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// Copyright (c) 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.h"
#include <mach/mach.h>
#include <sys/mman.h>
#include "base/basictypes.h"
#include "base/compiler_specific.h"
#include "base/logging.h"
#include "base/memory/discardable_memory_emulated.h"
#include "base/memory/discardable_memory_malloc.h"
#include "base/memory/scoped_ptr.h"
namespace base {
namespace {
// The VM subsystem allows tagging of memory and 240-255 is reserved for
// application use (see mach/vm_statistics.h). Pick 252 (after chromium's atomic
// weight of ~52).
const int kDiscardableMemoryTag = VM_MAKE_TAG(252);
class DiscardableMemoryMac : public DiscardableMemory {
public:
explicit DiscardableMemoryMac(size_t size)
: buffer_(0),
size_(size) {
}
bool Initialize() {
kern_return_t ret = vm_allocate(mach_task_self(),
&buffer_,
size_,
VM_FLAGS_PURGABLE |
VM_FLAGS_ANYWHERE |
kDiscardableMemoryTag);
if (ret != KERN_SUCCESS) {
DLOG(ERROR) << "vm_allocate() failed";
return false;
}
return true;
}
virtual ~DiscardableMemoryMac() {
if (buffer_)
vm_deallocate(mach_task_self(), buffer_, size_);
}
virtual DiscardableMemoryLockStatus Lock() OVERRIDE {
DCHECK_EQ(0, mprotect(reinterpret_cast<void*>(buffer_),
size_,
PROT_READ | PROT_WRITE));
int state = VM_PURGABLE_NONVOLATILE;
kern_return_t ret = vm_purgable_control(mach_task_self(),
buffer_,
VM_PURGABLE_SET_STATE,
&state);
if (ret != KERN_SUCCESS)
return DISCARDABLE_MEMORY_LOCK_STATUS_FAILED;
return state & VM_PURGABLE_EMPTY ? DISCARDABLE_MEMORY_LOCK_STATUS_PURGED
: DISCARDABLE_MEMORY_LOCK_STATUS_SUCCESS;
}
virtual void Unlock() OVERRIDE {
int state = VM_PURGABLE_VOLATILE | VM_VOLATILE_GROUP_DEFAULT;
kern_return_t ret = vm_purgable_control(mach_task_self(),
buffer_,
VM_PURGABLE_SET_STATE,
&state);
DCHECK_EQ(0, mprotect(reinterpret_cast<void*>(buffer_), size_, PROT_NONE));
if (ret != KERN_SUCCESS)
DLOG(ERROR) << "Failed to unlock memory.";
}
virtual void* Memory() const OVERRIDE {
return reinterpret_cast<void*>(buffer_);
}
private:
vm_address_t buffer_;
const size_t size_;
DISALLOW_COPY_AND_ASSIGN(DiscardableMemoryMac);
};
} // namespace
// static
void DiscardableMemory::RegisterMemoryPressureListeners() {
internal::DiscardableMemoryEmulated::RegisterMemoryPressureListeners();
}
// static
void DiscardableMemory::UnregisterMemoryPressureListeners() {
internal::DiscardableMemoryEmulated::UnregisterMemoryPressureListeners();
}
// static
void DiscardableMemory::GetSupportedTypes(
std::vector<DiscardableMemoryType>* types) {
const DiscardableMemoryType supported_types[] = {
DISCARDABLE_MEMORY_TYPE_MAC,
DISCARDABLE_MEMORY_TYPE_EMULATED,
DISCARDABLE_MEMORY_TYPE_MALLOC
};
types->assign(supported_types, supported_types + arraysize(supported_types));
}
// static
scoped_ptr<DiscardableMemory> DiscardableMemory::CreateLockedMemoryWithType(
DiscardableMemoryType type, size_t size) {
switch (type) {
case DISCARDABLE_MEMORY_TYPE_NONE:
case DISCARDABLE_MEMORY_TYPE_ANDROID:
return scoped_ptr<DiscardableMemory>();
case DISCARDABLE_MEMORY_TYPE_MAC: {
scoped_ptr<DiscardableMemoryMac> memory(new DiscardableMemoryMac(size));
if (!memory->Initialize())
return scoped_ptr<DiscardableMemory>();
return memory.PassAs<DiscardableMemory>();
}
case DISCARDABLE_MEMORY_TYPE_EMULATED: {
scoped_ptr<internal::DiscardableMemoryEmulated> memory(
new internal::DiscardableMemoryEmulated(size));
if (!memory->Initialize())
return scoped_ptr<DiscardableMemory>();
return memory.PassAs<DiscardableMemory>();
}
case DISCARDABLE_MEMORY_TYPE_MALLOC: {
scoped_ptr<internal::DiscardableMemoryMalloc> memory(
new internal::DiscardableMemoryMalloc(size));
if (!memory->Initialize())
return scoped_ptr<DiscardableMemory>();
return memory.PassAs<DiscardableMemory>();
}
}
NOTREACHED();
return scoped_ptr<DiscardableMemory>();
}
// static
bool DiscardableMemory::PurgeForTestingSupported() {
return true;
}
// static
void DiscardableMemory::PurgeForTesting() {
int state = 0;
vm_purgable_control(mach_task_self(), 0, VM_PURGABLE_PURGE_ALL, &state);
internal::DiscardableMemoryEmulated::PurgeForTesting();
}
} // namespace base
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