floodingrouter.java

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/*
 * ** Network and Service Differentiation Extensions to GridSim 3.0 **
 *
 * Gokul Poduval & Chen-Khong Tham
 * Computer Communication Networks (CCN) Lab
 * Dept of Electrical & Computer Engineering
 * National University of Singapore
 * August 2004
 *
 * Licence: GPL - http://www.gnu.org/copyleft/gpl.html
 *
 * FloodingRouter.java - Simulates a network router with Flooding as
 * the advertising protocol
 *
 */
package gridsim.net;

import eduni.simjava.*;
import gridsim.*;
import gridsim.util.*;
import java.util.*;


/**
 * This class implements a Router using a form of Flooding for routing.
 * The routing protocol is run before Gridlets etc. can be
 * submitted.
 * <p>
 * In case there are more than two routes to a destination, the
 * route with the lower hopcount is used. Since in this simulation routers
 * relay perfect information and links do not break down, flooding should be a
 * reliable protocol to use.
 *
 * @invariant $none
 * @since GridSim Toolkit 3.1
 * @author Gokul Poduval & Chen-Khong Tham, National University of Singapore
 */
public class FloodingRouter extends Router
{
    private Hashtable linkTable;
    private Hashtable schedTable; // table of schedulers
    private Hashtable hostTable;
    private Hashtable routerTable;
    private Hashtable forwardTable;
    private int id;
    private static final int BITS = 8;     // 1 byte in bits


    /**
     * Creates a new FloodingRouter object. By default,
     * <b>no recording or logging</b>
     * is done for packets' activities. If you want to log operations of this
     * entity, please use {@link #FloodingRouter(String, boolean)}.
     *
     * @param name Name of this router
     * @throws NullPointerException This happens when name is empty or null
     * @see #FloodingRouter(String, boolean)
     * @pre name != null
     * @post $none
     */
    public FloodingRouter(String name) throws NullPointerException {
        this(name, false);
    }

    /**
     * Creates a new FloodingRouter object with logging facility if it
     * is turned on.
     * <br>
     * NOTE: If logging facility is turned on, there are some overheads
     * in terms of performance and memory consumption.
     *
     * @param name      Name of this router
     * @param trace     <tt>true</tt> if you want to record this router's
     *                  activity, <tt>false</tt> otherwise
     * @throws NullPointerException This happens when name is empty or null
     * @pre name != null
     * @post $none
     */
    public FloodingRouter(String name, boolean trace) throws
                          NullPointerException
    {
        super(name, trace);
        init();
    }

    /**
     * Initialises all variables
     * @pre $none
     * @post $none
     */
    private void init()
    {
        this.id = super.get_id();
        linkTable = new Hashtable();
        hostTable = new Hashtable();
        routerTable = new Hashtable();
        forwardTable = new Hashtable();
        schedTable = new Hashtable();
    }

    /**
     * Informs the registered entities regarding to the end of a simulation.
     * @pre $none
     * @post $none
     */
    protected void processEndSimulation() {
        // ... empty - maybe need to clean up all the hashtables
    }

    /**
     * Joins two routers with a Link.
     * @param router    The router on the other side to which this one will
     *                  be attached.
     * @param link      This is the link that will be used to connect the two
     *                  routers.
     * @param thisSched The scheduling policy used on this routers egress port
     *                  when sending data through it.
     * @param otherSched    The scheduling policy that will be used on the
     *                      egress port of the router being connected to when
     *                      sending data to this router.
     * @pre router != null
     * @pre link != null
     * @pre thisSched != null
     * @pre otherSched != null
     * @post $none
     */
    public void attachRouter(Router router, Link link,
                    PacketScheduler thisSched, PacketScheduler otherSched)
    {
        String msg = super.get_name() + ".attachRouter(): Error - ";
        if (router == null)
        {
            System.out.println(msg + "the router is null.");
            return;
        }

        if (link == null)
        {
            System.out.println(msg + "the link is null.");
            return;
        }

        if (thisSched == null || otherSched == null)
        {
            System.out.println(msg +
                    "the one or more packet schedulers are null.");
            return;
        }

        thisSched.setBaudRate( link.getBaudRate() );
        otherSched.setBaudRate( link.getBaudRate() );

        link.attach(this, router);
        this.attachRouter(router, link, thisSched);
        router.attachRouter(this, link, otherSched);
    }

    /**
     * Joins two routers together. This is called by the routers themselves
     * and should not be called by other entities.
     *
     * @param router    The Router to which this router will be connected.
     * @param link      The Link that will be used to join these routers.
     * @param sched     The scheduling policy used on the egress port of the
     *                  router when sending data through this route.
     * @pre router != null
     * @pre link != null
     * @pre sched != null
     * @post $none
     */
    public void attachRouter(Router router, Link link, PacketScheduler sched)
    {
        String msg = super.get_name() + ".attachRouter(): Error - ";
        if (router == null)
        {
            System.out.println(msg + "the router is null.");
            return;
        }

        if (link == null)
        {
            System.out.println(msg + "the link is null.");
            return;
        }

        if (sched == null)
        {
            System.out.println(msg + "the packet scheduler is null.");
            return;
        }

        linkTable.put(router.get_name(), link.get_name());

        if (!schedTable.containsKey( link.get_name()) ) {
            schedTable.put(link.get_name(), sched);
        }

        routerTable.put( link.get_name(), router.get_name() );
        hostTable.put( link.get_name(), router.get_name() );

        // logging or recording ...
        if (reportWriter_ != null)
        {
            StringBuffer sb = null;
            sb = new StringBuffer("attach this ROUTER, with router, ");
            sb.append( router.get_name() );
            sb.append(", with link, ");
            sb.append( link.get_name() );
            sb.append(", with packet scheduler, ");
            sb.append( sched.getSchedName() );

            super.write( sb.toString() );
        }
    }

    /**
     * Attaches an entity to this router. The link between the router and the
     * entity being attached is taken from
     * {@link gridsim.GridSimCore#getLink()}.
     *
     * @param entity    The entity to be attached.
     * @param sched     The scheduling policy that will be used on the egress
     *                  port when the router sends data to the entity being
     *                  joined.
     * @see gridsim.GridSimCore#getLink()
     * @pre entity != null
     * @pre sched != null
     * @post $none
     */
    public void attachHost(GridSimCore entity, PacketScheduler sched)
    {
        String msg = super.get_name() + ".attachHost(): Error - ";
        if (entity == null)
        {
            System.out.println(msg + "the entity is null.");
            return;
        }

        if (sched == null)
        {
            System.out.println(msg + "the packet scheduler is null.");
            return;
        }

        Link link = entity.getLink();
        sched.setBaudRate( link.getBaudRate() );
        link.attach(this, entity);
        linkTable.put( entity.get_name(), link.get_name() );

        if (!schedTable.containsKey( link.get_name() )) {
            schedTable.put(link.get_name(), sched);
        }

        hostTable.put( link.get_name(), entity.get_name() );

        // recording ...
        if (reportWriter_ != null)
        {
            StringBuffer sb = null;
            sb = new StringBuffer("attach this ROUTER, to entity, ");
            sb.append( entity.get_name() );
            sb.append(", with packet scheduler, ");
            sb.append( sched.getSchedName() );

            super.write( sb.toString() );
        }
    }

    /**
     * Processes incoming events
     * @param ev    a Sim_event object
     * @pre ev != null
     * @post $none
     */
    protected synchronized void processEvent(Sim_event ev)
    {
        switch ( ev.get_tag() )
        {
            case GridSimTags.PKT_FORWARD:
            case GridSimTags.JUNK_PKT:
                processNetPacket(ev, ev.get_tag());
                break;

            case GridSimTags.ROUTER_AD:
                receiveAd(ev);
                break;

            case GridSimTags.INSIGNIFICANT:
                processInternalEvent(ev);
                break;

            default:
                System.out.println(super.get_name() + ".body(): Unable to " +
                        "handle request from GridSimTags " +
                        "with constant number " + ev.get_tag() );
                break;
        }
    }

    /**
     * Processes incoming network packets, one at a time.
     * The incoming packet will be split up into smaller pieces if
     * the packet size > MTU of the other end.
     *
     * @param ev    a Sim_event object
     * @pre ev != null
     * @post $none
     */
    private synchronized void processNetPacket(Sim_event ev, int tag)
    {
        double nextTime = 0;
        Packet pkt = (Packet) ev.get_data();
        PacketScheduler sched = getScheduler(pkt);

        // if a packet scheduler is not found, then try reschedule this packet
        // in the future
        if (sched == null)
        {
            System.out.println(super.get_name() + ".processNetPacket(): " +
                "Warning - can't find a packet scheduler for " + pkt);
            System.out.println("-> Will reschedule it again in the future.");

            super.sim_schedule(super.get_id(), Router.DELAY, tag, pkt);
            return;
        }

        // process ping() request
        if (pkt instanceof InfoPacket)
        {
            ((InfoPacket) pkt).addHop(id);
            ((InfoPacket) pkt).addEntryTime( GridSim.clock() );
            ((InfoPacket) pkt).addBaudRate(sched.getBaudRate());
        }

        // check downlink MTU, and split accordingly
        String linkName = getLinkName( pkt.getDestID() );
        Link downLink = (Link) Sim_system.get_entity(linkName);
        int MTU = downLink.getMTU();
        int numPackets = (int) Math.ceil(pkt.getSize() / (MTU * 1.0));

        // if no packets at the moment
        if (sched.size() == 0)
        {
            if (numPackets == 1) {
                nextTime = (pkt.getSize() * BITS) / sched.getBaudRate();
            }
            else {
                nextTime = (MTU * BITS * 1.0) / sched.getBaudRate();
            }

            sendInternalEvent(nextTime, sched);
        }