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-rw-r--r--memory/volatile/VolatileBufferAshmem.cpp120
1 files changed, 120 insertions, 0 deletions
diff --git a/memory/volatile/VolatileBufferAshmem.cpp b/memory/volatile/VolatileBufferAshmem.cpp
new file mode 100644
index 0000000000..99a0d1307f
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+++ b/memory/volatile/VolatileBufferAshmem.cpp
@@ -0,0 +1,120 @@
+/* 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 <fcntl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "mozilla/Ashmem.h"
+
+#ifdef MOZ_MEMORY
+extern "C" int posix_memalign(void** memptr, size_t alignment, size_t size);
+#endif
+
+#define MIN_VOLATILE_ALLOC_SIZE 8192
+
+namespace mozilla {
+
+VolatileBuffer::VolatileBuffer()
+ : mMutex("VolatileBuffer"),
+ mBuf(nullptr),
+ mSize(0),
+ mLockCount(0),
+ mFd(-1) {}
+
+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;
+ }
+
+ mFd = mozilla::android::ashmem_create(nullptr, mSize);
+ if (mFd < 0) {
+ goto heap_alloc;
+ }
+
+ mBuf = mmap(nullptr, mSize, PROT_READ | PROT_WRITE, MAP_SHARED, mFd, 0);
+ if (mBuf != MAP_FAILED) {
+ return true;
+ }
+
+heap_alloc:
+ mBuf = nullptr;
+ if (mFd >= 0) {
+ close(mFd);
+ mFd = -1;
+ }
+
+#ifdef MOZ_MEMORY
+ posix_memalign(&mBuf, aAlignment, aSize);
+#else
+ mBuf = memalign(aAlignment, aSize);
+#endif
+ return !!mBuf;
+}
+
+VolatileBuffer::~VolatileBuffer() {
+ MOZ_ASSERT(mLockCount == 0, "Being destroyed with non-zero lock count?");
+
+ if (OnHeap()) {
+ free(mBuf);
+ } else {
+ munmap(mBuf, mSize);
+ close(mFd);
+ }
+}
+
+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;
+ }
+
+ // Zero offset and zero length means we want to pin/unpin the entire thing.
+ struct ashmem_pin pin = {0, 0};
+ return ioctl(mFd, ASHMEM_PIN, &pin) == ASHMEM_NOT_PURGED;
+}
+
+void VolatileBuffer::Unlock() {
+ MutexAutoLock lock(mMutex);
+
+ MOZ_ASSERT(mLockCount > 0, "VolatileBuffer unlocked too many times!");
+ if (--mLockCount || OnHeap()) {
+ return;
+ }
+
+ struct ashmem_pin pin = {0, 0};
+ ioctl(mFd, ASHMEM_UNPIN, &pin);
+}
+
+bool VolatileBuffer::OnHeap() const { return mFd < 0; }
+
+size_t VolatileBuffer::HeapSizeOfExcludingThis(
+ MallocSizeOf aMallocSizeOf) const {
+ return OnHeap() ? aMallocSizeOf(mBuf) : 0;
+}
+
+size_t VolatileBuffer::NonHeapSizeOfExcludingThis() const {
+ if (OnHeap()) {
+ return 0;
+ }
+
+ return (mSize + (PAGE_SIZE - 1)) & PAGE_MASK;
+}
+
+} // namespace mozilla