libstdc++-v3/include/std/condition_variable

   1 // <condition_variable> -*- C++ -*-
   2
   3 // Copyright (C) 2008, 2009, 2010, 2011, 2012 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/condition_variable
  26  *  This is a Standard C++ Library header.
  27  */
  28
  29 #ifndef _GLIBCXX_CONDITION_VARIABLE
  30 #define _GLIBCXX_CONDITION_VARIABLE 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 <mutex> // unique_lock
  40
  41 #if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
  42
  43 namespace std _GLIBCXX_VISIBILITY(default)
  44 {
  45 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  46
  47   /**
  48    * @defgroup condition_variables Condition Variables
  49    * @ingroup concurrency
  50    *
  51    * Classes for condition_variable support.
  52    * @{
  53    */
  54
  55   /// cv_status
  56   enum class cv_status { no_timeout, timeout };
  57
  58   /// condition_variable
  59   class condition_variable
  60   {
  61     typedef chrono::system_clock        __clock_t;
  62     typedef __gthread_cond_t            __native_type;
  63
  64 #ifdef __GTHREAD_COND_INIT
  65     __native_type                       _M_cond = __GTHREAD_COND_INIT;
  66 #else
  67     __native_type                       _M_cond;
  68 #endif
  69
  70   public:
  71     typedef __native_type*              native_handle_type;
  72
  73     condition_variable() noexcept;
  74     ~condition_variable() noexcept;
  75
  76     condition_variable(const condition_variable&) = delete;
  77     condition_variable& operator=(const condition_variable&) = delete;
  78
  79     void
  80     notify_one() noexcept;
  81
  82     void
  83     notify_all() noexcept;
  84
  85     void
  86     wait(unique_lock<mutex>& __lock);
  87
  88     template<typename _Predicate>
  89       void
  90       wait(unique_lock<mutex>& __lock, _Predicate __p)
  91       {
  92         while (!__p())
  93           wait(__lock);
  94       }
  95
  96     template<typename _Duration>
  97       cv_status
  98       wait_until(unique_lock<mutex>& __lock,
  99                  const chrono::time_point<__clock_t, _Duration>& __atime)
 100       { return __wait_until_impl(__lock, __atime); }
 101
 102     template<typename _Clock, typename _Duration>
 103       cv_status
 104       wait_until(unique_lock<mutex>& __lock,
 105                  const chrono::time_point<_Clock, _Duration>& __atime)
 106       {
 107         // DR 887 - Sync unknown clock to known clock.
 108         const typename _Clock::time_point __c_entry = _Clock::now();
 109         const __clock_t::time_point __s_entry = __clock_t::now();
 110         const chrono::nanoseconds __delta = __atime - __c_entry;
 111         const __clock_t::time_point __s_atime = __s_entry + __delta;
 112
 113         return __wait_until_impl(__lock, __s_atime);
 114       }
 115
 116     template<typename _Clock, typename _Duration, typename _Predicate>
 117       bool
 118       wait_until(unique_lock<mutex>& __lock,
 119                  const chrono::time_point<_Clock, _Duration>& __atime,
 120                  _Predicate __p)
 121       {
 122         while (!__p())
 123           if (wait_until(__lock, __atime) == cv_status::timeout)
 124             return __p();
 125         return true;
 126       }
 127
 128     template<typename _Rep, typename _Period>
 129       cv_status
 130       wait_for(unique_lock<mutex>& __lock,
 131                const chrono::duration<_Rep, _Period>& __rtime)
 132       { return wait_until(__lock, __clock_t::now() + __rtime); }
 133
 134     template<typename _Rep, typename _Period, typename _Predicate>
 135       bool
 136       wait_for(unique_lock<mutex>& __lock,
 137                const chrono::duration<_Rep, _Period>& __rtime,
 138                _Predicate __p)
 139       { return wait_until(__lock, __clock_t::now() + __rtime, std::move(__p)); }
 140
 141     native_handle_type
 142     native_handle()
 143     { return &_M_cond; }
 144
 145   private:
 146     template<typename _Clock, typename _Duration>
 147       cv_status
 148       __wait_until_impl(unique_lock<mutex>& __lock,
 149                         const chrono::time_point<_Clock, _Duration>& __atime)
 150       {
 151         chrono::time_point<__clock_t, chrono::seconds> __s =
 152           chrono::time_point_cast<chrono::seconds>(__atime);
 153
 154         chrono::nanoseconds __ns =
 155           chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
 156
 157         __gthread_time_t __ts =
 158           {
 159             static_cast<std::time_t>(__s.time_since_epoch().count()),
 160             static_cast<long>(__ns.count())
 161           };
 162
 163         __gthread_cond_timedwait(&_M_cond, __lock.mutex()->native_handle(),
 164                                  &__ts);
 165
 166         return (_Clock::now() < __atime
 167                 ? cv_status::no_timeout : cv_status::timeout);
 168       }
 169   };
 170
 171   /// condition_variable_any
 172   // Like above, but mutex is not required to have try_lock.
 173   class condition_variable_any
 174   {
 175     typedef chrono::system_clock        __clock_t;
 176     condition_variable                  _M_cond;
 177     mutex                               _M_mutex;
 178
 179     // scoped unlock - unlocks in ctor, re-locks in dtor
 180     template<typename _Lock>
 181       struct _Unlock
 182       {
 183         explicit _Unlock(_Lock& __lk) : _M_lock(__lk) { __lk.unlock(); }
 184
 185         ~_Unlock() noexcept(false)
 186         {
 187           if (uncaught_exception())
 188             __try { _M_lock.lock(); } __catch(...) { }
 189           else
 190             _M_lock.lock();
 191         }
 192
 193         _Unlock(const _Unlock&) = delete;
 194         _Unlock& operator=(const _Unlock&) = delete;
 195
 196         _Lock& _M_lock;
 197       };
 198
 199   public:
 200
 201     condition_variable_any() noexcept;
 202     ~condition_variable_any() noexcept;
 203
 204     condition_variable_any(const condition_variable_any&) = delete;
 205     condition_variable_any& operator=(const condition_variable_any&) = delete;
 206
 207     void
 208     notify_one() noexcept
 209     {
 210       lock_guard<mutex> __lock(_M_mutex);
 211       _M_cond.notify_one();
 212     }
 213
 214     void
 215     notify_all() noexcept
 216     {
 217       lock_guard<mutex> __lock(_M_mutex);
 218       _M_cond.notify_all();
 219     }
 220
 221     template<typename _Lock>
 222       void
 223       wait(_Lock& __lock)
 224       {
 225         unique_lock<mutex> __my_lock(_M_mutex);
 226         _Unlock<_Lock> __unlock(__lock);
 227         // _M_mutex must be unlocked before re-locking __lock so move
 228         // ownership of _M_mutex lock to an object with shorter lifetime.
 229         unique_lock<mutex> __my_lock2(std::move(__my_lock));
 230         _M_cond.wait(__my_lock2);
 231       }
 232
 233
 234     template<typename _Lock, typename _Predicate>
 235       void
 236       wait(_Lock& __lock, _Predicate __p)
 237       {
 238         while (!__p())
 239           wait(__lock);
 240       }
 241
 242     template<typename _Lock, typename _Clock, typename _Duration>
 243       cv_status
 244       wait_until(_Lock& __lock,
 245                  const chrono::time_point<_Clock, _Duration>& __atime)
 246       {
 247         unique_lock<mutex> __my_lock(_M_mutex);
 248         _Unlock<_Lock> __unlock(__lock);
 249         // _M_mutex must be unlocked before re-locking __lock so move
 250         // ownership of _M_mutex lock to an object with shorter lifetime.
 251         unique_lock<mutex> __my_lock2(std::move(__my_lock));
 252         return _M_cond.wait_until(__my_lock2, __atime);
 253       }
 254
 255     template<typename _Lock, typename _Clock,
 256              typename _Duration, typename _Predicate>
 257       bool
 258       wait_until(_Lock& __lock,
 259                  const chrono::time_point<_Clock, _Duration>& __atime,
 260                  _Predicate __p)
 261       {
 262         while (!__p())
 263           if (wait_until(__lock, __atime) == cv_status::timeout)
 264             return __p();
 265         return true;
 266       }
 267
 268     template<typename _Lock, typename _Rep, typename _Period>
 269       cv_status
 270       wait_for(_Lock& __lock, const chrono::duration<_Rep, _Period>& __rtime)
 271       { return wait_until(__lock, __clock_t::now() + __rtime); }
 272
 273     template<typename _Lock, typename _Rep,
 274              typename _Period, typename _Predicate>
 275       bool
 276       wait_for(_Lock& __lock,
 277                const chrono::duration<_Rep, _Period>& __rtime, _Predicate __p)
 278       { return wait_until(__lock, __clock_t::now() + __rtime, std::move(__p)); }
 279   };
 280
 281   // @} group condition_variables
 282 _GLIBCXX_END_NAMESPACE_VERSION
 283 } // namespace
 284
 285 #endif // _GLIBCXX_HAS_GTHREADS && _GLIBCXX_USE_C99_STDINT_TR1
 286
 287 #endif // C++11
 288
 289 #endif // _GLIBCXX_CONDITION_VARIABLE