forked from mirrors/gecko-dev
265e672179
# ignore-this-changeset --HG-- extra : amend_source : 4d301d3b0b8711c4692392aa76088ba7fd7d1022
105 lines
2.7 KiB
C++
105 lines
2.7 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "VolatileBuffer.h"
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#include "mozilla/Assertions.h"
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#include "mozilla/DebugOnly.h"
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#include "mozilla/mozalloc.h"
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#include <mach/mach.h>
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#include <sys/mman.h>
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#include <unistd.h>
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#define MIN_VOLATILE_ALLOC_SIZE 8192
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namespace mozilla {
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VolatileBuffer::VolatileBuffer()
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: mMutex("VolatileBuffer"),
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mBuf(nullptr),
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mSize(0),
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mLockCount(0),
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mHeap(false) {}
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bool VolatileBuffer::Init(size_t aSize, size_t aAlignment) {
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MOZ_ASSERT(!mSize && !mBuf, "Init called twice");
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MOZ_ASSERT(!(aAlignment % sizeof(void*)),
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"Alignment must be multiple of pointer size");
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mSize = aSize;
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kern_return_t ret = 0;
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if (aSize < MIN_VOLATILE_ALLOC_SIZE) {
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goto heap_alloc;
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}
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ret = vm_allocate(mach_task_self(), (vm_address_t*)&mBuf, mSize,
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VM_FLAGS_PURGABLE | VM_FLAGS_ANYWHERE);
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if (ret == KERN_SUCCESS) {
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return true;
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}
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heap_alloc:
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(void)posix_memalign(&mBuf, aAlignment, aSize);
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mHeap = true;
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return !!mBuf;
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}
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VolatileBuffer::~VolatileBuffer() {
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MOZ_ASSERT(mLockCount == 0, "Being destroyed with non-zero lock count?");
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if (OnHeap()) {
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free(mBuf);
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} else {
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vm_deallocate(mach_task_self(), (vm_address_t)mBuf, mSize);
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}
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}
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bool VolatileBuffer::Lock(void** aBuf) {
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MutexAutoLock lock(mMutex);
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MOZ_ASSERT(mBuf, "Attempting to lock an uninitialized VolatileBuffer");
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*aBuf = mBuf;
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if (++mLockCount > 1 || OnHeap()) {
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return true;
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}
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int state = VM_PURGABLE_NONVOLATILE;
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kern_return_t ret = vm_purgable_control(mach_task_self(), (vm_address_t)mBuf,
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VM_PURGABLE_SET_STATE, &state);
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return ret == KERN_SUCCESS && !(state & VM_PURGABLE_EMPTY);
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}
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void VolatileBuffer::Unlock() {
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MutexAutoLock lock(mMutex);
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MOZ_ASSERT(mLockCount > 0, "VolatileBuffer unlocked too many times!");
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if (--mLockCount || OnHeap()) {
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return;
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}
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int state = VM_PURGABLE_VOLATILE | VM_VOLATILE_GROUP_DEFAULT;
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DebugOnly<kern_return_t> ret = vm_purgable_control(
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mach_task_self(), (vm_address_t)mBuf, VM_PURGABLE_SET_STATE, &state);
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MOZ_ASSERT(ret == KERN_SUCCESS, "Failed to set buffer as purgable");
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}
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bool VolatileBuffer::OnHeap() const { return mHeap; }
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size_t VolatileBuffer::HeapSizeOfExcludingThis(
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MallocSizeOf aMallocSizeOf) const {
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return OnHeap() ? aMallocSizeOf(mBuf) : 0;
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}
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size_t VolatileBuffer::NonHeapSizeOfExcludingThis() const {
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if (OnHeap()) {
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return 0;
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}
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unsigned long pagemask = getpagesize() - 1;
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return (mSize + pagemask) & ~pagemask;
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}
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} // namespace mozilla
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