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