1 // Support for concurrent programing -*- C++ -*-
2
3 // Copyright (C) 2003-2023 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 /** @file ext/concurrence.h
26 * This file is a GNU extension to the Standard C++ Library.
27 */
28
29 #ifndef _CONCURRENCE_H
30 #define _CONCURRENCE_H 1
31
32 #pragma GCC system_header
33
34 #include <exception>
35 #include <bits/gthr.h>
36 #include <bits/functexcept.h>
37 #include <bits/cpp_type_traits.h>
38 #include <ext/type_traits.h>
39
40 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
41 {
42 _GLIBCXX_BEGIN_NAMESPACE_VERSION
43
44 // Available locking policies:
45 // _S_single single-threaded code that doesn't need to be locked.
46 // _S_mutex multi-threaded code that requires additional support
47 // from gthr.h or abstraction layers in concurrence.h.
48 // _S_atomic multi-threaded code using atomic operations.
49 enum _Lock_policy { _S_single, _S_mutex, _S_atomic };
50
51 // Compile time constant that indicates prefered locking policy in
52 // the current configuration.
53 _GLIBCXX17_INLINE const _Lock_policy __default_lock_policy =
54 #ifndef __GTHREADS
55 _S_single;
56 #elif defined _GLIBCXX_HAVE_ATOMIC_LOCK_POLICY
57 _S_atomic;
58 #else
59 _S_mutex;
60 #endif
61
62 // NB: As this is used in libsupc++, need to only depend on
63 // exception. No stdexception classes, no use of std::string.
64 class __concurrence_lock_error : public std::exception
65 {
66 public:
67 virtual char const*
68 what() const throw()
69 { return "__gnu_cxx::__concurrence_lock_error"; }
70 };
71
72 class __concurrence_unlock_error : public std::exception
73 {
74 public:
75 virtual char const*
76 what() const throw()
77 { return "__gnu_cxx::__concurrence_unlock_error"; }
78 };
79
80 class __concurrence_broadcast_error : public std::exception
81 {
82 public:
83 virtual char const*
84 what() const throw()
85 { return "__gnu_cxx::__concurrence_broadcast_error"; }
86 };
87
88 class __concurrence_wait_error : public std::exception
89 {
90 public:
91 virtual char const*
92 what() const throw()
93 { return "__gnu_cxx::__concurrence_wait_error"; }
94 };
95
96 // Substitute for concurrence_error object in the case of -fno-exceptions.
97 inline void
98 __throw_concurrence_lock_error()
99 { _GLIBCXX_THROW_OR_ABORT(__concurrence_lock_error()); }
100
101 inline void
102 __throw_concurrence_unlock_error()
103 { _GLIBCXX_THROW_OR_ABORT(__concurrence_unlock_error()); }
104
105 #ifdef __GTHREAD_HAS_COND
106 inline void
107 __throw_concurrence_broadcast_error()
108 { _GLIBCXX_THROW_OR_ABORT(__concurrence_broadcast_error()); }
109
110 inline void
111 __throw_concurrence_wait_error()
112 { _GLIBCXX_THROW_OR_ABORT(__concurrence_wait_error()); }
113 #endif
114
115 class __mutex
116 {
117 private:
118 #if __GTHREADS && defined __GTHREAD_MUTEX_INIT
119 __gthread_mutex_t _M_mutex = __GTHREAD_MUTEX_INIT;
120 #else
121 __gthread_mutex_t _M_mutex;
122 #endif
123
124 __mutex(const __mutex&);
125 __mutex& operator=(const __mutex&);
126
127 public:
128 __mutex()
129 {
130 #if __GTHREADS && ! defined __GTHREAD_MUTEX_INIT
131 if (__gthread_active_p())
132 __GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex);
133 #endif
134 }
135
136 #if __GTHREADS && ! defined __GTHREAD_MUTEX_INIT
137 ~__mutex()
138 {
139 if (__gthread_active_p())
140 __gthread_mutex_destroy(&_M_mutex);
141 }
142 #endif
143
144 void lock()
145 {
146 #if __GTHREADS
147 if (__gthread_active_p())
148 {
149 if (__gthread_mutex_lock(&_M_mutex) != 0)
150 __throw_concurrence_lock_error();
151 }
152 #endif
153 }
154
155 void unlock()
156 {
157 #if __GTHREADS
158 if (__gthread_active_p())
159 {
160 if (__gthread_mutex_unlock(&_M_mutex) != 0)
161 __throw_concurrence_unlock_error();
162 }
163 #endif
164 }
165
166 __gthread_mutex_t* gthread_mutex(void)
167 { return &_M_mutex; }
168 };
169
170 class __recursive_mutex
171 {
172 private:
173 #if __GTHREADS && defined __GTHREAD_RECURSIVE_MUTEX_INIT
174 __gthread_recursive_mutex_t _M_mutex = __GTHREAD_RECURSIVE_MUTEX_INIT;
175 #else
176 __gthread_recursive_mutex_t _M_mutex;
177 #endif
178
179 __recursive_mutex(const __recursive_mutex&);
180 __recursive_mutex& operator=(const __recursive_mutex&);
181
182 public:
183 __recursive_mutex()
184 {
185 #if __GTHREADS && ! defined __GTHREAD_RECURSIVE_MUTEX_INIT
186 if (__gthread_active_p())
187 __GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION(&_M_mutex);
188 #endif
189 }
190
191 #if __GTHREADS && ! defined __GTHREAD_RECURSIVE_MUTEX_INIT
192 ~__recursive_mutex()
193 {
194 if (__gthread_active_p())
195 __gthread_recursive_mutex_destroy(&_M_mutex);
196 }
197 #endif
198
199 void lock()
200 {
201 #if __GTHREADS
202 if (__gthread_active_p())
203 {
204 if (__gthread_recursive_mutex_lock(&_M_mutex) != 0)
205 __throw_concurrence_lock_error();
206 }
207 #endif
208 }
209
210 void unlock()
211 {
212 #if __GTHREADS
213 if (__gthread_active_p())
214 {
215 if (__gthread_recursive_mutex_unlock(&_M_mutex) != 0)
216 __throw_concurrence_unlock_error();
217 }
218 #endif
219 }
220
221 __gthread_recursive_mutex_t* gthread_recursive_mutex(void)
222 { return &_M_mutex; }
223 };
224
225 /// Scoped lock idiom.
226 // Acquire the mutex here with a constructor call, then release with
227 // the destructor call in accordance with RAII style.
228 class __scoped_lock
229 {
230 public:
231 typedef __mutex __mutex_type;
232
233 private:
234 __mutex_type& _M_device;
235
236 __scoped_lock(const __scoped_lock&);
237 __scoped_lock& operator=(const __scoped_lock&);
238
239 public:
240 explicit __scoped_lock(__mutex_type& __name) : _M_device(__name)
241 { _M_device.lock(); }
242
243 ~__scoped_lock() throw()
244 { _M_device.unlock(); }
245 };
246
247 #ifdef __GTHREAD_HAS_COND
248 class __cond
249 {
250 private:
251 #if __GTHREADS && defined __GTHREAD_COND_INIT
252 __gthread_cond_t _M_cond = __GTHREAD_COND_INIT;
253 #else
254 __gthread_cond_t _M_cond;
255 #endif
256
257 __cond(const __cond&);
258 __cond& operator=(const __cond&);
259
260 public:
261 __cond()
262 {
263 #if __GTHREADS && ! defined __GTHREAD_COND_INIT
264 if (__gthread_active_p())
265 __GTHREAD_COND_INIT_FUNCTION(&_M_cond);
266 #endif
267 }
268
269 #if __GTHREADS && ! defined __GTHREAD_COND_INIT
270 ~__cond()
271 {
272 if (__gthread_active_p())
273 __gthread_cond_destroy(&_M_cond);
274 }
275 #endif
276
277 void broadcast()
278 {
279 #if __GTHREADS
280 if (__gthread_active_p())
281 {
282 if (__gthread_cond_broadcast(&_M_cond) != 0)
283 __throw_concurrence_broadcast_error();
284 }
285 #endif
286 }
287
288 void wait(__mutex *mutex)
289 {
290 #if __GTHREADS
291 {
292 if (__gthread_cond_wait(&_M_cond, mutex->gthread_mutex()) != 0)
293 __throw_concurrence_wait_error();
294 }
295 #endif
296 }
297
298 void wait_recursive(__recursive_mutex *mutex)
299 {
300 #if __GTHREADS
301 {
302 if (__gthread_cond_wait_recursive(&_M_cond,
303 mutex->gthread_recursive_mutex())
304 != 0)
305 __throw_concurrence_wait_error();
306 }
307 #endif
308 }
309 };
310 #endif
311
312 _GLIBCXX_END_NAMESPACE_VERSION
313 } // namespace
314
315 #endif