base/memory/discardable_memory_shmem_allocator.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_MEMORY_DISCARDABLE_MEMORY_SHMEM_ALLOCATOR_H_
   6 #define BASE_MEMORY_DISCARDABLE_MEMORY_SHMEM_ALLOCATOR_H_
   7
   8 #include "base/base_export.h"
   9 #include "base/memory/scoped_ptr.h"
  10
  11 namespace base {
  12
  13 // TODO(reveman): Remove this by having allocator interface return
  14 // real DiscardableMemory instances. crbug.com/442945
  15 class BASE_EXPORT DiscardableMemoryShmemChunk {
  16  public:
  17   virtual ~DiscardableMemoryShmemChunk() {}
  18
  19   virtual bool Lock() = 0;
  20   virtual void Unlock() = 0;
  21   virtual void* Memory() const = 0;
  22   virtual bool IsMemoryResident() const = 0;
  23 };
  24
  25 class BASE_EXPORT DiscardableMemoryShmemAllocator {
  26  public:
  27   // Returns the allocator instance.
  28   static DiscardableMemoryShmemAllocator* GetInstance();
  29
  30   // Sets the allocator instance. Can only be called once, e.g. on startup.
  31   // Ownership of |instance| remains with the caller.
  32   static void SetInstance(DiscardableMemoryShmemAllocator* allocator);
  33
  34   virtual scoped_ptr<DiscardableMemoryShmemChunk>
  35   AllocateLockedDiscardableMemory(size_t size) = 0;
  36
  37  protected:
  38   virtual ~DiscardableMemoryShmemAllocator() {}
  39 };
  40
  41 }  // namespace base
  42
  43 #endif  // BASE_MEMORY_DISCARDABLE_MEMORY_SHMEM_ALLOCATOR_H_