join.java

一个用于排队系统仿真的开源软件,有非常形象的图象仿真过程!

/**
 * 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.NodeSections;

import jmt.common.exception.NetException;
import jmt.engine.QueueNet.*;

import java.util.HashMap;

/**
 * <p>Title: Join</p>
 * <p>Description: This class is a Join input section, used to re-assemble previously
 * forked jobs. Jobs are kept until all fragments are collected. If a not-fragmented
 * job is received, it is simply routed to service section.</p>
 *
 * @author Bertoli Marco
 *         Date: 13-mar-2006
 *         Time: 16.19.58
 */
public class Join extends InputSection {
    /** Data structure used to store received fragments for each job */
    private HashMap jobs;


// --- Constructors -----------------------------------------------------------------------------
    /**
     * Constructs a new Join
     */
    public Join() {
        // Disables automatic handling of jobinfolists
        super(false);
        jobs = new HashMap();
    }
// ----------------------------------------------------------------------------------------------

    /**
     * Assemples splitted jobs and sends an EVENT_JOIN to reference fork when done
     *
     * @param message message to be processed.
     * @throws NetException if something goes wrong
     * @return message processing result.
     */
    protected int process(NetMessage message) throws NetException {
        switch(message.getEvent()) {
            case NetEvent.EVENT_JOB:
                Job job = message.getJob();
                // Sends ACK back
                send(NetEvent.EVENT_ACK, job, 0.0, message.getSourceSection(), message.getSource());

                if (job instanceof ForkJob) {
                    ForkJob fJob = (ForkJob) job;

                    // Removes job from global node list
                    JobInfoList info = getOwnerNode().getJobInfoList();
                    JobInfo jobData = info.lookFor(job);
                    if (jobData != null)
                        info.remove(jobData);

                    // Removes job from system list
                    GlobalJobInfoList global = getOwnerNode().getQueueNet().getJobInfoList();
                    global.removeForkedJob(fJob);

                    // Needed pieces
                    int needed;
                    if (jobs.containsKey(fJob.getForkedJob()))
                        needed = ((Integer)jobs.get(fJob.getForkedJob())).intValue();
                    else {
                        needed = fJob.getForkedNumber();
                        // As we are waiting for other fragments, adds merged job to global and local info list
                        JobInfo merged = new JobInfo(fJob.getForkedJob());
                        info.add(merged);
                        jobsList.add(merged);
                    }
                    // Decrement needed as we received this job
                    needed--;

                    // If needed is zero, all pieces has been retrived and job can be
                    // fowarded
                    if (needed == 0) {
                        jobs.remove(fJob.getForkedJob());
                        // Adds original job, otherwise we will have one less job in the network
                        global.addForkedJob(fJob.getForkedJob());
                        // Sends job forward
                        sendForward(fJob.getForkedJob(), 0.0);
                        // Notify fork node (to support blocking)
                        send(NetEvent.EVENT_JOIN, fJob.getForkedJob(), 0.0,
                                fJob.getReferenceFork().getSectionID(),
                                fJob.getReferenceFork().getOwnerNode());
                    }
                    else
                        // We must wait for more fragments before sending this to
                        // next section
                        jobs.put(fJob.getForkedJob(), new Integer(needed));
                }
                else
                    // If this is not a fork job, sends it forward
                    sendForward(job, 0.0);

                break;
            case NetEvent.EVENT_ACK:
                break;
        }

        // Everything was okay
        return MSG_PROCESSED;
    }


}