1//
2// system_timer.hpp
3// ~~~~~~~~~~~~~~~~
4//
5// Copyright (c) 2003-2024 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6//
7// Distributed under the Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9//
10
11#ifndef BOOST_ASIO_SYSTEM_TIMER_HPP
12#define BOOST_ASIO_SYSTEM_TIMER_HPP
13
14#if defined(_MSC_VER) && (_MSC_VER >= 1200)
15# pragma once
16#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
17
18#include <boost/asio/detail/config.hpp>
19#include <boost/asio/basic_waitable_timer.hpp>
20#include <boost/asio/detail/chrono.hpp>
21
22namespace boost {
23namespace asio {
24
25/// Typedef for a timer based on the system clock.
26/**
27 * This typedef uses the C++11 @c &lt;chrono&gt; standard library facility, if
28 * available. Otherwise, it may use the Boost.Chrono library. To explicitly
29 * utilise Boost.Chrono, use the basic_waitable_timer template directly:
30 * @code
31 * typedef basic_waitable_timer<boost::chrono::system_clock> timer;
32 * @endcode
33 */
34typedef basic_waitable_timer<chrono::system_clock> system_timer;
35
36} // namespace asio
37} // namespace boost
38
39#endif // BOOST_ASIO_SYSTEM_TIMER_HPP
40

source code of boost/libs/asio/include/boost/asio/system_timer.hpp