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[chromium-blink-merge.git] / base / memory / discardable_memory_emulated.cc
blob9820e2ea73842431f1ea32a1638c994c33c681d1
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.
5 #include "base/memory/discardable_memory_emulated.h"
7 #include "base/lazy_instance.h"
8 #include "base/memory/discardable_memory_manager.h"
10 namespace base {
11 namespace {
13 // This is admittedly pretty magical.
14 const size_t kEmulatedMemoryLimit = 512 * 1024 * 1024;
15 const size_t kEmulatedSoftMemoryLimit = 32 * 1024 * 1024;
16 const size_t kEmulatedHardMemoryLimitExpirationTimeMs = 1000;
18 // internal::DiscardableMemoryManager has an explicit constructor that takes
19 // a number of memory limit parameters. The LeakyLazyInstanceTraits doesn't
20 // handle the case. Thus, we need our own class here.
21 struct DiscardableMemoryManagerLazyInstanceTraits {
22 // Leaky as discardable memory clients can use this after the exit handler
23 // has been called.
24 static const bool kRegisterOnExit = false;
25 #ifndef NDEBUG
26 static const bool kAllowedToAccessOnNonjoinableThread = true;
27 #endif
29 static internal::DiscardableMemoryManager* New(void* instance) {
30 return new (instance) internal::DiscardableMemoryManager(
31 kEmulatedMemoryLimit,
32 kEmulatedSoftMemoryLimit,
33 TimeDelta::FromMilliseconds(kEmulatedHardMemoryLimitExpirationTimeMs));
35 static void Delete(internal::DiscardableMemoryManager* instance) {
36 instance->~DiscardableMemoryManager();
40 LazyInstance<internal::DiscardableMemoryManager,
41 DiscardableMemoryManagerLazyInstanceTraits>
42 g_manager = LAZY_INSTANCE_INITIALIZER;
44 } // namespace
46 namespace internal {
48 DiscardableMemoryEmulated::DiscardableMemoryEmulated(size_t bytes)
49 : bytes_(bytes),
50 is_locked_(false) {
51 g_manager.Pointer()->Register(this, bytes);
54 DiscardableMemoryEmulated::~DiscardableMemoryEmulated() {
55 if (is_locked_)
56 Unlock();
57 g_manager.Pointer()->Unregister(this);
60 // static
61 bool DiscardableMemoryEmulated::ReduceMemoryUsage() {
62 return g_manager.Pointer()->ReduceMemoryUsage();
65 // static
66 void DiscardableMemoryEmulated::ReduceMemoryUsageUntilWithinLimit(
67 size_t bytes) {
68 g_manager.Pointer()->ReduceMemoryUsageUntilWithinLimit(bytes);
71 // static
72 void DiscardableMemoryEmulated::PurgeForTesting() {
73 g_manager.Pointer()->PurgeAll();
76 bool DiscardableMemoryEmulated::Initialize() {
77 return Lock() != DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
80 DiscardableMemoryLockStatus DiscardableMemoryEmulated::Lock() {
81 DCHECK(!is_locked_);
83 bool purged = false;
84 if (!g_manager.Pointer()->AcquireLock(this, &purged))
85 return DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
87 is_locked_ = true;
88 return purged ? DISCARDABLE_MEMORY_LOCK_STATUS_PURGED
89 : DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS;
92 void DiscardableMemoryEmulated::Unlock() {
93 DCHECK(is_locked_);
94 g_manager.Pointer()->ReleaseLock(this);
95 is_locked_ = false;
98 void* DiscardableMemoryEmulated::Memory() const {
99 DCHECK(is_locked_);
100 DCHECK(memory_);
101 return memory_.get();
104 bool DiscardableMemoryEmulated::AllocateAndAcquireLock() {
105 if (memory_)
106 return true;
108 memory_.reset(new uint8[bytes_]);
109 return false;
112 void DiscardableMemoryEmulated::Purge() {
113 memory_.reset();
116 } // namespace internal
117 } // namespace base