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Diffstat (limited to 'contrib/libstdc++/include/bits/stl_threads.h')
| -rw-r--r-- | contrib/libstdc++/include/bits/stl_threads.h | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/contrib/libstdc++/include/bits/stl_threads.h b/contrib/libstdc++/include/bits/stl_threads.h new file mode 100644 index 0000000..0150cd5 --- /dev/null +++ b/contrib/libstdc++/include/bits/stl_threads.h @@ -0,0 +1,236 @@ +// Threading support -*- C++ -*- + +// Copyright (C) 2001 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 __SGI_STL_INTERNAL_THREADS_H +#define __SGI_STL_INTERNAL_THREADS_H + +// The only supported threading model is GCC's own gthr.h abstraction layer. +#include "bits/gthr.h" + +namespace std +{ + // Class _Refcount_Base provides a type, _RC_t, a data member, + // _M_ref_count, and member functions _M_incr and _M_decr, which perform + // atomic preincrement/predecrement. The constructor initializes + // _M_ref_count. + struct _Refcount_Base + { + // The type _RC_t + typedef size_t _RC_t; + + // The data member _M_ref_count + volatile _RC_t _M_ref_count; + + // Constructor + __gthread_mutex_t _M_ref_count_lock; + + _Refcount_Base(_RC_t __n) : _M_ref_count(__n) + { +#ifdef __GTHREAD_MUTEX_INIT + __gthread_mutex_t __tmp = __GTHREAD_MUTEX_INIT; + _M_ref_count_lock = __tmp; +#elif defined(__GTHREAD_MUTEX_INIT_FUNCTION) + __GTHREAD_MUTEX_INIT_FUNCTION (&_M_ref_count_lock); +#else +#error __GTHREAD_MUTEX_INIT or __GTHREAD_MUTEX_INIT_FUNCTION should be defined by gthr.h abstraction layer, report problem to libstdc++@gcc.gnu.org. +#endif + } + + void + _M_incr() + { + __gthread_mutex_lock(&_M_ref_count_lock); + ++_M_ref_count; + __gthread_mutex_unlock(&_M_ref_count_lock); + } + + _RC_t + _M_decr() + { + __gthread_mutex_lock(&_M_ref_count_lock); + volatile _RC_t __tmp = --_M_ref_count; + __gthread_mutex_unlock(&_M_ref_count_lock); + return __tmp; + } + }; + + // Atomic swap on unsigned long + // This is guaranteed to behave as though it were atomic only if all + // possibly concurrent updates use _Atomic_swap. + // In some cases the operation is emulated with a lock. +#if defined (__GTHREAD_MUTEX_INIT) + // This could be optimized to use the atomicity.h abstraction layer. + // vyzo: simple _Atomic_swap implementation following the guidelines above + // We use a template here only to get a unique initialized instance. + template<int __dummy> + struct _Swap_lock_struct + { static __gthread_mutex_t _S_swap_lock; }; + + template<int __dummy> + __gthread_mutex_t + _Swap_lock_struct<__dummy>::_S_swap_lock = __GTHREAD_MUTEX_INIT; + + // This should be portable, but performance is expected to be quite + // awful. This really needs platform specific code. + inline unsigned long + _Atomic_swap(unsigned long * __p, unsigned long __q) + { + __gthread_mutex_lock(&_Swap_lock_struct<0>::_S_swap_lock); + unsigned long __result = *__p; + *__p = __q; + __gthread_mutex_unlock(&_Swap_lock_struct<0>::_S_swap_lock); + return __result; + } +#endif + + // 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. + +#if !defined(__GTHREAD_MUTEX_INIT) && defined(__GTHREAD_MUTEX_INIT_FUNCTION) + extern __gthread_mutex_t _GLIBCPP_mutex; + extern __gthread_mutex_t *_GLIBCPP_mutex_address; + extern __gthread_once_t _GLIBCPP_once; + extern void _GLIBCPP_mutex_init (void); + extern void _GLIBCPP_mutex_address_init (void); +#endif + + 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 (&_GLIBCPP_once, _GLIBCPP_mutex_init) != 0 + && __gthread_active_p ()) + abort (); + __gthread_mutex_lock (&_GLIBCPP_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. + _GLIBCPP_mutex_address = &_M_lock; + if (__gthread_once (&_M_once, _GLIBCPP_mutex_address_init) != 0 + && __gthread_active_p ()) + abort (); + _M_init_flag = 1; + } + __gthread_mutex_unlock (&_GLIBCPP_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 + + // A locking class that uses _STL_mutex_lock. The constructor takes a + // reference to an _STL_mutex_lock, and acquires a lock. The + // destructor releases the lock. It's not clear that this is exactly + // the right functionality. It will probably change in the future. + struct _STL_auto_lock + { + _STL_mutex_lock& _M_lock; + + _STL_auto_lock(_STL_mutex_lock& __lock) : _M_lock(__lock) + { _M_lock._M_acquire_lock(); } + + ~_STL_auto_lock() { _M_lock._M_release_lock(); } + + private: + void operator=(const _STL_auto_lock&); + _STL_auto_lock(const _STL_auto_lock&); + }; + +} // namespace std + +#endif |
