null_mutex.h

Go to the documentation of this file.

// Copyright(c) 2015-present, Gabi Melman & spdlog contributors.
// Distributed under the MIT License (http://opensource.org/licenses/MIT)
 
#pragma once
 
#include <atomic>
#include <utility>
// null, no cost dummy "mutex" and dummy "atomic" int
 
namespace spdlog
{
    namespace details
    {
        struct null_mutex
        {
            void lock() const
            {
            }
            void unlock() const
            {
            }
        };
 
        struct null_atomic_int
        {
            int value;
            null_atomic_int() = default;
 
            explicit null_atomic_int(int new_value)
                : value(new_value)
            {
            }
 
            int load(std::memory_order = std::memory_order_relaxed) const
            {
                return value;
            }
 
            void store(int new_value, std::memory_order = std::memory_order_relaxed)
            {
                value = new_value;
            }
 
            int exchange(int new_value, std::memory_order = std::memory_order_relaxed)
            {
                std::swap(new_value, value);
                return new_value; // return value before the call
            }
        };
 
    } // namespace details
} // namespace spdlog