media/gpu/chromeos/platform_video_frame_pool.h

// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_GPU_CHROMEOS_PLATFORM_VIDEO_FRAME_POOL_H_
#define MEDIA_GPU_CHROMEOS_PLATFORM_VIDEO_FRAME_POOL_H_

#include <stddef.h>

#include <map>
#include <optional>
#include <vector>

#include "base/containers/circular_deque.h"
#include "base/files/scoped_file.h"
#include "base/functional/bind.h"
#include "base/memory/weak_ptr.h"
#include "base/synchronization/lock.h"
#include "base/task/sequenced_task_runner.h"
#include "base/thread_annotations.h"
#include "media/base/video_types.h"
#include "media/gpu/chromeos/dmabuf_video_frame_pool.h"
#include "media/gpu/media_gpu_export.h"
#include "ui/gfx/gpu_memory_buffer.h"

namespace media {

// Simple frame pool used to avoid unnecessarily allocating and destroying frame
// objects. The pool manages the memory for the frame returned by GetFrame().
// When one of these frames is destroyed, the memory is returned to the pool for
// use by a subsequent GetFrame() call. The memory in the pool is retained for
// the life of the PlatformVideoFramePool object. Before calling GetFrame(), the
// client should call NegotiateFrameFormat(). If the parameters passed to
// NegotiateFrameFormat() are changed, then the memory used by frames with the
// old parameter values will be purged from the pool.
class MEDIA_GPU_EXPORT PlatformVideoFramePool : public DmabufVideoFramePool {
 public:
  PlatformVideoFramePool();
  PlatformVideoFramePool(const PlatformVideoFramePool&) = delete;
  PlatformVideoFramePool& operator=(const PlatformVideoFramePool&) = delete;
  ~PlatformVideoFramePool() override;

  // DmabufVideoFramePool implementation.
  PlatformVideoFramePool* AsPlatformVideoFramePool() override;
  CroStatus::Or<GpuBufferLayout> Initialize(const Fourcc& fourcc,
                                            const gfx::Size& coded_size,
                                            const gfx::Rect& visible_rect,
                                            const gfx::Size& natural_size,
                                            size_t max_num_frames,
                                            bool use_protected,
                                            bool use_linear_buffers) override;
  scoped_refptr<FrameResource> GetFrame() override;
  VideoFrame::StorageType GetFrameStorageType() const override;
  bool IsExhausted() override;
  void NotifyWhenFrameAvailable(base::OnceClosure cb) override;
  void ReleaseAllFrames() override;
  std::optional<GpuBufferLayout> GetGpuBufferLayout() override;

  // Returns the original frame from a frame's shared memory ID. We need this
  // method to determine whether the frame returned by GetFrame() is the same
  // one after recycling, and bind destruction callback at original frames.
  FrameResource* GetOriginalFrame(gfx::GenericSharedMemoryId frame_id);

  // Returns the number of frames in the pool for testing purposes.
  size_t GetPoolSizeForTesting();

  // Allows the client to specify how to allocate buffers. |allocator| only runs
  // during a call to Initialize() or GetFrame(), so it's guaranteed to be
  // called in the same thread as those two methods. VaapiVideoDecoder uses this
  // on linux to delegate dmabuf allocation to the libva driver.
  void SetCustomFrameAllocator(DmabufVideoFramePool::CreateFrameCB allocator,
                               VideoFrame::StorageType frame_storage_type);

 private:
  friend class PlatformVideoFramePoolTestBase;

  // Thunk to post OnFrameReleased() to |task_runner|.
  // Because this thunk may be called in any thread, We don't want to
  // dereference WeakPtr. Therefore we wrap the WeakPtr by std::optional to
  // avoid the task runner defererencing the WeakPtr.
  static void OnFrameReleasedThunk(
      std::optional<base::WeakPtr<PlatformVideoFramePool>> pool,
      scoped_refptr<base::SequencedTaskRunner> task_runner,
      scoped_refptr<FrameResource> origin_frame);
  // Called when a wrapped frame gets destroyed.
  // When returning a frame to the pool, the pool might have already been
  // destroyed. In this case, the WeakPtr of the pool will have been invalidated
  // at |parent_task_runner_|, and OnFrameReleased() will not get executed.
  void OnFrameReleased(scoped_refptr<FrameResource> origin_frame);

  void InsertFreeFrame_Locked(scoped_refptr<FrameResource> frame)
      EXCLUSIVE_LOCKS_REQUIRED(lock_);
  size_t GetTotalNumFrames_Locked() const EXCLUSIVE_LOCKS_REQUIRED(lock_);
  bool IsSameFormat_Locked(VideoPixelFormat format,
                           const gfx::Size& coded_size,
                           const gfx::Rect& visible_rect,
                           bool use_protected) const
      EXCLUSIVE_LOCKS_REQUIRED(lock_);
  bool IsExhausted_Locked() EXCLUSIVE_LOCKS_REQUIRED(lock_);

  // Lock to protect all data members.
  // Every public method and OnFrameReleased() acquire this lock.
  mutable base::Lock lock_;

  // The function used to allocate new frames.
  CreateFrameCB create_frame_cb_ GUARDED_BY(lock_);

  // The storage type that |create_frame_cb_| produces.
  VideoFrame::StorageType frame_storage_type_ GUARDED_BY(lock_);

  // The arguments of current frame. We allocate new frames only if a pixel
  // format or size in |frame_layout_| is changed. When GetFrame() is
  // called, we update |visible_rect_| and |natural_size_| of wrapped frames.
  std::optional<GpuBufferLayout> frame_layout_ GUARDED_BY(lock_);
  gfx::Rect visible_rect_ GUARDED_BY(lock_);
  gfx::Size natural_size_ GUARDED_BY(lock_);

  // The pool of free frames. The layout of all the frames in |free_frames_|
  // should be the same as |format_| and |coded_size_|.
  base::circular_deque<scoped_refptr<FrameResource>> free_frames_
      GUARDED_BY(lock_);
  // Mapping from the frame's shared memory ID to the original frame.
  std::map<gfx::GenericSharedMemoryId, FrameResource*> frames_in_use_
      GUARDED_BY(lock_);

  // The maximum number of frames created by the pool.
  size_t max_num_frames_ GUARDED_BY(lock_) = 0;

  // If we are using HW protected buffers.
  bool use_protected_ GUARDED_BY(lock_) = false;

  // True if we need to allocate GPU buffers in a way that is accessible from
  // the CPU with a linear layout. Can only be set once per instance.
  std::optional<bool> use_linear_buffers_ GUARDED_BY(lock_);

  // Callback which is called when the pool is not exhausted.
  base::OnceClosure frame_available_cb_ GUARDED_BY(lock_);

  // The weak pointer of this, bound at |parent_task_runner_|.
  // Used at the FrameResource destruction callback.
  base::WeakPtr<PlatformVideoFramePool> weak_this_;
  base::WeakPtrFactory<PlatformVideoFramePool> weak_this_factory_{this};
};

}  // namespace media
#endif  // MEDIA_GPU_CHROMEOS_PLATFORM_VIDEO_FRAME_POOL_H_