Implemented get and put offset synchronization via NPObject interface in GPU plugin CommandBuffer.

Added GPUProcessor which handles commands (currently 4-byte "colors") put into the command buffer.
TEST=none
BUG=none

Review URL: http://codereview.chromium.org/203003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@26762 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 40 insertions, 9 deletions

diff --git a/o3d/gpu_plugin/command_buffer.h b/o3d/gpu_plugin/command_buffer.h
index d7be196..40b8ff3 100644
--- a/o3d/gpu_plugin/command_buffer.h
+++ b/o3d/gpu_plugin/command_buffer.h
@@ -5,6 +5,9 @@
 #ifndef O3D_GPU_PLUGIN_COMMAND_BUFFER_H_
 #define O3D_GPU_PLUGIN_COMMAND_BUFFER_H_
 
+#include "base/message_loop.h"
+#include "base/scoped_ptr.h"
+#include "base/task.h"
 #include "o3d/gpu_plugin/np_utils/default_np_object.h"
 #include "o3d/gpu_plugin/np_utils/np_dispatcher.h"
 #include "o3d/gpu_plugin/system_services/shared_memory_public.h"
@@ -22,28 +25,56 @@ class CommandBuffer : public DefaultNPObject<NPObject> {
   // Create a shared memory buffer of the given size.
   virtual bool Initialize(int32 size);
 
-  // Gets the shared memory object for the command buffer.
-  virtual NPObjectPointer<NPObject> GetSharedMemory();
+  // Gets the shared memory ring buffer object for the command buffer.
+  virtual NPObjectPointer<CHRSharedMemory> GetRingBuffer();
 
-  // The client calls this to update its put offset.
-  virtual void SetPutOffset(int32 offset);
+  virtual int32 GetSize();
 
-  // The client calls this to get the servers current get offset.
+  // The writer calls this to update its put offset. This function returns the
+  // reader's most recent get offset. Does not return until after the put offset
+  // change callback has been invoked. Returns -1 if the put offset is invalid.
+  virtual int32 SyncOffsets(int32 put_offset);
+
+  // Returns the current get offset. This can be called from any thread.
   virtual int32 GetGetOffset();
 
+  // Sets the current get offset. This can be called from any thread.
+  virtual void SetGetOffset(int32 get_offset);
+
+  // Returns the current put offset. This can be called from any thread.
+  virtual int32 GetPutOffset();
+
+  // Sets a callback that should be posted on another thread whenever the put
+  // offset is changed. The callback must not return until some progress has
+  // been made (unless the command buffer is empty), i.e. the
+  // get offset must have changed. It need not process the entire command
+  // buffer though. This allows concurrency between the writer and the reader
+  // while giving the writer a means of waiting for the reader to make some
+  // progress before attempting to write more to the command buffer. Avoiding
+  // the use of a synchronization primitive like a condition variable to
+  // synchronize reader and writer reduces the risk of deadlock.
+  // Takes ownership of callback. The callback is invoked on the plugin thread.
+  virtual void SetPutOffsetChangeCallback(Callback0::Type* callback);
+  
   NP_UTILS_BEGIN_DISPATCHER_CHAIN(CommandBuffer, DefaultNPObject<NPObject>)
     NP_UTILS_DISPATCHER(Initialize, bool(int32))
-    NP_UTILS_DISPATCHER(SetPutOffset, void(int32))
-    NP_UTILS_DISPATCHER(GetGetOffset, int32())
-    NP_UTILS_DISPATCHER(GetSharedMemory, NPObjectPointer<NPObject>())
+    NP_UTILS_DISPATCHER(GetRingBuffer, NPObjectPointer<CHRSharedMemory>())
+    NP_UTILS_DISPATCHER(GetSize, int32())
+    NP_UTILS_DISPATCHER(SyncOffsets, int32(int32))
+    NP_UTILS_DISPATCHER(GetGetOffset, int32());
+    NP_UTILS_DISPATCHER(GetPutOffset, int32());
   NP_UTILS_END_DISPATCHER_CHAIN
 
  private:
   NPP npp_;
   NPObjectPointer<CHRSharedMemory> shared_memory_;
+  int32 size_;
+  int32 get_offset_;
+  int32 put_offset_;
+  scoped_ptr<Callback0::Type> put_offset_change_callback_;
 };
 
 }  // namespace gpu_plugin
 }  // namespace o3d
 
-#endif  // O3D_GPU_PLUGIN_COMMAND_BUFFER_H_
+#endif  // O3D_GPU_PLUGIN_COMMAND_BUFFER_H_
\ No newline at end of file