base/memory/discardable_memory_emulated.h

   1 // Copyright 2013 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_EMULATED_H_
   6 #define BASE_MEMORY_DISCARDABLE_MEMORY_EMULATED_H_
   7
   8 #include "base/memory/discardable_memory.h"
   9
  10 #include "base/memory/discardable_memory_manager.h"
  11
  12 namespace base {
  13 namespace internal {
  14
  15 class DiscardableMemoryEmulated
  16     : public DiscardableMemory,
  17       public internal::DiscardableMemoryManagerAllocation {
  18  public:
  19   explicit DiscardableMemoryEmulated(size_t bytes);
  20   ~DiscardableMemoryEmulated() override;
  21
  22   static bool ReduceMemoryUsage();
  23
  24   // TODO(reveman): Remove this as it is breaking the discardable memory design
  25   // principle that implementations should not rely on information this is
  26   // unavailable in kernel space. crbug.com/400423
  27   BASE_EXPORT static void ReduceMemoryUsageUntilWithinLimit(size_t bytes);
  28
  29   bool Initialize();
  30
  31   // Overridden from DiscardableMemory:
  32   DiscardableMemoryLockStatus Lock() override;
  33   void Unlock() override;
  34   void* Memory() const override;
  35
  36   // Overridden from internal::DiscardableMemoryManagerAllocation:
  37   bool AllocateAndAcquireLock() override;
  38   void ReleaseLock() override {}
  39   void Purge() override;
  40
  41  private:
  42   const size_t bytes_;
  43   scoped_ptr<uint8[]> memory_;
  44   bool is_locked_;
  45
  46   DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryEmulated);
  47 };
  48
  49 }  // namespace internal
  50 }  // namespace base
  51
  52 #endif  // BASE_MEMORY_DISCARDABLE_MEMORY_EMULATED_H_