@Override
public void handleAccepted(PaxosMessage proposal) {
ensureSize(chosen, proposal.getInstanceNum() + 1); // Prevent NPE
if (chosen.get(proposal.getInstanceNum()) != null)
return; // Something has already been chosen so I dont care anymore.
List<PaxosMessage> acceptedVotes = proposalAcceptedVotes.get(proposal.getInstanceNum());
if (acceptedVotes == null) {
acceptedVotes = new ArrayList<PaxosMessage>();
acceptedVotes.add(proposal);
proposalAcceptedVotes.put(proposal.getInstanceNum(), acceptedVotes);
} else {
for (PaxosMessage acceptedVote : acceptedVotes) {
if (proposal.getProposerId() == acceptedVote.getProposerId())
return; // This person is reaffirming their acceptance of this instances proposal.
}
acceptedVotes.add(proposal);
proposalAcceptedVotes.put(proposal.getInstanceNum(), acceptedVotes);
}
// handle being chosen
if (proposalAcceptedVotes.get(proposal.getInstanceNum()).size() >= serverSet.getQuorumSize()) {
onChosen(proposal);
}
}
public void messageReceived(IoSession ioSession, Object message) throws Exception {
if (message instanceof DefaultPaxosMessage) {
PaxosMessage paxosMessage = (DefaultPaxosMessage) message;
switch (paxosMessage.getType()) {
case PROPOSE:
handlePropose(paxosMessage);
break;
case ACCEPTED:
handleAccepted(paxosMessage);
break;
case PREPARE:
handlePrepare(
(Integer) paxosMessage.getValue(),
paxosMessage.getProposerId()); // PSN and consensus instance dont matter
break;
case PREPARE_RESP:
handlePrepareResponse(paxosMessage);
break;
case RECOVERY:
handleRecovery(paxosMessage);
break;
case RECOVERY_RESP:
handleRecoveryResponse(paxosMessage);
break;
case PING:
if (paxosMessage.getProposerId() == getLeader()) // Leaders HeartBeat
leaderLastHeard = new Date();
else if (((Integer) paxosMessage.getValue())
> preparedFor) { // I came alive and the leader is not who I thought.
preparedFor = ((Integer) paxosMessage.getValue());
handlePrepare(preparedFor, getLeader());
sendRecovery();
}
break;
default:
throw new Exception(
"received PaxosMessage of unknown type" + paxosMessage.getType().name());
}
} else if (message instanceof ChatMessage) { // Some client sent or some server forwarded.
if (nodeIsLeader()) {
propose(
new DefaultPaxosMessage(
nextInstance, nextPropose, id, PaxosMessageType.PROPOSE, (ChatMessage) message));
nextInstance++;
} else {
sendToLeader((ChatMessage) message);
}
} else {
throw new Exception("Unknown message type:" + message.getClass().getSimpleName());
}
}
@Override
public void handlePrepareResponse(PaxosMessage response) {
if (!prepareResponseFrom.contains(response.getProposerId()))
prepareResponseFrom.add(
response.getProposerId()); // This is a new server accepted our prepare request.
List<ChatMessage> remoteAccepted = (List<ChatMessage>) response.getValue();
for (int i = 0; i < remoteAccepted.size(); i++) {
if (chosen.size() > i && chosen.get(i) != null) continue;
if (remoteAccepted.get(i) != null) {
propose(
new DefaultPaxosMessage(
i, nextPropose, id, PaxosMessageType.PROPOSE, remoteAccepted.get(i)));
if (i > nextInstance) nextInstance = i;
}
}
}
private void handleRecovery(PaxosMessage recoveryRequest) {
PaxosMessage recoveryResponse =
new DefaultPaxosMessage(-1, -1, id, PaxosMessageType.RECOVERY_RESP, chosen);
sendMessage(recoveryResponse, recoveryRequest.getProposerId());
}