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// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/memory/discardable_memory_provider.h"
#include "base/bind.h"
#include "base/containers/hash_tables.h"
#include "base/containers/mru_cache.h"
#include "base/debug/trace_event.h"
#include "base/synchronization/lock.h"
#include "base/sys_info.h"
namespace base {
namespace internal {
namespace {
// This is admittedly pretty magical. It's approximately enough memory for two
// 2560x1600 images.
static const size_t kDefaultDiscardableMemoryLimit = 32 * 1024 * 1024;
static const size_t kDefaultBytesToReclaimUnderModeratePressure =
kDefaultDiscardableMemoryLimit / 2;
} // namespace
DiscardableMemoryProvider::DiscardableMemoryProvider()
: allocations_(AllocationMap::NO_AUTO_EVICT),
bytes_allocated_(0),
discardable_memory_limit_(kDefaultDiscardableMemoryLimit),
bytes_to_reclaim_under_moderate_pressure_(
kDefaultBytesToReclaimUnderModeratePressure),
memory_pressure_listener_(
base::Bind(&DiscardableMemoryProvider::NotifyMemoryPressure,
Unretained(this))) {
}
DiscardableMemoryProvider::~DiscardableMemoryProvider() {
DCHECK(allocations_.empty());
DCHECK_EQ(0u, bytes_allocated_);
}
void DiscardableMemoryProvider::NotifyMemoryPressure(
MemoryPressureListener::MemoryPressureLevel pressure_level) {
switch (pressure_level) {
case MemoryPressureListener::MEMORY_PRESSURE_MODERATE:
Purge();
return;
case MemoryPressureListener::MEMORY_PRESSURE_CRITICAL:
PurgeAll();
return;
}
NOTREACHED();
}
void DiscardableMemoryProvider::SetDiscardableMemoryLimit(size_t bytes) {
AutoLock lock(lock_);
discardable_memory_limit_ = bytes;
EnforcePolicyWithLockAcquired();
}
void DiscardableMemoryProvider::SetBytesToReclaimUnderModeratePressure(
size_t bytes) {
AutoLock lock(lock_);
bytes_to_reclaim_under_moderate_pressure_ = bytes;
}
void DiscardableMemoryProvider::Register(
const DiscardableMemory* discardable, size_t bytes) {
AutoLock lock(lock_);
DCHECK(allocations_.Peek(discardable) == allocations_.end());
allocations_.Put(discardable, Allocation(bytes));
}
void DiscardableMemoryProvider::Unregister(
const DiscardableMemory* discardable) {
AutoLock lock(lock_);
AllocationMap::iterator it = allocations_.Peek(discardable);
if (it == allocations_.end())
return;
if (it->second.memory) {
size_t bytes = it->second.bytes;
DCHECK_LE(bytes, bytes_allocated_);
bytes_allocated_ -= bytes;
free(it->second.memory);
}
allocations_.Erase(it);
}
scoped_ptr<uint8, FreeDeleter> DiscardableMemoryProvider::Acquire(
const DiscardableMemory* discardable,
bool* purged) {
AutoLock lock(lock_);
// NB: |allocations_| is an MRU cache, and use of |Get| here updates that
// cache.
AllocationMap::iterator it = allocations_.Get(discardable);
CHECK(it != allocations_.end());
if (it->second.memory) {
scoped_ptr<uint8, FreeDeleter> memory(it->second.memory);
it->second.memory = NULL;
*purged = false;
return memory.Pass();
}
size_t bytes = it->second.bytes;
if (!bytes)
return scoped_ptr<uint8, FreeDeleter>();
if (discardable_memory_limit_) {
size_t limit = 0;
if (bytes < discardable_memory_limit_)
limit = discardable_memory_limit_ - bytes;
PurgeLRUWithLockAcquiredUntilUsageIsWithin(limit);
}
// Check for overflow.
if (std::numeric_limits<size_t>::max() - bytes < bytes_allocated_)
return scoped_ptr<uint8, FreeDeleter>();
scoped_ptr<uint8, FreeDeleter> memory(static_cast<uint8*>(malloc(bytes)));
if (!memory)
return scoped_ptr<uint8, FreeDeleter>();
bytes_allocated_ += bytes;
*purged = true;
return memory.Pass();
}
void DiscardableMemoryProvider::Release(
const DiscardableMemory* discardable,
scoped_ptr<uint8, FreeDeleter> memory) {
AutoLock lock(lock_);
// NB: |allocations_| is an MRU cache, and use of |Get| here updates that
// cache.
AllocationMap::iterator it = allocations_.Get(discardable);
CHECK(it != allocations_.end());
DCHECK(!it->second.memory);
it->second.memory = memory.release();
EnforcePolicyWithLockAcquired();
}
void DiscardableMemoryProvider::PurgeAll() {
AutoLock lock(lock_);
PurgeLRUWithLockAcquiredUntilUsageIsWithin(0);
}
bool DiscardableMemoryProvider::IsRegisteredForTest(
const DiscardableMemory* discardable) const {
AutoLock lock(lock_);
AllocationMap::const_iterator it = allocations_.Peek(discardable);
return it != allocations_.end();
}
bool DiscardableMemoryProvider::CanBePurgedForTest(
const DiscardableMemory* discardable) const {
AutoLock lock(lock_);
AllocationMap::const_iterator it = allocations_.Peek(discardable);
return it != allocations_.end() && it->second.memory;
}
size_t DiscardableMemoryProvider::GetBytesAllocatedForTest() const {
AutoLock lock(lock_);
return bytes_allocated_;
}
void DiscardableMemoryProvider::Purge() {
AutoLock lock(lock_);
if (bytes_to_reclaim_under_moderate_pressure_ == 0)
return;
size_t limit = 0;
if (bytes_to_reclaim_under_moderate_pressure_ < bytes_allocated_)
limit = bytes_allocated_ - bytes_to_reclaim_under_moderate_pressure_;
PurgeLRUWithLockAcquiredUntilUsageIsWithin(limit);
}
void DiscardableMemoryProvider::PurgeLRUWithLockAcquiredUntilUsageIsWithin(
size_t limit) {
TRACE_EVENT1(
"base",
"DiscardableMemoryProvider::PurgeLRUWithLockAcquiredUntilUsageIsWithin",
"limit", limit);
lock_.AssertAcquired();
for (AllocationMap::reverse_iterator it = allocations_.rbegin();
it != allocations_.rend();
++it) {
if (bytes_allocated_ <= limit)
break;
if (!it->second.memory)
continue;
size_t bytes = it->second.bytes;
DCHECK_LE(bytes, bytes_allocated_);
bytes_allocated_ -= bytes;
free(it->second.memory);
it->second.memory = NULL;
}
}
void DiscardableMemoryProvider::EnforcePolicyWithLockAcquired() {
PurgeLRUWithLockAcquiredUntilUsageIsWithin(discardable_memory_limit_);
}
} // namespace internal
} // namespace base
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