public Vote lookForLeader() throws InterruptedException {
try {
self.jmxLeaderElectionBean = new LeaderElectionBean();
MBeanRegistry.getInstance().register(self.jmxLeaderElectionBean, self.jmxLocalPeerBean);
} catch (Exception e) {
LOG.warn("Failed to register with JMX", e);
self.jmxLeaderElectionBean = null;
}
try {
self.setCurrentVote(new Vote(self.getId(), self.getLastLoggedZxid()));
// We are going to look for a leader by casting a vote for ourself
byte requestBytes[] = new byte[4];
ByteBuffer requestBuffer = ByteBuffer.wrap(requestBytes);
byte responseBytes[] = new byte[28];
ByteBuffer responseBuffer = ByteBuffer.wrap(responseBytes);
/* The current vote for the leader. Initially me! */
DatagramSocket s = null;
try {
s = new DatagramSocket();
s.setSoTimeout(200);
} catch (SocketException e1) {
LOG.error("Socket exception when creating socket for leader election", e1);
System.exit(4);
}
DatagramPacket requestPacket = new DatagramPacket(requestBytes, requestBytes.length);
DatagramPacket responsePacket = new DatagramPacket(responseBytes, responseBytes.length);
HashMap<InetSocketAddress, Vote> votes =
new HashMap<InetSocketAddress, Vote>(self.quorumPeers.size());
int xid = epochGen.nextInt();
while (self.running) {
votes.clear();
requestBuffer.clear();
requestBuffer.putInt(xid);
requestPacket.setLength(4);
HashSet<Long> heardFrom = new HashSet<Long>();
for (QuorumServer server : self.quorumPeers.values()) {
LOG.info("Server address: " + server.addr);
try {
requestPacket.setSocketAddress(server.addr);
} catch (IllegalArgumentException e) {
// Sun doesn't include the address that causes this
// exception to be thrown, so we wrap the exception
// in order to capture this critical detail.
throw new IllegalArgumentException(
"Unable to set socket address on packet, msg:"
+ e.getMessage()
+ " with addr:"
+ server.addr,
e);
}
try {
s.send(requestPacket);
responsePacket.setLength(responseBytes.length);
s.receive(responsePacket);
if (responsePacket.getLength() != responseBytes.length) {
LOG.error("Got a short response: " + responsePacket.getLength());
continue;
}
responseBuffer.clear();
int recvedXid = responseBuffer.getInt();
if (recvedXid != xid) {
LOG.error("Got bad xid: expected " + xid + " got " + recvedXid);
continue;
}
long peerId = responseBuffer.getLong();
heardFrom.add(peerId);
// if(server.id != peerId){
Vote vote = new Vote(responseBuffer.getLong(), responseBuffer.getLong());
InetSocketAddress addr = (InetSocketAddress) responsePacket.getSocketAddress();
votes.put(addr, vote);
// }
} catch (IOException e) {
LOG.warn("Ignoring exception while looking for leader", e);
// Errors are okay, since hosts may be
// down
}
}
ElectionResult result = countVotes(votes, heardFrom);
if (result.winner.id >= 0) {
self.setCurrentVote(result.vote);
if (result.winningCount > (self.quorumPeers.size() / 2)) {
self.setCurrentVote(result.winner);
s.close();
Vote current = self.getCurrentVote();
self.setPeerState(
(current.id == self.getId()) ? ServerState.LEADING : ServerState.FOLLOWING);
if (self.getPeerState() == ServerState.FOLLOWING) {
Thread.sleep(100);
}
return current;
}
}
Thread.sleep(1000);
}
return null;
} finally {
try {
if (self.jmxLeaderElectionBean != null) {
MBeanRegistry.getInstance().unregister(self.jmxLeaderElectionBean);
}
} catch (Exception e) {
LOG.warn("Failed to unregister with JMX", e);
}
self.jmxLeaderElectionBean = null;
}
}
/** 寻找对应的leader */
public Vote lookForLeader() throws InterruptedException {
try {
self.jmxLeaderElectionBean = new LeaderElectionBean();
MBeanRegistry.getInstance().register(self.jmxLeaderElectionBean, self.jmxLocalPeerBean);
} catch (Exception e) {
LOG.warn("Failed to register with JMX", e);
self.jmxLeaderElectionBean = null;
}
if (self.start_fle == 0) {
self.start_fle = System.currentTimeMillis();
}
try {
HashMap<Long, Vote> recvset = new HashMap<Long, Vote>();
HashMap<Long, Vote> outofelection = new HashMap<Long, Vote>();
int notTimeout = finalizeWait;
synchronized (this) {
logicalclock++;
updateProposal(getInitId(), getInitLastLoggedZxid(), getPeerEpoch());
}
LOG.info(
"New election. My id = "
+ self.getId()
+ ", proposed zxid=0x"
+ Long.toHexString(proposedZxid));
sendNotifications();
/*
* Loop in which we exchange notifications until we find a leader
*/
while ((self.getPeerState() == ServerState.LOOKING) && (!stop)) {
/*
* Remove next notification from queue, times out after 2 times
* the termination time
*/
Notification n = recvqueue.poll(notTimeout, TimeUnit.MILLISECONDS);
/*
* Sends more notifications if haven't received enough.
* Otherwise processes new notification.
*/
if (n == null) {
if (manager.haveDelivered()) {
sendNotifications();
} else {
manager.connectAll();
}
/*
* Exponential backoff
*/
int tmpTimeOut = notTimeout * 2;
notTimeout =
(tmpTimeOut < maxNotificationInterval ? tmpTimeOut : maxNotificationInterval);
LOG.info("Notification time out: " + notTimeout);
} else if (self.getVotingView().containsKey(n.sid)) {
/*
* Only proceed if the vote comes from a replica in the
* voting view.
*/
switch (n.state) {
case LOOKING:
// If notification > current, replace and send messages
// out
if (n.electionEpoch > logicalclock) {
logicalclock = n.electionEpoch;
recvset.clear();
if (totalOrderPredicate(
n.leader,
n.zxid,
n.peerEpoch,
getInitId(),
getInitLastLoggedZxid(),
getPeerEpoch())) {
updateProposal(n.leader, n.zxid, n.peerEpoch);
} else {
updateProposal(getInitId(), getInitLastLoggedZxid(), getPeerEpoch());
}
sendNotifications();
} else if (n.electionEpoch < logicalclock) {
if (LOG.isDebugEnabled()) {
LOG.debug(
"Notification election epoch is smaller than logicalclock. n.electionEpoch = 0x"
+ Long.toHexString(n.electionEpoch)
+ ", logicalclock=0x"
+ Long.toHexString(logicalclock));
}
break;
} else if (totalOrderPredicate(
n.leader, n.zxid, n.peerEpoch, proposedLeader, proposedZxid, proposedEpoch)) {
updateProposal(n.leader, n.zxid, n.peerEpoch);
sendNotifications();
}
if (LOG.isDebugEnabled()) {
LOG.debug(
"Adding vote: from="
+ n.sid
+ ", proposed leader="
+ n.leader
+ ", proposed zxid=0x"
+ Long.toHexString(n.zxid)
+ ", proposed election epoch=0x"
+ Long.toHexString(n.electionEpoch));
}
recvset.put(n.sid, new Vote(n.leader, n.zxid, n.electionEpoch, n.peerEpoch));
if (termPredicate(
recvset, new Vote(proposedLeader, proposedZxid, logicalclock, proposedEpoch))) {
// Verify if there is any change in the proposed
// leader
while ((n = recvqueue.poll(finalizeWait, TimeUnit.MILLISECONDS)) != null) {
if (totalOrderPredicate(
n.leader, n.zxid, n.peerEpoch, proposedLeader, proposedZxid, proposedEpoch)) {
recvqueue.put(n);
break;
}
}
/*
* This predicate is true once we don't read any new
* relevant message from the reception queue
*/
if (n == null) {
self.setPeerState(
(proposedLeader == self.getId()) ? ServerState.LEADING : learningState());
Vote endVote =
new Vote(proposedLeader, proposedZxid, logicalclock, proposedEpoch);
leaveInstance(endVote);
return endVote;
}
}
break;
case OBSERVING:
LOG.debug("Notification from observer: " + n.sid);
break;
case FOLLOWING:
case LEADING:
/*
* Consider all notifications from the same epoch
* together.
*/
if (n.electionEpoch == logicalclock) {
recvset.put(n.sid, new Vote(n.leader, n.zxid, n.electionEpoch, n.peerEpoch));
if (ooePredicate(recvset, outofelection, n)) {
self.setPeerState(
(n.leader == self.getId()) ? ServerState.LEADING : learningState());
Vote endVote = new Vote(n.leader, n.zxid, n.electionEpoch, n.peerEpoch);
leaveInstance(endVote);
return endVote;
}
}
/*
* Before joining an established ensemble, verify a
* majority is following the same leader.
*/
outofelection.put(
n.sid,
new Vote(n.version, n.leader, n.zxid, n.electionEpoch, n.peerEpoch, n.state));
if (ooePredicate(outofelection, outofelection, n)) {
synchronized (this) {
logicalclock = n.electionEpoch;
self.setPeerState(
(n.leader == self.getId()) ? ServerState.LEADING : learningState());
}
Vote endVote = new Vote(n.leader, n.zxid, n.electionEpoch, n.peerEpoch);
leaveInstance(endVote);
return endVote;
}
break;
default:
LOG.warn("Notification state unrecognized: {} (n.state), {} (n.sid)", n.state, n.sid);
break;
}
} else {
LOG.warn("Ignoring notification from non-cluster member " + n.sid);
}
}
return null;
} finally {
try {
if (self.jmxLeaderElectionBean != null) {
MBeanRegistry.getInstance().unregister(self.jmxLeaderElectionBean);
}
} catch (Exception e) {
LOG.warn("Failed to unregister with JMX", e);
}
self.jmxLeaderElectionBean = null;
}
}
