/*
* Mojito Distributed Hash Table (Mojito DHT)
* Copyright (C) 2006-2007 LimeWire LLC
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package org.limewire.mojito.handler.response;
import java.io.IOException;
import java.math.BigInteger;
import java.net.SocketAddress;
import java.net.SocketException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.limewire.mojito.Context;
import org.limewire.mojito.KUID;
import org.limewire.mojito.exceptions.DHTBackendException;
import org.limewire.mojito.exceptions.DHTBadResponseException;
import org.limewire.mojito.exceptions.DHTException;
import org.limewire.mojito.messages.PingResponse;
import org.limewire.mojito.messages.RequestMessage;
import org.limewire.mojito.messages.ResponseMessage;
import org.limewire.mojito.result.PingResult;
import org.limewire.mojito.routing.Contact;
import org.limewire.mojito.settings.PingSettings;
import org.limewire.mojito.util.ContactUtils;
/**
* This class pings a given number of hosts in parallel
* and returns the first successful ping.
*/
public class PingResponseHandler extends AbstractResponseHandler<PingResult> {
private static final Log LOG = LogFactory.getLog(PingResponseHandler.class);
/** The number of pings to send in parallel. */
private int parallelism;
private int maxParallelPingFailures;
private final Contact sender;
private int active = 0;
private int failures = 0;
private final PingIterator pinger;
public PingResponseHandler(Context context, PingIterator pinger) {
this(context, null, pinger);
}
public PingResponseHandler(Context context, Contact sender, PingIterator pinger) {
super(context);
this.sender = sender;
this.pinger = pinger;
setParallelism(-1);
setMaxParallelPingFailures(-1);
}
public void setParallelism(int parallelism) {
if (parallelism < 0) {
this.parallelism = PingSettings.PARALLEL_PINGS.getValue();
} else if (parallelism > 0) {
this.parallelism = parallelism;
} else {
throw new IllegalArgumentException("parallelism=" + parallelism);
}
}
public int getParallelism() {
return parallelism;
}
public void setMaxParallelPingFailures(int maxParallelPingFailures) {
if (maxParallelPingFailures < 0) {
this.maxParallelPingFailures
= PingSettings.MAX_PARALLEL_PING_FAILURES.getValue();
} else {
this.maxParallelPingFailures = maxParallelPingFailures;
}
}
public int getMaxParallelPingFailures() {
return maxParallelPingFailures;
}
@Override
protected void start() throws DHTException {
if (!pinger.hasNext()) {
throw new DHTException("No hosts to ping");
}
try {
pingNextAndThrowIfDone(new DHTException(
"All SocketAddresses were invalid and there are no Hosts left to Ping: "
+ context.getLocalNode() + "; " + pinger));
} catch (IOException e) {
throw new DHTException(e);
}
}
@Override
protected void response(ResponseMessage message, long time) throws IOException {
decrementActive();
PingResponse response = (PingResponse)message;
Contact node = response.getContact();
SocketAddress externalAddress = response.getExternalAddress();
BigInteger estimatedSize = response.getEstimatedSize();
if (node.getContactAddress().equals(externalAddress)) {
pingNextAndThrowIfDone(new DHTBadResponseException(node
+ " is trying to set our external address to its address!"));
return;
}
// Check if the other Node has the same ID as we do
if (context.isLocalNodeID(node.getNodeID())) {
// If so check if this was a Node ID collision
// test ping. To do so see if we've set a customized
// sender which has a different Node ID than our
// actual Node ID
if (sender == null) {
pingNextAndThrowIfDone(new DHTBadResponseException(node
+ " is trying to spoof our Node ID"));
} else {
setReturnValue(new PingResult(node, externalAddress, estimatedSize, time));
}
return;
}
context.setExternalAddress(externalAddress);
context.addEstimatedRemoteSize(estimatedSize);
setReturnValue(new PingResult(node, externalAddress, estimatedSize, time));
}
@Override
protected void timeout(KUID nodeId, SocketAddress dst, RequestMessage message, long time) throws IOException {
decrementActive();
incrementFailures();
if (LOG.isInfoEnabled()) {
LOG.info("Timeout: " + ContactUtils.toString(nodeId, dst));
}
if (giveUp()) {
if (!hasActive()) {
fireTimeoutException(nodeId, dst, message, time);
} // else wait for the last response, timeout or error
} else {
pingNextAndThrowIfDone(createTimeoutException(nodeId, dst, message, time));
}
}
@Override
protected void error(KUID nodeId, SocketAddress dst, RequestMessage message, IOException e) {
decrementActive();
incrementFailures();
if(e instanceof SocketException && !giveUp()) {
try {
timeout(nodeId, dst, message, -1L);
} catch (IOException err) {
LOG.error("IOException", err);
if (!pinger.hasNext()) {
setException(new DHTException(err));
}
}
} else {
setException(new DHTBackendException(nodeId, dst, message, e));
}
}
private void pingNextAndThrowIfDone(DHTException e) throws IOException {
while(pinger.hasNext() && canMore()) {
if (pinger.pingNext(context, this)) {
incrementActive();
}
}
if (!hasActive()) {
setException(e);
}
}
private void decrementActive() {
active--;
}
private void incrementActive() {
active++;
}
private void incrementFailures() {
failures++;
}
private boolean canMore() {
return active < getParallelism();
}
private boolean hasActive() {
return active > 0;
}
private boolean giveUp() {
return (!pinger.hasNext() || failures >= getMaxParallelPingFailures());
}
/**
* The PingIterator interfaces allows PingResponseHandler to
* send ping requests to any type of contacts like SocketAddress
* or an actual Contact.
*/
public static interface PingIterator {
/**
* Returns true if there are more elements to ping.
*/
public boolean hasNext();
/**
* Sends a ping to the next element.
*/
public boolean pingNext(Context context,
PingResponseHandler responseHandler) throws IOException;
}
}