concurrence.h revision 1.1.1.9
1// Support for concurrent programing -*- C++ -*-
2
3// Copyright (C) 2003-2019 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
40namespace __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  static 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
316