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// Copyright (c) 2006-2008 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 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"
namespace o3d {
namespace gpu_plugin {
// An NPObject that implements a shared memory command buffer and a synchronous
// API to manage the put and get pointers.
class CommandBuffer : public DefaultNPObject<NPObject> {
public:
explicit CommandBuffer(NPP npp);
virtual ~CommandBuffer();
// Create a shared memory buffer of the given size.
virtual bool Initialize(int32 size);
// Gets the shared memory ring buffer object for the command buffer.
virtual NPObjectPointer<CHRSharedMemory> GetRingBuffer();
virtual int32 GetSize();
// 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(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_
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