/**
* 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.QueuePutStrategies;
import java.util.List;
import java.util.ListIterator;
import jmt.engine.NetStrategies.QueuePutStrategy;
import jmt.engine.QueueNet.Job;
import jmt.engine.QueueNet.JobInfo;
import jmt.engine.QueueNet.JobInfoList;
import jmt.engine.QueueNet.NetNode;
import jmt.engine.QueueNet.NodeSection;
/**
* This class implements a specific queue put strategy: all arriving jobs
* are ordered according JobClass priorities. Between jobs of the same
* priority level, the last come is put at the beginning.
* @author Stefano Omini
*/
public class HeadStrategyPriority implements QueuePutStrategy {
/** This method should be overridden to implement a specific job strategy.
* @param job Job to be added to the queue.
* @param queue Queue.
* @param sourceSection Job source section.
* @param sourceNode Job source node.
* @param callingSection The section which calls this strategy.
*/
public void put(Job job, JobInfoList queue, byte sourceSection, NetNode sourceNode, NodeSection callingSection) {
//priority of this job
int priority = job.getJobClass().getPriority();
//list of jobs in queue
List<JobInfo> list = queue.getJobList();
if (list.size() == 0) {
//empty list: add first in general and class lists
queue.addFirst(new JobInfo(job), false);
return;
}
//else creates an iterator and find the correct position
//according to the job priority
ListIterator<JobInfo> iterator = list.listIterator();
JobInfo current = null;
int currentJobPriority = 0;
int index = -1;
//iterator starts from the first (i.e. the job with highest priority)
while (iterator.hasNext()) {
index++;
current = iterator.next();
currentJobPriority = current.getJob().getJobClass().getPriority();
if (priority >= currentJobPriority) {
//the job to be added must be inserted before the current job
//(because has greater priority or has equal priority but it is the last come)
//index is the position of the current element, which will be shifted together
//with the following ones
queue.add(index, new JobInfo(job), false);
return;
}
//else if priority is lower than current, continue iteration
}
//exiting from the "while" means that the job to be inserted is the job with
//lowest priority
//add last
queue.addLast(new JobInfo(job), false);
return;
}
/* (non-Javadoc)
* @see jmt.common.AutoCheck#check()
*/
public boolean check() {
return true;
}
}