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 public: 00106 thread() noexcept = default; 00107 // _GLIBCXX_RESOLVE_LIB_DEFECTS 00108 // 2097. packaged_task constructors should be constrained 00109 thread(thread&) = delete; 00110 thread(const thread&) = delete; 00111 thread(const thread&&) = delete; 00112 00113 thread(thread&& __t) noexcept 00114 { swap(__t); } 00115 00116 template<typename _Callable, typename... _Args> 00117 explicit 00118 thread(_Callable&& __f, _Args&&... __args) 00119 { 00120 #ifdef GTHR_ACTIVE_PROXY 00121 // Create a reference to pthread_create, not just the gthr weak symbol. 00122 auto __depend = reinterpret_cast<void(*)()>(&pthread_create); 00123 #else 00124 auto __depend = nullptr; 00125 #endif 00126 _M_start_thread(_S_make_state( 00127 __make_invoker(std::forward<_Callable>(__f), 00128 std::forward<_Args>(__args)...)), 00129 __depend); 00130 } 00131 00132 ~thread() 00133 { 00134 if (joinable()) 00135 std::terminate(); 00136 } 00137 00138 thread& operator=(const thread&) = delete; 00139 00140 thread& operator=(thread&& __t) noexcept 00141 { 00142 if (joinable()) 00143 std::terminate(); 00144 swap(__t); 00145 return *this; 00146 } 00147 00148 void 00149 swap(thread& __t) noexcept 00150 { std::swap(_M_id, __t._M_id); } 00151 00152 bool 00153 joinable() const noexcept 00154 { return !(_M_id == id()); } 00155 00156 void 00157 join(); 00158 00159 void 00160 detach(); 00161 00162 thread::id 00163 get_id() const noexcept 00164 { return _M_id; } 00165 00166 /** @pre thread is joinable 00167 */ 00168 native_handle_type 00169 native_handle() 00170 { return _M_id._M_thread; } 00171 00172 // Returns a value that hints at the number of hardware thread contexts. 00173 static unsigned int 00174 hardware_concurrency() noexcept; 00175 00176 private: 00177 template<typename _Callable> 00178 struct _State_impl : public _State 00179 { 00180 _Callable _M_func; 00181 00182 _State_impl(_Callable&& __f) : _M_func(std::forward<_Callable>(__f)) 00183 { } 00184 00185 void 00186 _M_run() { _M_func(); } 00187 }; 00188 00189 void 00190 _M_start_thread(_State_ptr, void (*)()); 00191 00192 template<typename _Callable> 00193 static _State_ptr 00194 _S_make_state(_Callable&& __f) 00195 { 00196 using _Impl = _State_impl<_Callable>; 00197 return _State_ptr{new _Impl{std::forward<_Callable>(__f)}}; 00198 } 00199 #if _GLIBCXX_THREAD_ABI_COMPAT 00200 public: 00201 struct _Impl_base; 00202 typedef shared_ptr<_Impl_base> __shared_base_type; 00203 struct _Impl_base 00204 { 00205 __shared_base_type _M_this_ptr; 00206 virtual ~_Impl_base() = default; 00207 virtual void _M_run() = 0; 00208 }; 00209 00210 private: 00211 void 00212 _M_start_thread(__shared_base_type, void (*)()); 00213 00214 void 00215 _M_start_thread(__shared_base_type); 00216 #endif 00217 00218 private: 00219 // A call wrapper that does INVOKE(forwarded tuple elements...) 00220 template<typename _Tuple> 00221 struct _Invoker 00222 { 00223 _Tuple _M_t; 00224 00225 template<size_t _Index> 00226 static __tuple_element_t<_Index, _Tuple>&& 00227 _S_declval(); 00228 00229 template<size_t... _Ind> 00230 auto 00231 _M_invoke(_Index_tuple<_Ind...>) 00232 noexcept(noexcept(std::__invoke(_S_declval<_Ind>()...))) 00233 -> decltype(std::__invoke(_S_declval<_Ind>()...)) 00234 { return std::__invoke(std::get<_Ind>(std::move(_M_t))...); } 00235 00236 using _Indices 00237 = typename _Build_index_tuple<tuple_size<_Tuple>::value>::__type; 00238 00239 auto 00240 operator()() 00241 noexcept(noexcept(std::declval<_Invoker&>()._M_invoke(_Indices()))) 00242 -> decltype(std::declval<_Invoker&>()._M_invoke(_Indices())) 00243 { return _M_invoke(_Indices()); } 00244 }; 00245 00246 template<typename... _Tp> 00247 using __decayed_tuple = tuple<typename std::decay<_Tp>::type...>; 00248 00249 public: 00250 // Returns a call wrapper that stores 00251 // tuple{DECAY_COPY(__callable), DECAY_COPY(__args)...}. 00252 template<typename _Callable, typename... _Args> 00253 static _Invoker<__decayed_tuple<_Callable, _Args...>> 00254 __make_invoker(_Callable&& __callable, _Args&&... __args) 00255 { 00256 return { __decayed_tuple<_Callable, _Args...>{ 00257 std::forward<_Callable>(__callable), std::forward<_Args>(__args)... 00258 } }; 00259 } 00260 }; 00261 00262 inline void 00263 swap(thread& __x, thread& __y) noexcept 00264 { __x.swap(__y); } 00265 00266 inline bool 00267 operator==(thread::id __x, thread::id __y) noexcept 00268 { 00269 // pthread_equal is undefined if either thread ID is not valid, so we 00270 // can't safely use __gthread_equal on default-constructed values (nor 00271 // the non-zero value returned by this_thread::get_id() for 00272 // single-threaded programs using GNU libc). Assume EqualityComparable. 00273 return __x._M_thread == __y._M_thread; 00274 } 00275 00276 inline bool 00277 operator!=(thread::id __x, thread::id __y) noexcept 00278 { return !(__x == __y); } 00279 00280 inline bool 00281 operator<(thread::id __x, thread::id __y) noexcept 00282 { 00283 // Pthreads doesn't define any way to do this, so we just have to 00284 // assume native_handle_type is LessThanComparable. 00285 return __x._M_thread < __y._M_thread; 00286 } 00287 00288 inline bool 00289 operator<=(thread::id __x, thread::id __y) noexcept 00290 { return !(__y < __x); } 00291 00292 inline bool 00293 operator>(thread::id __x, thread::id __y) noexcept 00294 { return __y < __x; } 00295 00296 inline bool 00297 operator>=(thread::id __x, thread::id __y) noexcept 00298 { return !(__x < __y); } 00299 00300 // DR 889. 00301 /// std::hash specialization for thread::id. 00302 template<> 00303 struct hash<thread::id> 00304 : public __hash_base<size_t, thread::id> 00305 { 00306 size_t 00307 operator()(const thread::id& __id) const noexcept 00308 { return std::_Hash_impl::hash(__id._M_thread); } 00309 }; 00310 00311 template<class _CharT, class _Traits> 00312 inline basic_ostream<_CharT, _Traits>& 00313 operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id) 00314 { 00315 if (__id == thread::id()) 00316 return __out << "thread::id of a non-executing thread"; 00317 else 00318 return __out << __id._M_thread; 00319 } 00320 00321 /** @namespace std::this_thread 00322 * @brief ISO C++ 2011 entities sub-namespace for thread. 00323 * 30.3.2 Namespace this_thread. 00324 */ 00325 namespace this_thread 00326 { 00327 /// get_id 00328 inline thread::id 00329 get_id() noexcept 00330 { 00331 #ifdef __GLIBC__ 00332 // For the GNU C library pthread_self() is usable without linking to 00333 // libpthread.so but returns 0, so we cannot use it in single-threaded 00334 // programs, because this_thread::get_id() != thread::id{} must be true. 00335 // We know that pthread_t is an integral type in the GNU C library. 00336 if (!__gthread_active_p()) 00337 return thread::id(1); 00338 #endif 00339 return thread::id(__gthread_self()); 00340 } 00341 00342 /// yield 00343 inline void 00344 yield() noexcept 00345 { 00346 #ifdef _GLIBCXX_USE_SCHED_YIELD 00347 __gthread_yield(); 00348 #endif 00349 } 00350 00351 void 00352 __sleep_for(chrono::seconds, chrono::nanoseconds); 00353 00354 /// sleep_for 00355 template<typename _Rep, typename _Period> 00356 inline void 00357 sleep_for(const chrono::duration<_Rep, _Period>& __rtime) 00358 { 00359 if (__rtime <= __rtime.zero()) 00360 return; 00361 auto __s = chrono::duration_cast<chrono::seconds>(__rtime); 00362 auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s); 00363 #ifdef _GLIBCXX_USE_NANOSLEEP 00364 __gthread_time_t __ts = 00365 { 00366 static_cast<std::time_t>(__s.count()), 00367 static_cast<long>(__ns.count()) 00368 }; 00369 while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR) 00370 { } 00371 #else 00372 __sleep_for(__s, __ns); 00373 #endif 00374 } 00375 00376 /// sleep_until 00377 template<typename _Clock, typename _Duration> 00378 inline void 00379 sleep_until(const chrono::time_point<_Clock, _Duration>& __atime) 00380 { 00381 auto __now = _Clock::now(); 00382 if (_Clock::is_steady) 00383 { 00384 if (__now < __atime) 00385 sleep_for(__atime - __now); 00386 return; 00387 } 00388 while (__now < __atime) 00389 { 00390 sleep_for(__atime - __now); 00391 __now = _Clock::now(); 00392 } 00393 } 00394 } 00395 00396 // @} group threads 00397 00398 _GLIBCXX_END_NAMESPACE_VERSION 00399 } // namespace 00400 00401 #endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1 00402 00403 #endif // C++11 00404 00405 #endif // _GLIBCXX_THREAD