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-rw-r--r--memory/volatile/VolatileBufferWindows.cpp136
1 files changed, 136 insertions, 0 deletions
diff --git a/memory/volatile/VolatileBufferWindows.cpp b/memory/volatile/VolatileBufferWindows.cpp
new file mode 100644
index 0000000000..6615f89299
--- /dev/null
+++ b/memory/volatile/VolatileBufferWindows.cpp
@@ -0,0 +1,136 @@
+/* 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/DebugOnly.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;
+ }
+
+ DebugOnly<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