ClientDiscardableManager Implementation

gpu/command_buffer/client/client_discardable_manager.h

+// 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.
+//
+// The GLES2 impl can call GetForTexture to retreive the
+// ClientDiscardableHandle for a given texture. If no handle exists, one
+// will be created.
+//
+// When the GLES2 impl is done with a texture (the texture is being deleted),
+// it should call FreeForTexture to allow helper memory to be reclaimed.
+class GPU_EXPORT ClientDiscardableManager {
+ public:
+  ClientDiscardableManager();
+  ~ClientDiscardableManager();
+  ClientDiscardableHandle GetForTexture(CommandBuffer* command_buffer,
+                                        uint32_t texture_id);
+  void FreeForTexture(uint32_t texture_id);
+
+  // Test only functions.
+  void CheckPendingForTesting(CommandBuffer* command_buffer) {
+    CheckPending(command_buffer);
+  }
+  void SetElementCountForTesting(size_t count) {
+    elements_per_allocation_ = count;
+    allocation_size_ = count * element_size_;
+  }
+
+ 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_ = 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_