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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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
#include "RefCountedShmem.h"
#include "mozilla/Atomics.h"
#include "mozilla/ipc/ProtocolUtils.h"
#include "mozilla/layers/WebRenderMessages.h"
#define SHM_REFCOUNT_HEADER_SIZE 16
namespace mozilla {
namespace layers {
uint8_t* RefCountedShm::GetBytes(const RefCountedShmem& aShm) {
uint8_t* data = aShm.buffer().get<uint8_t>();
if (!data) {
return nullptr;
}
return data + SHM_REFCOUNT_HEADER_SIZE;
}
size_t RefCountedShm::GetSize(const RefCountedShmem& aShm) {
if (!IsValid(aShm)) {
return 0;
}
size_t totalSize = aShm.buffer().Size<uint8_t>();
if (totalSize < SHM_REFCOUNT_HEADER_SIZE) {
return 0;
}
return totalSize - SHM_REFCOUNT_HEADER_SIZE;
}
bool RefCountedShm::IsValid(const RefCountedShmem& aShm) {
return aShm.buffer().IsWritable() &&
aShm.buffer().Size<uint8_t>() > SHM_REFCOUNT_HEADER_SIZE;
}
int32_t RefCountedShm::GetReferenceCount(const RefCountedShmem& aShm) {
if (!IsValid(aShm)) {
return 0;
}
return *aShm.buffer().get<Atomic<int32_t>>();
}
int32_t RefCountedShm::AddRef(const RefCountedShmem& aShm) {
if (!IsValid(aShm)) {
return 0;
}
auto* counter = aShm.buffer().get<Atomic<int32_t>>();
if (counter) {
return (*counter)++;
}
return 0;
}
int32_t RefCountedShm::Release(const RefCountedShmem& aShm) {
if (!IsValid(aShm)) {
return 0;
}
auto* counter = aShm.buffer().get<Atomic<int32_t>>();
if (counter) {
return --(*counter);
}
return 0;
}
bool RefCountedShm::Alloc(mozilla::ipc::IProtocol* aAllocator, size_t aSize,
RefCountedShmem& aShm) {
MOZ_ASSERT(!IsValid(aShm));
auto size = aSize + SHM_REFCOUNT_HEADER_SIZE;
if (!aAllocator->AllocUnsafeShmem(size, &aShm.buffer())) {
return false;
}
return true;
}
void RefCountedShm::Dealloc(mozilla::ipc::IProtocol* aAllocator,
RefCountedShmem& aShm) {
aAllocator->DeallocShmem(aShm.buffer());
aShm.buffer() = ipc::Shmem();
}
} // namespace layers
} // namespace mozilla