1// <thread> -*- C++ -*-
2
3// Copyright (C) 2008-2018 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#include <chrono>
39#include <memory>
40#include <tuple>
41#include <cerrno>
42#include <bits/functexcept.h>
43#include <bits/functional_hash.h>
44#include <bits/invoke.h>
45#include <bits/gthr.h>
46
47#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
48
49namespace std _GLIBCXX_VISIBILITY(default)
50{
51_GLIBCXX_BEGIN_NAMESPACE_VERSION
52
53 /**
54 * @defgroup threads Threads
55 * @ingroup concurrency
56 *
57 * Classes for thread support.
58 * @{
59 */
60
61 /// thread
62 class thread
63 {
64 public:
65 // Abstract base class for types that wrap arbitrary functors to be
66 // invoked in the new thread of execution.
67 struct _State
68 {
69 virtual ~_State();
70 virtual void _M_run() = 0;
71 };
72 using _State_ptr = unique_ptr<_State>;
73
74 typedef __gthread_t native_handle_type;
75
76 /// thread::id
77 class id
78 {
79 native_handle_type _M_thread;
80
81 public:
82 id() noexcept : _M_thread() { }
83
84 explicit
85 id(native_handle_type __id) : _M_thread(__id) { }
86
87 private:
88 friend class thread;
89 friend class hash<thread::id>;
90
91 friend bool
92 operator==(thread::id __x, thread::id __y) noexcept;
93
94 friend bool
95 operator<(thread::id __x, thread::id __y) noexcept;
96
97 template<class _CharT, class _Traits>
98 friend basic_ostream<_CharT, _Traits>&
99 operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id);
100 };
101
102 private:
103 id _M_id;
104
105 // _GLIBCXX_RESOLVE_LIB_DEFECTS
106 // 2097. packaged_task constructors should be constrained
107 template<typename _Tp>
108 using __not_same = __not_<is_same<
109 typename remove_cv<typename remove_reference<_Tp>::type>::type,
110 thread>>;
111
112 public:
113 thread() noexcept = default;
114
115 template<typename _Callable, typename... _Args,
116 typename = _Require<__not_same<_Callable>>>
117 explicit
118 thread(_Callable&& __f, _Args&&... __args)
119 {
120 static_assert( __is_invocable<typename decay<_Callable>::type,
121 typename decay<_Args>::type...>::value,
122 "std::thread arguments must be invocable after conversion to rvalues"
123 );
124
125#ifdef GTHR_ACTIVE_PROXY
126 // Create a reference to pthread_create, not just the gthr weak symbol.
127 auto __depend = reinterpret_cast<void(*)()>(&pthread_create);
128#else
129 auto __depend = nullptr;
130#endif
131 _M_start_thread(_S_make_state(
132 __make_invoker(std::forward<_Callable>(__f),
133 std::forward<_Args>(__args)...)),
134 __depend);
135 }
136
137 ~thread()
138 {
139 if (joinable())
140 std::terminate();
141 }
142
143 thread(const thread&) = delete;
144
145 thread(thread&& __t) noexcept
146 { swap(__t); }
147
148 thread& operator=(const thread&) = delete;
149
150 thread& operator=(thread&& __t) noexcept
151 {
152 if (joinable())
153 std::terminate();
154 swap(__t);
155 return *this;
156 }
157
158 void
159 swap(thread& __t) noexcept
160 { std::swap(_M_id, __t._M_id); }
161
162 bool
163 joinable() const noexcept
164 { return !(_M_id == id()); }
165
166 void
167 join();
168
169 void
170 detach();
171
172 thread::id
173 get_id() const noexcept
174 { return _M_id; }
175
176 /** @pre thread is joinable
177 */
178 native_handle_type
179 native_handle()
180 { return _M_id._M_thread; }
181
182 // Returns a value that hints at the number of hardware thread contexts.
183 static unsigned int
184 hardware_concurrency() noexcept;
185
186 private:
187 template<typename _Callable>
188 struct _State_impl : public _State
189 {
190 _Callable _M_func;
191
192 _State_impl(_Callable&& __f) : _M_func(std::forward<_Callable>(__f))
193 { }
194
195 void
196 _M_run() { _M_func(); }
197 };
198
199 void
200 _M_start_thread(_State_ptr, void (*)());
201
202 template<typename _Callable>
203 static _State_ptr
204 _S_make_state(_Callable&& __f)
205 {
206 using _Impl = _State_impl<_Callable>;
207 return _State_ptr{new _Impl{std::forward<_Callable>(__f)}};
208 }
209#if _GLIBCXX_THREAD_ABI_COMPAT
210 public:
211 struct _Impl_base;
212 typedef shared_ptr<_Impl_base> __shared_base_type;
213 struct _Impl_base
214 {
215 __shared_base_type _M_this_ptr;
216 virtual ~_Impl_base() = default;
217 virtual void _M_run() = 0;
218 };
219
220 private:
221 void
222 _M_start_thread(__shared_base_type, void (*)());
223
224 void
225 _M_start_thread(__shared_base_type);
226#endif
227
228 private:
229 // A call wrapper that does INVOKE(forwarded tuple elements...)
230 template<typename _Tuple>
231 struct _Invoker
232 {
233 _Tuple _M_t;
234
235 template<size_t _Index>
236 static __tuple_element_t<_Index, _Tuple>&&
237 _S_declval();
238
239 template<size_t... _Ind>
240 auto
241 _M_invoke(_Index_tuple<_Ind...>)
242 noexcept(noexcept(std::__invoke(_S_declval<_Ind>()...)))
243 -> decltype(std::__invoke(_S_declval<_Ind>()...))
244 { return std::__invoke(std::get<_Ind>(std::move(_M_t))...); }
245
246 using _Indices
247 = typename _Build_index_tuple<tuple_size<_Tuple>::value>::__type;
248
249 auto
250 operator()()
251 noexcept(noexcept(std::declval<_Invoker&>()._M_invoke(_Indices())))
252 -> decltype(std::declval<_Invoker&>()._M_invoke(_Indices()))
253 { return _M_invoke(_Indices()); }
254 };
255
256 template<typename... _Tp>
257 using __decayed_tuple = tuple<typename std::decay<_Tp>::type...>;
258
259 public:
260 // Returns a call wrapper that stores
261 // tuple{DECAY_COPY(__callable), DECAY_COPY(__args)...}.
262 template<typename _Callable, typename... _Args>
263 static _Invoker<__decayed_tuple<_Callable, _Args...>>
264 __make_invoker(_Callable&& __callable, _Args&&... __args)
265 {
266 return { __decayed_tuple<_Callable, _Args...>{
267 std::forward<_Callable>(__callable), std::forward<_Args>(__args)...
268 } };
269 }
270 };
271
272 inline void
273 swap(thread& __x, thread& __y) noexcept
274 { __x.swap(__y); }
275
276 inline bool
277 operator==(thread::id __x, thread::id __y) noexcept
278 {
279 // pthread_equal is undefined if either thread ID is not valid, so we
280 // can't safely use __gthread_equal on default-constructed values (nor
281 // the non-zero value returned by this_thread::get_id() for
282 // single-threaded programs using GNU libc). Assume EqualityComparable.
283 return __x._M_thread == __y._M_thread;
284 }
285
286 inline bool
287 operator!=(thread::id __x, thread::id __y) noexcept
288 { return !(__x == __y); }
289
290 inline bool
291 operator<(thread::id __x, thread::id __y) noexcept
292 {
293 // Pthreads doesn't define any way to do this, so we just have to
294 // assume native_handle_type is LessThanComparable.
295 return __x._M_thread < __y._M_thread;
296 }
297
298 inline bool
299 operator<=(thread::id __x, thread::id __y) noexcept
300 { return !(__y < __x); }
301
302 inline bool
303 operator>(thread::id __x, thread::id __y) noexcept
304 { return __y < __x; }
305
306 inline bool
307 operator>=(thread::id __x, thread::id __y) noexcept
308 { return !(__x < __y); }
309
310 // DR 889.
311 /// std::hash specialization for thread::id.
312 template<>
313 struct hash<thread::id>
314 : public __hash_base<size_t, thread::id>
315 {
316 size_t
317 operator()(const thread::id& __id) const noexcept
318 { return std::_Hash_impl::hash(__id._M_thread); }
319 };
320
321 template<class _CharT, class _Traits>
322 inline basic_ostream<_CharT, _Traits>&
323 operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
324 {
325 if (__id == thread::id())
326 return __out << "thread::id of a non-executing thread";
327 else
328 return __out << __id._M_thread;
329 }
330
331 /** @namespace std::this_thread
332 * @brief ISO C++ 2011 entities sub-namespace for thread.
333 * 30.3.2 Namespace this_thread.
334 */
335 namespace this_thread
336 {
337 /// get_id
338 inline thread::id
339 get_id() noexcept
340 {
341#ifdef __GLIBC__
342 // For the GNU C library pthread_self() is usable without linking to
343 // libpthread.so but returns 0, so we cannot use it in single-threaded
344 // programs, because this_thread::get_id() != thread::id{} must be true.
345 // We know that pthread_t is an integral type in the GNU C library.
346 if (!__gthread_active_p())
347 return thread::id(1);
348#endif
349 return thread::id(__gthread_self());
350 }
351
352 /// yield
353 inline void
354 yield() noexcept
355 {
356#ifdef _GLIBCXX_USE_SCHED_YIELD
357 __gthread_yield();
358#endif
359 }
360
361 void
362 __sleep_for(chrono::seconds, chrono::nanoseconds);
363
364 /// sleep_for
365 template<typename _Rep, typename _Period>
366 inline void
367 sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
368 {
369 if (__rtime <= __rtime.zero())
370 return;
371 auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
372 auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
373#ifdef _GLIBCXX_USE_NANOSLEEP
374 __gthread_time_t __ts =
375 {
376 static_cast<std::time_t>(__s.count()),
377 static_cast<long>(__ns.count())
378 };
379 while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
380 { }
381#else
382 __sleep_for(__s, __ns);
383#endif
384 }
385
386 /// sleep_until
387 template<typename _Clock, typename _Duration>
388 inline void
389 sleep_until(const chrono::time_point<_Clock, _Duration>& __atime)
390 {
391 auto __now = _Clock::now();
392 if (_Clock::is_steady)
393 {
394 if (__now < __atime)
395 sleep_for(__atime - __now);
396 return;
397 }
398 while (__now < __atime)
399 {
400 sleep_for(__atime - __now);
401 __now = _Clock::now();
402 }
403 }
404 }
405
406 // @} group threads
407
408_GLIBCXX_END_NAMESPACE_VERSION
409} // namespace
410
411#endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
412
413#endif // C++11
414
415#endif // _GLIBCXX_THREAD
416