1// <thread> -*- C++ -*-
2
3// Copyright (C) 2008-2021 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/thread
26 *  This is a Standard C++ Library header.
27 */
28
29#ifndef _GLIBCXX_THREAD
30#define _GLIBCXX_THREAD 1
31
32#pragma GCC system_header
33
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
36#else
37
38#if __cplusplus > 201703L
39# include <compare>	// std::strong_ordering
40# include <stop_token>	// std::stop_source, std::stop_token, std::nostopstate
41#endif
42
43#include <bits/std_thread.h> // std::thread, get_id, yield
44#include <bits/this_thread_sleep.h> // std::this_thread::sleep_for, sleep_until
45
46namespace std _GLIBCXX_VISIBILITY(default)
47{
48_GLIBCXX_BEGIN_NAMESPACE_VERSION
49
50  /**
51   * @defgroup threads Threads
52   * @ingroup concurrency
53   *
54   * Classes for thread support.
55   * @{
56   */
57
58  // std::thread is defined in <bits/std_thread.h>
59
60#if __cpp_lib_three_way_comparison
61  inline strong_ordering
62  operator<=>(thread::id __x, thread::id __y) noexcept
63  { return __x._M_thread <=> __y._M_thread; }
64#else
65  inline bool
66  operator!=(thread::id __x, thread::id __y) noexcept
67  { return !(__x == __y); }
68
69  inline bool
70  operator<(thread::id __x, thread::id __y) noexcept
71  {
72    // Pthreads doesn't define any way to do this, so we just have to
73    // assume native_handle_type is LessThanComparable.
74    return __x._M_thread < __y._M_thread;
75  }
76
77  inline bool
78  operator<=(thread::id __x, thread::id __y) noexcept
79  { return !(__y < __x); }
80
81  inline bool
82  operator>(thread::id __x, thread::id __y) noexcept
83  { return __y < __x; }
84
85  inline bool
86  operator>=(thread::id __x, thread::id __y) noexcept
87  { return !(__x < __y); }
88#endif // __cpp_lib_three_way_comparison
89
90  template<class _CharT, class _Traits>
91    inline basic_ostream<_CharT, _Traits>&
92    operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
93    {
94      if (__id == thread::id())
95	return __out << "thread::id of a non-executing thread";
96      else
97	return __out << __id._M_thread;
98    }
99
100#ifdef __cpp_lib_jthread
101
102  /// A thread that can be requested to stop and automatically joined.
103  class jthread
104  {
105  public:
106    using id = thread::id;
107    using native_handle_type = thread::native_handle_type;
108
109    jthread() noexcept
110    : _M_stop_source{nostopstate}
111    { }
112
113    template<typename _Callable, typename... _Args,
114	     typename = enable_if_t<!is_same_v<remove_cvref_t<_Callable>,
115					       jthread>>>
116      explicit
117      jthread(_Callable&& __f, _Args&&... __args)
118      : _M_thread{_S_create(_M_stop_source, std::forward<_Callable>(__f),
119			    std::forward<_Args>(__args)...)}
120      { }
121
122    jthread(const jthread&) = delete;
123    jthread(jthread&&) noexcept = default;
124
125    ~jthread()
126    {
127      if (joinable())
128        {
129          request_stop();
130          join();
131        }
132    }
133
134    jthread&
135    operator=(const jthread&) = delete;
136
137    jthread&
138    operator=(jthread&& __other) noexcept
139    {
140      std::jthread(std::move(__other)).swap(*this);
141      return *this;
142    }
143
144    void
145    swap(jthread& __other) noexcept
146    {
147      std::swap(_M_stop_source, __other._M_stop_source);
148      std::swap(_M_thread, __other._M_thread);
149    }
150
151    [[nodiscard]] bool
152    joinable() const noexcept
153    {
154      return _M_thread.joinable();
155    }
156
157    void
158    join()
159    {
160      _M_thread.join();
161    }
162
163    void
164    detach()
165    {
166      _M_thread.detach();
167    }
168
169    [[nodiscard]] id
170    get_id() const noexcept
171    {
172      return _M_thread.get_id();
173    }
174
175    [[nodiscard]] native_handle_type
176    native_handle()
177    {
178      return _M_thread.native_handle();
179    }
180
181    [[nodiscard]] static unsigned
182    hardware_concurrency() noexcept
183    {
184      return thread::hardware_concurrency();
185    }
186
187    [[nodiscard]] stop_source
188    get_stop_source() noexcept
189    {
190      return _M_stop_source;
191    }
192
193    [[nodiscard]] stop_token
194    get_stop_token() const noexcept
195    {
196      return _M_stop_source.get_token();
197    }
198
199    bool request_stop() noexcept
200    {
201      return _M_stop_source.request_stop();
202    }
203
204    friend void swap(jthread& __lhs, jthread& __rhs) noexcept
205    {
206      __lhs.swap(__rhs);
207    }
208
209  private:
210    template<typename _Callable, typename... _Args>
211      static thread
212      _S_create(stop_source& __ssrc, _Callable&& __f, _Args&&... __args)
213      {
214	if constexpr(is_invocable_v<decay_t<_Callable>, stop_token,
215				    decay_t<_Args>...>)
216	  return thread{std::forward<_Callable>(__f), __ssrc.get_token(),
217			std::forward<_Args>(__args)...};
218	else
219	  {
220	    static_assert(is_invocable_v<decay_t<_Callable>,
221					 decay_t<_Args>...>,
222			  "std::thread arguments must be invocable after"
223			  " conversion to rvalues");
224	    return thread{std::forward<_Callable>(__f),
225			  std::forward<_Args>(__args)...};
226	  }
227      }
228
229    stop_source _M_stop_source;
230    thread _M_thread;
231  };
232#endif // __cpp_lib_jthread
233
234  /// @} group threads
235
236_GLIBCXX_END_NAMESPACE_VERSION
237} // namespace
238#endif // C++11
239#endif // _GLIBCXX_THREAD
240