138 lines
3.1 KiB
C++
138 lines
3.1 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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{
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}
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bool
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VolatileBuffer::Init(size_t aSize, size_t aAlignment)
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{
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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(),
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(vm_address_t*)&mBuf,
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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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#if(0)
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(void)moz_posix_memalign(&mBuf, aAlignment, aSize);
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#else
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// 10.4 doesn't have memalign, but our malloc()s are always aligned to
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// 16 bytes anyway, and that's all we need to support right now.
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if(MOZ_UNLIKELY(aAlignment > 16))
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fprintf(stderr, "Warning: volatile alignment %i.\n", aAlignment);
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mBuf = malloc(aSize);
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#endif
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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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{
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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
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VolatileBuffer::Lock(void** aBuf)
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{
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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 =
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vm_purgable_control(mach_task_self(),
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(vm_address_t)mBuf,
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VM_PURGABLE_SET_STATE,
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&state);
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return ret == KERN_SUCCESS && !(state & VM_PURGABLE_EMPTY);
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}
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void
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VolatileBuffer::Unlock()
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{
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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; // 10.4
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DebugOnly<kern_return_t> ret =
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vm_purgable_control(mach_task_self(),
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(vm_address_t)mBuf,
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VM_PURGABLE_SET_STATE,
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&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
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VolatileBuffer::OnHeap() const
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{
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return mHeap;
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}
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size_t
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VolatileBuffer::HeapSizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
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{
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return OnHeap() ? aMallocSizeOf(mBuf) : 0;
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}
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size_t
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VolatileBuffer::NonHeapSizeOfExcludingThis() const
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{
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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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