1// Support for concurrent programing -*- C++ -*-
2
3// Copyright (C) 2003-2013 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#ifdef __GTHREADS
55#if (defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2) \
56     && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4))
57  _S_atomic;
58#else
59  _S_mutex;
60#endif
61#else
62  _S_single;
63#endif
64
65  // NB: As this is used in libsupc++, need to only depend on
66  // exception. No stdexception classes, no use of std::string.
67  class __concurrence_lock_error : public std::exception
68  {
69  public:
70    virtual char const*
71    what() const throw()
72    { return "__gnu_cxx::__concurrence_lock_error"; }
73  };
74
75  class __concurrence_unlock_error : public std::exception
76  {
77  public:
78    virtual char const*
79    what() const throw()
80    { return "__gnu_cxx::__concurrence_unlock_error"; }
81  };
82
83  class __concurrence_broadcast_error : public std::exception
84  {
85  public:
86    virtual char const*
87    what() const throw()
88    { return "__gnu_cxx::__concurrence_broadcast_error"; }
89  };
90
91  class __concurrence_wait_error : public std::exception
92  {
93  public:
94    virtual char const*
95    what() const throw()
96    { return "__gnu_cxx::__concurrence_wait_error"; }
97  };
98
99  // Substitute for concurrence_error object in the case of -fno-exceptions.
100  inline void
101  __throw_concurrence_lock_error()
102  { _GLIBCXX_THROW_OR_ABORT(__concurrence_lock_error()); }
103
104  inline void
105  __throw_concurrence_unlock_error()
106  { _GLIBCXX_THROW_OR_ABORT(__concurrence_unlock_error()); }
107
108#ifdef __GTHREAD_HAS_COND
109  inline void
110  __throw_concurrence_broadcast_error()
111  { _GLIBCXX_THROW_OR_ABORT(__concurrence_broadcast_error()); }
112
113  inline void
114  __throw_concurrence_wait_error()
115  { _GLIBCXX_THROW_OR_ABORT(__concurrence_wait_error()); }
116#endif
117
118  class __mutex
119  {
120  private:
121#if __GTHREADS && defined __GTHREAD_MUTEX_INIT
122    __gthread_mutex_t _M_mutex = __GTHREAD_MUTEX_INIT;
123#else
124    __gthread_mutex_t _M_mutex;
125#endif
126
127    __mutex(const __mutex&);
128    __mutex& operator=(const __mutex&);
129
130  public:
131    __mutex()
132    {
133#if __GTHREADS && ! defined __GTHREAD_MUTEX_INIT
134      if (__gthread_active_p())
135	__GTHREAD_MUTEX_INIT_FUNCTION(&_M_mutex);
136#endif
137    }
138
139#if __GTHREADS && ! defined __GTHREAD_MUTEX_INIT
140    ~__mutex()
141    {
142      if (__gthread_active_p())
143	__gthread_mutex_destroy(&_M_mutex);
144    }
145#endif
146
147    void lock()
148    {
149#if __GTHREADS
150      if (__gthread_active_p())
151	{
152	  if (__gthread_mutex_lock(&_M_mutex) != 0)
153	    __throw_concurrence_lock_error();
154	}
155#endif
156    }
157
158    void unlock()
159    {
160#if __GTHREADS
161      if (__gthread_active_p())
162	{
163	  if (__gthread_mutex_unlock(&_M_mutex) != 0)
164	    __throw_concurrence_unlock_error();
165	}
166#endif
167    }
168
169    __gthread_mutex_t* gthread_mutex(void)
170      { return &_M_mutex; }
171  };
172
173  class __recursive_mutex
174  {
175  private:
176#if __GTHREADS && defined __GTHREAD_RECURSIVE_MUTEX_INIT
177    __gthread_recursive_mutex_t _M_mutex = __GTHREAD_RECURSIVE_MUTEX_INIT;
178#else
179    __gthread_recursive_mutex_t _M_mutex;
180#endif
181
182    __recursive_mutex(const __recursive_mutex&);
183    __recursive_mutex& operator=(const __recursive_mutex&);
184
185  public:
186    __recursive_mutex()
187    {
188#if __GTHREADS && ! defined __GTHREAD_RECURSIVE_MUTEX_INIT
189      if (__gthread_active_p())
190	__GTHREAD_RECURSIVE_MUTEX_INIT_FUNCTION(&_M_mutex);
191#endif
192    }
193
194#if __GTHREADS && ! defined __GTHREAD_RECURSIVE_MUTEX_INIT
195    ~__recursive_mutex()
196    {
197      if (__gthread_active_p())
198	__gthread_recursive_mutex_destroy(&_M_mutex);
199    }
200#endif
201
202    void lock()
203    {
204#if __GTHREADS
205      if (__gthread_active_p())
206	{
207	  if (__gthread_recursive_mutex_lock(&_M_mutex) != 0)
208	    __throw_concurrence_lock_error();
209	}
210#endif
211    }
212
213    void unlock()
214    {
215#if __GTHREADS
216      if (__gthread_active_p())
217	{
218	  if (__gthread_recursive_mutex_unlock(&_M_mutex) != 0)
219	    __throw_concurrence_unlock_error();
220	}
221#endif
222    }
223
224    __gthread_recursive_mutex_t* gthread_recursive_mutex(void)
225    { return &_M_mutex; }
226  };
227
228  /// Scoped lock idiom.
229  // Acquire the mutex here with a constructor call, then release with
230  // the destructor call in accordance with RAII style.
231  class __scoped_lock
232  {
233  public:
234    typedef __mutex __mutex_type;
235
236  private:
237    __mutex_type& _M_device;
238
239    __scoped_lock(const __scoped_lock&);
240    __scoped_lock& operator=(const __scoped_lock&);
241
242  public:
243    explicit __scoped_lock(__mutex_type& __name) : _M_device(__name)
244    { _M_device.lock(); }
245
246    ~__scoped_lock() throw()
247    { _M_device.unlock(); }
248  };
249
250#ifdef __GTHREAD_HAS_COND
251  class __cond
252  {
253  private:
254#if __GTHREADS && defined __GTHREAD_COND_INIT
255    __gthread_cond_t _M_cond = __GTHREAD_COND_INIT;
256#else
257    __gthread_cond_t _M_cond;
258#endif
259
260    __cond(const __cond&);
261    __cond& operator=(const __cond&);
262
263  public:
264    __cond()
265    {
266#if __GTHREADS && ! defined __GTHREAD_COND_INIT
267      if (__gthread_active_p())
268	__GTHREAD_COND_INIT_FUNCTION(&_M_cond);
269#endif
270    }
271
272#if __GTHREADS && ! defined __GTHREAD_COND_INIT
273    ~__cond()
274    {
275      if (__gthread_active_p())
276	__gthread_cond_destroy(&_M_cond);
277    }
278#endif
279
280    void broadcast()
281    {
282#if __GTHREADS
283      if (__gthread_active_p())
284	{
285	  if (__gthread_cond_broadcast(&_M_cond) != 0)
286	    __throw_concurrence_broadcast_error();
287	}
288#endif
289    }
290
291    void wait(__mutex *mutex)
292    {
293#if __GTHREADS
294      {
295	  if (__gthread_cond_wait(&_M_cond, mutex->gthread_mutex()) != 0)
296	    __throw_concurrence_wait_error();
297      }
298#endif
299    }
300
301    void wait_recursive(__recursive_mutex *mutex)
302    {
303#if __GTHREADS
304      {
305	  if (__gthread_cond_wait_recursive(&_M_cond,
306					    mutex->gthread_recursive_mutex())
307	      != 0)
308	    __throw_concurrence_wait_error();
309      }
310#endif
311    }
312  };
313#endif
314
315_GLIBCXX_END_NAMESPACE_VERSION
316} // namespace
317
318#endif
319