1// <thread> -*- C++ -*- 2 3// Copyright (C) 2008-2022 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/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 * @since C++11 54 * 55 * Classes for thread support. 56 * @{ 57 */ 58 59 // std::thread is defined in <bits/std_thread.h> 60 61 /// @relates std::thread::id @{ 62 63#if __cpp_lib_three_way_comparison 64 inline strong_ordering 65 operator<=>(thread::id __x, thread::id __y) noexcept 66 { return __x._M_thread <=> __y._M_thread; } 67#else 68 inline bool 69 operator!=(thread::id __x, thread::id __y) noexcept 70 { return !(__x == __y); } 71 72 inline bool 73 operator<(thread::id __x, thread::id __y) noexcept 74 { 75 // Pthreads doesn't define any way to do this, so we just have to 76 // assume native_handle_type is LessThanComparable. 77 return __x._M_thread < __y._M_thread; 78 } 79 80 inline bool 81 operator<=(thread::id __x, thread::id __y) noexcept 82 { return !(__y < __x); } 83 84 inline bool 85 operator>(thread::id __x, thread::id __y) noexcept 86 { return __y < __x; } 87 88 inline bool 89 operator>=(thread::id __x, thread::id __y) noexcept 90 { return !(__x < __y); } 91#endif // __cpp_lib_three_way_comparison 92 93 template<class _CharT, class _Traits> 94 inline basic_ostream<_CharT, _Traits>& 95 operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id) 96 { 97 if (__id == thread::id()) 98 return __out << "thread::id of a non-executing thread"; 99 else 100 return __out << __id._M_thread; 101 } 102 /// @} 103 104#ifdef __cpp_lib_jthread 105 106 /// @cond undocumented 107#ifndef __STRICT_ANSI__ 108 template<typename _Callable, typename... _Args> 109 constexpr bool __pmf_expects_stop_token = false; 110 111 template<typename _Callable, typename _Obj, typename... _Args> 112 constexpr bool __pmf_expects_stop_token<_Callable, _Obj, _Args...> 113 = __and_<is_member_function_pointer<remove_reference_t<_Callable>>, 114 is_invocable<_Callable, _Obj, stop_token, _Args...>>::value; 115#endif 116 /// @endcond 117 118 /** A thread with cancellation and automatic joining. 119 * 120 * Unlike `std::thread`, destroying a joinable `std::jthread` will not 121 * terminate the process. Instead, it will try to request its thread to 122 * stop, then will join it. 123 * 124 * A `std::jthread` has a `std::stop_source` member which will be passed 125 * as the first argument to the callable that runs in the new thread 126 * (as long as the callable will accept that argument). That can then 127 * be used to send a stop request that the new thread can test for. 128 * 129 * @headerfile thread 130 * @since C++20 131 */ 132 class jthread 133 { 134 public: 135 using id = thread::id; 136 using native_handle_type = thread::native_handle_type; 137 138 jthread() noexcept 139 : _M_stop_source{nostopstate} 140 { } 141 142 template<typename _Callable, typename... _Args, 143 typename = enable_if_t<!is_same_v<remove_cvref_t<_Callable>, 144 jthread>>> 145 explicit 146 jthread(_Callable&& __f, _Args&&... __args) 147 : _M_thread{_S_create(_M_stop_source, std::forward<_Callable>(__f), 148 std::forward<_Args>(__args)...)} 149 { } 150 151 jthread(const jthread&) = delete; 152 jthread(jthread&&) noexcept = default; 153 154 ~jthread() 155 { 156 if (joinable()) 157 { 158 request_stop(); 159 join(); 160 } 161 } 162 163 jthread& 164 operator=(const jthread&) = delete; 165 166 jthread& 167 operator=(jthread&& __other) noexcept 168 { 169 std::jthread(std::move(__other)).swap(*this); 170 return *this; 171 } 172 173 void 174 swap(jthread& __other) noexcept 175 { 176 std::swap(_M_stop_source, __other._M_stop_source); 177 std::swap(_M_thread, __other._M_thread); 178 } 179 180 [[nodiscard]] bool 181 joinable() const noexcept 182 { 183 return _M_thread.joinable(); 184 } 185 186 void 187 join() 188 { 189 _M_thread.join(); 190 } 191 192 void 193 detach() 194 { 195 _M_thread.detach(); 196 } 197 198 [[nodiscard]] id 199 get_id() const noexcept 200 { 201 return _M_thread.get_id(); 202 } 203 204 [[nodiscard]] native_handle_type 205 native_handle() 206 { 207 return _M_thread.native_handle(); 208 } 209 210 [[nodiscard]] static unsigned 211 hardware_concurrency() noexcept 212 { 213 return thread::hardware_concurrency(); 214 } 215 216 [[nodiscard]] stop_source 217 get_stop_source() noexcept 218 { 219 return _M_stop_source; 220 } 221 222 [[nodiscard]] stop_token 223 get_stop_token() const noexcept 224 { 225 return _M_stop_source.get_token(); 226 } 227 228 bool request_stop() noexcept 229 { 230 return _M_stop_source.request_stop(); 231 } 232 233 friend void swap(jthread& __lhs, jthread& __rhs) noexcept 234 { 235 __lhs.swap(__rhs); 236 } 237 238 private: 239 template<typename _Callable, typename... _Args> 240 static thread 241 _S_create(stop_source& __ssrc, _Callable&& __f, _Args&&... __args) 242 { 243#ifndef __STRICT_ANSI__ 244 if constexpr (__pmf_expects_stop_token<_Callable, _Args...>) 245 return _S_create_pmf(__ssrc, __f, std::forward<_Args>(__args)...); 246 else 247#endif 248 if constexpr(is_invocable_v<decay_t<_Callable>, stop_token, 249 decay_t<_Args>...>) 250 return thread{std::forward<_Callable>(__f), __ssrc.get_token(), 251 std::forward<_Args>(__args)...}; 252 else 253 { 254 static_assert(is_invocable_v<decay_t<_Callable>, 255 decay_t<_Args>...>, 256 "std::jthread arguments must be invocable after" 257 " conversion to rvalues"); 258 return thread{std::forward<_Callable>(__f), 259 std::forward<_Args>(__args)...}; 260 } 261 } 262 263#ifndef __STRICT_ANSI__ 264 template<typename _Callable, typename _Obj, typename... _Args> 265 static thread 266 _S_create_pmf(stop_source& __ssrc, _Callable __f, _Obj&& __obj, 267 _Args&&... __args) 268 { 269 return thread{__f, std::forward<_Obj>(__obj), __ssrc.get_token(), 270 std::forward<_Args>(__args)...}; 271 } 272#endif 273 274 stop_source _M_stop_source; 275 thread _M_thread; 276 }; 277#endif // __cpp_lib_jthread 278 279 /// @} group threads 280 281_GLIBCXX_END_NAMESPACE_VERSION 282} // namespace 283#endif // C++11 284#endif // _GLIBCXX_THREAD 285