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

   1 // condition_variable -*- C++ -*-
   2
   3 // Copyright (C) 2008-2020 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 #ifdef __GTHREAD_COND_INIT
  35   condition_variable::condition_variable() noexcept = default;
  36 #else
  37   condition_variable::condition_variable() noexcept
  38   {
  39     __GTHREAD_COND_INIT_FUNCTION(&_M_cond);
  40   }
  41 #endif
  42
  43   condition_variable::~condition_variable() noexcept
  44   {
  45     // XXX no thread blocked
  46     /* int __e = */ __gthread_cond_destroy(&_M_cond);
  47     // if __e == EBUSY then blocked
  48   }
  49
  50   void
  51   condition_variable::wait(unique_lock<mutex>& __lock) noexcept
  52   {
  53     int __e = __gthread_cond_wait(&_M_cond, __lock.mutex()->native_handle());
  54
  55     if (__e)
  56       std::terminate();
  57   }
  58
  59   void
  60   condition_variable::notify_one() noexcept
  61   {
  62     int __e = __gthread_cond_signal(&_M_cond);
  63
  64     // XXX not in spec
  65     // EINVAL
  66     if (__e)
  67       __throw_system_error(__e);
  68   }
  69
  70   void
  71   condition_variable::notify_all() noexcept
  72   {
  73     int __e = __gthread_cond_broadcast(&_M_cond);
  74
  75     // XXX not in spec
  76     // EINVAL
  77     if (__e)
  78       __throw_system_error(__e);
  79   }
  80
  81   extern void
  82   __at_thread_exit(__at_thread_exit_elt*);
  83
  84   namespace
  85   {
  86     __gthread_key_t key;
  87
  88     void run(void* p)
  89     {
  90       auto elt = (__at_thread_exit_elt*)p;
  91       while (elt)
  92         {
  93           auto next = elt->_M_next;
  94           elt->_M_cb(elt);
  95           elt = next;
  96         }
  97     }
  98
  99     void run()
 100     {
 101       auto elt = (__at_thread_exit_elt*)__gthread_getspecific(key);
 102       __gthread_setspecific(key, nullptr);
 103       run(elt);
 104     }
 105
 106     struct notifier final : __at_thread_exit_elt
 107     {
 108       notifier(condition_variable& cv, unique_lock<mutex>& l)
 109       : cv(&cv), mx(l.release())
 110       {
 111         _M_cb = &notifier::run;
 112         __at_thread_exit(this);
 113       }
 114
 115       ~notifier()
 116       {
 117         mx->unlock();
 118         cv->notify_all();
 119       }
 120
 121       condition_variable* cv;
 122       mutex* mx;
 123
 124       static void run(void* p) { delete static_cast<notifier*>(p); }
 125     };
 126
 127
 128     void key_init() {
 129       struct key_s {
 130         key_s() { __gthread_key_create (&key, run); }
 131         ~key_s() { __gthread_key_delete (key); }
 132       };
 133       static key_s ks;
 134       // Also make sure the callbacks are run by std::exit.
 135       std::atexit (run);
 136     }
 137   }
 138
 139   void
 140   __at_thread_exit(__at_thread_exit_elt* elt)
 141   {
 142     static __gthread_once_t once = __GTHREAD_ONCE_INIT;
 143     __gthread_once (&once, key_init);
 144
 145     elt->_M_next = (__at_thread_exit_elt*)__gthread_getspecific(key);
 146     __gthread_setspecific(key, elt);
 147   }
 148
 149   void
 150   notify_all_at_thread_exit(condition_variable& cv, unique_lock<mutex> l)
 151   {
 152     (void) new notifier{cv, l};
 153   }
 154
 155 _GLIBCXX_END_NAMESPACE_VERSION
 156 } // namespace
 157
 158 #endif // _GLIBCXX_HAS_GTHREADS