libstdc++-v3/include/std/semaphore

   1 // <semaphore> -*- C++ -*-
   2
   3 // Copyright (C) 2020-2022 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 include/semaphore
  26  *  This is a Standard C++ Library header.
  27  */
  28
  29 #ifndef _GLIBCXX_SEMAPHORE
  30 #define _GLIBCXX_SEMAPHORE 1
  31
  32 #pragma GCC system_header
  33
  34 #if __cplusplus > 201703L
  35 #include <bits/semaphore_base.h>
  36
  37 #if __cpp_lib_atomic_wait || _GLIBCXX_HAVE_POSIX_SEMAPHORE
  38 namespace std _GLIBCXX_VISIBILITY(default)
  39 {
  40 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  41
  42 #define __cpp_lib_semaphore 201907L
  43
  44   template<ptrdiff_t __least_max_value = __semaphore_impl::_S_max>
  45     class counting_semaphore
  46     {
  47       static_assert(__least_max_value >= 0);
  48       static_assert(__least_max_value <= __semaphore_impl::_S_max);
  49
  50       __semaphore_impl _M_sem;
  51
  52     public:
  53       explicit counting_semaphore(ptrdiff_t __desired) noexcept
  54         : _M_sem(__desired)
  55       { }
  56
  57       ~counting_semaphore() = default;
  58
  59       counting_semaphore(const counting_semaphore&) = delete;
  60       counting_semaphore& operator=(const counting_semaphore&) = delete;
  61
  62       static constexpr ptrdiff_t
  63       max() noexcept
  64       { return __least_max_value; }
  65
  66       void
  67       release(ptrdiff_t __update = 1) noexcept(noexcept(_M_sem._M_release(1)))
  68       { _M_sem._M_release(__update); }
  69
  70       void
  71       acquire() noexcept(noexcept(_M_sem._M_acquire()))
  72       { _M_sem._M_acquire(); }
  73
  74       bool
  75       try_acquire() noexcept(noexcept(_M_sem._M_try_acquire()))
  76       { return _M_sem._M_try_acquire(); }
  77
  78       template<typename _Rep, typename _Period>
  79         bool
  80         try_acquire_for(const std::chrono::duration<_Rep, _Period>& __rtime)
  81         { return _M_sem._M_try_acquire_for(__rtime); }
  82
  83       template<typename _Clock, typename _Dur>
  84         bool
  85         try_acquire_until(const std::chrono::time_point<_Clock, _Dur>& __atime)
  86         { return _M_sem._M_try_acquire_until(__atime); }
  87     };
  88
  89   using binary_semaphore = std::counting_semaphore<1>;
  90
  91 _GLIBCXX_END_NAMESPACE_VERSION
  92 } // namespace
  93 #endif // cpp_lib_atomic_wait || _GLIBCXX_HAVE_POSIX_SEMAPHORE
  94 #endif // C++20
  95 #endif // _GLIBCXX_SEMAPHORE