/*
* 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.request;
import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.Map;
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.db.DHTValueEntity;
import org.limewire.mojito.db.DHTValueType;
import org.limewire.mojito.db.Database;
import org.limewire.mojito.messages.FindValueRequest;
import org.limewire.mojito.messages.FindValueResponse;
import org.limewire.mojito.messages.RequestMessage;
import org.limewire.mojito.util.CollectionUtils;
import org.limewire.mojito.util.DatabaseUtils;
/**
* Handles incoming FIND_VALUE requests.
*/
public class FindValueRequestHandler extends AbstractRequestHandler {
private static final Log LOG = LogFactory.getLog(FindValueRequestHandler.class);
/**
* Delegate to the FIND_NODE request handler
*/
private final FindNodeRequestHandler findNodeDelegate;
public FindValueRequestHandler(Context context,
FindNodeRequestHandler findNodeDelegate) {
super(context);
this.findNodeDelegate = findNodeDelegate;
}
@Override
protected void request(RequestMessage message) throws IOException {
FindValueRequest request = (FindValueRequest)message;
KUID lookupId = request.getLookupID();
DHTValueType valueType = request.getDHTValueType();
Map<KUID, DHTValueEntity> bag = null;
float requestLoad = 0f;
Database database = context.getDatabase();
synchronized (database) {
bag = database.get(lookupId);
requestLoad = database.getRequestLoad(lookupId, true);
}
// The keys and values we'll return
Collection<KUID> availableKeys = Collections.emptySet();
Collection<DHTValueEntity> valuesToReturn = Collections.emptySet();
// The keys the remote Node is requesting
Collection<KUID> requestedSecondaryKeys = request.getSecondaryKeys();
if (bag != null && !bag.isEmpty()) {
availableKeys = new HashSet<KUID>();
valuesToReturn = new HashSet<DHTValueEntity>();
Collection<? extends DHTValueEntity> filtered
= DatabaseUtils.filter(valueType, bag.values());
if (requestedSecondaryKeys.isEmpty()) {
if (valuesToReturn.isEmpty()
&& filtered.size() == 1) {
valuesToReturn.addAll(filtered);
} else {
for (DHTValueEntity entity : filtered) {
availableKeys.add(entity.getSecondaryKey());
}
}
} else {
// Send all requested values back.
// TODO: http://en.wikipedia.org/wiki/Knapsack_problem
for (DHTValueEntity entity : filtered) {
KUID secondaryKey = entity.getSecondaryKey();
if (requestedSecondaryKeys.contains(secondaryKey)) {
valuesToReturn.add(entity);
}
}
}
}
if (valuesToReturn.isEmpty()
&& availableKeys.isEmpty()) {
if (LOG.isInfoEnabled()) {
LOG.info("No values for " + lookupId
+ ", returning Contacts instead to " + request.getContact());
}
// OK, send Contacts instead!
findNodeDelegate.handleRequest(message);
} else {
if (LOG.isInfoEnabled()) {
LOG.info("Return " + CollectionUtils.toString(valuesToReturn) + " and "
+ CollectionUtils.toString(availableKeys) + " for "
+ lookupId + " to " + request.getContact());
}
FindValueResponse response = context.getMessageHelper()
.createFindValueResponse(request, requestLoad,
valuesToReturn, availableKeys);
context.getMessageDispatcher().send(request.getContact(), response);
}
}
}