rdvconnection.java

jxta平台的开发包

/*
 *  $Id: RdvConnection.java,v 1.4 2006/05/30 21:01:51 hamada 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.edge;

import net.jxta.id.ID;
import net.jxta.impl.rendezvous.PeerConnection;
import net.jxta.impl.rendezvous.RendezVousServiceImpl;
import net.jxta.impl.util.TimeUtils;
import net.jxta.peergroup.PeerGroup;
import net.jxta.protocol.PeerAdvertisement;

import org.apache.log4j.Level;
import org.apache.log4j.Logger;


/**
 *  Manages a connection with a client or a rendezvous peer.
 */
public class RdvConnection extends PeerConnection {
    
    /**
     *  Log4J Logger
     */
    private final static transient Logger LOG = Logger.getLogger(RdvConnection.class.getName());
    
    protected long leasedTil;
    protected long beginRenewalAt;
    
    protected PeerAdvertisement cachedPeerAdvertisement = null;
    protected int cachedModCount = -1;
    
    /**
     *  Constructor for the PeerConnection object
     *
     * @param  group          group context
     * @param  rdvService     the rendezvous service to use for sending messages.
     * @param  peer         destination peerid
     * @param  leaseDuration  connection duration in relative milliseconds.
     */
    public RdvConnection(PeerGroup group, RendezVousServiceImpl rdvService, ID peer) {
        super(group, rdvService.endpoint, peer);
        
        cachedPeerAdvertisement = group.getPeerAdvertisement();
        cachedModCount = cachedPeerAdvertisement.getModCount();
    }
    
    /**
     *  {@inheritDoc}
     */
    public String toString() {
        return super.toString() + " / " + Long.toString(TimeUtils.toRelativeTimeMillis(beginRenewalAt));
    }
    
    public synchronized boolean peerAdvertisementHasChanged() {
        
        boolean changed = false;
        PeerAdvertisement currPeerAdv = group.getPeerAdvertisement();
        int currModCount = currPeerAdv.getModCount();
        
        if ((cachedPeerAdvertisement != currPeerAdv) || (cachedModCount != currModCount)) {
            
            if (LOG.isEnabledFor(Level.DEBUG)) {
                LOG.debug(
                        "PeerAdvertisement has changed :" + "\n\t" + System.identityHashCode(cachedPeerAdvertisement) + " != "
                        + System.identityHashCode(currPeerAdv) + "\n\t" + cachedModCount + " != " + currModCount);
            }
            
            // If our peer adv has changed, it is possible that our rdv has lost
            // all routes to us. Refresh its knowlege by reconnecting.
            
            cachedPeerAdvertisement = currPeerAdv;
            cachedModCount = currModCount;
            
            changed = true;
        }
        
        return changed;
    }
    
    /**
     *  {@inheritDoc}
     */
    protected void setLease(long leaseDuration) {
        setLease(leaseDuration, 0);
    }
    
    /**
     *  Set the lease duration in relative milliseconds.
     *
     *  @param  leaseDuration the lease duration in relative milliseconds.
     *  @param  earlyRenewal  amount of time in relative milliseconds before lease end to begin renewal
     */
    public void setLease(long leaseDuration, long earlyRenewal) {
        
        if (leaseDuration < earlyRenewal) {
            throw new IllegalArgumentException("Renewal scheduled before begining of lease");
        }
        
        super.setLease(leaseDuration);
        beginRenewalAt = TimeUtils.toAbsoluteTimeMillis(leaseDuration - earlyRenewal);
    }
    
    /**
     *  Declare that we are connected.
     */
    public void connect(PeerAdvertisement padv, long leaseDuration, long earlyRenewal) {
        super.connect(leaseDuration);
        
        setLease(leaseDuration, earlyRenewal);
        
        // We will almost certainly need a messenger soon. Get it now.
        getCachedMessenger(padv);
    }

    /**
     *  Time at which the lease needs renewal in absolute milliseconds.
     *
     *@return    The lease value
     */
    public long getRenewal() {
        return beginRenewalAt;
    }
}