riprouter.java

中間件開發详细说明：清华大学J2EE教程讲义（ppt）-Tsinghua University J2EE tutorial lectures (ppt) [上载源码成为会员下载此源码] [成为VIP会

        // log / record ....
        if (super.reportWriter_ != null)
        {
            super.write("");
            super.write("receive incoming, " + pkt + ", delay, " + nextTime);
            super.write("break this packet into, " + numPackets);
        }

        // break a large packet into smaller ones that fit into MTU
        // by making null or empty packets except for the last one
        for (int i = 0; i < numPackets - 1; i++)
        {
            NetPacket np = new NetPacket(null, pkt.getID(), MTU, tag,
                                         pkt.getSrcID(), pkt.getDestID(),
                                         pkt.getNetServiceType(),i+1,numPackets);

            np.setLast(id);
            super.write("enqueing, " + np);
            sched.enque(np);  // put the packet into the scheduler
        }

        // put the actual packet into the last one and resize it accordingly
        pkt.setLast(id);
        pkt.setSize(pkt.getSize() - MTU * (numPackets - 1));
        super.write("enqueing, " + pkt);
        sched.enque(pkt);  // put the packet into the scheduler
    }

    /**
     * Gets the link's name for a given id
     * @param destID    a destination id
     * @return the link's man
     * @pre destID > 0
     * @post $none
     */
    private synchronized String getLinkName(int destID)
    {
        String destName = GridSim.getEntityName(destID);
        String linkName = null;

        //directly connected
        if (hostTable.containsValue(destName)) {
            linkName = (String)linkTable.get(destName);
        }
        else
        {
            // need to forward to another router
            Object[] data = (Object[]) forwardTable.get(destName);
            String router = (String) data[0];
            linkName = (String) linkTable.get(router);
        }

        return linkName;
    }

    /**
     * Returns the Scheduler associated with a packet.
     *
     * @param np NetPacket for which the associated scheduler is to be returned
     * @return the packet's scheduler or <tt>null</tt> if the packet is empty
     * @pre np != null
     * @post $none
     */
    public PacketScheduler getScheduler(Packet np)
    {
        if (np == null) {
            return null;
        }

        String destName = GridSim.getEntityName( np.getDestID() );
        return getScheduler(destName);
    }

    /**
     * Returns the Scheduler that the router would use to reach a particular
     * destination. This can be used to set weigths, priorities etc. as the
     * case may be on the Scheduler
     *
     * @param dest id of the destination for which the Scheduler is required.
     * @return the destination's packet scheduler
     * @pre dest > 0
     * @post $none
     */
    public PacketScheduler getScheduler(int dest)
    {
        if (dest < 0) {
            return null;
        }

        String destName = GridSim.getEntityName(dest);
        return getScheduler(destName);
    }

    /**
     * Returns the Scheduler that the router would use to reach a particular
     * destination. This can be used to set weigths, priorities etc. as the
     * case may be on the Scheduler
     *
     * @param dest Name of the destination for which the Scheduler is required.
     * @return destination's packet scheduler or <tt>null</tt> if destination
     *         name is invalid.
     * @pre dest != null
     * @post $none
     */
    public PacketScheduler getScheduler(String dest)
    {
        if (dest == null || dest.length() == 0) {
            return null;
        }

        PacketScheduler sched = null;
        try
        {
            if ( hostTable.containsValue(dest) )
            {
                String linkName = (String) linkTable.get(dest);
                sched = (PacketScheduler) schedTable.get(linkName);
            }
            else
            {
                // need to forward to another router
                Object[] data = (Object[]) forwardTable.get(dest);

                // in case the forwarding table is incomplete
                if (data == null) {
                    return null;
                }

                String router = (String) data[0];
                String linkName = (String) linkTable.get(router);
                sched = (PacketScheduler) schedTable.get(linkName);
            }
        }
        catch (Exception e) {
            sched = null;
        }

        return sched;
    }

    /**
     * Processes internal event
     * @param ev    a Sim_event object
     * @pre ev != null
     * @post $none
     */
    private synchronized void processInternalEvent(Sim_event ev)
    {
        PacketScheduler sched = (PacketScheduler) ev.get_data();
        dequeue(sched);
    }

    /**
     * Dequeue a packet from the scheduler and sends it to the next
     * destination via a link.
     * @param sched  the packet scheduler
     * @pre sched != null
     * @post $none
     */
    private synchronized void dequeue(PacketScheduler sched)
    {
        Packet np = sched.deque();

        // process ping() packet
        if (np instanceof InfoPacket) {
            ((InfoPacket) np).addExitTime( GridSim.clock() );
        }

        super.write("dequeuing, " + np);

        // must distinguish between normal and junk packet
        int tag = GridSimTags.PKT_FORWARD;
        if (np.getTag() == GridSimTags.JUNK_PKT) {
            tag = GridSimTags.JUNK_PKT;
        }

        // sends the packet via the link
        String linkName = getLinkName( np.getDestID() );
        super.sim_schedule(GridSim.getEntityId(linkName),
                           GridSimTags.SCHEDULE_NOW, tag, np);

        // process the next packet in the scheduler
        if ( !sched.isEmpty() )
        {
            double nextTime = (np.getSize() * BITS) / sched.getBaudRate();
            sendInternalEvent(nextTime, sched);
        }
    }

    /**
     * Sends an internal event to itself
     * @param time  the delay time period
     * @param data  the data to be sent
     * @return <tt>true</tt> if it is successful, <tt>false</tt> otherwise
     * @pre time >= 0
     * @post $none
     */
    private synchronized boolean sendInternalEvent(double time, Object data)
    {
        if (time < 0.0) {
            return false;
        }

        super.sim_schedule(id, time, GridSimTags.INSIGNIFICANT, data);
        return true;
    }

    /**
     * Prints this router's routing table in a nice-formatted layout
     * @pre $none
     * @post $none
     */
    public synchronized void printRoutingTable()
    {
        synchronized (System.out)
        {
            System.out.println();
            System.out.println("--- Routing Table for " +
                               super.get_name() + " ---");

            for (Enumeration e = hostTable.keys(); e.hasMoreElements(); )
            {
                String link = (String) e.nextElement();
                System.out.println(hostTable.get(link) + "\t\t" + link);
            }

            for (Enumeration e = forwardTable.keys(); e.hasMoreElements(); )
            {
                String host = (String)e.nextElement();
                Object[] data = (Object[])forwardTable.get(host);
                String nextHop = (String)data[0];
                System.out.println(host + "\t\t" + nextHop);
            }

            System.out.println("-------------------------------------");
            System.out.println();
        }
    }


    //----------- ADVERTISING FUNCTIONS --------------//

    /**
     * All hosts connected to this router are advertised to adjacent routers
     * @pre $none
     * @post $none
     */
    protected synchronized void advertiseHosts()
    {
        Collection hosts = hostTable.values(); // who to advertise
        Enumeration routers = routerTable.elements();

        while ( routers.hasMoreElements() )
        {
            RIPAdPack ad = new RIPAdPack(super.get_name(), hosts);
            String router = (String) routers.nextElement();
            super.write("advertise to router, " + router);
            sim_schedule(Sim_system.get_entity_id(router),
                         GridSimTags.SCHEDULE_NOW, GridSimTags.ROUTER_AD, ad);
        }

        super.sim_pause(5);   // wait for 5 secs to gather the results
    }

    /**
     * When an ad is recieved, the forwarding table is updated. After that we
     * need to propogate this ad along all links except the incoming one.
     * {@link #forwardAd(RIPAdPack)} is used for that
     * @param ev  a Sim_event object
     * @pre ev != null
     * @post $none
     */
    private synchronized void receiveAd(Sim_event ev)
    {
        super.write("receive router ad from, "+GridSim.getEntityName(ev.get_src()));

        // what to do when an ad is received
        RIPAdPack ad = (RIPAdPack)ev.get_data();

        // prevent count-to-infinity
        if (ad.getHopCount() > 15) {
            return;
        }

        String sender = ad.getSender();
        Iterator it = ad.getHosts().iterator();

        while ( it.hasNext() )
        {
            String host = (String) it.next();

            if ( host.equals(super.get_name()) ) {
                continue;
            }

            if (hostTable.containsValue(host)) { // direct connection
                continue;
            }

            if (forwardTable.containsKey(host))
            {
                Object[] data = (Object[])forwardTable.get(host);
                int hop = ((Integer)data[1]).intValue();

                if ((hop) > ad.getHopCount())
                {
                    Object[] toPut = { sender, new Integer(ad.getHopCount()) };
                    forwardTable.put(host, toPut);
                }
            }
            else
            {
                Object[] toPut = { sender, new Integer(ad.getHopCount()) };
                forwardTable.put(host, toPut);
            }
        }

        forwardAd(ad);
    }

    /**
     * Received ads should be forwarded along all links except the incoming
     * one. Also need to change id to onself
     *
     * @param ad    a RIPAdPack object
     * @pre ad != null
     * @post $none
     */
    private synchronized void forwardAd(RIPAdPack ad)
    {
        String sender = ad.getSender();
        ad.incrementHopCount();
        RIPAdPack newad = new RIPAdPack(super.get_name(),ad.getHosts());
        newad.setHopCount(ad.getHopCount());

        Enumeration routers = routerTable.elements();
        while ( routers.hasMoreElements() )
        {
            String router = (String)routers.nextElement();
            if (!router.equals(sender))
            {
                sim_schedule(Sim_system.get_entity_id(router),
                      GridSimTags.SCHEDULE_NOW, GridSimTags.ROUTER_AD, newad);
            }
        }
    }

} // end class