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/* 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
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