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
30namespace 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
159