// 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 BASE_MEMORY_DISCARDABLE_MEMORY_SHMEM_ALLOCATOR_H_
#define BASE_MEMORY_DISCARDABLE_MEMORY_SHMEM_ALLOCATOR_H_

#include "base/base_export.h"
#include "base/memory/scoped_ptr.h"

namespace base {

// TODO(reveman): Remove this by having allocator interface return
// real DiscardableMemory instances. crbug.com/442945
class BASE_EXPORT DiscardableMemoryShmemChunk {
 public:
  virtual ~DiscardableMemoryShmemChunk() {}

  virtual bool Lock() = 0;
  virtual void Unlock() = 0;
  virtual void* Memory() const = 0;
  virtual bool IsMemoryResident() const = 0;
};

class BASE_EXPORT DiscardableMemoryShmemAllocator {
 public:
  // Returns the allocator instance.
  static DiscardableMemoryShmemAllocator* GetInstance();

  // Sets the allocator instance. Can only be called once, e.g. on startup.
  // Ownership of |instance| remains with the caller.
  static void SetInstance(DiscardableMemoryShmemAllocator* allocator);

  virtual scoped_ptr<DiscardableMemoryShmemChunk>
  AllocateLockedDiscardableMemory(size_t size) = 0;

 protected:
  virtual ~DiscardableMemoryShmemAllocator() {}
};

}  // namespace base

#endif  // BASE_MEMORY_DISCARDABLE_MEMORY_SHMEM_ALLOCATOR_H_