delayedshortestqlength.java

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/**    
  * Copyright (C) 2006, Laboratorio di Valutazione delle Prestazioni - Politecnico di Milano

  * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
  
package jmt.engine.NetStrategies.RoutingStrategies;

import jmt.common.exception.NetException;
import jmt.engine.NetStrategies.RoutingStrategy;
import jmt.engine.QueueNet.JobClass;
import jmt.engine.QueueNet.NetNode;
import jmt.engine.QueueNet.NodeList;
import jmt.engine.QueueNet.NodeSection;
import jmt.engine.random.engine.RandomEngine;


/**
 * <p>Title:</p>
 * <p>Description:</p>
 * 
 * @author Bertoli Marco
 *         Date: 16-nov-2005
 *         Time: 14.27.27
 * TODO provvisoria per testing
 */
public class DelayedShortestQLength extends RoutingStrategy {
    private byte inputSection = NodeSection.INPUT;
    private byte serviceSection = NodeSection.SERVICE;
    private int property = NodeSection.PROPERTY_ID_RESIDENT_JOBS;
    private RandomEngine random = RandomEngine.makeDefault();
    private int num = 0;
    private int[] qlen, newQlen;

    /**
     * This method should be overridden to implement a specific strategy.
     *
     * @param Nodes    List of nodes.
     * @param jobClass class ofcurrent job to be routed
     * @return Selected node .
     */
    public NetNode getOutNode(NodeList Nodes, JobClass jobClass) {
        int shortestQueue;
        if (qlen == null) {
            qlen = new int[Nodes.size()];
            newQlen = new int[Nodes.size()];
        }
        int[] next = new int[qlen.length];
        try {
            // Simulate delay (need to be reimplemented if used)
            num++;
            if (num == 1)
                for (int i=0; i<Nodes.size(); i++)
                    newQlen[i] = Nodes.get(i).getSection(inputSection).getIntSectionProperty(property)
                        + Nodes.get(i).getSection(serviceSection).getIntSectionProperty(property);
            if (num > 8) // 2 sec.
                num = 0;
            else if  (num > 4) { // approx 1 sec passed TODO occorre implementare un giusto test con il calendario
               qlen = newQlen;
               newQlen = new int[Nodes.size()];
            }

            // Finds shortest queue in stored array
            int cur = 1;
            next[0] = 0;
            shortestQueue = qlen[0];
            for (int i=1; i<qlen.length; i++) {
                if (qlen[i] < next[0]) {
                    next[0] = qlen[i];
                    cur = 1;
                }
                else if (qlen[i]==next[0])
                    next[cur++]=i;
            }
            if (cur == 1)
                return Nodes.get(next[0]);
            else
                return Nodes.get(next[(int)Math.floor(random.raw() * cur)]);
        } catch (NetException e) {
            System.out.println("Error: ");
            e.printStackTrace();
        }
        return null;
    }
}