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/* -*-c++-*-
*
* $Id: Mutex.h,v 1.1.1.1 2003/02/08 00:42:21 dairiki Exp $
*
* Copyright (C) 2003 Geoffrey T. Dairiki
*
* This file is part of Pyxine, Python bindings for xine.
*
* Pyxine 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
* of the License, or (at your option) any later version.
*
* Pyxine 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 program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#pragma interface
#ifndef _Mutex_H
#define _Mutex_H
#include "pxlib.h"
extern "C" {
# include <pthread.h>
}
BEGIN_PXLIB_NAMESPACE
class Mutex
{
private:
pthread_mutex_t m;
public:
Mutex() { pthread_mutex_init(&m, NULL); }
~Mutex() { pthread_mutex_destroy(&m); }
operator pthread_mutex_t * () { return &m; }
};
class MutexLock
{
struct lock_t {
pthread_mutex_t * mp;
int ref_cnt;
lock_t(pthread_mutex_t * _mp)
: mp(_mp), ref_cnt(1)
{ pthread_mutex_lock(mp); }
~lock_t() { pthread_mutex_unlock(mp); }
};
lock_t * lock;
public:
MutexLock() : lock(0) {}
MutexLock(pthread_mutex_t * m) : lock(new lock_t(m)) {}
MutexLock(Mutex * m) : lock(new lock_t(*m)) {}
MutexLock(const MutexLock& l) : lock(l.lock) {
if (lock)
lock->ref_cnt++;
}
MutexLock& operator= (const MutexLock& l) {
if (lock && --lock->ref_cnt == 0)
delete lock;
lock = l.lock;
if (lock)
lock->ref_cnt++;
return *this;
}
~MutexLock () {
if (lock && --lock->ref_cnt == 0)
delete lock;
}
};
/** A atomic data item.
*
* The data contained within is protected by a mutex, so that
* access to the data is guaranteed to be atomic.
*/
template <class T>
class atomic
{
public:
typedef T data_type;
private:
data_type value;
mutable Mutex mutex;
public:
atomic() {}
atomic(const data_type& x) : value(x) {}
atomic(const atomic& a) : value(a) {}
/** Assigment.
*
* Data only comes in with the mutex held.
*/
atomic& operator= (const data_type& new_value) {
MutexLock l(mutex);
value = new_value;
return *this;
}
/** Update value.
*
* Update the value.
*
* @return True iff the update changed the value.
*/
bool update (const data_type& new_value) {
MutexLock l(mutex);
bool changed = value != new_value;
if (changed)
value = new_value;
return changed;
}
/**
* Conversion to data_type.
*
* This is the only way to access the data.
*/
operator data_type () const {
MutexLock l(mutex);
return value;
}
};
END_PXLIB_NAMESPACE
#endif // !_Mutex_H
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