text: // Copyright (c) 2017 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 GPU_COMMAND_BUFFER_CLIENT_CLIENT_DISCARDABLE_MANAGER_H_
  #define GPU_COMMAND_BUFFER_CLIENT_CLIENT_DISCARDABLE_MANAGER_H_
  
  #include <map>
  #include <queue>
  #include <set>
  
  #include "gpu/command_buffer/common/command_buffer.h"
  #include "gpu/command_buffer/common/discardable_handle.h"
  #include "gpu/gpu_export.h"
  
  namespace gpu {
  
  // ClientDiscardableManager is a helper class used by the client GLES2
  // implementation. Currently, this class only supports textures, but it could
  // be extended to other types in the future.
  //
  // When the GLES2 impl is done with a texture (the texture is being deleted),
  // it should call FreeTexture to allow helper memory to be reclaimed.
  class GPU_EXPORT ClientDiscardableManager {
   public:
    ClientDiscardableManager();
    ~ClientDiscardableManager();
    ClientDiscardableHandle InitializeTexture(CommandBuffer* command_buffer,
                                              uint32_t texture_id);
    bool LockTexture(uint32_t texture_id);
    void FreeTexture(uint32_t texture_id);
    bool TextureIsValid(uint32_t texture_id) const;
  
    // Test only functions.
    void CheckPendingForTesting(CommandBuffer* command_buffer) {
      CheckPending(command_buffer);
    }
    void SetElementCountForTesting(uint32_t count) {
      elements_per_allocation_ = count;
      allocation_size_ = count * element_size_;
    }
    ClientDiscardableHandle GetHandleForTesting(uint32_t texture_id);
  
   private:
    void FindAllocation(CommandBuffer* command_buffer,
                        scoped_refptr<Buffer>* buffer,
                        int32_t* shm_id,
                        uint32_t* offset);
    void ReturnAllocation(CommandBuffer* command_buffer,
                          const ClientDiscardableHandle& handle);
    void CheckPending(CommandBuffer* command_buffer);
  
   private:
    size_t allocation_size_;
    size_t element_size_ = sizeof(base::subtle::Atomic32);
    uint32_t elements_per_allocation_ =
        static_cast<uint32_t>(allocation_size_ / element_size_);
  
    struct Allocation;
    std::vector<std::unique_ptr<Allocation>> allocations_;
    std::map<uint32_t, ClientDiscardableHandle> texture_handles_;
  
    // Handles that are pending service deletion, and can be re-used once
    // ClientDiscardableHandle::CanBeReUsed returns true.
    std::queue<ClientDiscardableHandle> pending_handles_;
  
    DISALLOW_COPY_AND_ASSIGN(ClientDiscardableManager);
  };
  
  }  // namespace gpu
  
  #endif  // GPU_COMMAND_BUFFER_CLIENT_CLIENT_DISCARDABLE_MANAGER_H_
  