cc/surfaces/surface_id_allocator.h

// Copyright 2014 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 CC_SURFACES_SURFACE_ID_ALLOCATOR_H_
#define CC_SURFACES_SURFACE_ID_ALLOCATOR_H_

#include <stdint.h>

#include "base/macros.h"
#include "cc/surfaces/surface_id.h"
#include "cc/surfaces/surfaces_export.h"

namespace cc {

class SurfaceManager;

// This is a helper class for generating surface IDs within a specified
// namespace.  This is not threadsafe, to use from multiple threads wrap this
// class in a mutex.
class CC_SURFACES_EXPORT SurfaceIdAllocator {
 public:
  explicit SurfaceIdAllocator(uint32_t id_namespace);
  ~SurfaceIdAllocator();

  SurfaceId GenerateId();

  // This needs to be called before any sequences with this allocator's
  // namespace will be used to enforce destruction dependencies.
  // When this SurfaceIdAllocator is destroyed, its namespace is
  // automatically invalidated and any remaining sequences with that
  // namespace will be ignored. This method does not need to be called in
  // contexts where there is no SurfaceManager (e.g. a renderer process).
  void RegisterSurfaceIdNamespace(SurfaceManager* manager);

  uint32_t id_namespace() const { return id_namespace_; }

  // SurfaceIdAllocator's owner can call this when it find out that
  // SurfaceManager is no longer alive during destruction.
  void DidDestroySurfaceManager() { manager_ = nullptr; }

 private:
  const uint32_t id_namespace_;
  uint32_t next_id_;
  SurfaceManager* manager_;

  DISALLOW_COPY_AND_ASSIGN(SurfaceIdAllocator);
};

}  // namespace cc

#endif  // CC_SURFACES_SURFACE_ID_ALLOCATOR_H_