gecko-dev/memory/volatile/VolatileBufferWindows.cpp

161 lines
3.2 KiB
C++

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "VolatileBuffer.h"
#include "mozilla/Assertions.h"
#include "mozilla/mozalloc.h"
#include "mozilla/WindowsVersion.h"
#include <windows.h>
#ifdef MOZ_MEMORY
extern "C" int posix_memalign(void** memptr, size_t alignment, size_t size);
#endif
#ifndef MEM_RESET_UNDO
#define MEM_RESET_UNDO 0x1000000
#endif
#define MIN_VOLATILE_ALLOC_SIZE 8192
namespace mozilla {
VolatileBuffer::VolatileBuffer()
: mMutex("VolatileBuffer")
, mBuf(nullptr)
, mSize(0)
, mLockCount(0)
, mHeap(false)
, mFirstLock(true)
{
}
bool
VolatileBuffer::Init(size_t aSize, size_t aAlignment)
{
MOZ_ASSERT(!mSize && !mBuf, "Init called twice");
MOZ_ASSERT(!(aAlignment % sizeof(void *)),
"Alignment must be multiple of pointer size");
mSize = aSize;
if (aSize < MIN_VOLATILE_ALLOC_SIZE) {
goto heap_alloc;
}
static bool sUndoSupported = IsWin8OrLater();
if (!sUndoSupported) {
goto heap_alloc;
}
mBuf = VirtualAllocEx(GetCurrentProcess(),
nullptr,
mSize,
MEM_COMMIT | MEM_RESERVE,
PAGE_READWRITE);
if (mBuf) {
return true;
}
heap_alloc:
#ifdef MOZ_MEMORY
posix_memalign(&mBuf, aAlignment, aSize);
#else
mBuf = _aligned_malloc(aSize, aAlignment);
#endif
mHeap = true;
return !!mBuf;
}
VolatileBuffer::~VolatileBuffer()
{
MOZ_ASSERT(mLockCount == 0, "Being destroyed with non-zero lock count?");
if (OnHeap()) {
#ifdef MOZ_MEMORY
free(mBuf);
#else
_aligned_free(mBuf);
#endif
} else {
VirtualFreeEx(GetCurrentProcess(), mBuf, 0, MEM_RELEASE);
}
}
bool
VolatileBuffer::Lock(void** aBuf)
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(mBuf, "Attempting to lock an uninitialized VolatileBuffer");
*aBuf = mBuf;
if (++mLockCount > 1 || OnHeap()) {
return true;
}
// MEM_RESET_UNDO's behavior is undefined when called on memory that
// hasn't been MEM_RESET.
if (mFirstLock) {
mFirstLock = false;
return true;
}
void* addr = VirtualAllocEx(GetCurrentProcess(),
mBuf,
mSize,
MEM_RESET_UNDO,
PAGE_READWRITE);
return !!addr;
}
void
VolatileBuffer::Unlock()
{
MutexAutoLock lock(mMutex);
MOZ_ASSERT(mLockCount > 0, "VolatileBuffer unlocked too many times!");
if (--mLockCount || OnHeap()) {
return;
}
void* addr = VirtualAllocEx(GetCurrentProcess(),
mBuf,
mSize,
MEM_RESET,
PAGE_READWRITE);
MOZ_ASSERT(addr, "Failed to MEM_RESET");
}
bool
VolatileBuffer::OnHeap() const
{
return mHeap;
}
size_t
VolatileBuffer::HeapSizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const
{
if (OnHeap()) {
#ifdef MOZ_MEMORY
return aMallocSizeOf(mBuf);
#else
return mSize;
#endif
}
return 0;
}
size_t
VolatileBuffer::NonHeapSizeOfExcludingThis() const
{
if (OnHeap()) {
return 0;
}
return (mSize + 4095) & ~4095;
}
} // namespace mozilla