/**
* read a packet from the leader
*
* @param pp the packet to be instantiated
* @throws IOException
*/
void readPacket(QuorumPacket pp) throws IOException {
synchronized (leaderIs) {
leaderIs.readRecord(pp, "packet");
}
long traceMask = ZooTrace.SERVER_PACKET_TRACE_MASK;
if (pp.getType() == Leader.PING) {
traceMask = ZooTrace.SERVER_PING_TRACE_MASK;
}
if (LOG.isTraceEnabled()) {
ZooTrace.logQuorumPacket(LOG, traceMask, 'i', pp);
}
}
/**
* Finally, synchronize our history with the Leader.
*
* @param newLeaderZxid
* @throws IOException
* @throws InterruptedException
*/
protected void syncWithLeader(long newLeaderZxid) throws IOException, InterruptedException {
QuorumPacket ack = new QuorumPacket(Leader.ACK, 0, null);
QuorumPacket qp = new QuorumPacket();
long newEpoch = ZxidUtils.getEpochFromZxid(newLeaderZxid);
readPacket(qp);
LinkedList<Long> packetsCommitted = new LinkedList<Long>();
LinkedList<PacketInFlight> packetsNotCommitted = new LinkedList<PacketInFlight>();
synchronized (zk) {
if (qp.getType() == Leader.DIFF) {
LOG.info("Getting a diff from the leader 0x" + Long.toHexString(qp.getZxid()));
} else if (qp.getType() == Leader.SNAP) {
LOG.info("Getting a snapshot from leader");
// The leader is going to dump the database
// clear our own database and read
zk.getZKDatabase().clear();
zk.getZKDatabase().deserializeSnapshot(leaderIs);
String signature = leaderIs.readString("signature");
if (!signature.equals("BenWasHere")) {
LOG.error("Missing signature. Got " + signature);
throw new IOException("Missing signature");
}
zk.getZKDatabase().commit();
zk.getZKDatabase().getM2mData().clear();
} else if (qp.getType() == Leader.TRUNC) {
// we need to truncate the log to the lastzxid of the leader
LOG.warn(
"Truncating log to get in sync with the leader 0x" + Long.toHexString(qp.getZxid()));
boolean truncated = zk.getZKDatabase().truncateLog(qp.getZxid());
if (!truncated) {
// not able to truncate the log
LOG.error("Not able to truncate the log " + Long.toHexString(qp.getZxid()));
System.exit(13);
}
} else {
LOG.error("Got unexpected packet from leader " + qp.getType() + " exiting ... ");
System.exit(13);
}
zk.getZKDatabase().setlastProcessedZxid(qp.getZxid());
zk.createSessionTracker();
long lastQueued = 0;
// in V1.0 we take a snapshot when we get the NEWLEADER message, but
// in pre V1.0
// we take the snapshot at the UPDATE, since V1.0 also gets the
// UPDATE (after the NEWLEADER)
// we need to make sure that we don't take the snapshot twice.
boolean snapshotTaken = false;
// we are now going to start getting transactions to apply followed
// by an UPTODATE
outerLoop:
while (self.isRunning()) {
readPacket(qp);
switch (qp.getType()) {
case Leader.PROPOSAL:
PacketInFlight pif = new PacketInFlight();
pif.hdr = new M2mTxnHeader();
pif.rec = M2mSerializeUtils.deserializeTxn(qp.getData(), pif.hdr);
if (pif.hdr.getZxid() != lastQueued + 1) {
LOG.warn(
"Got zxid 0x"
+ Long.toHexString(pif.hdr.getZxid())
+ " expected 0x"
+ Long.toHexString(lastQueued + 1));
}
lastQueued = pif.hdr.getZxid();
packetsNotCommitted.add(pif);
break;
case Leader.COMMIT:
if (!snapshotTaken) {
pif = packetsNotCommitted.peekFirst();
if (pif.hdr.getZxid() != qp.getZxid()) {
LOG.warn(
"Committing " + qp.getZxid() + ", but next proposal is " + pif.hdr.getZxid());
} else {
zk.processTxn(pif.hdr, pif.rec);
packetsNotCommitted.remove();
}
} else {
packetsCommitted.add(qp.getZxid());
}
break;
case Leader.INFORM:
/*
* Only observer get this type of packet. We treat this as
* receiving PROPOSAL and COMMMIT.
*/
PacketInFlight packet = new PacketInFlight();
packet.hdr = new M2mTxnHeader();
packet.rec = M2mSerializeUtils.deserializeTxn(qp.getData(), packet.hdr);
// Log warning message if txn comes out-of-order
if (packet.hdr.getZxid() != lastQueued + 1) {
LOG.warn(
"Got zxid 0x"
+ Long.toHexString(packet.hdr.getZxid())
+ " expected 0x"
+ Long.toHexString(lastQueued + 1));
}
lastQueued = packet.hdr.getZxid();
if (!snapshotTaken) {
// Apply to db directly if we haven't taken the snapshot
zk.processTxn(packet.hdr, packet.rec);
} else {
packetsNotCommitted.add(packet);
packetsCommitted.add(qp.getZxid());
}
break;
case Leader.UPTODATE:
if (!snapshotTaken) { // true for the pre v1.0 case
zk.takeSnapshot();
self.setCurrentEpoch(newEpoch);
}
self.cnxnFactory.addZooKeeperServer(self.getHandleIp(), zk);
break outerLoop;
case Leader.NEWLEADER: // it will be NEWLEADER in v1.0
// Create updatingEpoch file and remove it after current
// epoch is set. QuorumPeer.loadDataBase() uses this file to
// detect the case where the server was terminated after
// taking a snapshot but before setting the current epoch.
// File updating = new
// File(self.getTxnFactory().getSnapDir(),
// QuorumPeer.UPDATING_EPOCH_FILENAME);
// if (!updating.exists() && !updating.createNewFile()) {
// throw new IOException("Failed to create "
// + updating.toString());
// }
// zk.takeSnapshot();
// self.setCurrentEpoch(newEpoch);
// if (!updating.delete()) {
// throw new IOException("Failed to delete "
// + updating.toString());
// }
snapshotTaken = true;
writePacket(new QuorumPacket(Leader.ACK, newLeaderZxid, null), true);
break;
}
}
}
ack.setZxid(ZxidUtils.makeZxid(newEpoch, 0));
writePacket(ack, true);
sock.setSoTimeout(self.tickTime * self.syncLimit);
zk.startup();
/*
* Update the election vote here to ensure that all members of the
* ensemble report the same vote to new servers that start up and send
* leader election notifications to the ensemble.
*
* @see https://issues.apache.org/jira/browse/ZOOKEEPER-1732
*/
self.updateElectionVote(newEpoch);
// We need to log the stuff that came in between the snapshot and the
// uptodate
if (zk instanceof FollowerZooKeeperServer) {
FollowerZooKeeperServer fzk = (FollowerZooKeeperServer) zk;
for (PacketInFlight p : packetsNotCommitted) {
fzk.logRequest(p.hdr, p.rec);
}
for (Long zxid : packetsCommitted) {
fzk.commit(zxid);
}
} else {
// New server type need to handle in-flight packets
throw new UnsupportedOperationException("Unknown server type");
}
}