1 files changed, 67 insertions, 0 deletions
diff --git a/memory/volatile/VolatileBufferFallback.cpp b/memory/volatile/VolatileBufferFallback.cpp
new file mode 100644
index 0000000000..d4311788ff
--- /dev/null
+++ b/memory/volatile/VolatileBufferFallback.cpp
@@ -0,0 +1,67 @@
+/* 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"
+
+#ifdef MOZ_MEMORY
+int posix_memalign(void** memptr, size_t alignment, size_t size);
+#endif
+
+namespace mozilla {
+
+VolatileBuffer::VolatileBuffer()
+    : mMutex("VolatileBuffer"), mBuf(nullptr), mSize(0), mLockCount(0) {}
+
+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 defined(MOZ_MEMORY) || defined(HAVE_POSIX_MEMALIGN)
+  if (posix_memalign(&mBuf, aAlignment, aSize) != 0) {
+    return false;
+  }
+#else
+#  error "No memalign implementation found"
+#endif
+  return !!mBuf;
+}
+
+VolatileBuffer::~VolatileBuffer() {
+  MOZ_ASSERT(mLockCount == 0, "Being destroyed with non-zero lock count?");
+
+  free(mBuf);
+}
+
+bool VolatileBuffer::Lock(void** aBuf) {
+  MutexAutoLock lock(mMutex);
+
+  MOZ_ASSERT(mBuf, "Attempting to lock an uninitialized VolatileBuffer");
+
+  *aBuf = mBuf;
+  mLockCount++;
+
+  return true;
+}
+
+void VolatileBuffer::Unlock() {
+  MutexAutoLock lock(mMutex);
+
+  mLockCount--;
+  MOZ_ASSERT(mLockCount >= 0, "VolatileBuffer unlocked too many times!");
+}
+
+bool VolatileBuffer::OnHeap() const { return true; }
+
+size_t VolatileBuffer::HeapSizeOfExcludingThis(
+    MallocSizeOf aMallocSizeOf) const {
+  return aMallocSizeOf(mBuf);
+}
+
+size_t VolatileBuffer::NonHeapSizeOfExcludingThis() const { return 0; }
+
+}  // namespace mozilla