devel/libmdw/trunk/libmdw/src/ObjectPool.h

/***************************************************************************
 *   Copyright (C) 2010 by Jean-Baptiste Wons   *
 *   wonsjb@gmail.com   *
 *                                                                         *
 *   This program 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.                                   *
 *                                                                         *
 *   This program 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.             *
 ***************************************************************************/
#ifndef MDWOBJECTPOOL_H
#define MDWOBJECTPOOL_H

namespace mdw
{

template<class T>
class ObjectPool
{
public:
    // size must be a power of 2
    ObjectPool (int size);

    ~ObjectPool();

    T& obtain();
    void release (T& object);
    int availableObjects();

private:
    T ** _pool;
    int _begin;
    int _end;
    int _size;
    int _mask;
};

template <class T>
ObjectPool<T>::ObjectPool (int size)
{
    _pool = new T*[size];
    _begin = 0;
    _end = size;
    _size = size;
    _mask = (size << 1) - 1;
    for (int i = 0; i < size; ++i)
    {
        _pool[i] = new T();
    }
}

template <class T>
ObjectPool<T>::~ObjectPool()
{
    for (int i = 0; i < _size; ++i)
    {
        delete _pool[i];
    }

    delete[] _pool;
}

template<class T>
T& ObjectPool<T>::obtain()
{
    if (_end != _begin)
    {
        int pos = _begin;
        ++_begin;
        _begin &= _mask;
        return *_pool[pos];
    }
}

template <class T>
void ObjectPool<T>::release (T& object)
{
    if (_end <= (_begin + _size))
    {
        _pool[_end] = &object;
        ++_end;
        _end &= _mask;
    }
}

template <class T>
int ObjectPool<T>::availableObjects()
{
    return (_end > _begin) ? _end - _begin : _end - _begin + _size;
}

}

#endif

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