dolphin/Source/Core/VideoBackends/Vulkan/StreamBuffer.h

// Copyright 2016 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#pragma once

#include <cstddef>
#include <deque>
#include <memory>
#include <utility>

#include "VideoBackends/Vulkan/Constants.h"

namespace Vulkan
{
class StreamBuffer
{
public:
  StreamBuffer(VkBufferUsageFlags usage, size_t max_size);
  ~StreamBuffer();

  VkBuffer GetBuffer() const { return m_buffer; }
  VkDeviceMemory GetDeviceMemory() const { return m_memory; }
  u8* GetHostPointer() const { return m_host_pointer; }
  u8* GetCurrentHostPointer() const { return m_host_pointer + m_current_offset; }
  size_t GetCurrentSize() const { return m_current_size; }
  size_t GetCurrentOffset() const { return m_current_offset; }
  bool ReserveMemory(size_t num_bytes, size_t alignment, bool allow_reuse = true,
                     bool allow_growth = true, bool reallocate_if_full = false);
  void CommitMemory(size_t final_num_bytes);

  static std::unique_ptr<StreamBuffer> Create(VkBufferUsageFlags usage, size_t initial_size,
                                              size_t max_size);

private:
  bool ResizeBuffer(size_t size);
  void OnCommandBufferQueued(VkCommandBuffer command_buffer, VkFence fence);
  void OnCommandBufferExecuted(VkFence fence);

  // Waits for as many fences as needed to allocate num_bytes bytes from the buffer.
  bool WaitForClearSpace(size_t num_bytes);

  VkBufferUsageFlags m_usage;
  size_t m_current_size = 0;
  size_t m_maximum_size;
  size_t m_current_offset = 0;
  size_t m_current_gpu_position = 0;
  size_t m_last_allocation_size = 0;

  VkBuffer m_buffer = VK_NULL_HANDLE;
  VkDeviceMemory m_memory = VK_NULL_HANDLE;
  u8* m_host_pointer = nullptr;

  // List of fences and the corresponding positions in the buffer
  std::deque<std::pair<VkFence, size_t>> m_tracked_fences;

  bool m_coherent_mapping = false;
};

}  // namespace Vulkan