chromium/v8/src/base/atomic-utils.h

// Copyright 2015 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_BASE_ATOMIC_UTILS_H_
#define V8_BASE_ATOMIC_UTILS_H_

#include <limits.h>

#include <atomic>
#include <type_traits>

#include "src/base/atomicops.h"
#include "src/base/macros.h"

namespace v8 {
namespace base {

// Deprecated. Use std::atomic<T> for new code.
// Flag using T atomically. Also accepts void* as T.
template <typename T>
class AtomicValue { … };

// Provides atomic operations for a values stored at some address.
template <typename TAtomicStorageType>
class AsAtomicImpl { … };

AsAtomic8;
AsAtomic16;
AsAtomic32;
AsAtomicWord;

template <int Width>
struct AtomicTypeFromByteWidth { … };
template <>
struct AtomicTypeFromByteWidth<1> { … };
template <>
struct AtomicTypeFromByteWidth<2> { … };
template <>
struct AtomicTypeFromByteWidth<4> { … };
#if V8_HOST_ARCH_64_BIT
template <>
struct AtomicTypeFromByteWidth<8> { … };
#endif

// This is similar to AsAtomicWord but it explicitly deletes functionality
// provided atomic access to bit representation of stored values.
template <typename TAtomicStorageType>
class AsAtomicPointerImpl : public AsAtomicImpl<TAtomicStorageType> { … };

AsAtomicPointer;

template <typename T,
          typename = typename std::enable_if<std::is_unsigned<T>::value>::type>
inline void CheckedIncrement(
    std::atomic<T>* number, T amount,
    std::memory_order order = std::memory_order_seq_cst) { … }

template <typename T,
          typename = typename std::enable_if<std::is_unsigned<T>::value>::type>
inline void CheckedDecrement(
    std::atomic<T>* number, T amount,
    std::memory_order order = std::memory_order_seq_cst) { … }

template <typename T>
V8_INLINE std::atomic<T>* AsAtomicPtr(T* t) { … }

template <typename T>
V8_INLINE const std::atomic<T>* AsAtomicPtr(const T* t) { … }

}  // namespace base
}  // namespace v8

#endif  // V8_BASE_ATOMIC_UTILS_H_