1// <thread> -*- C++ -*-
2
3// Copyright (C) 2008-2017 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 public:
106 thread() noexcept = default;
107 // _GLIBCXX_RESOLVE_LIB_DEFECTS
108 // 2097. packaged_task constructors should be constrained
109 thread(thread&) = delete;
110 thread(const thread&) = delete;
111 thread(const thread&&) = delete;
112
113 thread(thread&& __t) noexcept
114 { swap(__t); }
115
116 template<typename _Callable, typename... _Args>
117 explicit
118 thread(_Callable&& __f, _Args&&... __args)
119 {
120#ifdef GTHR_ACTIVE_PROXY
121 // Create a reference to pthread_create, not just the gthr weak symbol.
122 auto __depend = reinterpret_cast<void(*)()>(&pthread_create);
123#else
124 auto __depend = nullptr;
125#endif
126 _M_start_thread(_S_make_state(
127 __make_invoker(std::forward<_Callable>(__f),
128 std::forward<_Args>(__args)...)),
129 __depend);
130 }
131
132 ~thread()
133 {
134 if (joinable())
135 std::terminate();
136 }
137
138 thread& operator=(const thread&) = delete;
139
140 thread& operator=(thread&& __t) noexcept
141 {
142 if (joinable())
143 std::terminate();
144 swap(__t);
145 return *this;
146 }
147
148 void
149 swap(thread& __t) noexcept
150 { std::swap(_M_id, __t._M_id); }
151
152 bool
153 joinable() const noexcept
154 { return !(_M_id == id()); }
155
156 void
157 join();
158
159 void
160 detach();
161
162 thread::id
163 get_id() const noexcept
164 { return _M_id; }
165
166 /** @pre thread is joinable
167 */
168 native_handle_type
169 native_handle()
170 { return _M_id._M_thread; }
171
172 // Returns a value that hints at the number of hardware thread contexts.
173 static unsigned int
174 hardware_concurrency() noexcept;
175
176 private:
177 template<typename _Callable>
178 struct _State_impl : public _State
179 {
180 _Callable _M_func;
181
182 _State_impl(_Callable&& __f) : _M_func(std::forward<_Callable>(__f))
183 { }
184
185 void
186 _M_run() { _M_func(); }
187 };
188
189 void
190 _M_start_thread(_State_ptr, void (*)());
191
192 template<typename _Callable>
193 static _State_ptr
194 _S_make_state(_Callable&& __f)
195 {
196 using _Impl = _State_impl<_Callable>;
197 return _State_ptr{new _Impl{std::forward<_Callable>(__f)}};
198 }
199#if _GLIBCXX_THREAD_ABI_COMPAT
200 public:
201 struct _Impl_base;
202 typedef shared_ptr<_Impl_base> __shared_base_type;
203 struct _Impl_base
204 {
205 __shared_base_type _M_this_ptr;
206 virtual ~_Impl_base() = default;
207 virtual void _M_run() = 0;
208 };
209
210 private:
211 void
212 _M_start_thread(__shared_base_type, void (*)());
213
214 void
215 _M_start_thread(__shared_base_type);
216#endif
217
218 private:
219 // A call wrapper that does INVOKE(forwarded tuple elements...)
220 template<typename _Tuple>
221 struct _Invoker
222 {
223 _Tuple _M_t;
224
225 template<size_t _Index>
226 static __tuple_element_t<_Index, _Tuple>&&
227 _S_declval();
228
229 template<size_t... _Ind>
230 auto
231 _M_invoke(_Index_tuple<_Ind...>)
232 noexcept(noexcept(std::__invoke(_S_declval<_Ind>()...)))
233 -> decltype(std::__invoke(_S_declval<_Ind>()...))
234 { return std::__invoke(std::get<_Ind>(std::move(_M_t))...); }
235
236 using _Indices
237 = typename _Build_index_tuple<tuple_size<_Tuple>::value>::__type;
238
239 auto
240 operator()()
241 noexcept(noexcept(std::declval<_Invoker&>()._M_invoke(_Indices())))
242 -> decltype(std::declval<_Invoker&>()._M_invoke(_Indices()))
243 { return _M_invoke(_Indices()); }
244 };
245
246 // Alias for _Invoker<tuple<DECAY_COPY(_Tp)...>>
247 template<typename... _Tp>
248 using __invoker_type
249 = _Invoker<decltype(std::make_tuple(std::declval<_Tp>()...))>;
250
251 public:
252 // Returns a call wrapper that does
253 // INVOKE(DECAY_COPY(__callable), DECAY_COPY(__args)).
254 template<typename _Callable, typename... _Args>
255 static __invoker_type<_Callable, _Args...>
256 __make_invoker(_Callable&& __callable, _Args&&... __args)
257 {
258 return { {
259 std::make_tuple(std::forward<_Callable>(__callable),
260 std::forward<_Args>(__args)...)
261 } };
262 }
263 };
264
265 inline void
266 swap(thread& __x, thread& __y) noexcept
267 { __x.swap(__y); }
268
269 inline bool
270 operator==(thread::id __x, thread::id __y) noexcept
271 {
272 // pthread_equal is undefined if either thread ID is not valid, so we
273 // can't safely use __gthread_equal on default-constructed values (nor
274 // the non-zero value returned by this_thread::get_id() for
275 // single-threaded programs using GNU libc). Assume EqualityComparable.
276 return __x._M_thread == __y._M_thread;
277 }
278
279 inline bool
280 operator!=(thread::id __x, thread::id __y) noexcept
281 { return !(__x == __y); }
282
283 inline bool
284 operator<(thread::id __x, thread::id __y) noexcept
285 {
286 // Pthreads doesn't define any way to do this, so we just have to
287 // assume native_handle_type is LessThanComparable.
288 return __x._M_thread < __y._M_thread;
289 }
290
291 inline bool
292 operator<=(thread::id __x, thread::id __y) noexcept
293 { return !(__y < __x); }
294
295 inline bool
296 operator>(thread::id __x, thread::id __y) noexcept
297 { return __y < __x; }
298
299 inline bool
300 operator>=(thread::id __x, thread::id __y) noexcept
301 { return !(__x < __y); }
302
303 // DR 889.
304 /// std::hash specialization for thread::id.
305 template<>
306 struct hash<thread::id>
307 : public __hash_base<size_t, thread::id>
308 {
309 size_t
310 operator()(const thread::id& __id) const noexcept
311 { return std::_Hash_impl::hash(__id._M_thread); }
312 };
313
314 template<class _CharT, class _Traits>
315 inline basic_ostream<_CharT, _Traits>&
316 operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
317 {
318 if (__id == thread::id())
319 return __out << "thread::id of a non-executing thread";
320 else
321 return __out << __id._M_thread;
322 }
323
324 /** @namespace std::this_thread
325 * @brief ISO C++ 2011 entities sub-namespace for thread.
326 * 30.3.2 Namespace this_thread.
327 */
328 namespace this_thread
329 {
330 /// get_id
331 inline thread::id
332 get_id() noexcept
333 {
334#ifdef __GLIBC__
335 // For the GNU C library pthread_self() is usable without linking to
336 // libpthread.so but returns 0, so we cannot use it in single-threaded
337 // programs, because this_thread::get_id() != thread::id{} must be true.
338 // We know that pthread_t is an integral type in the GNU C library.
339 if (!__gthread_active_p())
340 return thread::id(1);
341#endif
342 return thread::id(__gthread_self());
343 }
344
345 /// yield
346 inline void
347 yield() noexcept
348 {
349#ifdef _GLIBCXX_USE_SCHED_YIELD
350 __gthread_yield();
351#endif
352 }
353
354 void
355 __sleep_for(chrono::seconds, chrono::nanoseconds);
356
357 /// sleep_for
358 template<typename _Rep, typename _Period>
359 inline void
360 sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
361 {
362 if (__rtime <= __rtime.zero())
363 return;
364 auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
365 auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
366#ifdef _GLIBCXX_USE_NANOSLEEP
367 __gthread_time_t __ts =
368 {
369 static_cast<std::time_t>(__s.count()),
370 static_cast<long>(__ns.count())
371 };
372 while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
373 { }
374#else
375 __sleep_for(__s, __ns);
376#endif
377 }
378
379 /// sleep_until
380 template<typename _Clock, typename _Duration>
381 inline void
382 sleep_until(const chrono::time_point<_Clock, _Duration>& __atime)
383 {
384 auto __now = _Clock::now();
385 if (_Clock::is_steady)
386 {
387 if (__now < __atime)
388 sleep_for(__atime - __now);
389 return;
390 }
391 while (__now < __atime)
392 {
393 sleep_for(__atime - __now);
394 __now = _Clock::now();
395 }
396 }
397 }
398
399 // @} group threads
400
401_GLIBCXX_END_NAMESPACE_VERSION
402} // namespace
403
404#endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
405
406#endif // C++11
407
408#endif // _GLIBCXX_THREAD
409