gpu/command_buffer/client/internal/mappable_buffer_dxgi.h

// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef GPU_COMMAND_BUFFER_CLIENT_INTERNAL_MAPPABLE_BUFFER_DXGI_H_
#define GPU_COMMAND_BUFFER_CLIENT_INTERNAL_MAPPABLE_BUFFER_DXGI_H_

#include <stddef.h>
#include <stdint.h>

#include <memory>
#include <optional>

#include "base/containers/span.h"
#include "base/functional/callback.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/raw_span.h"
#include "base/memory/scoped_refptr.h"
#include "base/memory/unsafe_shared_memory_pool.h"
#include "base/memory/unsafe_shared_memory_region.h"
#include "base/unguessable_token.h"
#include "base/win/scoped_handle.h"
#include "components/viz/common/resources/shared_image_format.h"
#include "gpu/command_buffer/client/gpu_command_buffer_client_export.h"
#include "gpu/command_buffer/client/internal/mappable_buffer.h"
#include "ui/gfx/color_space.h"

namespace gpu {

class ClientSharedImage;

// Implementation of MappableBuffer based on dxgi textures.
class GPU_COMMAND_BUFFER_CLIENT_EXPORT MappableBufferDXGI
    : public MappableBuffer {
 public:
  MappableBufferDXGI(const MappableBufferDXGI&) = delete;
  MappableBufferDXGI& operator=(const MappableBufferDXGI&) = delete;

  ~MappableBufferDXGI() override;

  static constexpr gfx::GpuMemoryBufferType kBufferType =
      gfx::DXGI_SHARED_HANDLE;

  static std::unique_ptr<MappableBufferDXGI> CreateFromHandleForTesting(
      gfx::GpuMemoryBufferHandle handle,
      const gfx::Size& size,
      viz::SharedImageFormat format) {
    return CreateFromHandle(std::move(handle), size, format);
  }

  static base::OnceClosure AllocateForTesting(
      const gfx::Size& size,
      viz::SharedImageFormat format,
      gfx::BufferUsage usage,
      gfx::GpuMemoryBufferHandle* handle);

  bool Map() override;
  void MapAsync(base::OnceCallback<void(bool)> result_cb) override;
  bool AsyncMappingIsNonBlocking() const override;
  base::span<uint8_t> memory(size_t plane) override;
  void Unmap() override;
  int stride(size_t plane) const override;
  gfx::GpuMemoryBufferType GetType() const override;
  gfx::GpuMemoryBufferHandle CloneHandle() const override;

  // This method allows clients to explicitly specify that it wants to use the
  // |premapped_memory_| which is internally created by this class from the GMB
  // handle shared memory |region_| instead of client providing it.
  // This method is also used when the clients wants to specify that it no
  // longer should be using the pre mapped memory.
  // Windows media capture code will need to use this api in order to transition
  // to MappableSI. It is currently not used until the media capture code is
  // converted to MappableSI.
  void SetUsePreMappedMemory(bool use_premapped_memory) override;

  gfx::GpuMemoryBufferHandle CloneHandleWithRegion(
      base::UnsafeSharedMemoryRegion region) const;

  HANDLE GetHandle() const;
  const gfx::DXGIHandleToken& GetToken() const;

 private:
  friend ClientSharedImage;

  static std::unique_ptr<MappableBufferDXGI> CreateFromHandle(
      gfx::GpuMemoryBufferHandle handle,
      const gfx::Size& size,
      viz::SharedImageFormat format,
      CopyNativeBufferToShMemCallback copy_native_buffer_to_shmem_callback =
          CopyNativeBufferToShMemCallback(),
      scoped_refptr<base::UnsafeSharedMemoryPool> pool = nullptr);

  MappableBufferDXGI(
      const gfx::Size& size,
      viz::SharedImageFormat format,
      gfx::DXGIHandle dxgi_handle,
      CopyNativeBufferToShMemCallback copy_native_buffer_to_shmem_callback,
      scoped_refptr<base::UnsafeSharedMemoryPool> pool);

  // Returns callback for reporting early result.
  // `DoMapAsync` can't invoke it directly as it holds a mapping lock.
  std::optional<base::OnceClosure> DoMapAsync(base::OnceCallback<void(bool)>);
  void CheckAsyncMapResult(bool result);
  void AssertMapped();

  const gfx::Size size_;
  const viz::SharedImageFormat format_;

  // This is currently always set to false until media capture code is converted
  // to use MappableSI.
  bool use_premapped_memory_ = false;

  // The DXGIHandle's |region_| is not used currently. It will be eventually be
  // used to pre-map the |region_| internally in this class instead of clients
  // doing the pre-map.
  gfx::DXGIHandle dxgi_handle_;

  // It is created when |region_| is mapped via Map(). It is to keep the
  // |premapped_memory_| alive till its being used. Destroying this makes the
  // |premapped_memory_| invalid in cases where |premapped_memory_| is created
  // from it.
  base::WritableSharedMemoryMapping region_mapping_;

  CopyNativeBufferToShMemCallback copy_native_buffer_to_shmem_callback_;

  // Note: This lock must be held throughout the entirety of the Map() and
  // Unmap() operations to avoid corrupt mutation across multiple threads.
  base::Lock map_lock_;
  uint32_t map_count_ GUARDED_BY(map_lock_) = 0u;

  std::vector<base::OnceCallback<void(bool)>> map_callbacks_
      GUARDED_BY(map_lock_);

  // Used to create and store shared memory for data, copied via request to
  // gpu process.
  scoped_refptr<base::UnsafeSharedMemoryPool> shared_memory_pool_;
  std::unique_ptr<base::UnsafeSharedMemoryPool::Handle> shared_memory_handle_;

  // When |use_premapped_memory_| is false, the caller(which is the video
  // capturer in the render process) maps a memory region and
  // |premapped_memory_| is a view of that region owned by the caller.
  // When |use_premapped_memory_| is true, caller provides |region_| which is a
  // handle to a memory region. This region is mapped via |region_|.Map()
  // which maps the memory region and returns the handle called
  // |region_mapping_| to that mapping. |premapped_memory_| is now the view of
  // |region_mapping_| in this case.
  base::raw_span<uint8_t> premapped_memory_;
  bool async_mapping_in_progress_ GUARDED_BY(map_lock_) = false;
};

}  // namespace gpu

#endif  // GPU_COMMAND_BUFFER_CLIENT_INTERNAL_MAPPABLE_BUFFER_DXGI_H_