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- // Threading support -*- C++ -*-
-
- // Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
- //
- // This file is part of the GNU ISO C++ Library. This library is free
- // software; you can redistribute it and/or modify it under the
- // terms of the GNU General Public License as published by the
- // Free Software Foundation; either version 2, or (at your option)
- // any later version.
-
- // This library is distributed in the hope that it will be useful,
- // but WITHOUT ANY WARRANTY; without even the implied warranty of
- // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- // GNU General Public License for more details.
-
- // You should have received a copy of the GNU General Public License along
- // with this library; see the file COPYING. If not, write to the Free
- // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
- // USA.
-
- // As a special exception, you may use this file as part of a free software
- // library without restriction. Specifically, if other files instantiate
- // templates or use macros or inline functions from this file, or you compile
- // this file and link it with other files to produce an executable, this
- // file does not by itself cause the resulting executable to be covered by
- // the GNU General Public License. This exception does not however
- // invalidate any other reasons why the executable file might be covered by
- // the GNU General Public License.
-
- /*
- * Copyright (c) 1997-1999
- * Silicon Graphics Computer Systems, Inc.
- *
- * Permission to use, copy, modify, distribute and sell this software
- * and its documentation for any purpose is hereby granted without fee,
- * provided that the above copyright notice appear in all copies and
- * that both that copyright notice and this permission notice appear
- * in supporting documentation. Silicon Graphics makes no
- * representations about the suitability of this software for any
- * purpose. It is provided "as is" without express or implied warranty.
- */
-
- /** @file stl_threads.h
- * This is an internal header file, included by other library headers.
- * You should not attempt to use it directly.
- */
-
- #ifndef _STL_THREADS_H
- #define _STL_THREADS_H 1
-
- #include <cstddef>
-
- // The only supported threading model is GCC's own gthr.h abstraction
- // layer.
- #include "bits/gthr.h"
-
- namespace __gnu_internal
- {
- #if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
- extern __gthread_mutex_t _GLIBCXX_mutex;
- extern __gthread_mutex_t *_GLIBCXX_mutex_address;
- extern __gthread_once_t _GLIBCXX_once;
- extern void _GLIBCXX_mutex_init(void);
- extern void _GLIBCXX_mutex_address_init(void);
- #endif
- } // namespace __gnu_internal
-
- namespace __gnu_cxx
- {
- // Locking class. Note that this class *does not have a
- // constructor*. It must be initialized either statically, with
- // __STL_MUTEX_INITIALIZER, or dynamically, by explicitly calling
- // the _M_initialize member function. (This is similar to the ways
- // that a pthreads mutex can be initialized.) There are explicit
- // member functions for acquiring and releasing the lock.
-
- // There is no constructor because static initialization is
- // essential for some uses, and only a class aggregate (see section
- // 8.5.1 of the C++ standard) can be initialized that way. That
- // means we must have no constructors, no base classes, no virtual
- // functions, and no private or protected members.
- struct _STL_mutex_lock
- {
- // The class must be statically initialized with __STL_MUTEX_INITIALIZER.
- #if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
- volatile int _M_init_flag;
- __gthread_once_t _M_once;
- #endif
- __gthread_mutex_t _M_lock;
-
- void
- _M_initialize()
- {
- #ifdef __GTHREAD_MUTEX_INIT
- // There should be no code in this path given the usage rules above.
- #elif defined(__GTHREAD_MUTEX_INIT_FUNCTION)
- if (_M_init_flag) return;
- if (__gthread_once(&__gnu_internal::_GLIBCXX_once,
- __gnu_internal::_GLIBCXX_mutex_init) != 0
- && __gthread_active_p())
- abort ();
- __gthread_mutex_lock(&__gnu_internal::_GLIBCXX_mutex);
- if (!_M_init_flag)
- {
- // Even though we have a global lock, we use __gthread_once to be
- // absolutely certain the _M_lock mutex is only initialized once on
- // multiprocessor systems.
- __gnu_internal::_GLIBCXX_mutex_address = &_M_lock;
- if (__gthread_once(&_M_once,
- __gnu_internal::_GLIBCXX_mutex_address_init) != 0
- && __gthread_active_p())
- abort();
- _M_init_flag = 1;
- }
- __gthread_mutex_unlock(&__gnu_internal::_GLIBCXX_mutex);
- #endif
- }
-
- void
- _M_acquire_lock()
- {
- #if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
- if (!_M_init_flag) _M_initialize();
- #endif
- __gthread_mutex_lock(&_M_lock);
- }
-
- void
- _M_release_lock()
- {
- #if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION)
- if (!_M_init_flag) _M_initialize();
- #endif
- __gthread_mutex_unlock(&_M_lock);
- }
- };
-
- #ifdef __GTHREAD_MUTEX_INIT
- #define __STL_MUTEX_INITIALIZER = { __GTHREAD_MUTEX_INIT }
- #elif defined(__GTHREAD_MUTEX_INIT_FUNCTION)
- #ifdef __GTHREAD_MUTEX_INIT_DEFAULT
- #define __STL_MUTEX_INITIALIZER \
- = { 0, __GTHREAD_ONCE_INIT, __GTHREAD_MUTEX_INIT_DEFAULT }
- #else
- #define __STL_MUTEX_INITIALIZER = { 0, __GTHREAD_ONCE_INIT }
- #endif
- #endif
- } // namespace __gnu_cxx
-
- #endif
-