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/*
This file is part of GNUnet.
Copyright (C) 2013 Christian Grothoff (and other contributing authors)
GNUnet 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 3, or (at your
option) any later version.
GNUnet 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 GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
package org.gnunet.consensus;
import com.google.common.base.Preconditions;
import org.gnunet.consensus.messages.*;
import org.gnunet.mq.Envelope;
import org.gnunet.mq.NotifySentHandler;
import org.gnunet.util.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Multi-peer set reconciliation.
*/
public class Consensus {
/**
* Class logger.
*/
private static final Logger logger = LoggerFactory
.getLogger(Consensus.class);
/**
* Client connected to the consensus service.
*/
private Client client;
/**
* Called when conclude has finished.
*/
private ConsensusCallback consensusCallback;
/**
* Message dispatch for messages from the consensus service.
*/
private class ConsensusMessageReceiver extends RunaboutMessageReceiver {
public void visit(ConcludeDoneMessage m) {
if (null == consensusCallback) {
logger.error("unexpected conclude done message");
return;
}
consensusCallback.onDone();
}
public void visit(NewElementMessage m) {
ConsensusElement element = new ConsensusElement(m.elementData, m.elementType);
element.elementType = m.elementType;
element.data = m.elementData;
consensusCallback.onElement(element);
}
@Override
public void handleError() {
System.out.println("Error receiving from consensus service.");
consensusCallback.onElement(null);
}
}
/**
* Create a consensus session. The set being reconciled is initially
* empty.
*
* @param peers array of peers participating in this consensus session
* Inclusion of the local peer is optional.
* @param sessionId session identifier
* Allows a group of peers to have more than consensus session.
* @param startTime when should the consensus start?
* @param deadline when should we be done?
*/
public Consensus(Configuration cfg, PeerIdentity[] peers, HashCode sessionId,
AbsoluteTime startTime, AbsoluteTime deadline) {
client = new Client("consensus", cfg);
client.installReceiver(new ConsensusMessageReceiver());
String peersString = "";
for (PeerIdentity pi : peers)
peersString += pi + ", ";
logger.info("starting consensus with {} peers given to consensus ({})", peers.length, peersString);
JoinMessage m = new JoinMessage();
m.numPeers = peers.length;
m.peers = peers;
m.sessionId = sessionId;
m.startTime = startTime.asMessage();
m.deadline = deadline.asMessage();
client.send(m);
}
/**
* Insert an element into the consensus set.
*
* @param element element to insert in the consensus
*/
public void insertElement(ConsensusElement element) {
insertElement(element, null);
}
/**
* Insert an element into the consensus set.
*
* @param element element to insert in the consensus
* @param idc called when the element has been sent to the service
*/
public void insertElement(ConsensusElement element, final InsertDoneCallback idc) {
InsertElementMessage m = new InsertElementMessage();
m.elementData = element.data;
m.elementType = element.elementType;
Envelope ev = new Envelope(m);
if (null != idc) {
ev.notifySent(new NotifySentHandler() {
@Override
public void onSent() {
idc.onInsertDone();
}
});
}
client.send(ev);
}
/**
* We are done with inserting new elements into the consensus;
* try to conclude the consensus within a given time window.
* After conclude has been called, no further elements may be
* inserted by the client.
*
* @param concludeCallback called when the consensus has concluded
*/
public void conclude(ConsensusCallback concludeCallback) {
Preconditions.checkNotNull(concludeCallback, "conclude with null callback");
Preconditions.checkState(null == this.consensusCallback, "called conclude twice");
this.consensusCallback = concludeCallback;
ConcludeMessage m = new ConcludeMessage();
client.send(m);
}
/**
* Destroy a consensus handle.
* Free all state associated with
* it, no longer call any of the callbacks.
*/
public void destroy() {
client.disconnect();
client = null;
}
}
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