libstdc++
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00001 // <thread> -*- C++ -*- 00002 00003 // Copyright (C) 2008-2018 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 3, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // Under Section 7 of GPL version 3, you are granted additional 00017 // permissions described in the GCC Runtime Library Exception, version 00018 // 3.1, as published by the Free Software Foundation. 00019 00020 // You should have received a copy of the GNU General Public License and 00021 // a copy of the GCC Runtime Library Exception along with this program; 00022 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00023 // <http://www.gnu.org/licenses/>. 00024 00025 /** @file include/thread 00026 * This is a Standard C++ Library header. 00027 */ 00028 00029 #ifndef _GLIBCXX_THREAD 00030 #define _GLIBCXX_THREAD 1 00031 00032 #pragma GCC system_header 00033 00034 #if __cplusplus < 201103L 00035 # include <bits/c++0x_warning.h> 00036 #else 00037 00038 #include <chrono> 00039 #include <memory> 00040 #include <tuple> 00041 #include <cerrno> 00042 #include <bits/functexcept.h> 00043 #include <bits/functional_hash.h> 00044 #include <bits/invoke.h> 00045 #include <bits/gthr.h> 00046 00047 #if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1) 00048 00049 namespace std _GLIBCXX_VISIBILITY(default) 00050 { 00051 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00052 00053 /** 00054 * @defgroup threads Threads 00055 * @ingroup concurrency 00056 * 00057 * Classes for thread support. 00058 * @{ 00059 */ 00060 00061 /// thread 00062 class thread 00063 { 00064 public: 00065 // Abstract base class for types that wrap arbitrary functors to be 00066 // invoked in the new thread of execution. 00067 struct _State 00068 { 00069 virtual ~_State(); 00070 virtual void _M_run() = 0; 00071 }; 00072 using _State_ptr = unique_ptr<_State>; 00073 00074 typedef __gthread_t native_handle_type; 00075 00076 /// thread::id 00077 class id 00078 { 00079 native_handle_type _M_thread; 00080 00081 public: 00082 id() noexcept : _M_thread() { } 00083 00084 explicit 00085 id(native_handle_type __id) : _M_thread(__id) { } 00086 00087 private: 00088 friend class thread; 00089 friend class hash<thread::id>; 00090 00091 friend bool 00092 operator==(thread::id __x, thread::id __y) noexcept; 00093 00094 friend bool 00095 operator<(thread::id __x, thread::id __y) noexcept; 00096 00097 template<class _CharT, class _Traits> 00098 friend basic_ostream<_CharT, _Traits>& 00099 operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id); 00100 }; 00101 00102 private: 00103 id _M_id; 00104 00105 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00106 // 2097. packaged_task constructors should be constrained 00107 template<typename _Tp> 00108 using __not_same = __not_<is_same< 00109 typename remove_cv<typename remove_reference<_Tp>::type>::type, 00110 thread>>; 00111 00112 public: 00113 thread() noexcept = default; 00114 00115 template<typename _Callable, typename... _Args, 00116 typename = _Require<__not_same<_Callable>>> 00117 explicit 00118 thread(_Callable&& __f, _Args&&... __args) 00119 { 00120 static_assert( __is_invocable<typename decay<_Callable>::type, 00121 typename decay<_Args>::type...>::value, 00122 "std::thread arguments must be invocable after conversion to rvalues" 00123 ); 00124 00125 #ifdef GTHR_ACTIVE_PROXY 00126 // Create a reference to pthread_create, not just the gthr weak symbol. 00127 auto __depend = reinterpret_cast<void(*)()>(&pthread_create); 00128 #else 00129 auto __depend = nullptr; 00130 #endif 00131 _M_start_thread(_S_make_state( 00132 __make_invoker(std::forward<_Callable>(__f), 00133 std::forward<_Args>(__args)...)), 00134 __depend); 00135 } 00136 00137 ~thread() 00138 { 00139 if (joinable()) 00140 std::terminate(); 00141 } 00142 00143 thread(const thread&) = delete; 00144 00145 thread(thread&& __t) noexcept 00146 { swap(__t); } 00147 00148 thread& operator=(const thread&) = delete; 00149 00150 thread& operator=(thread&& __t) noexcept 00151 { 00152 if (joinable()) 00153 std::terminate(); 00154 swap(__t); 00155 return *this; 00156 } 00157 00158 void 00159 swap(thread& __t) noexcept 00160 { std::swap(_M_id, __t._M_id); } 00161 00162 bool 00163 joinable() const noexcept 00164 { return !(_M_id == id()); } 00165 00166 void 00167 join(); 00168 00169 void 00170 detach(); 00171 00172 thread::id 00173 get_id() const noexcept 00174 { return _M_id; } 00175 00176 /** @pre thread is joinable 00177 */ 00178 native_handle_type 00179 native_handle() 00180 { return _M_id._M_thread; } 00181 00182 // Returns a value that hints at the number of hardware thread contexts. 00183 static unsigned int 00184 hardware_concurrency() noexcept; 00185 00186 private: 00187 template<typename _Callable> 00188 struct _State_impl : public _State 00189 { 00190 _Callable _M_func; 00191 00192 _State_impl(_Callable&& __f) : _M_func(std::forward<_Callable>(__f)) 00193 { } 00194 00195 void 00196 _M_run() { _M_func(); } 00197 }; 00198 00199 void 00200 _M_start_thread(_State_ptr, void (*)()); 00201 00202 template<typename _Callable> 00203 static _State_ptr 00204 _S_make_state(_Callable&& __f) 00205 { 00206 using _Impl = _State_impl<_Callable>; 00207 return _State_ptr{new _Impl{std::forward<_Callable>(__f)}}; 00208 } 00209 #if _GLIBCXX_THREAD_ABI_COMPAT 00210 public: 00211 struct _Impl_base; 00212 typedef shared_ptr<_Impl_base> __shared_base_type; 00213 struct _Impl_base 00214 { 00215 __shared_base_type _M_this_ptr; 00216 virtual ~_Impl_base() = default; 00217 virtual void _M_run() = 0; 00218 }; 00219 00220 private: 00221 void 00222 _M_start_thread(__shared_base_type, void (*)()); 00223 00224 void 00225 _M_start_thread(__shared_base_type); 00226 #endif 00227 00228 private: 00229 // A call wrapper that does INVOKE(forwarded tuple elements...) 00230 template<typename _Tuple> 00231 struct _Invoker 00232 { 00233 _Tuple _M_t; 00234 00235 template<size_t _Index> 00236 static __tuple_element_t<_Index, _Tuple>&& 00237 _S_declval(); 00238 00239 template<size_t... _Ind> 00240 auto 00241 _M_invoke(_Index_tuple<_Ind...>) 00242 noexcept(noexcept(std::__invoke(_S_declval<_Ind>()...))) 00243 -> decltype(std::__invoke(_S_declval<_Ind>()...)) 00244 { return std::__invoke(std::get<_Ind>(std::move(_M_t))...); } 00245 00246 using _Indices 00247 = typename _Build_index_tuple<tuple_size<_Tuple>::value>::__type; 00248 00249 auto 00250 operator()() 00251 noexcept(noexcept(std::declval<_Invoker&>()._M_invoke(_Indices()))) 00252 -> decltype(std::declval<_Invoker&>()._M_invoke(_Indices())) 00253 { return _M_invoke(_Indices()); } 00254 }; 00255 00256 template<typename... _Tp> 00257 using __decayed_tuple = tuple<typename std::decay<_Tp>::type...>; 00258 00259 public: 00260 // Returns a call wrapper that stores 00261 // tuple{DECAY_COPY(__callable), DECAY_COPY(__args)...}. 00262 template<typename _Callable, typename... _Args> 00263 static _Invoker<__decayed_tuple<_Callable, _Args...>> 00264 __make_invoker(_Callable&& __callable, _Args&&... __args) 00265 { 00266 return { __decayed_tuple<_Callable, _Args...>{ 00267 std::forward<_Callable>(__callable), std::forward<_Args>(__args)... 00268 } }; 00269 } 00270 }; 00271 00272 inline void 00273 swap(thread& __x, thread& __y) noexcept 00274 { __x.swap(__y); } 00275 00276 inline bool 00277 operator==(thread::id __x, thread::id __y) noexcept 00278 { 00279 // pthread_equal is undefined if either thread ID is not valid, so we 00280 // can't safely use __gthread_equal on default-constructed values (nor 00281 // the non-zero value returned by this_thread::get_id() for 00282 // single-threaded programs using GNU libc). Assume EqualityComparable. 00283 return __x._M_thread == __y._M_thread; 00284 } 00285 00286 inline bool 00287 operator!=(thread::id __x, thread::id __y) noexcept 00288 { return !(__x == __y); } 00289 00290 inline bool 00291 operator<(thread::id __x, thread::id __y) noexcept 00292 { 00293 // Pthreads doesn't define any way to do this, so we just have to 00294 // assume native_handle_type is LessThanComparable. 00295 return __x._M_thread < __y._M_thread; 00296 } 00297 00298 inline bool 00299 operator<=(thread::id __x, thread::id __y) noexcept 00300 { return !(__y < __x); } 00301 00302 inline bool 00303 operator>(thread::id __x, thread::id __y) noexcept 00304 { return __y < __x; } 00305 00306 inline bool 00307 operator>=(thread::id __x, thread::id __y) noexcept 00308 { return !(__x < __y); } 00309 00310 // DR 889. 00311 /// std::hash specialization for thread::id. 00312 template<> 00313 struct hash<thread::id> 00314 : public __hash_base<size_t, thread::id> 00315 { 00316 size_t 00317 operator()(const thread::id& __id) const noexcept 00318 { return std::_Hash_impl::hash(__id._M_thread); } 00319 }; 00320 00321 template<class _CharT, class _Traits> 00322 inline basic_ostream<_CharT, _Traits>& 00323 operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id) 00324 { 00325 if (__id == thread::id()) 00326 return __out << "thread::id of a non-executing thread"; 00327 else 00328 return __out << __id._M_thread; 00329 } 00330 00331 /** @namespace std::this_thread 00332 * @brief ISO C++ 2011 entities sub-namespace for thread. 00333 * 30.3.2 Namespace this_thread. 00334 */ 00335 namespace this_thread 00336 { 00337 /// get_id 00338 inline thread::id 00339 get_id() noexcept 00340 { 00341 #ifdef __GLIBC__ 00342 // For the GNU C library pthread_self() is usable without linking to 00343 // libpthread.so but returns 0, so we cannot use it in single-threaded 00344 // programs, because this_thread::get_id() != thread::id{} must be true. 00345 // We know that pthread_t is an integral type in the GNU C library. 00346 if (!__gthread_active_p()) 00347 return thread::id(1); 00348 #endif 00349 return thread::id(__gthread_self()); 00350 } 00351 00352 /// yield 00353 inline void 00354 yield() noexcept 00355 { 00356 #ifdef _GLIBCXX_USE_SCHED_YIELD 00357 __gthread_yield(); 00358 #endif 00359 } 00360 00361 void 00362 __sleep_for(chrono::seconds, chrono::nanoseconds); 00363 00364 /// sleep_for 00365 template<typename _Rep, typename _Period> 00366 inline void 00367 sleep_for(const chrono::duration<_Rep, _Period>& __rtime) 00368 { 00369 if (__rtime <= __rtime.zero()) 00370 return; 00371 auto __s = chrono::duration_cast<chrono::seconds>(__rtime); 00372 auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s); 00373 #ifdef _GLIBCXX_USE_NANOSLEEP 00374 __gthread_time_t __ts = 00375 { 00376 static_cast<std::time_t>(__s.count()), 00377 static_cast<long>(__ns.count()) 00378 }; 00379 while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR) 00380 { } 00381 #else 00382 __sleep_for(__s, __ns); 00383 #endif 00384 } 00385 00386 /// sleep_until 00387 template<typename _Clock, typename _Duration> 00388 inline void 00389 sleep_until(const chrono::time_point<_Clock, _Duration>& __atime) 00390 { 00391 auto __now = _Clock::now(); 00392 if (_Clock::is_steady) 00393 { 00394 if (__now < __atime) 00395 sleep_for(__atime - __now); 00396 return; 00397 } 00398 while (__now < __atime) 00399 { 00400 sleep_for(__atime - __now); 00401 __now = _Clock::now(); 00402 } 00403 } 00404 } 00405 00406 // @} group threads 00407 00408 _GLIBCXX_END_NAMESPACE_VERSION 00409 } // namespace 00410 00411 #endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1 00412 00413 #endif // C++11 00414 00415 #endif // _GLIBCXX_THREAD