/*
* Copyright (c) 2002-2007 Sun Micro//Systems, Inc. All rights reserved.
*
* The Sun Project JXTA(TM) Software License
*
* 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 Sun Microsystems, Inc. for JXTA(TM) technology."
* 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.
*
* JXTA is a registered trademark of Sun Microsystems, Inc. in the United
* States and other countries.
*
* Please see the license information page at :
* <http://www.jxta.org/project/www/license.html> for instructions on use of
* the license in source files.
*
* ====================================================================
*
* 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.rpv;
import net.jxta.endpoint.EndpointService;
import net.jxta.endpoint.Message;
import net.jxta.endpoint.Messenger;
import net.jxta.endpoint.OutgoingMessageEvent;
import net.jxta.endpoint.OutgoingMessageEventListener;
import net.jxta.impl.util.TimeUtils;
import net.jxta.logging.Logging;
import net.jxta.protocol.RdvAdvertisement;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* An element of the PeerView.
*
* <p/>The destination address (peerID) is part of PeerViewDestination, which implements the
* comparable interface. That makes it possible to sort and create ordered lists of
* PeerViewElements, and to search these lists while knowing only a destination address.
*/
public final class PeerViewElement extends PeerViewDestination implements OutgoingMessageEventListener {
/**
* Logger
*/
private final static transient Logger LOG = Logger.getLogger(PeerViewElement.class.getName());
/**
* EndpointService that this PeerViewElement must use.
*/
private final EndpointService endpoint;
/**
* Absolute time in milliseconds at which this element was created.
*/
private final long created;
/**
* Absolute time in milliseconds at which this element was created.
*/
private long lastUpdate = 0;
/**
* The encapsulated RdvAdvertisement for the Peer this instance
* represents.
*/
private RdvAdvertisement radv = null;
/**
* True is the remote peer is known to be alive, false otherwise.
* It is always alive at birth. It may die soon after and we want to
* generate an event in that case.
*/
private boolean alive = true;
/**
* If true then we are not accepting new messages until something unclogs.
*/
private volatile boolean throttling = false;
/**
* PeerView that owns this PeerViewElement.
*/
private PeerView peerview = null;
/**
* A cached Messenger for sending to the destination peer.
*/
private Messenger cachedMessenger = null;
/**
* Initialize from a RdvAdvertisement.
*
* @param endpoint The endpoint service.
* @param radv the RdvAdvertisement from which to initialize
*/
PeerViewElement(EndpointService endpoint, RdvAdvertisement radv) {
super(radv.getPeerID());
this.endpoint = endpoint;
this.radv = radv;
created = TimeUtils.timeNow();
lastUpdate = created;
}
/**
* {@inheritDoc}
* <p/>
* A simple implementation for debugging. Do not attempt to parse this value!
*/
@Override
public String toString() {
StringBuilder asString = new StringBuilder();
asString.append('\"');
asString.append(radv.getName());
asString.append('\"');
asString.append(alive ? " A " : " a ");
asString.append(isInPeerView() ? " P " : " p ");
asString.append(throttling ? " T " : " t ");
asString.append(" [");
asString.append(TimeUtils.toRelativeTimeMillis(TimeUtils.timeNow(), created) / TimeUtils.ASECOND);
asString.append("/");
asString.append(TimeUtils.toRelativeTimeMillis(TimeUtils.timeNow(), lastUpdate) / TimeUtils.ASECOND);
asString.append("]");
return asString.toString();
}
/**
* {@inheritDoc}
*/
public void messageSendSucceeded(OutgoingMessageEvent e) {
// As far as we know, connectivity is fine.
setAlive(true, true);
throttling = false;
}
/**
* {@inheritDoc}
*/
public void messageSendFailed(OutgoingMessageEvent e) {
// As far as we know, connectivity is down.
// Except if failure is null; then it's just a queue overflow.
if (null != e.getFailure()) {
setAlive(false, true);
}
throttling = (e.getFailure() == null);
}
/**
* Return <code>true</code> if the remote peer is known to be alive,
* <code>false</code> otherwise.
*
* @return Return <code>true</code> if the remote peer is known to be
* alive, <code>false</code> otherwise.
*/
public boolean isAlive() {
return alive;
}
/**
* Update the connection status based upon the result of the last message
* send.
*
* <p/>We track the current dead-alive state and If we're in a peerview
* notify it of the transitions from alive to dead.
*
* @param live The known liveness of our connection to this peer.
* @param doNotify {@code true} will cause failure notifications to be sent.
* {@code false} makes notifications the caller's responsibility.
* @return {@code true} if a failure notification needs to be sent otherwise
* {@code false}.
*/
boolean setAlive(boolean live, boolean doNotify) {
boolean mustNotify;
synchronized (this) {
mustNotify = alive && !live;
alive = live;
}
// Since we do this out of sync, it is in theory possible that our alive
// status has already changed. It is rare but will only cause a little
// shake. So leave the sync behind, it causes a deadlock.
if (mustNotify && doNotify) {
PeerView temp = peerview;
if (null != temp) {
temp.notifyFailure(this, true);
}
}
return mustNotify;
}
boolean isInPeerView() {
return (null != peerview);
}
/**
* Sets the peerview
*/
synchronized void setPeerView(PeerView pv) {
if ((null != peerview) && (null != pv)) {
throw new IllegalStateException("Element already in " + peerview);
}
peerview = pv;
}
/**
* Return the time in absolute milliseconds at which we last updated this peer.
*/
long getLastUpdateTime() {
return lastUpdate;
}
/**
* Sets the time in absolute milliseconds at which we last updated this peer.
*/
void setLastUpdateTime(long last) {
lastUpdate = last;
}
/**
* Send a message to the peer which is represented by the current
* PeerViewElement.
*
* @param msg the message to send
*
* @param serviceName the service name on the destination peer to
* which the message will be demultiplexed
*
* @param serviceParam the service param on the destination peer
* to which the message will be demultiplexed
*
* @return true if the message was successfully handed off to the
* endpoint for delivery, false otherwise
*/
public boolean sendMessage(Message msg, String serviceName, String serviceParam) {
if (throttling) {
if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
LOG.warning("Declining to send -- throttling on " + this);
}
return false;
}
Messenger sendVia = getCachedMessenger();
if (null == sendVia) {
// There is nothing really we can do.
if (Logging.SHOW_WARNING && LOG.isLoggable(Level.WARNING)) {
LOG.warning("Could not get messenger for " + getPeerID());
}
OutgoingMessageEvent event = new OutgoingMessageEvent(msg,
new IOException("Couldn't get messenger for " + getPeerID()));
messageSendFailed(event);
return false;
}
sendVia.sendMessage(msg, serviceName, serviceParam, this);
return true;
}
/**
* Get the encapsulated Peer Advertisement.
*
* @return the Advertisement of the Peer represented by this
* object
*/
public RdvAdvertisement getRdvAdvertisement() {
return radv;
}
/**
* Set the encapsulated Peer Advertisement.
*
* @param adv is the RdvAdvertisement to be set.
* @return RdvAdvertisement the old Advertisement of the Peer represented by this
* object
*/
RdvAdvertisement setRdvAdvertisement(RdvAdvertisement adv) {
if (!radv.getPeerID().equals(adv.getPeerID())) {
if (Logging.SHOW_SEVERE && LOG.isLoggable(Level.SEVERE)) {
LOG.severe("adv refers to a different peer");
}
throw new IllegalArgumentException("adv refers to a different peer");
}
RdvAdvertisement old = radv;
this.radv = adv;
setLastUpdateTime(TimeUtils.timeNow());
return old;
}
/**
* Return a messenger suitable for sending to this peer.
*
* @return a messenger to this PVE peer or if {@code null} if peer is
* unreachable.
*/
private Messenger getCachedMessenger() {
boolean mustNotify = false;
synchronized (this) {
if ((null == cachedMessenger) || ((cachedMessenger.getState() & Messenger.USABLE) == 0)) {
cachedMessenger = null;
if (Logging.SHOW_FINE && LOG.isLoggable(Level.FINE)) {
LOG.fine("Getting cached Messenger for " + radv.getName());
}
cachedMessenger = endpoint.getMessengerImmediate(getDestAddress(), radv.getRouteAdv());
if (null == cachedMessenger) {
mustNotify = setAlive(false, false);
} else if ((cachedMessenger.getState() & Messenger.RESOLVED) != 0) {
mustNotify = setAlive(true, false);
}
}
}
// Since we do this out of sync, it is in theory possible that our alive
// status has already changed. It is rare but will only cause a little
// shake. So leave the sync behind, it causes a deadlock.
if (mustNotify) {
PeerView temp = peerview;
if (null != temp) {
temp.notifyFailure(this, true);
}
}
return cachedMessenger;
}
}