/**
* 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.engine.NetStrategies.RoutingStrategy;
import jmt.engine.QueueNet.JobClass;
import jmt.engine.QueueNet.NetNode;
import jmt.engine.QueueNet.NodeList;
import jmt.engine.random.engine.RandomEngine;
/**
* This class implements a random strategy: the output node
* is chosen with a random number
* @author Stefano Omini, Bertoli Marco
* @version 13/11/2005
* Reimplemented by Bertoli Marco to correct behaviour with closed classes and sinks
*/
public class RandomStrategy extends RoutingStrategy {
private RandomEngine randomEngine;
private int CLOSED_CLASS = JobClass.CLOSED_CLASS;
public RandomStrategy() {
randomEngine = RandomEngine.makeDefault();
}
/**
* Gets the output node, into which the job must be routed, using a random
* strategy.
* @param Nodes the list of output nodes
* @param jobClass class ofcurrent job to be routed
* @return The selected node.
*/
@Override
public NetNode getOutNode(NodeList Nodes, JobClass jobClass) {
int outNodes = Nodes.size();
// Find output node
NetNode output;
if (outNodes > 1) {
output = Nodes.get((int) Math.floor(randomEngine.raw() * outNodes));
} else {
output = Nodes.getFirst();
}
// Check to avoid discarding closed classes into a sink
if (jobClass.getType() == CLOSED_CLASS && output.isSink()) {
NetNode[] validOutputs = new NetNode[outNodes];
outNodes = 0; // Here outNodes is used as a counter to valid elements into valisOutputs array
for (int i = 0; i < Nodes.size(); i++) {
if (!Nodes.get(i).isSink()) {
validOutputs[outNodes++] = Nodes.get(i);
}
}
if (outNodes == 0) {
output = null;
} else if (outNodes == 1) {
output = validOutputs[0];
} else {
output = validOutputs[(int) Math.floor(randomEngine.raw() * outNodes)];
}
}
return output;
}
}