libstdc++-v3/src/c++11/chrono.cc

   1 // chrono -*- C++ -*-
   2
   3 // Copyright (C) 2008-2020 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 #include <bits/c++config.h>
  26 #include <chrono>
  27
  28 // Conditional inclusion of sys/time.h for gettimeofday
  29 #if !defined(_GLIBCXX_USE_CLOCK_MONOTONIC) && \
  30     !defined(_GLIBCXX_USE_CLOCK_REALTIME) && \
  31      defined(_GLIBCXX_USE_GETTIMEOFDAY)
  32 #include <sys/time.h>
  33 #endif
  34
  35 #ifdef _GLIBCXX_USE_CLOCK_GETTIME_SYSCALL
  36 #include <unistd.h>
  37 #include <sys/syscall.h>
  38 #endif
  39
  40 namespace std _GLIBCXX_VISIBILITY(default)
  41 {
  42 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  43
  44   namespace chrono
  45   {
  46     // XXX GLIBCXX_ABI Deprecated
  47     inline namespace _V2 {
  48
  49     constexpr bool system_clock::is_steady;
  50
  51     system_clock::time_point
  52     system_clock::now() noexcept
  53     {
  54 #ifdef _GLIBCXX_USE_CLOCK_REALTIME
  55       timespec tp;
  56       // -EINVAL, -EFAULT
  57 #ifdef _GLIBCXX_USE_CLOCK_GETTIME_SYSCALL
  58       syscall(SYS_clock_gettime, CLOCK_REALTIME, &tp);
  59 #else
  60       clock_gettime(CLOCK_REALTIME, &tp);
  61 #endif
  62       return time_point(duration(chrono::seconds(tp.tv_sec)
  63                                  + chrono::nanoseconds(tp.tv_nsec)));
  64 #elif defined(_GLIBCXX_USE_GETTIMEOFDAY)
  65       timeval tv;
  66       // EINVAL, EFAULT
  67       gettimeofday(&tv, 0);
  68       return time_point(duration(chrono::seconds(tv.tv_sec)
  69                                  + chrono::microseconds(tv.tv_usec)));
  70 #else
  71       std::time_t __sec = std::time(0);
  72       return system_clock::from_time_t(__sec);
  73 #endif
  74     }
  75
  76
  77     constexpr bool steady_clock::is_steady;
  78
  79     steady_clock::time_point
  80     steady_clock::now() noexcept
  81     {
  82 #ifdef _GLIBCXX_USE_CLOCK_MONOTONIC
  83       timespec tp;
  84       // -EINVAL, -EFAULT
  85 #ifdef _GLIBCXX_USE_CLOCK_GETTIME_SYSCALL
  86       syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &tp);
  87 #else
  88       clock_gettime(CLOCK_MONOTONIC, &tp);
  89 #endif
  90       return time_point(duration(chrono::seconds(tp.tv_sec)
  91                                  + chrono::nanoseconds(tp.tv_nsec)));
  92 #else
  93       return time_point(system_clock::now().time_since_epoch());
  94 #endif
  95     }
  96
  97   } // end inline namespace _V2
  98   } // namespace chrono
  99
 100 _GLIBCXX_END_NAMESPACE_VERSION
 101 } // namespace std