libstdc++-v3/include/bits/this_thread_sleep.h

   1 // std::this_thread::sleep_for/until declarations -*- C++ -*-
   2
   3 // Copyright (C) 2008-2024 Free Software Foundation, Inc.
   4 //
   5 // This file is part of the GNU ISO C++ Library.  This library is free
   6 // software; you can redistribute it and/or modify it under the
   7 // terms of the GNU General Public License as published by the
   8 // Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10
  11 // This library is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 /** @file bits/this_thread_sleep.h
  26  *  This is an internal header file, included by other library headers.
  27  *  Do not attempt to use it directly. @headername{thread}
  28  */
  29
  30 #ifndef _GLIBCXX_THIS_THREAD_SLEEP_H
  31 #define _GLIBCXX_THIS_THREAD_SLEEP_H 1
  32
  33 #pragma GCC system_header
  34
  35 #if __cplusplus >= 201103L
  36 #include <bits/chrono.h> // std::chrono::*
  37
  38 #ifdef _GLIBCXX_USE_NANOSLEEP
  39 # include <cerrno>  // errno, EINTR
  40 # include <time.h>  // nanosleep
  41 #endif
  42
  43 namespace std _GLIBCXX_VISIBILITY(default)
  44 {
  45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  46
  47   /** @addtogroup threads
  48    *  @{
  49    */
  50
  51   /** @namespace std::this_thread
  52    *  @brief ISO C++ 2011 namespace for interacting with the current thread
  53    *
  54    *  C++11 30.3.2 [thread.thread.this] Namespace this_thread.
  55    */
  56   namespace this_thread
  57   {
  58 #ifndef _GLIBCXX_NO_SLEEP
  59
  60 #ifndef _GLIBCXX_USE_NANOSLEEP
  61     void
  62     __sleep_for(chrono::seconds, chrono::nanoseconds);
  63 #endif
  64
  65     /// this_thread::sleep_for
  66     template<typename _Rep, typename _Period>
  67       inline void
  68       sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
  69       {
  70         if (__rtime <= __rtime.zero())
  71           return;
  72         auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
  73         auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
  74 #ifdef _GLIBCXX_USE_NANOSLEEP
  75         struct ::timespec __ts =
  76           {
  77             static_cast<std::time_t>(__s.count()),
  78             static_cast<long>(__ns.count())
  79           };
  80         while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
  81           { }
  82 #else
  83         __sleep_for(__s, __ns);
  84 #endif
  85       }
  86
  87     /// this_thread::sleep_until
  88     template<typename _Clock, typename _Duration>
  89       inline void
  90       sleep_until(const chrono::time_point<_Clock, _Duration>& __atime)
  91       {
  92 #if __cplusplus > 201703L
  93         static_assert(chrono::is_clock_v<_Clock>);
  94 #endif
  95         auto __now = _Clock::now();
  96         if (_Clock::is_steady)
  97           {
  98             if (__now < __atime)
  99               sleep_for(__atime - __now);
 100             return;
 101           }
 102         while (__now < __atime)
 103           {
 104             sleep_for(__atime - __now);
 105             __now = _Clock::now();
 106           }
 107       }
 108 #endif // ! NO_SLEEP
 109   } // namespace this_thread
 110
 111   /// @}
 112
 113 _GLIBCXX_END_NAMESPACE_VERSION
 114 } // namespace
 115 #endif // C++11
 116
 117 #endif // _GLIBCXX_THIS_THREAD_SLEEP_H