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 <functional>
  40 #include <memory>
  41 #include <cerrno>
  42 #include <bits/functexcept.h>
  43 #include <bits/functional_hash.h>
  44 #include <bits/gthr.h>
  45
  46 #if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
  47
  48 namespace std _GLIBCXX_VISIBILITY(default)
  49 {
  50 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  51
  52   /**
  53    * @defgroup threads Threads
  54    * @ingroup concurrency
  55    *
  56    * Classes for thread support.
  57    * @{
  58    */
  59
  60   /// thread
  61   class thread
  62   {
  63   public:
  64     // Abstract base class for types that wrap arbitrary functors to be
  65     // invoked in the new thread of execution.
  66     struct _State
  67     {
  68       virtual ~_State();
  69       virtual void _M_run() = 0;
  70     };
  71     using _State_ptr = unique_ptr<_State>;
  72
  73     typedef __gthread_t                 native_handle_type;
  74
  75     /// thread::id
  76     class id
  77     {
  78       native_handle_type        _M_thread;
  79
  80     public:
  81       id() noexcept : _M_thread() { }
  82
  83       explicit
  84       id(native_handle_type __id) : _M_thread(__id) { }
  85
  86     private:
  87       friend class thread;
  88       friend class hash<thread::id>;
  89
  90       friend bool
  91       operator==(thread::id __x, thread::id __y) noexcept
  92       {
  93         // pthread_equal is undefined if either thread ID is not valid, so we
  94         // can't safely use __gthread_equal on default-constructed values (nor
  95         // the non-zero value returned by this_thread::get_id() for
  96         // single-threaded programs using GNU libc). Assume EqualityComparable.
  97         return __x._M_thread == __y._M_thread;
  98       }
  99
 100       friend bool
 101       operator<(thread::id __x, thread::id __y) noexcept
 102       {
 103         // Pthreads doesn't define any way to do this, so we just have to
 104         // assume native_handle_type is LessThanComparable.
 105         return __x._M_thread < __y._M_thread;
 106       }
 107
 108       template<class _CharT, class _Traits>
 109         friend basic_ostream<_CharT, _Traits>&
 110         operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id);
 111     };
 112
 113   private:
 114     id                          _M_id;
 115
 116   public:
 117     thread() noexcept = default;
 118     // _GLIBCXX_RESOLVE_LIB_DEFECTS
 119     // 2097.  packaged_task constructors should be constrained
 120     thread(thread&) = delete;
 121     thread(const thread&) = delete;
 122
 123     thread(thread&& __t) noexcept
 124     { swap(__t); }
 125
 126     template<typename _Callable, typename... _Args>
 127       explicit
 128       thread(_Callable&& __f, _Args&&... __args)
 129       {
 130 #ifdef GTHR_ACTIVE_PROXY
 131         // Create a reference to pthread_create, not just the gthr weak symbol.
 132         auto __depend = reinterpret_cast<void(*)()>(&pthread_create);
 133 #else
 134         auto __depend = nullptr;
 135 #endif
 136         _M_start_thread(_S_make_state(
 137               std::__bind_simple(std::forward<_Callable>(__f),
 138                                  std::forward<_Args>(__args)...)),
 139             __depend);
 140       }
 141
 142     ~thread()
 143     {
 144       if (joinable())
 145         std::terminate();
 146     }
 147
 148     thread& operator=(const thread&) = delete;
 149
 150     thread& operator=(thread&& __t) noexcept
 151     {
 152       if (joinable())
 153         std::terminate();
 154       swap(__t);
 155       return *this;
 156     }
 157
 158     void
 159     swap(thread& __t) noexcept
 160     { std::swap(_M_id, __t._M_id); }
 161
 162     bool
 163     joinable() const noexcept
 164     { return !(_M_id == id()); }
 165
 166     void
 167     join();
 168
 169     void
 170     detach();
 171
 172     thread::id
 173     get_id() const noexcept
 174     { return _M_id; }
 175
 176     /** @pre thread is joinable
 177      */
 178     native_handle_type
 179     native_handle()
 180     { return _M_id._M_thread; }
 181
 182     // Returns a value that hints at the number of hardware thread contexts.
 183     static unsigned int
 184     hardware_concurrency() noexcept;
 185
 186   private:
 187     template<typename _Callable>
 188       struct _State_impl : public _State
 189       {
 190         _Callable               _M_func;
 191
 192         _State_impl(_Callable&& __f) : _M_func(std::forward<_Callable>(__f))
 193         { }
 194
 195         void
 196         _M_run() { _M_func(); }
 197       };
 198
 199     void
 200     _M_start_thread(_State_ptr, void (*)());
 201
 202     template<typename _Callable>
 203       static _State_ptr
 204       _S_make_state(_Callable&& __f)
 205       {
 206         using _Impl = _State_impl<_Callable>;
 207         return _State_ptr{new _Impl{std::forward<_Callable>(__f)}};
 208       }
 209 #if _GLIBCXX_THREAD_ABI_COMPAT
 210   public:
 211     struct _Impl_base;
 212     typedef shared_ptr<_Impl_base>      __shared_base_type;
 213     struct _Impl_base
 214     {
 215       __shared_base_type        _M_this_ptr;
 216       virtual ~_Impl_base() = default;
 217       virtual void _M_run() = 0;
 218     };
 219
 220   private:
 221     void
 222     _M_start_thread(__shared_base_type, void (*)());
 223
 224     void
 225     _M_start_thread(__shared_base_type);
 226 #endif
 227   };
 228
 229   inline void
 230   swap(thread& __x, thread& __y) noexcept
 231   { __x.swap(__y); }
 232
 233   inline bool
 234   operator!=(thread::id __x, thread::id __y) noexcept
 235   { return !(__x == __y); }
 236
 237   inline bool
 238   operator<=(thread::id __x, thread::id __y) noexcept
 239   { return !(__y < __x); }
 240
 241   inline bool
 242   operator>(thread::id __x, thread::id __y) noexcept
 243   { return __y < __x; }
 244
 245   inline bool
 246   operator>=(thread::id __x, thread::id __y) noexcept
 247   { return !(__x < __y); }
 248
 249   // DR 889.
 250   /// std::hash specialization for thread::id.
 251   template<>
 252     struct hash<thread::id>
 253     : public __hash_base<size_t, thread::id>
 254     {
 255       size_t
 256       operator()(const thread::id& __id) const noexcept
 257       { return std::_Hash_impl::hash(__id._M_thread); }
 258     };
 259
 260   template<class _CharT, class _Traits>
 261     inline basic_ostream<_CharT, _Traits>&
 262     operator<<(basic_ostream<_CharT, _Traits>& __out, thread::id __id)
 263     {
 264       if (__id == thread::id())
 265         return __out << "thread::id of a non-executing thread";
 266       else
 267         return __out << __id._M_thread;
 268     }
 269
 270 _GLIBCXX_END_NAMESPACE_VERSION
 271
 272   /** @namespace std::this_thread
 273    *  @brief ISO C++ 2011 entities sub-namespace for thread.
 274    *  30.3.2 Namespace this_thread.
 275    */
 276   namespace this_thread
 277   {
 278   _GLIBCXX_BEGIN_NAMESPACE_VERSION
 279
 280     /// get_id
 281     inline thread::id
 282     get_id() noexcept
 283     {
 284 #ifdef __GLIBC__
 285       // For the GNU C library pthread_self() is usable without linking to
 286       // libpthread.so but returns 0, so we cannot use it in single-threaded
 287       // programs, because this_thread::get_id() != thread::id{} must be true.
 288       // We know that pthread_t is an integral type in the GNU C library.
 289       if (!__gthread_active_p())
 290         return thread::id(1);
 291 #endif
 292       return thread::id(__gthread_self());
 293     }
 294
 295     /// yield
 296     inline void
 297     yield() noexcept
 298     {
 299 #ifdef _GLIBCXX_USE_SCHED_YIELD
 300       __gthread_yield();
 301 #endif
 302     }
 303
 304     void
 305     __sleep_for(chrono::seconds, chrono::nanoseconds);
 306
 307     /// sleep_for
 308     template<typename _Rep, typename _Period>
 309       inline void
 310       sleep_for(const chrono::duration<_Rep, _Period>& __rtime)
 311       {
 312         if (__rtime <= __rtime.zero())
 313           return;
 314         auto __s = chrono::duration_cast<chrono::seconds>(__rtime);
 315         auto __ns = chrono::duration_cast<chrono::nanoseconds>(__rtime - __s);
 316 #ifdef _GLIBCXX_USE_NANOSLEEP
 317         __gthread_time_t __ts =
 318           {
 319             static_cast<std::time_t>(__s.count()),
 320             static_cast<long>(__ns.count())
 321           };
 322         while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR)
 323           { }
 324 #else
 325         __sleep_for(__s, __ns);
 326 #endif
 327       }
 328
 329     /// sleep_until
 330     template<typename _Clock, typename _Duration>
 331       inline void
 332       sleep_until(const chrono::time_point<_Clock, _Duration>& __atime)
 333       {
 334         auto __now = _Clock::now();
 335         if (_Clock::is_steady)
 336           {
 337             if (__now < __atime)
 338               sleep_for(__atime - __now);
 339             return;
 340           }
 341         while (__now < __atime)
 342           {
 343             sleep_for(__atime - __now);
 344             __now = _Clock::now();
 345           }
 346       }
 347
 348   _GLIBCXX_END_NAMESPACE_VERSION
 349   }
 350
 351   // @} group threads
 352
 353 } // namespace
 354
 355 #endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
 356
 357 #endif // C++11
 358
 359 #endif // _GLIBCXX_THREAD