1// <semaphore> -*- C++ -*-
2
3// Copyright (C) 2020-2021 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
38namespace 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
96

source code of include/c++/11/semaphore