rdvmonitor.java

jxme的一些相关程序,主要是手机上程序开发以及手机和计算机通信的一些程序资料,程序编译需要Ant支持

/**
 * $Id: RdvMonitor.java,v 1.2 2002/03/04 21:43:00 echtcherbina Exp $
 *
 * Copyright (c) 2001 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
 *    must not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 */

package net.jxta.impl.rendezvous;

import java.util.*;
import org.apache.log4j.Category; import org.apache.log4j.Priority;

import net.jxta.peer.*;
import net.jxta.protocol.*;
import net.jxta.document.*;
import net.jxta.rendezvous.*;
import net.jxta.discovery.*;
import net.jxta.peergroup.*;
import net.jxta.impl.peergroup.*;
import net.jxta.util.*;
import net.jxta.impl.util.*;

import java.io.*;

/**
 * This class implements a very simple RendezVousService Monitor
 */

public class RdvMonitor implements RendezVousMonitor, JxtaTimerHandler {
    private final static Category LOG = Category.getInstance(RdvMonitor.class.getName());

    // Must start worrying about renewing a lease 10 minutes before it
    // expires. Renewal is attempted at each iteration until it is
    // either safe again or expired.

    private final static long LeaseMargin = 10 * 60 * 1000;

    // LeaseRenewalDelay is the period of the timer that will renew the lease
    // to the rendezvous. We check every 2 minutes but renew only the
    // endangered ones.
    // If a rendezvous gives a lease less than that the delay
    // this client may lose the lease. A lease of less than 5 minutes does not
    // seem to make any sense, since some of the endpoint protocols have at
    // least a 2 minutes latency, 2 minutes should be safe enough.

    private final static long LeaseRenewalDelay = 2 * 60 * 1000;


    private PeerGroup group = null;
    private String gId = null;
    private DiscoveryService discovery = null;
    private long lease = 0;
    private JxtaTimer timer = null;
    private Vector rdvs = null;
    private RendezVousServiceImpl rendezvous = null;


    /**
     *Constructor for the RdvMonitor object
     *
     * @param  g           Description of Parameter
     * @param  rendezvous  Description of Parameter
     */
    public RdvMonitor(PeerGroup g, RendezVousServiceImpl rendezvous) {

        this.group = g;
        this.gId = g.getPeerGroupID().toString();
        this.rdvs = new Vector();
        this.timer = null;
        this.rendezvous = rendezvous;
        discovery = group.getDiscoveryService();

        if (group.isRendezvous()) {
            // This peer is a rendezvous for the group. Let's publish an rdv adv
            publishAdv((PeerID) group.getPeerID(), LeaseRenewalDelay);
        }
    }


    /**
     * This method is called by the RendezVousService service to notify the
     * monitor that a new RendezVousService has accepted the connection.
     *
     * @param  peer   is the PeerId of the new connect RendezVousService peer.
     * @param  lease  is the time in millisecond that the RendezVousService is
     * ready to serve.
     */
    public void connected(PeerID peer, long lease) {

        if (LOG.isDebugEnabled() ) {
         if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("connected: new connection to a RendezVousService");
         if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("   peer = " + peer.toString());
         if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("  lease = " + lease);
        }

        addRendezVous(peer.toString(), lease);

        // Publish locally an rendezvous advertisement for that rendezvous
        publishAdv(peer, lease);
    }


    /**
     * This method is called each time a RendezVousService peer is not
     * reachable anymore.
     *
     * @param  peer  is the PeerId of the RendezVousService peer.
     */
    public void disconnected(PeerID peer) {
        
        if (LOG.isDebugEnabled() ) {
         if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("disconnected with RendezVousService");
         if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("     peerId = " + peer.toString());
        }
    }


    /**
     * This method is called by the RendezVousService service in order
     * to provide advertisement about other RendezVousService peers.
     * This is usefull when a RendezVousService peer wants to balance its load
     * to other RendezVousService
     *
     * @param  adv  Description of Parameter
     */
    public void discovered(Advertisement adv) {

        if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("discovered: got new RendezVousService advertisement.");
        // Publish the rendez vous advertisement
        // First publish the advertisement
        if (discovery != null) {
            try {
                discovery.publish(adv, DiscoveryService.ADV);
            } catch (Exception e) {
            }
        }
    }


    /**
     *Description of the Method
     *
     * @param  timer  Description of Parameter
     */
    public synchronized void signal(JxtaTimer timer) {

        if (group.isRendezvous()) {
            // This peer is a rendezvous for the group. Let's publish an rdv adv
            publishAdv((PeerID) group.getPeerID(), LeaseRenewalDelay);
        }

        if (rdvs == null) {
            return;
        }

        RdV rdv = null;
        for (int i = 0; i < rdvs.size(); ++i) {
            try {
                rdv = (RdV) rdvs.elementAt(i);
                if (rdv.lease - System.currentTimeMillis() < LeaseMargin) {
                    rendezvous.reconnectToRendezVous(rdv.peer);
                }
            } catch (Exception e) {
                continue;
            }
        }
    }


    /**
     *Adds a feature to the RendezVousService attribute of the RdvMonitor object
     *
     * @param  peer   The feature to be added to the RendezVousService attribute
     * @param  lease  The feature to be added to the RendezVousService attribute
     */
    private synchronized void addRendezVous(String peer, long lease) {

        RdV rdv = new RdV(peer);
        if (rdvs.contains(rdv)) {
            // This is only a confirmation of a renewal of the lease.
            try {
                int index = rdvs.indexOf(rdv);
                if (index == -1) {
                    // This should not happen
                    if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("addRendezVous cannot access RdV object");
                    return;
                }
                rdv = (RdV) rdvs.elementAt(index);
            } catch (Exception e) {
                if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("addRendez failed [1] " + e);
            }
        } else {
            // This is a new Rendezvous
            rdvs.addElement(rdv);
        }
        // Set the lease
        long time = System.currentTimeMillis();
        if ( lease < 0) {
            // The rendez has given an infinite lease.
            // However, it is a good thing to still renew the lease once in a while
            lease = 60 * 60 * 1000;
            // 1 Hour
        }
        rdv.lease = time + lease;
        // Check if the timer thread is already started
        if (timer == null) {
            timer = new JxtaTimer(this, LeaseRenewalDelay, true);
        }
    }


    /**
     *Description of the Method
     *
     * @param  gid      Description of Parameter
     * @param  rdvid    Description of Parameter
     * @param  timeout  Description of Parameter
     * @return          Description of the Returned Value
     */
    private RdvAdvertisement createRdvAdv(PeerGroupID gid,
            PeerID rdvid,
            long timeout) {

        RdvAdvertisement adv = null;
        try {
            // Create a rendezvous advertisement
            adv = (RdvAdvertisement)
                    AdvertisementFactory.newAdvertisement(
                    RdvAdvertisement.getAdvertisementType());
        } catch (Exception all) {
            if (LOG.isEnabledFor(Priority.WARN)) LOG.warn("Advertisement document could not be created");
            return null;
        }

        adv.setGroupID(gid);
        adv.setPeerID(rdvid);

        return adv;
    }

    protected void startRdv() {
        publishAdv((PeerID) group.getPeerID(), LeaseRenewalDelay);
    }

    /**
     *Description of the Method
     *
     * @param  pid    Description of Parameter
     * @param  lease  Description of Parameter
     */
    private void publishAdv(PeerID pid, long lease) {
        if (LOG.isDebugEnabled() ) {
         if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("Publish RdvAdvertisement:");
         if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("        gid = " + group.getPeerGroupID().toString());
         if (LOG.isEnabledFor(Priority.DEBUG)) LOG.debug("        pid = " + pid.toString());
        }

        RdvAdvertisement rdv =
            createRdvAdv((PeerGroupID) group.getPeerGroupID(),
                         pid,
                         lease);
        if (rdv == null) {
            return;
        }

        // Publish into the parent group.
        RefPeerGroup parent = ((GenericPeerGroup) group).getParentGroup();
        if (parent == null) {
            // No parent... nothing to do.
            return;
        }
        DiscoveryService parentDiscovery = parent.getDiscoveryService();
        if (parentDiscovery == null) {
            if (LOG.isEnabledFor(Priority.WARN)) LOG.warn("Cannot access parent's DiscoveryService Service");
            return;
        }

        try {
            parentDiscovery.publish(rdv,
				    DiscoveryService.ADV,
				    lease,
				    lease);
        } catch (IOException e) {
            if (LOG.isEnabledFor(Priority.WARN)) LOG.warn("Cannot locally publish advertisement");
        }
    }

    /**
     *Description of the Class
     */
    public class RdV {

        /**
         *Description of the Field
         */
        protected String peer;
        /**
         *Description of the Field
         */
        protected long lease;


        /**
         *Constructor for the RdV object
         *
         * @param  peer  Description of Parameter
         */
        public RdV(String peer) {

            this.peer = peer;
            this.lease = 0;
        }


        /**
         *Description of the Method
         *
         * @param  obj  Description of Parameter
         * @return      Description of the Returned Value
         */
        public boolean equals(Object obj) {

            RdV rdv = (RdV) obj;
            return (rdv.peer.equals(peer));
        }
    }

}