boost/atomic/posix_clock_traits_fwd.hpp

0001 /*
0002  * Distributed under the Boost Software License, Version 1.0.
0003  * (See accompanying file LICENSE_1_0.txt or copy at
0004  * http://www.boost.org/LICENSE_1_0.txt)
0005  *
0006  * Copyright (c) 2025 Andrey Semashev
0007  */
0008 /*!
0009  * \file   atomic/posix_clock_traits_fwd.hpp
0010  *
0011  * This header contains declaration of the \c posix_clock_traits class template.
0012  */
0013
0014 #ifndef BOOST_ATOMIC_POSIX_CLOCK_TRAITS_FWD_HPP_INCLUDED_
0015 #define BOOST_ATOMIC_POSIX_CLOCK_TRAITS_FWD_HPP_INCLUDED_
0016
0017 #include <boost/atomic/detail/config.hpp>
0018 #include <boost/atomic/detail/header.hpp>
0019
0020 #ifdef BOOST_HAS_PRAGMA_ONCE
0021 #pragma once
0022 #endif
0023
0024 namespace boost {
0025 namespace atomics {
0026
0027 /*!
0028  * \brief The structure contains traits for compatibility between chrono clocks and POSIX clocks.
0029  *
0030  * This class template is meant to be specialized for clock types that are compatible with `std::chrono`
0031  * requirements and are based on one of the POSIX clocks identified by
0032  * a [`clockid_t`](https://man7.org/linux/man-pages/man3/clockid_t.3type.html) constant.
0033  *
0034  * Every specialization of this class must support the following interface:
0035  *
0036  * ```
0037  * // POSIX clock identifier
0038  * static constexpr clockid_t clock_id = ...;
0039  *
0040  * // Function that converts a time point to a timespec structure
0041  * static timespec to_timespec(Clock::time_point time_point) noexcept;
0042  * ```
0043  *
0044  * Note that the `timespec` structure returned from `to_timespec` must use the identified POSIX
0045  * clock epoch and time units. There are no invalid input `time_point` values, so `to_timespec`
0046  * must never fail with an exception.
0047  *
0048  * The second template parameter of this class template may be used by partial specializations
0049  * to leverage SFINAE to selectively enable it for a set of clock types.
0050  */
0051 template< typename Clock, typename = void >
0052 struct posix_clock_traits;
0053
0054 } // namespace atomics
0055 } // namespace boost
0056
0057 #include <boost/atomic/detail/footer.hpp>
0058
0059 #endif // BOOST_ATOMIC_POSIX_CLOCK_TRAITS_FWD_HPP_INCLUDED_