1// condition_variable -*- C++ -*-
2
3// Copyright (C) 2008-2022 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
30namespace 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
134