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