3// Copyright (C) 2008-2024 Free Software Foundation, Inc.
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)
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.
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.
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/>.
25/** @file include/thread
26 * This is a Standard C++ Library header.
29#ifndef _GLIBCXX_THREAD
30#define _GLIBCXX_THREAD 1
33#pragma GCC system_header
36#include <bits/requires_hosted.h> // concurrency
38#if __cplusplus < 201103L
39# include <bits/c++0x_warning.h>
42#if __cplusplus > 201703L
43# include <compare> // std::strong_ordering
44# include <stop_token> // std::stop_source, std::stop_token, std::nostopstate
47#include <bits/std_thread.h> // std::thread, get_id, yield
48#include <bits/this_thread_sleep.h> // std::this_thread::sleep_for, sleep_until
50#define __glibcxx_want_jthread
51#define __glibcxx_want_formatters
52#include <bits/version.h>
54#if __cpp_lib_formatters
58namespace std _GLIBCXX_VISIBILITY(default)
60_GLIBCXX_BEGIN_NAMESPACE_VERSION
63 * @defgroup threads Threads
64 * @ingroup concurrency
67 * Classes for thread support.
71 // std::thread is defined in <bits/std_thread.h>
73 /// @relates std::thread::id @{
75#if __cpp_lib_three_way_comparison
76 inline strong_ordering
77 operator<=>(thread::id __x, thread::id __y) noexcept
78 { return __x._M_thread <=> __y._M_thread; }
81 operator!=(thread::id __x, thread::id __y) noexcept
82 { return !(__x == __y); }
85 operator<(thread::id __x, thread::id __y) noexcept
87 // Pthreads doesn't define any way to do this, so we just have to
88 // assume native_handle_type is LessThanComparable.
89 return __x._M_thread < __y._M_thread;
93 operator<=(thread::id __x, thread::id __y) noexcept
94 { return !(__y < __x); }
97 operator>(thread::id __x, thread::id __y) noexcept
101 operator>=(thread::id __x, thread::id __y) noexcept
102 { return !(__x < __y); }
103#endif // __cpp_lib_three_way_comparison
105 template<class _CharT, class _Traits>
106 inline basic_ostream<_CharT, _Traits>&
107 operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
109 // Convert non-void pointers to const void* for formatted output.
111 = __conditional_t<is_pointer<thread::native_handle_type>::value,
113 thread::native_handle_type>;
115 if (__id == thread::id())
116 return __out << "thread::id of a non-executing thread";
118 return __out << static_cast<__output_type>(__id._M_thread);
122#ifdef __cpp_lib_jthread // C++ >= 20
124 /// @cond undocumented
125#ifndef __STRICT_ANSI__
126 template<typename _Callable, typename... _Args>
127 constexpr bool __pmf_expects_stop_token = false;
129 template<typename _Callable, typename _Obj, typename... _Args>
130 constexpr bool __pmf_expects_stop_token<_Callable, _Obj, _Args...>
131 = __and_<is_member_function_pointer<remove_reference_t<_Callable>>,
132 is_invocable<_Callable, _Obj, stop_token, _Args...>>::value;
136 /** A thread with cancellation and automatic joining.
138 * Unlike `std::thread`, destroying a joinable `std::jthread` will not
139 * terminate the process. Instead, it will try to request its thread to
140 * stop, then will join it.
142 * A `std::jthread` has a `std::stop_source` member which will be passed
143 * as the first argument to the callable that runs in the new thread
144 * (as long as the callable will accept that argument). That can then
145 * be used to send a stop request that the new thread can test for.
153 using id = thread::id;
154 using native_handle_type = thread::native_handle_type;
157 : _M_stop_source{nostopstate}
160 template<typename _Callable, typename... _Args,
161 typename = enable_if_t<!is_same_v<remove_cvref_t<_Callable>,
164 jthread(_Callable&& __f, _Args&&... __args)
165 : _M_thread{_S_create(_M_stop_source, std::forward<_Callable>(__f),
166 std::forward<_Args>(__args)...)}
169 jthread(const jthread&) = delete;
170 jthread(jthread&&) noexcept = default;
182 operator=(const jthread&) = delete;
185 operator=(jthread&& __other) noexcept
187 std::jthread(std::move(__other)).swap(*this);
192 swap(jthread& __other) noexcept
194 std::swap(_M_stop_source, __other._M_stop_source);
195 std::swap(_M_thread, __other._M_thread);
199 joinable() const noexcept
201 return _M_thread.joinable();
217 get_id() const noexcept
219 return _M_thread.get_id();
222 [[nodiscard]] native_handle_type
225 return _M_thread.native_handle();
228 [[nodiscard]] static unsigned
229 hardware_concurrency() noexcept
231 return thread::hardware_concurrency();
234 [[nodiscard]] stop_source
235 get_stop_source() noexcept
237 return _M_stop_source;
240 [[nodiscard]] stop_token
241 get_stop_token() const noexcept
243 return _M_stop_source.get_token();
246 bool request_stop() noexcept
248 return _M_stop_source.request_stop();
251 friend void swap(jthread& __lhs, jthread& __rhs) noexcept
257 template<typename _Callable, typename... _Args>
259 _S_create(stop_source& __ssrc, _Callable&& __f, _Args&&... __args)
261#ifndef __STRICT_ANSI__
262 if constexpr (__pmf_expects_stop_token<_Callable, _Args...>)
263 return _S_create_pmf(__ssrc, __f, std::forward<_Args>(__args)...);
266 if constexpr(is_invocable_v<decay_t<_Callable>, stop_token,
268 return thread{std::forward<_Callable>(__f), __ssrc.get_token(),
269 std::forward<_Args>(__args)...};
272 static_assert(is_invocable_v<decay_t<_Callable>,
274 "std::jthread arguments must be invocable after"
275 " conversion to rvalues");
276 return thread{std::forward<_Callable>(__f),
277 std::forward<_Args>(__args)...};
281#ifndef __STRICT_ANSI__
282 template<typename _Callable, typename _Obj, typename... _Args>
284 _S_create_pmf(stop_source& __ssrc, _Callable __f, _Obj&& __obj,
287 return thread{__f, std::forward<_Obj>(__obj), __ssrc.get_token(),
288 std::forward<_Args>(__args)...};
292 stop_source _M_stop_source;
295#endif // __cpp_lib_jthread
297#ifdef __cpp_lib_formatters // C++ >= 23
298 template<typename _CharT>
299 requires is_pointer_v<thread::native_handle_type>
300 || is_integral_v<thread::native_handle_type>
301 class formatter<thread::id, _CharT>
304 constexpr typename basic_format_parse_context<_CharT>::iterator
305 parse(basic_format_parse_context<_CharT>& __pc)
307 __format::_Spec<_CharT> __spec{};
308 const auto __last = __pc.end();
309 auto __first = __pc.begin();
311 auto __finalize = [this, &__spec] {
315 auto __finished = [&] {
316 if (__first == __last || *__first == '}')
327 __first = __spec._M_parse_fill_and_align(__first, __last);
331 __first = __spec._M_parse_width(__first, __last, __pc);
335 __throw_format_error("format error: invalid format-spec for "
339 template<typename _Out>
340 typename basic_format_context<_Out, _CharT>::iterator
341 format(thread::id __id, basic_format_context<_Out, _CharT>& __fc) const
343 basic_string_view<_CharT> __sv;
344 if constexpr (is_same_v<_CharT, char>)
345 __sv = "{}thread::id of a non-executing thread";
347 __sv = L"{}thread::id of a non-executing thread";
348 basic_string<_CharT> __str;
349 if (__id == thread::id())
350 __sv.remove_prefix(2);
353 using _FmtStr = __format::_Runtime_format_string<_CharT>;
354 // Convert non-void pointers to const void* for formatted output.
356 = __conditional_t<is_pointer_v<thread::native_handle_type>,
358 thread::native_handle_type>;
359 auto __o = static_cast<__output_type>(__id._M_thread);
360 __sv = __str = std::format(_FmtStr(__sv.substr(0, 2)), __o);
362 return __format::__write_padded_as_spec(__sv, __sv.size(),
364 __format::_Align_right);
368 __format::_Spec<_CharT> _M_spec;
370#endif // __cpp_lib_formatters
374_GLIBCXX_END_NAMESPACE_VERSION
377#endif // _GLIBCXX_THREAD