1 // Threading support -*- C++ -*-
3 // Copyright (C) 2001, 2002 Free Software Foundation, Inc.
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 2, or (at your option)
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.
16 // You should have received a copy of the GNU General Public License along
17 // with this library; see the file COPYING. If not, write to the Free
18 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
21 // As a special exception, you may use this file as part of a free software
22 // library without restriction. Specifically, if other files instantiate
23 // templates or use macros or inline functions from this file, or you compile
24 // this file and link it with other files to produce an executable, this
25 // file does not by itself cause the resulting executable to be covered by
26 // the GNU General Public License. This exception does not however
27 // invalidate any other reasons why the executable file might be covered by
28 // the GNU General Public License.
31 * Copyright (c) 1997-1999
32 * Silicon Graphics Computer Systems, Inc.
34 * Permission to use, copy, modify, distribute and sell this software
35 * and its documentation for any purpose is hereby granted without fee,
36 * provided that the above copyright notice appear in all copies and
37 * that both that copyright notice and this permission notice appear
38 * in supporting documentation. Silicon Graphics makes no
39 * representations about the suitability of this software for any
40 * purpose. It is provided "as is" without express or implied warranty.
43 /** @file stl_threads.h
44 * This is an internal header file, included by other library headers.
45 * You should not attempt to use it directly.
48 #ifndef __SGI_STL_INTERNAL_THREADS_H
49 #define __SGI_STL_INTERNAL_THREADS_H
51 // The only supported threading model is GCC's own gthr.h abstraction layer.
52 #include "bits/gthr.h"
56 // Class _Refcount_Base provides a type, _RC_t, a data member,
57 // _M_ref_count, and member functions _M_incr and _M_decr, which perform
58 // atomic preincrement/predecrement. The constructor initializes
65 // The data member _M_ref_count
66 volatile _RC_t _M_ref_count;
69 __gthread_mutex_t _M_ref_count_lock;
71 _Refcount_Base(_RC_t __n) : _M_ref_count(__n)
73 #ifdef __GTHREAD_MUTEX_INIT
74 __gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT;
75 _M_ref_count_lock = __tmp;
76 #elif defined(__GTHREAD_MUTEX_INIT_FUNCTION)
77 __GTHREAD_MUTEX_INIT_FUNCTION (&_M_ref_count_lock);
79 #error __GTHREAD_MUTEX_INIT or __GTHREAD_MUTEX_INIT_FUNCTION should be defined by gthr.h abstraction layer, report problem to libstdc++@gcc.gnu.org.
86 __gthread_mutex_lock(&_M_ref_count_lock);
88 __gthread_mutex_unlock(&_M_ref_count_lock);
94 __gthread_mutex_lock(&_M_ref_count_lock);
95 volatile _RC_t __tmp = --_M_ref_count;
96 __gthread_mutex_unlock(&_M_ref_count_lock);
102 // Locking class. Note that this class *does not have a
103 // constructor*. It must be initialized either statically, with
104 // __STL_MUTEX_INITIALIZER, or dynamically, by explicitly calling
105 // the _M_initialize member function. (This is similar to the ways
106 // that a pthreads mutex can be initialized.) There are explicit
107 // member functions for acquiring and releasing the lock.
109 // There is no constructor because static initialization is
110 // essential for some uses, and only a class aggregate (see section
111 // 8.5.1 of the C++ standard) can be initialized that way. That
112 // means we must have no constructors, no base classes, no virtual
113 // functions, and no private or protected members.
115 #if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
118 extern __gthread_mutex_t _GLIBCPP_mutex;
119 extern __gthread_mutex_t *_GLIBCPP_mutex_address;
120 extern __gthread_once_t _GLIBCPP_once;
121 extern void _GLIBCPP_mutex_init (void);
122 extern void _GLIBCPP_mutex_address_init (void);
128 struct _STL_mutex_lock
130 // The class must be statically initialized with __STL_MUTEX_INITIALIZER.
131 #if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
132 volatile int _M_init_flag;
133 __gthread_once_t _M_once;
135 __gthread_mutex_t _M_lock;
140 #ifdef __GTHREAD_MUTEX_INIT
141 // There should be no code in this path given the usage rules above.
142 #elif defined(__GTHREAD_MUTEX_INIT_FUNCTION)
143 if (_M_init_flag) return;
144 if (__gthread_once (&__gnu_cxx::_GLIBCPP_once,
145 __gnu_cxx::_GLIBCPP_mutex_init) != 0
146 && __gthread_active_p ())
148 __gthread_mutex_lock (&__gnu_cxx::_GLIBCPP_mutex);
151 // Even though we have a global lock, we use __gthread_once to be
152 // absolutely certain the _M_lock mutex is only initialized once on
153 // multiprocessor systems.
154 __gnu_cxx::_GLIBCPP_mutex_address = &_M_lock;
155 if (__gthread_once (&_M_once,
156 __gnu_cxx::_GLIBCPP_mutex_address_init) != 0
157 && __gthread_active_p ())
161 __gthread_mutex_unlock (&__gnu_cxx::_GLIBCPP_mutex);
168 #if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
169 if (!_M_init_flag) _M_initialize();
171 __gthread_mutex_lock(&_M_lock);
177 #if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
178 if (!_M_init_flag) _M_initialize();
180 __gthread_mutex_unlock(&_M_lock);
184 #ifdef __GTHREAD_MUTEX_INIT
185 #define __STL_MUTEX_INITIALIZER = { __GTHREAD_MUTEX_INIT }
186 #elif defined(__GTHREAD_MUTEX_INIT_FUNCTION)
187 #ifdef __GTHREAD_MUTEX_INIT_DEFAULT
188 #define __STL_MUTEX_INITIALIZER \
189 = { 0, __GTHREAD_ONCE_INIT, __GTHREAD_MUTEX_INIT_DEFAULT }
191 #define __STL_MUTEX_INITIALIZER = { 0, __GTHREAD_ONCE_INIT }
195 // A locking class that uses _STL_mutex_lock. The constructor takes a
196 // reference to an _STL_mutex_lock, and acquires a lock. The
197 // destructor releases the lock. It's not clear that this is exactly
198 // the right functionality. It will probably change in the future.
199 struct _STL_auto_lock
201 _STL_mutex_lock& _M_lock;
203 _STL_auto_lock(_STL_mutex_lock& __lock) : _M_lock(__lock)
204 { _M_lock._M_acquire_lock(); }
206 ~_STL_auto_lock() { _M_lock._M_release_lock(); }
209 void operator=(const _STL_auto_lock&);
210 _STL_auto_lock(const _STL_auto_lock&);
211 } __attribute__ ((__unused__));