161 lines
3.2 KiB
C++
161 lines
3.2 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/mozalloc.h"
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#include "mozilla/WindowsVersion.h"
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#include <windows.h>
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#ifdef MOZ_MEMORY
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extern "C" int posix_memalign(void** memptr, size_t alignment, size_t size);
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#endif
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#ifndef MEM_RESET_UNDO
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#define MEM_RESET_UNDO 0x1000000
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#endif
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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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, mFirstLock(true)
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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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if (aSize < MIN_VOLATILE_ALLOC_SIZE) {
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goto heap_alloc;
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}
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static bool sUndoSupported = IsWin8OrLater();
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if (!sUndoSupported) {
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goto heap_alloc;
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}
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mBuf = VirtualAllocEx(GetCurrentProcess(),
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nullptr,
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mSize,
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MEM_COMMIT | MEM_RESERVE,
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PAGE_READWRITE);
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if (mBuf) {
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return true;
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}
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heap_alloc:
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#ifdef MOZ_MEMORY
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posix_memalign(&mBuf, aAlignment, aSize);
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#else
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mBuf = _aligned_malloc(aSize, aAlignment);
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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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#ifdef MOZ_MEMORY
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free(mBuf);
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#else
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_aligned_free(mBuf);
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#endif
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} else {
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VirtualFreeEx(GetCurrentProcess(), mBuf, 0, MEM_RELEASE);
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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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// MEM_RESET_UNDO's behavior is undefined when called on memory that
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// hasn't been MEM_RESET.
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if (mFirstLock) {
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mFirstLock = false;
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return true;
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}
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void* addr = VirtualAllocEx(GetCurrentProcess(),
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mBuf,
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mSize,
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MEM_RESET_UNDO,
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PAGE_READWRITE);
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return !!addr;
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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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void* addr = VirtualAllocEx(GetCurrentProcess(),
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mBuf,
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mSize,
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MEM_RESET,
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PAGE_READWRITE);
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MOZ_ASSERT(addr, "Failed to MEM_RESET");
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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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if (OnHeap()) {
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#ifdef MOZ_MEMORY
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return aMallocSizeOf(mBuf);
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#else
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return mSize;
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#endif
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}
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return 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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return (mSize + 4095) & ~4095;
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}
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} // namespace mozilla
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