forked from mirrors/gecko-dev
e5e885ae31
# ignore-this-changeset --HG-- extra : amend_source : 7221c8d15a765df71171099468e7c7faa648f37c extra : histedit_source : a0cce6015636202bff09e35a13f72e03257a7695
136 lines
3.1 KiB
C++
136 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 "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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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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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(), nullptr, mSize,
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MEM_COMMIT | MEM_RESERVE, 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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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 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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// 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(), mBuf, mSize, MEM_RESET_UNDO,
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PAGE_READWRITE);
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return !!addr;
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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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DebugOnly<void*> addr = VirtualAllocEx(GetCurrentProcess(), mBuf, mSize,
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MEM_RESET, PAGE_READWRITE);
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MOZ_ASSERT(addr, "Failed to MEM_RESET");
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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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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 VolatileBuffer::NonHeapSizeOfExcludingThis() const {
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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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