
+  int32 last_put_offset_;
+  base::Lock service_lock_;

[piman, 2013/07/23 01:57:14]

Can you document what exactly this lock protects? And more generally which field
is expected to be accessed on which thread? E.g. command_buffer_ is definitely
accessed from both threads with the lock held, but last_state_ and
last_put_offset_ are only used from the main thread without the lock, and
context_lost_ is only used from the GPU thread without the lock.

[no sievers, 2013/07/25 00:41:23]

Done.

+
+  DISALLOW_COPY_AND_ASSIGN(InProcessCommandBuffer);
+};
+
+}  // namespace gpu
+
+#endif  // GPU_COMMAND_BUFFER_SERVICE_IN_PROCESS_COMMAND_BUFFER_H_