237 lines
8.0 KiB
C
237 lines
8.0 KiB
C
|
// 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
|