libstdc++
thread
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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 
46 namespace 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
constexpr std::remove_reference< _Tp >::type && move(_Tp &&__t) noexcept
Convert a value to an rvalue.
Definition: move.h:104
thread::id get_id() noexcept
this_thread::get_id
Definition: std_thread.h:307
constexpr bool is_invocable_v
std::is_invocable_v
Definition: type_traits:3001
auto_ptr & operator=(auto_ptr &__a)
auto_ptr assignment operator.
Definition: auto_ptr.h:128