103 lines
2.5 KiB
C++
103 lines
2.5 KiB
C++
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// Copyright (c) 2013 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/memory/discardable_memory.h"
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#include <mach/mach.h>
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#include "base/logging.h"
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namespace base {
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namespace {
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// The VM subsystem allows tagging of memory and 240-255 is reserved for
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// application use (see mach/vm_statistics.h). Pick 252 (after chromium's atomic
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// weight of ~52).
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const int kDiscardableMemoryTag = VM_MAKE_TAG(252);
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} // namespace
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// static
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bool DiscardableMemory::Supported() {
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return true;
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}
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DiscardableMemory::~DiscardableMemory() {
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if (memory_) {
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vm_deallocate(mach_task_self(),
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reinterpret_cast<vm_address_t>(memory_),
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size_);
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}
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}
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bool DiscardableMemory::InitializeAndLock(size_t size) {
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DCHECK(!memory_);
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size_ = size;
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vm_address_t buffer = 0;
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kern_return_t ret = vm_allocate(mach_task_self(),
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&buffer,
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size,
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VM_FLAGS_PURGABLE |
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VM_FLAGS_ANYWHERE |
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kDiscardableMemoryTag);
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if (ret != KERN_SUCCESS) {
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DLOG(ERROR) << "vm_allocate() failed";
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return false;
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}
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is_locked_ = true;
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memory_ = reinterpret_cast<void*>(buffer);
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return true;
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}
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LockDiscardableMemoryStatus DiscardableMemory::Lock() {
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DCHECK(!is_locked_);
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int state = VM_PURGABLE_NONVOLATILE;
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kern_return_t ret = vm_purgable_control(
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mach_task_self(),
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reinterpret_cast<vm_address_t>(memory_),
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VM_PURGABLE_SET_STATE,
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&state);
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if (ret != KERN_SUCCESS)
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return DISCARDABLE_MEMORY_FAILED;
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is_locked_ = true;
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return state & VM_PURGABLE_EMPTY ? DISCARDABLE_MEMORY_PURGED
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: DISCARDABLE_MEMORY_SUCCESS;
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}
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void DiscardableMemory::Unlock() {
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DCHECK(is_locked_);
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int state = VM_PURGABLE_VOLATILE | VM_VOLATILE_GROUP_DEFAULT;
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kern_return_t ret = vm_purgable_control(
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mach_task_self(),
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reinterpret_cast<vm_address_t>(memory_),
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VM_PURGABLE_SET_STATE,
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&state);
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if (ret != KERN_SUCCESS)
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DLOG(ERROR) << "Failed to unlock memory.";
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is_locked_ = false;
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}
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// static
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bool DiscardableMemory::PurgeForTestingSupported() {
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return true;
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}
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// static
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void DiscardableMemory::PurgeForTesting() {
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int state = 0;
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vm_purgable_control(mach_task_self(), 0, VM_PURGABLE_PURGE_ALL, &state);
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}
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} // namespace base
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