src/base/memory/discardable_memory_emulated.cc

   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 #include "base/memory/discardable_memory.h"
   6
   7 #include "base/memory/discardable_memory_provider.h"
   8
   9 using base::internal::DiscardableMemoryProvider;
  10
  11 namespace base {
  12 namespace {
  13
  14 class DiscardableMemoryEmulated : public DiscardableMemory {
  15  public:
  16   explicit DiscardableMemoryEmulated(size_t size) : is_locked_(false) {
  17     DiscardableMemoryProvider::GetInstance()->Register(this, size);
  18   }
  19
  20   virtual ~DiscardableMemoryEmulated() {
  21     if (is_locked_)
  22       Unlock();
  23     DiscardableMemoryProvider::GetInstance()->Unregister(this);
  24   }
  25
  26   // DiscardableMemory:
  27   virtual LockDiscardableMemoryStatus Lock() OVERRIDE {
  28     DCHECK(!is_locked_);
  29
  30     bool purged = false;
  31     memory_ = DiscardableMemoryProvider::GetInstance()->Acquire(this, &purged);
  32     if (!memory_)
  33       return DISCARDABLE_MEMORY_FAILED;
  34
  35     is_locked_ = true;
  36     return purged ? DISCARDABLE_MEMORY_PURGED : DISCARDABLE_MEMORY_SUCCESS;
  37   }
  38
  39   virtual void Unlock() OVERRIDE {
  40     DCHECK(is_locked_);
  41     DiscardableMemoryProvider::GetInstance()->Release(this, memory_.Pass());
  42     is_locked_ = false;
  43   }
  44
  45   virtual void* Memory() const OVERRIDE {
  46     DCHECK(memory_);
  47     return memory_.get();
  48   }
  49
  50  private:
  51   scoped_ptr<uint8, FreeDeleter> memory_;
  52   bool is_locked_;
  53
  54   DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryEmulated);
  55 };
  56
  57 }  // namespace
  58
  59 // static
  60 bool DiscardableMemory::SupportedNatively() {
  61   return false;
  62 }
  63
  64 // static
  65 scoped_ptr<DiscardableMemory> DiscardableMemory::CreateLockedMemory(
  66     size_t size) {
  67   scoped_ptr<DiscardableMemory> memory(new DiscardableMemoryEmulated(size));
  68   if (!memory)
  69     return scoped_ptr<DiscardableMemory>();
  70   if (memory->Lock() != DISCARDABLE_MEMORY_PURGED)
  71     return scoped_ptr<DiscardableMemory>();
  72   return memory.Pass();
  73 }
  74
  75 // static
  76 bool DiscardableMemory::PurgeForTestingSupported() {
  77   return true;
  78 }
  79
  80 // static
  81 void DiscardableMemory::PurgeForTesting() {
  82   DiscardableMemoryProvider::GetInstance()->PurgeAll();
  83 }
  84
  85 }  // namespace base