94 lines
3.2 KiB
C++
94 lines
3.2 KiB
C++
/*
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* Distributed under the Boost Software License, Version 1.0.
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* (See accompanying file LICENSE_1_0.txt or copy at
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* http://www.boost.org/LICENSE_1_0.txt)
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*
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* Copyright (c) 2025 Andrey Semashev
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*/
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/*!
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* \file atomic/detail/chrono.hpp
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*
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* This header contains \c std::chrono utilities.
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*/
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#ifndef BOOST_ATOMIC_DETAIL_CHRONO_HPP_INCLUDED_
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#define BOOST_ATOMIC_DETAIL_CHRONO_HPP_INCLUDED_
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#include <time.h>
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#include <chrono>
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#if !defined(__cpp_lib_chrono) || (__cpp_lib_chrono < 201510l)
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#include <ratio>
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#include <type_traits>
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#endif // !defined(__cpp_lib_chrono) || (__cpp_lib_chrono < 201510l)
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#if defined(CLOCK_REALTIME)
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#include <boost/atomic/posix_clock_traits_fwd.hpp>
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#endif // defined(CLOCK_REALTIME)
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#include <boost/atomic/detail/config.hpp>
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#include <boost/atomic/detail/header.hpp>
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#ifdef BOOST_HAS_PRAGMA_ONCE
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#pragma once
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#endif
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namespace boost {
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namespace atomics {
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namespace detail {
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namespace chrono {
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#if defined(__cpp_lib_chrono) && (__cpp_lib_chrono >= 201510l)
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using std::chrono::ceil;
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#else // defined(__cpp_lib_chrono) && (__cpp_lib_chrono >= 201510l)
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template< typename To, typename Rep, typename Period >
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inline constexpr To ceil(std::chrono::duration< Rep, Period > from) noexcept
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{
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using conv_ratio = std::ratio_divide< Period, typename To::period >;
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using common_rep = typename std::common_type< Rep, typename To::rep, decltype(conv_ratio::num) >::type;
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return To(static_cast< typename To::rep >((static_cast< common_rep >(from.count()) * conv_ratio::num) / conv_ratio::den +
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static_cast< common_rep >(((static_cast< common_rep >(from.count()) * conv_ratio::num) % conv_ratio::den) != static_cast< common_rep >(0))));
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}
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#endif // defined(__cpp_lib_chrono) && (__cpp_lib_chrono >= 201510l)
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} // namespace chrono
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} // namespace detail
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#if defined(CLOCK_REALTIME)
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//! Integrate `std::chrono::system_clock` with POSIX clocks
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template< >
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struct posix_clock_traits< std::chrono::system_clock >
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{
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//! POSIX clock identifier
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static constexpr clockid_t clock_id = CLOCK_REALTIME;
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//! Function that converts a time point to a timespec structure
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static timespec to_timespec(std::chrono::system_clock::time_point time_point) noexcept
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{
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timespec ts{};
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std::chrono::nanoseconds::rep time_ns = std::chrono::duration_cast< std::chrono::nanoseconds >(time_point.time_since_epoch()).count();
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// Note: The standard doesn't require that std::chrono::system_clock epoch matches the POSIX CLOCK_REALTIME epoch. Also, std::chrono::system_clock::to_time_t
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// is allowed to round or truncate the time point when converting to time_t resolution, which means to_time_t may return a time before or after time_point.
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ts.tv_sec = std::chrono::system_clock::to_time_t(std::chrono::system_clock::time_point()) + static_cast< decltype(ts.tv_sec) >(time_ns / 1000000000);
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time_ns %= 1000000000;
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if (BOOST_UNLIKELY(time_ns < 0))
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{
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--ts.tv_sec;
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time_ns += 1000000000;
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}
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ts.tv_nsec = static_cast< decltype(ts.tv_nsec) >(time_ns);
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return ts;
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}
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};
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#endif // defined(CLOCK_REALTIME)
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} // namespace atomics
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} // namespace boost
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#include <boost/atomic/detail/footer.hpp>
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#endif // BOOST_ATOMIC_DETAIL_CHRONO_HPP_INCLUDED_
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