зеркало из https://github.com/mozilla/gecko-dev.git
95 строки
2.4 KiB
C++
95 строки
2.4 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "RefCountedShmem.h"
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#include "mozilla/Atomics.h"
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#include "mozilla/ipc/ProtocolUtils.h"
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#include "mozilla/layers/WebRenderMessages.h"
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#define SHM_REFCOUNT_HEADER_SIZE 16
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namespace mozilla {
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namespace layers {
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uint8_t* RefCountedShm::GetBytes(const RefCountedShmem& aShm) {
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uint8_t* data = aShm.buffer().get<uint8_t>();
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if (!data) {
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return nullptr;
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}
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return data + SHM_REFCOUNT_HEADER_SIZE;
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}
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size_t RefCountedShm::GetSize(const RefCountedShmem& aShm) {
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if (!IsValid(aShm)) {
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return 0;
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}
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size_t totalSize = aShm.buffer().Size<uint8_t>();
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if (totalSize < SHM_REFCOUNT_HEADER_SIZE) {
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return 0;
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}
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return totalSize - SHM_REFCOUNT_HEADER_SIZE;
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}
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bool RefCountedShm::IsValid(const RefCountedShmem& aShm) {
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return aShm.buffer().IsWritable() &&
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aShm.buffer().Size<uint8_t>() > SHM_REFCOUNT_HEADER_SIZE;
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}
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int32_t RefCountedShm::GetReferenceCount(const RefCountedShmem& aShm) {
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if (!IsValid(aShm)) {
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return 0;
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}
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return *aShm.buffer().get<Atomic<int32_t>>();
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}
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int32_t RefCountedShm::AddRef(const RefCountedShmem& aShm) {
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if (!IsValid(aShm)) {
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return 0;
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}
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auto* counter = aShm.buffer().get<Atomic<int32_t>>();
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if (counter) {
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return (*counter)++;
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}
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return 0;
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}
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int32_t RefCountedShm::Release(const RefCountedShmem& aShm) {
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if (!IsValid(aShm)) {
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return 0;
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}
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auto* counter = aShm.buffer().get<Atomic<int32_t>>();
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if (counter) {
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return --(*counter);
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}
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return 0;
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}
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bool RefCountedShm::Alloc(mozilla::ipc::IProtocol* aAllocator, size_t aSize,
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RefCountedShmem& aShm) {
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MOZ_ASSERT(!IsValid(aShm));
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auto shmType = ipc::SharedMemory::SharedMemoryType::TYPE_BASIC;
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auto size = aSize + SHM_REFCOUNT_HEADER_SIZE;
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if (!aAllocator->AllocUnsafeShmem(size, shmType, &aShm.buffer())) {
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return false;
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}
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return true;
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}
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void RefCountedShm::Dealloc(mozilla::ipc::IProtocol* aAllocator,
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RefCountedShmem& aShm) {
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aAllocator->DeallocShmem(aShm.buffer());
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aShm.buffer() = ipc::Shmem();
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}
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} // namespace layers
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} // namespace mozilla
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