libstdc++-v3/src/c++11/condition_variable.cc

   1 // condition_variable -*- C++ -*-
   2
   3 // Copyright (C) 2008-2024 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 #include <condition_variable>
  26 #include <cstdlib>
  27
  28 #ifdef _GLIBCXX_HAS_GTHREADS
  29
  30 namespace std _GLIBCXX_VISIBILITY(default)
  31 {
  32 _GLIBCXX_BEGIN_NAMESPACE_VERSION
  33
  34   condition_variable::condition_variable() noexcept = default;
  35
  36   condition_variable::~condition_variable() noexcept = default;
  37
  38   void
  39   condition_variable::wait(unique_lock<mutex>& __lock)
  40   {
  41     _M_cond.wait(*__lock.mutex());
  42   }
  43
  44   void
  45   condition_variable::notify_one() noexcept
  46   {
  47     _M_cond.notify_one();
  48   }
  49
  50   void
  51   condition_variable::notify_all() noexcept
  52   {
  53     _M_cond.notify_all();
  54   }
  55
  56   extern void
  57   __at_thread_exit(__at_thread_exit_elt*);
  58
  59   namespace
  60   {
  61     __gthread_key_t key;
  62
  63     void run(void* p)
  64     {
  65       auto elt = (__at_thread_exit_elt*)p;
  66       while (elt)
  67         {
  68           auto next = elt->_M_next;
  69           elt->_M_cb(elt);
  70           elt = next;
  71         }
  72     }
  73
  74     void run()
  75     {
  76       auto elt = (__at_thread_exit_elt*)__gthread_getspecific(key);
  77       __gthread_setspecific(key, nullptr);
  78       run(elt);
  79     }
  80
  81     struct notifier final : __at_thread_exit_elt
  82     {
  83       notifier(condition_variable& cv, unique_lock<mutex>& l)
  84       : cv(&cv), mx(l.release())
  85       {
  86         _M_cb = &notifier::run;
  87         __at_thread_exit(this);
  88       }
  89
  90       ~notifier()
  91       {
  92         mx->unlock();
  93         cv->notify_all();
  94       }
  95
  96       condition_variable* cv;
  97       mutex* mx;
  98
  99       static void run(void* p) { delete static_cast<notifier*>(p); }
 100     };
 101
 102
 103     void key_init() {
 104       struct key_s {
 105         key_s() { __gthread_key_create (&key, run); }
 106         ~key_s() { __gthread_key_delete (key); }
 107       };
 108       static key_s ks;
 109       // Also make sure the callbacks are run by std::exit.
 110       std::atexit (run);
 111     }
 112   }
 113
 114   void
 115   __at_thread_exit(__at_thread_exit_elt* elt)
 116   {
 117     static __gthread_once_t once = __GTHREAD_ONCE_INIT;
 118     __gthread_once (&once, key_init);
 119
 120     elt->_M_next = (__at_thread_exit_elt*)__gthread_getspecific(key);
 121     __gthread_setspecific(key, elt);
 122   }
 123
 124   void
 125   notify_all_at_thread_exit(condition_variable& cv, unique_lock<mutex> l)
 126   {
 127     (void) new notifier{cv, l};
 128   }
 129
 130 _GLIBCXX_END_NAMESPACE_VERSION
 131 } // namespace
 132
 133 #endif // _GLIBCXX_HAS_GTHREADS