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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "gpu/command_buffer/common/shm_count.h"
#include "base/check.h"
#include "base/check_op.h"
#include "base/memory/shared_memory_mapping.h"
#include "base/memory/unsafe_shared_memory_region.h"
namespace gpu {
ShmCountBase::ShmCountBase() = default;
ShmCountBase::ShmCountBase(ShmCountBase&& other) = default;
ShmCountBase& ShmCountBase::operator=(ShmCountBase&& other) = default;
ShmCountBase::~ShmCountBase() = default;
void ShmCountBase::Initialize(base::UnsafeSharedMemoryRegion region) {
region_ = std::move(region);
mapping_ = region_.Map();
}
bool ShmCountBase::IsInitialized() const {
return region().IsValid();
}
volatile ShmCountBase::AtomicType* ShmCountBase::AsAtomic() {
return reinterpret_cast<volatile AtomicType*>(mapping_.memory());
}
GpuProcessShmCount::GpuProcessShmCount() = default;
GpuProcessShmCount::GpuProcessShmCount(base::UnsafeSharedMemoryRegion region) {
// In cases where we are running without a GpuProcessHost, we may not
// have a valid handle. In this case, just return.
if (!region.IsValid()) {
return;
}
Initialize(std::move(region));
}
void GpuProcessShmCount::Increment() {
// In cases where we are running without a GpuProcessHost, we may not
// initialize the GpuProcessShmCount. In this case, just return.
if (!IsInitialized()) {
return;
}
AsAtomic()->fetch_add(1, std::memory_order_release);
}
void GpuProcessShmCount::Decrement() {
// In cases where we are running without a GpuProcessHost, we may not
// initialize the GpuProcessShmCount. In this case, just return.
if (!IsInitialized()) {
return;
}
CountType old_value = AsAtomic()->fetch_add(-1, std::memory_order_release);
CHECK_GE(old_value, 1);
}
GpuProcessHostShmCount::GpuProcessHostShmCount() {
Initialize(base::UnsafeSharedMemoryRegion::Create(sizeof(AtomicType)));
}
GpuProcessShmCount::CountType GpuProcessHostShmCount::GetCount() {
DCHECK(IsInitialized());
return AsAtomic()->load(std::memory_order_acquire);
}
} // namespace gpu
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