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_emulated.h"
   6
   7 #include "base/lazy_instance.h"
   8 #include "base/memory/discardable_memory_manager.h"
   9
  10 namespace base {
  11 namespace {
  12
  13 base::LazyInstance<internal::DiscardableMemoryManager>::Leaky g_manager =
  14     LAZY_INSTANCE_INITIALIZER;
  15
  16 }  // namespace
  17
  18 namespace internal {
  19
  20 DiscardableMemoryEmulated::DiscardableMemoryEmulated(size_t bytes)
  21     : bytes_(bytes),
  22       is_locked_(false) {
  23   g_manager.Pointer()->Register(this, bytes);
  24 }
  25
  26 DiscardableMemoryEmulated::~DiscardableMemoryEmulated() {
  27   if (is_locked_)
  28     Unlock();
  29   g_manager.Pointer()->Unregister(this);
  30 }
  31
  32 // static
  33 void DiscardableMemoryEmulated::RegisterMemoryPressureListeners() {
  34   g_manager.Pointer()->RegisterMemoryPressureListener();
  35 }
  36
  37 // static
  38 void DiscardableMemoryEmulated::UnregisterMemoryPressureListeners() {
  39   g_manager.Pointer()->UnregisterMemoryPressureListener();
  40 }
  41
  42 // static
  43 void DiscardableMemoryEmulated::PurgeForTesting() {
  44   g_manager.Pointer()->PurgeAll();
  45 }
  46
  47 bool DiscardableMemoryEmulated::Initialize() {
  48   return Lock() == DISCARDABLE_MEMORY_LOCK_STATUS_PURGED;
  49 }
  50
  51 DiscardableMemoryLockStatus DiscardableMemoryEmulated::Lock() {
  52   DCHECK(!is_locked_);
  53
  54   bool purged = false;
  55   if (!g_manager.Pointer()->AcquireLock(this, &purged))
  56     return DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
  57
  58   is_locked_ = true;
  59   return purged ? DISCARDABLE_MEMORY_LOCK_STATUS_PURGED
  60                 : DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS;
  61 }
  62
  63 void DiscardableMemoryEmulated::Unlock() {
  64   DCHECK(is_locked_);
  65   g_manager.Pointer()->ReleaseLock(this);
  66   is_locked_ = false;
  67 }
  68
  69 void* DiscardableMemoryEmulated::Memory() const {
  70   DCHECK(is_locked_);
  71   DCHECK(memory_);
  72   return memory_.get();
  73 }
  74
  75 bool DiscardableMemoryEmulated::AllocateAndAcquireLock() {
  76   if (memory_)
  77     return true;
  78
  79   memory_.reset(new uint8[bytes_]);
  80   return false;
  81 }
  82
  83 void DiscardableMemoryEmulated::Purge() {
  84   memory_.reset();
  85 }
  86
  87 }  // namespace internal
  88 }  // namespace base