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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 :
49 : namespace 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 : template<typename... _Tp>
247 : using __decayed_tuple = tuple<typename std::decay<_Tp>::type...>;
248 :
249 : public:
250 : // Returns a call wrapper that stores
251 : // tuple{DECAY_COPY(__callable), DECAY_COPY(__args)...}.
252 : template<typename _Callable, typename... _Args>
253 : static _Invoker<__decayed_tuple<_Callable, _Args...>>
254 : __make_invoker(_Callable&& __callable, _Args&&... __args)
255 : {
256 : return { __decayed_tuple<_Callable, _Args...>{
257 : std::forward<_Callable>(__callable), std::forward<_Args>(__args)...
258 : } };
259 : }
260 : };
261 :
262 : inline void
263 : swap(thread& __x, thread& __y) noexcept
264 : { __x.swap(__y); }
265 :
266 : inline bool
267 : operator==(thread::id __x, thread::id __y) noexcept
268 : {
269 : // pthread_equal is undefined if either thread ID is not valid, so we
270 : // can't safely use __gthread_equal on default-constructed values (nor
271 : // the non-zero value returned by this_thread::get_id() for
272 : // single-threaded programs using GNU libc). Assume EqualityComparable.
273 : return __x._M_thread == __y._M_thread;
274 : }
275 :
276 : inline bool
277 : operator!=(thread::id __x, thread::id __y) noexcept
278 : { return !(__x == __y); }
279 :
280 : inline bool
281 : operator<(thread::id __x, thread::id __y) noexcept
282 : {
283 : // Pthreads doesn't define any way to do this, so we just have to
284 : // assume native_handle_type is LessThanComparable.
285 : return __x._M_thread < __y._M_thread;
286 : }
287 :
288 : inline bool
289 : operator<=(thread::id __x, thread::id __y) noexcept
290 : { return !(__y < __x); }
291 :
292 : inline bool
293 : operator>(thread::id __x, thread::id __y) noexcept
294 : { return __y < __x; }
295 :
296 : inline bool
297 : operator>=(thread::id __x, thread::id __y) noexcept
298 : { return !(__x < __y); }
299 :
300 : // DR 889.
301 : /// std::hash specialization for thread::id.
302 : template<>
303 : struct hash<thread::id>
304 : : public __hash_base<size_t, thread::id>
305 : {
306 : size_t
307 : operator()(const thread::id& __id) const noexcept
308 : { return std::_Hash_impl::hash(__id._M_thread); }
309 : };
310 :
311 : template<class _CharT, class _Traits>
312 : inline basic_ostream<_CharT, _Traits>&
313 : operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
314 : {
315 : if (__id == thread::id())
316 : return __out << "thread::id of a non-executing thread";
317 : else
318 : return __out << __id._M_thread;
319 : }
320 :
321 : _GLIBCXX_END_NAMESPACE_VERSION
322 :
323 : /** @namespace std::this_thread
324 : * @brief ISO C++ 2011 entities sub-namespace for thread.
325 : * 30.3.2 Namespace this_thread.
326 : */
327 : namespace this_thread
328 : {
329 : _GLIBCXX_BEGIN_NAMESPACE_VERSION
330 :
331 : /// get_id
332 : inline thread::id
333 : get_id() noexcept
334 : {
335 : #ifdef __GLIBC__
336 : // For the GNU C library pthread_self() is usable without linking to
337 : // libpthread.so but returns 0, so we cannot use it in single-threaded
338 : // programs, because this_thread::get_id() != thread::id{} must be true.
339 : // We know that pthread_t is an integral type in the GNU C library.
340 : if (!__gthread_active_p())
341 : return thread::id(1);
342 : #endif
343 : return thread::id(__gthread_self());
344 : }
345 :
346 : /// yield
347 : inline void
348 : yield() noexcept
349 : {
350 : #ifdef _GLIBCXX_USE_SCHED_YIELD
351 : __gthread_yield();
352 : #endif
353 : }
354 :
355 : void
356 : __sleep_for(chrono::seconds, chrono::nanoseconds);
357 :
358 : /// sleep_for
359 : template<typename _Rep, typename _Period>
360 : inline void
361 5 : sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
362 : {
363 5 : if (__rtime <= __rtime.zero())
364 0 : return;
365 5 : auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
366 5 : auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
367 : #ifdef _GLIBCXX_USE_NANOSLEEP
368 10 : __gthread_time_t __ts =
369 : {
370 5 : static_cast<std::time_t>(__s.count()),
371 5 : static_cast<long>(__ns.count())
372 : };
373 5 : while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
374 : { }
375 : #else
376 : __sleep_for(__s, __ns);
377 : #endif
378 : }
379 :
380 : /// sleep_until
381 : template<typename _Clock, typename _Duration>
382 : inline void
383 : sleep_until(const chrono::time_point<_Clock, _Duration>& __atime)
384 : {
385 : auto __now = _Clock::now();
386 : if (_Clock::is_steady)
387 : {
388 : if (__now < __atime)
389 : sleep_for(__atime - __now);
390 : return;
391 : }
392 : while (__now < __atime)
393 : {
394 : sleep_for(__atime - __now);
395 : __now = _Clock::now();
396 : }
397 : }
398 :
399 : _GLIBCXX_END_NAMESPACE_VERSION
400 : }
401 :
402 : // @} group threads
403 :
404 : } // namespace
405 :
406 : #endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
407 :
408 : #endif // C++11
409 :
410 : #endif // _GLIBCXX_THREAD
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