1 // condition_variable -*- C++ -*-
2 
3 // Copyright (C) 2008-2021 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
wait(unique_lock<mutex> & __lock)39   condition_variable::wait(unique_lock<mutex>& __lock) noexcept
40   {
41     _M_cond.wait(*__lock.mutex());
42   }
43 
44   void
notify_one()45   condition_variable::notify_one() noexcept
46   {
47     _M_cond.notify_one();
48   }
49 
50   void
notify_all()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 
run(void * p)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 
run()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     {
notifierstd::__anon888f517b0111::notifier83       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 
~notifierstd::__anon888f517b0111::notifier90       ~notifier()
91       {
92 	mx->unlock();
93 	cv->notify_all();
94       }
95 
96       condition_variable* cv;
97       mutex* mx;
98 
runstd::__anon888f517b0111::notifier99       static void run(void* p) { delete static_cast<notifier*>(p); }
100     };
101 
102 
key_init()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
__at_thread_exit(__at_thread_exit_elt * elt)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
notify_all_at_thread_exit(condition_variable & cv,unique_lock<mutex> l)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