libstdc++-v3/include/std/thread

   1 // <thread> -*- C++ -*-
   2
   3 // Copyright (C) 2008-2016 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
 112     thread(thread&& __t) noexcept
 113     { swap(__t); }
 114
 115     template<typename _Callable, typename... _Args>
 116       explicit
 117       thread(_Callable&& __f, _Args&&... __args)
 118       {
 119 #ifdef GTHR_ACTIVE_PROXY
 120         // Create a reference to pthread_create, not just the gthr weak symbol.
 121         auto __depend = reinterpret_cast<void(*)()>(&pthread_create);
 122 #else
 123         auto __depend = nullptr;
 124 #endif
 125         _M_start_thread(_S_make_state(
 126               __make_invoker(std::forward<_Callable>(__f),
 127                              std::forward<_Args>(__args)...)),
 128             __depend);
 129       }
 130
 131     ~thread()
 132     {
 133       if (joinable())
 134         std::terminate();
 135     }
 136
 137     thread& operator=(const thread&) = delete;
 138
 139     thread& operator=(thread&& __t) noexcept
 140     {
 141       if (joinable())
 142         std::terminate();
 143       swap(__t);
 144       return *this;
 145     }
 146
 147     void
 148     swap(thread& __t) noexcept
 149     { std::swap(_M_id, __t._M_id); }
 150
 151     bool
 152     joinable() const noexcept
 153     { return !(_M_id == id()); }
 154
 155     void
 156     join();
 157
 158     void
 159     detach();
 160
 161     thread::id
 162     get_id() const noexcept
 163     { return _M_id; }
 164
 165     /** @pre thread is joinable
 166      */
 167     native_handle_type
 168     native_handle()
 169     { return _M_id._M_thread; }
 170
 171     // Returns a value that hints at the number of hardware thread contexts.
 172     static unsigned int
 173     hardware_concurrency() noexcept;
 174
 175   private:
 176     template<typename _Callable>
 177       struct _State_impl : public _State
 178       {
 179         _Callable               _M_func;
 180
 181         _State_impl(_Callable&& __f) : _M_func(std::forward<_Callable>(__f))
 182         { }
 183
 184         void
 185         _M_run() { _M_func(); }
 186       };
 187
 188     void
 189     _M_start_thread(_State_ptr, void (*)());
 190
 191     template<typename _Callable>
 192       static _State_ptr
 193       _S_make_state(_Callable&& __f)
 194       {
 195         using _Impl = _State_impl<_Callable>;
 196         return _State_ptr{new _Impl{std::forward<_Callable>(__f)}};
 197       }
 198 #if _GLIBCXX_THREAD_ABI_COMPAT
 199   public:
 200     struct _Impl_base;
 201     typedef shared_ptr<_Impl_base>      __shared_base_type;
 202     struct _Impl_base
 203     {
 204       __shared_base_type        _M_this_ptr;
 205       virtual ~_Impl_base() = default;
 206       virtual void _M_run() = 0;
 207     };
 208
 209   private:
 210     void
 211     _M_start_thread(__shared_base_type, void (*)());
 212
 213     void
 214     _M_start_thread(__shared_base_type);
 215 #endif
 216
 217   private:
 218     // A call wrapper that does INVOKE(forwarded tuple elements...)
 219     template<typename _Tuple>
 220       struct _Invoker
 221       {
 222         _Tuple _M_t;
 223
 224         template<size_t _Index>
 225           static __tuple_element_t<_Index, _Tuple>&&
 226           _S_declval();
 227
 228         template<size_t... _Ind>
 229           auto
 230           _M_invoke(_Index_tuple<_Ind...>)
 231           noexcept(noexcept(std::__invoke(_S_declval<_Ind>()...)))
 232           -> decltype(std::__invoke(_S_declval<_Ind>()...))
 233           { return std::__invoke(std::get<_Ind>(std::move(_M_t))...); }
 234
 235         using _Indices
 236           = typename _Build_index_tuple<tuple_size<_Tuple>::value>::__type;
 237
 238         auto
 239         operator()()
 240         noexcept(noexcept(std::declval<_Invoker&>()._M_invoke(_Indices())))
 241         -> decltype(std::declval<_Invoker&>()._M_invoke(_Indices()))
 242         { return _M_invoke(_Indices()); }
 243       };
 244
 245     // Alias for _Invoker<tuple<DECAY_COPY(_Tp)...>>
 246     template<typename... _Tp>
 247       using __invoker_type
 248         = _Invoker<decltype(std::make_tuple(std::declval<_Tp>()...))>;
 249
 250   public:
 251     // Returns a call wrapper that does
 252     // INVOKE(DECAY_COPY(__callable), DECAY_COPY(__args)).
 253     template<typename _Callable, typename... _Args>
 254       static __invoker_type<_Callable, _Args...>
 255       __make_invoker(_Callable&& __callable, _Args&&... __args)
 256       {
 257         return { {
 258             std::make_tuple(std::forward<_Callable>(__callable),
 259                             std::forward<_Args>(__args)...)
 260         } };
 261       }
 262   };
 263
 264   inline void
 265   swap(thread& __x, thread& __y) noexcept
 266   { __x.swap(__y); }
 267
 268   inline bool
 269   operator==(thread::id __x, thread::id __y) noexcept
 270   {
 271     // pthread_equal is undefined if either thread ID is not valid, so we
 272     // can't safely use __gthread_equal on default-constructed values (nor
 273     // the non-zero value returned by this_thread::get_id() for
 274     // single-threaded programs using GNU libc). Assume EqualityComparable.
 275     return __x._M_thread == __y._M_thread;
 276   }
 277
 278   inline bool
 279   operator!=(thread::id __x, thread::id __y) noexcept
 280   { return !(__x == __y); }
 281
 282   inline bool
 283   operator<(thread::id __x, thread::id __y) noexcept
 284   {
 285     // Pthreads doesn't define any way to do this, so we just have to
 286     // assume native_handle_type is LessThanComparable.
 287     return __x._M_thread < __y._M_thread;
 288   }
 289
 290   inline bool
 291   operator<=(thread::id __x, thread::id __y) noexcept
 292   { return !(__y < __x); }
 293
 294   inline bool
 295   operator>(thread::id __x, thread::id __y) noexcept
 296   { return __y < __x; }
 297
 298   inline bool
 299   operator>=(thread::id __x, thread::id __y) noexcept
 300   { return !(__x < __y); }
 301
 302   // DR 889.
 303   /// std::hash specialization for thread::id.
 304   template<>
 305     struct hash<thread::id>
 306     : public __hash_base<size_t, thread::id>
 307     {
 308       size_t
 309       operator()(const thread::id& __id) const noexcept
 310       { return std::_Hash_impl::hash(__id._M_thread); }
 311     };
 312
 313   template<class _CharT, class _Traits>
 314     inline basic_ostream<_CharT, _Traits>&
 315     operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
 316     {
 317       if (__id == thread::id())
 318         return __out << "thread::id of a non-executing thread";
 319       else
 320         return __out << __id._M_thread;
 321     }
 322
 323 _GLIBCXX_END_NAMESPACE_VERSION
 324
 325   /** @namespace std::this_thread
 326    *  @brief ISO C++ 2011 entities sub-namespace for thread.
 327    *  30.3.2 Namespace this_thread.
 328    */
 329   namespace this_thread
 330   {
 331   _GLIBCXX_BEGIN_NAMESPACE_VERSION
 332
 333     /// get_id
 334     inline thread::id
 335     get_id() noexcept
 336     {
 337 #ifdef __GLIBC__
 338       // For the GNU C library pthread_self() is usable without linking to
 339       // libpthread.so but returns 0, so we cannot use it in single-threaded
 340       // programs, because this_thread::get_id() != thread::id{} must be true.
 341       // We know that pthread_t is an integral type in the GNU C library.
 342       if (!__gthread_active_p())
 343         return thread::id(1);
 344 #endif
 345       return thread::id(__gthread_self());
 346     }
 347
 348     /// yield
 349     inline void
 350     yield() noexcept
 351     {
 352 #ifdef _GLIBCXX_USE_SCHED_YIELD
 353       __gthread_yield();
 354 #endif
 355     }
 356
 357     void
 358     __sleep_for(chrono::seconds, chrono::nanoseconds);
 359
 360     /// sleep_for
 361     template<typename _Rep, typename _Period>
 362       inline void
 363       sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
 364       {
 365         if (__rtime <= __rtime.zero())
 366           return;
 367         auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
 368         auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
 369 #ifdef _GLIBCXX_USE_NANOSLEEP
 370         __gthread_time_t __ts =
 371           {
 372             static_cast<std::time_t>(__s.count()),
 373             static_cast<long>(__ns.count())
 374           };
 375         while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
 376           { }
 377 #else
 378         __sleep_for(__s, __ns);
 379 #endif
 380       }
 381
 382     /// sleep_until
 383     template<typename _Clock, typename _Duration>
 384       inline void
 385       sleep_until(const chrono::time_point<_Clock, _Duration>& __atime)
 386       {
 387         auto __now = _Clock::now();
 388         if (_Clock::is_steady)
 389           {
 390             if (__now < __atime)
 391               sleep_for(__atime - __now);
 392             return;
 393           }
 394         while (__now < __atime)
 395           {
 396             sleep_for(__atime - __now);
 397             __now = _Clock::now();
 398           }
 399       }
 400
 401   _GLIBCXX_END_NAMESPACE_VERSION
 402   }
 403
 404   // @} group threads
 405
 406 } // namespace
 407
 408 #endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
 409
 410 #endif // C++11
 411
 412 #endif // _GLIBCXX_THREAD