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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.zookeeper.server.quorum;
import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketAddress;
import java.net.SocketException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicLong;
import java.util.stream.Collectors;
import javax.security.sasl.SaslException;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.ZooDefs.OpCode;
import org.apache.zookeeper.common.Time;
import org.apache.zookeeper.jmx.MBeanRegistry;
import org.apache.zookeeper.server.FinalRequestProcessor;
import org.apache.zookeeper.server.Request;
import org.apache.zookeeper.server.RequestProcessor;
import org.apache.zookeeper.server.ServerMetrics;
import org.apache.zookeeper.server.ZKDatabase;
import org.apache.zookeeper.server.ZooKeeperCriticalThread;
import org.apache.zookeeper.server.ZooTrace;
import org.apache.zookeeper.server.quorum.QuorumPeer.LearnerType;
import org.apache.zookeeper.server.quorum.auth.QuorumAuthServer;
import org.apache.zookeeper.server.quorum.flexible.QuorumVerifier;
import org.apache.zookeeper.server.util.SerializeUtils;
import org.apache.zookeeper.server.util.ZxidUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This class has the control logic for the Leader.
*/
public class Leader extends LearnerMaster {
private static final Logger LOG = LoggerFactory.getLogger(Leader.class);
private static final boolean nodelay = System.getProperty("leader.nodelay", "true").equals("true");
static {
LOG.info("TCP NoDelay set to: {}", nodelay);
}
public static class Proposal extends SyncedLearnerTracker {
public QuorumPacket packet;
public Request request;
@Override
public String toString() {
return packet.getType() + ", " + packet.getZxid() + ", " + request;
}
}
// log ack latency if zxid is a multiple of ackLoggingFrequency. If <=0, disable logging.
private static final String ACK_LOGGING_FREQUENCY = "zookeeper.leader.ackLoggingFrequency";
private static int ackLoggingFrequency;
static {
ackLoggingFrequency = Integer.getInteger(ACK_LOGGING_FREQUENCY, 1000);
LOG.info("{} = {}", ACK_LOGGING_FREQUENCY, ackLoggingFrequency);
}
public static void setAckLoggingFrequency(int frequency) {
ackLoggingFrequency = frequency;
}
public static int getAckLoggingFrequency() {
return ackLoggingFrequency;
}
final LeaderZooKeeperServer zk;
final QuorumPeer self;
// VisibleForTesting
protected boolean quorumFormed = false;
// the follower acceptor thread
volatile LearnerCnxAcceptor cnxAcceptor = null;
// list of all the learners, including followers and observers
private final HashSet learners = new HashSet();
private final BufferStats proposalStats;
public BufferStats getProposalStats() {
return proposalStats;
}
// beans for all learners
private final ConcurrentHashMap connectionBeans = new ConcurrentHashMap<>();
/**
* Returns a copy of the current learner snapshot
*/
public List getLearners() {
synchronized (learners) {
return new ArrayList(learners);
}
}
// list of followers that are ready to follow (i.e synced with the leader)
private final HashSet forwardingFollowers = new HashSet();
/**
* Returns a copy of the current forwarding follower snapshot
*/
public List getForwardingFollowers() {
synchronized (forwardingFollowers) {
return new ArrayList(forwardingFollowers);
}
}
public List getNonVotingFollowers() {
List nonVotingFollowers = new ArrayList();
synchronized (forwardingFollowers) {
for (LearnerHandler lh : forwardingFollowers) {
if (!isParticipant(lh.getSid())) {
nonVotingFollowers.add(lh);
}
}
}
return nonVotingFollowers;
}
void addForwardingFollower(LearnerHandler lh) {
synchronized (forwardingFollowers) {
forwardingFollowers.add(lh);
}
}
private final HashSet observingLearners = new HashSet();
/**
* Returns a copy of the current observer snapshot
*/
public List getObservingLearners() {
synchronized (observingLearners) {
return new ArrayList(observingLearners);
}
}
private void addObserverLearnerHandler(LearnerHandler lh) {
synchronized (observingLearners) {
observingLearners.add(lh);
}
}
public Iterable> getObservingLearnersInfo() {
Set> info = new HashSet<>();
synchronized (observingLearners) {
for (LearnerHandler lh : observingLearners) {
info.add(lh.getLearnerHandlerInfo());
}
}
return info;
}
public void resetObserverConnectionStats() {
synchronized (observingLearners) {
for (LearnerHandler lh : observingLearners) {
lh.resetObserverConnectionStats();
}
}
}
// Pending sync requests. Must access under 'this' lock.
private final Map> pendingSyncs = new HashMap>();
public synchronized int getNumPendingSyncs() {
return pendingSyncs.size();
}
//Follower counter
final AtomicLong followerCounter = new AtomicLong(-1);
/**
* Adds peer to the leader.
*
* @param learner
* instance of learner handle
*/
@Override
public void addLearnerHandler(LearnerHandler learner) {
synchronized (learners) {
learners.add(learner);
}
}
/**
* Remove the learner from the learner list
*
* @param peer
*/
@Override
public void removeLearnerHandler(LearnerHandler peer) {
synchronized (forwardingFollowers) {
forwardingFollowers.remove(peer);
}
synchronized (learners) {
learners.remove(peer);
}
synchronized (observingLearners) {
observingLearners.remove(peer);
}
}
boolean isLearnerSynced(LearnerHandler peer) {
synchronized (forwardingFollowers) {
return forwardingFollowers.contains(peer);
}
}
/**
* Returns true if a quorum in qv is connected and synced with the leader
* and false otherwise
*
* @param qv, a QuorumVerifier
*/
public boolean isQuorumSynced(QuorumVerifier qv) {
HashSet ids = new HashSet();
if (qv.getVotingMembers().containsKey(self.getId())) {
ids.add(self.getId());
}
synchronized (forwardingFollowers) {
for (LearnerHandler learnerHandler : forwardingFollowers) {
if (learnerHandler.synced() && qv.getVotingMembers().containsKey(learnerHandler.getSid())) {
ids.add(learnerHandler.getSid());
}
}
}
return qv.containsQuorum(ids);
}
private final List serverSockets = new LinkedList<>();
public Leader(QuorumPeer self, LeaderZooKeeperServer zk) throws IOException {
this.self = self;
this.proposalStats = new BufferStats();
Set addresses;
if (self.getQuorumListenOnAllIPs()) {
addresses = self.getQuorumAddress().getWildcardAddresses();
} else {
addresses = self.getQuorumAddress().getAllAddresses();
}
addresses.stream()
.map(address -> createServerSocket(address, self.shouldUsePortUnification(), self.isSslQuorum()))
.filter(Optional::isPresent)
.map(Optional::get)
.forEach(serverSockets::add);
if (serverSockets.isEmpty()) {
throw new IOException("Leader failed to initialize any of the following sockets: " + addresses);
}
this.zk = zk;
}
Optional createServerSocket(InetSocketAddress address, boolean portUnification, boolean sslQuorum) {
ServerSocket serverSocket;
try {
if (portUnification || sslQuorum) {
serverSocket = new UnifiedServerSocket(self.getX509Util(), portUnification);
} else {
serverSocket = new ServerSocket();
}
serverSocket.setReuseAddress(true);
serverSocket.bind(address);
return Optional.of(serverSocket);
} catch (IOException e) {
LOG.error("Couldn't bind to {}", address.toString(), e);
}
return Optional.empty();
}
/**
* This message is for follower to expect diff
*/
static final int DIFF = 13;
/**
* This is for follower to truncate its logs
*/
static final int TRUNC = 14;
/**
* This is for follower to download the snapshots
*/
static final int SNAP = 15;
/**
* This tells the leader that the connecting peer is actually an observer
*/
static final int OBSERVERINFO = 16;
/**
* This message type is sent by the leader to indicate it's zxid and if
* needed, its database.
*/
static final int NEWLEADER = 10;
/**
* This message type is sent by a follower to pass the last zxid. This is here
* for backward compatibility purposes.
*/
static final int FOLLOWERINFO = 11;
/**
* This message type is sent by the leader to indicate that the follower is
* now uptodate andt can start responding to clients.
*/
static final int UPTODATE = 12;
/**
* This message is the first that a follower receives from the leader.
* It has the protocol version and the epoch of the leader.
*/
public static final int LEADERINFO = 17;
/**
* This message is used by the follow to ack a proposed epoch.
*/
public static final int ACKEPOCH = 18;
/**
* This message type is sent to a leader to request and mutation operation.
* The payload will consist of a request header followed by a request.
*/
static final int REQUEST = 1;
/**
* This message type is sent by a leader to propose a mutation.
*/
public static final int PROPOSAL = 2;
/**
* This message type is sent by a follower after it has synced a proposal.
*/
static final int ACK = 3;
/**
* This message type is sent by a leader to commit a proposal and cause
* followers to start serving the corresponding data.
*/
static final int COMMIT = 4;
/**
* This message type is enchanged between follower and leader (initiated by
* follower) to determine liveliness.
*/
static final int PING = 5;
/**
* This message type is to validate a session that should be active.
*/
static final int REVALIDATE = 6;
/**
* This message is a reply to a synchronize command flushing the pipe
* between the leader and the follower.
*/
static final int SYNC = 7;
/**
* This message type informs observers of a committed proposal.
*/
static final int INFORM = 8;
/**
* Similar to COMMIT, only for a reconfig operation.
*/
static final int COMMITANDACTIVATE = 9;
/**
* Similar to INFORM, only for a reconfig operation.
*/
static final int INFORMANDACTIVATE = 19;
final ConcurrentMap outstandingProposals = new ConcurrentHashMap();
private final ConcurrentLinkedQueue toBeApplied = new ConcurrentLinkedQueue();
// VisibleForTesting
protected final Proposal newLeaderProposal = new Proposal();
class LearnerCnxAcceptor extends ZooKeeperCriticalThread {
private final AtomicBoolean stop = new AtomicBoolean(false);
private final AtomicBoolean fail = new AtomicBoolean(false);
LearnerCnxAcceptor() {
super("LearnerCnxAcceptor-" + serverSockets.stream()
.map(ServerSocket::getLocalSocketAddress)
.map(Objects::toString)
.collect(Collectors.joining("|")),
zk.getZooKeeperServerListener());
}
@Override
public void run() {
if (!stop.get() && !serverSockets.isEmpty()) {
ExecutorService executor = Executors.newFixedThreadPool(serverSockets.size());
CountDownLatch latch = new CountDownLatch(serverSockets.size());
serverSockets.forEach(serverSocket ->
executor.submit(new LearnerCnxAcceptorHandler(serverSocket, latch)));
try {
latch.await();
} catch (InterruptedException ie) {
LOG.error("Interrupted while sleeping in LearnerCnxAcceptor.", ie);
} finally {
closeSockets();
executor.shutdown();
try {
if (!executor.awaitTermination(1, TimeUnit.SECONDS)) {
LOG.error("not all the LearnerCnxAcceptorHandler terminated properly");
}
} catch (InterruptedException ie) {
LOG.error("Interrupted while terminating LearnerCnxAcceptor.", ie);
}
}
}
}
public void halt() {
stop.set(true);
closeSockets();
}
class LearnerCnxAcceptorHandler implements Runnable {
private ServerSocket serverSocket;
private CountDownLatch latch;
LearnerCnxAcceptorHandler(ServerSocket serverSocket, CountDownLatch latch) {
this.serverSocket = serverSocket;
this.latch = latch;
}
@Override
public void run() {
try {
Thread.currentThread().setName("LearnerCnxAcceptorHandler-" + serverSocket.getLocalSocketAddress());
while (!stop.get()) {
acceptConnections();
}
} catch (Exception e) {
LOG.warn("Exception while accepting follower", e);
if (fail.compareAndSet(false, true)) {
handleException(getName(), e);
halt();
}
} finally {
latch.countDown();
}
}
private void acceptConnections() throws IOException {
Socket socket = null;
boolean error = false;
try {
socket = serverSocket.accept();
// start with the initLimit, once the ack is processed
// in LearnerHandler switch to the syncLimit
socket.setSoTimeout(self.tickTime * self.initLimit);
socket.setTcpNoDelay(nodelay);
BufferedInputStream is = new BufferedInputStream(socket.getInputStream());
LearnerHandler fh = new LearnerHandler(socket, is, Leader.this);
fh.start();
} catch (SocketException e) {
error = true;
if (stop.get()) {
LOG.warn("Exception while shutting down acceptor.", e);
} else {
throw e;
}
} catch (SaslException e) {
LOG.error("Exception while connecting to quorum learner", e);
error = true;
} catch (Exception e) {
error = true;
throw e;
} finally {
// Don't leak sockets on errors
if (error && socket != null && !socket.isClosed()) {
try {
socket.close();
} catch (IOException e) {
LOG.warn("Error closing socket: " + socket, e);
}
}
}
}
}
}
StateSummary leaderStateSummary;
long epoch = -1;
boolean waitingForNewEpoch = true;
// when a reconfig occurs where the leader is removed or becomes an observer,
// it does not commit ops after committing the reconfig
boolean allowedToCommit = true;
/**
* Timestamp when this leader started serving request (Quorum is running)
*/
private long leaderStartTime;
public long getUptime() {
if (leaderStartTime > 0) {
return Time.currentElapsedTime() - leaderStartTime;
}
return 0;
}
/**
* This method is main function that is called to lead
*
* @throws IOException
* @throws InterruptedException
*/
void lead() throws IOException, InterruptedException {
self.end_fle = Time.currentElapsedTime();
long electionTimeTaken = self.end_fle - self.start_fle;
self.setElectionTimeTaken(electionTimeTaken);
ServerMetrics.getMetrics().ELECTION_TIME.add(electionTimeTaken);
LOG.info("LEADING - LEADER ELECTION TOOK - {} {}", electionTimeTaken, QuorumPeer.FLE_TIME_UNIT);
self.start_fle = 0;
self.end_fle = 0;
zk.registerJMX(new LeaderBean(this, zk), self.jmxLocalPeerBean);
try {
self.setZabState(QuorumPeer.ZabState.DISCOVERY);
self.tick.set(0);
zk.loadData();
leaderStateSummary = new StateSummary(self.getCurrentEpoch(), zk.getLastProcessedZxid());
// Start thread that waits for connection requests from
// new followers.
cnxAcceptor = new LearnerCnxAcceptor();
cnxAcceptor.start();
long epoch = getEpochToPropose(self.getId(), self.getAcceptedEpoch());
zk.setZxid(ZxidUtils.makeZxid(epoch, 0));
synchronized (this) {
lastProposed = zk.getZxid();
}
newLeaderProposal.packet = new QuorumPacket(NEWLEADER, zk.getZxid(), null, null);
if ((newLeaderProposal.packet.getZxid() & 0xffffffffL) != 0) {
LOG.info("NEWLEADER proposal has Zxid of {}", Long.toHexString(newLeaderProposal.packet.getZxid()));
}
QuorumVerifier lastSeenQV = self.getLastSeenQuorumVerifier();
QuorumVerifier curQV = self.getQuorumVerifier();
if (curQV.getVersion() == 0 && curQV.getVersion() == lastSeenQV.getVersion()) {
// This was added in ZOOKEEPER-1783. The initial config has version 0 (not explicitly
// specified by the user; the lack of version in a config file is interpreted as version=0).
// As soon as a config is established we would like to increase its version so that it
// takes presedence over other initial configs that were not established (such as a config
// of a server trying to join the ensemble, which may be a partial view of the system, not the full config).
// We chose to set the new version to the one of the NEWLEADER message. However, before we can do that
// there must be agreement on the new version, so we can only change the version when sending/receiving UPTODATE,
// not when sending/receiving NEWLEADER. In other words, we can't change curQV here since its the committed quorum verifier,
// and there's still no agreement on the new version that we'd like to use. Instead, we use
// lastSeenQuorumVerifier which is being sent with NEWLEADER message
// so its a good way to let followers know about the new version. (The original reason for sending
// lastSeenQuorumVerifier with NEWLEADER is so that the leader completes any potentially uncommitted reconfigs
// that it finds before starting to propose operations. Here we're reusing the same code path for
// reaching consensus on the new version number.)
// It is important that this is done before the leader executes waitForEpochAck,
// so before LearnerHandlers return from their waitForEpochAck
// hence before they construct the NEWLEADER message containing
// the last-seen-quorumverifier of the leader, which we change below
try {
QuorumVerifier newQV = self.configFromString(curQV.toString());
newQV.setVersion(zk.getZxid());
self.setLastSeenQuorumVerifier(newQV, true);
} catch (Exception e) {
throw new IOException(e);
}
}
newLeaderProposal.addQuorumVerifier(self.getQuorumVerifier());
if (self.getLastSeenQuorumVerifier().getVersion() > self.getQuorumVerifier().getVersion()) {
newLeaderProposal.addQuorumVerifier(self.getLastSeenQuorumVerifier());
}
// We have to get at least a majority of servers in sync with
// us. We do this by waiting for the NEWLEADER packet to get
// acknowledged
waitForEpochAck(self.getId(), leaderStateSummary);
self.setCurrentEpoch(epoch);
self.setLeaderAddressAndId(self.getQuorumAddress(), self.getId());
self.setZabState(QuorumPeer.ZabState.SYNCHRONIZATION);
try {
waitForNewLeaderAck(self.getId(), zk.getZxid());
} catch (InterruptedException e) {
shutdown("Waiting for a quorum of followers, only synced with sids: [ "
+ newLeaderProposal.ackSetsToString()
+ " ]");
HashSet followerSet = new HashSet();
for (LearnerHandler f : getLearners()) {
if (self.getQuorumVerifier().getVotingMembers().containsKey(f.getSid())) {
followerSet.add(f.getSid());
}
}
boolean initTicksShouldBeIncreased = true;
for (Proposal.QuorumVerifierAcksetPair qvAckset : newLeaderProposal.qvAcksetPairs) {
if (!qvAckset.getQuorumVerifier().containsQuorum(followerSet)) {
initTicksShouldBeIncreased = false;
break;
}
}
if (initTicksShouldBeIncreased) {
LOG.warn("Enough followers present. Perhaps the initTicks need to be increased.");
}
return;
}
startZkServer();
/**
* WARNING: do not use this for anything other than QA testing
* on a real cluster. Specifically to enable verification that quorum
* can handle the lower 32bit roll-over issue identified in
* ZOOKEEPER-1277. Without this option it would take a very long
* time (on order of a month say) to see the 4 billion writes
* necessary to cause the roll-over to occur.
*
* This field allows you to override the zxid of the server. Typically
* you'll want to set it to something like 0xfffffff0 and then
* start the quorum, run some operations and see the re-election.
*/
String initialZxid = System.getProperty("zookeeper.testingonly.initialZxid");
if (initialZxid != null) {
long zxid = Long.parseLong(initialZxid);
zk.setZxid((zk.getZxid() & 0xffffffff00000000L) | zxid);
}
if (!System.getProperty("zookeeper.leaderServes", "yes").equals("no")) {
self.setZooKeeperServer(zk);
}
self.setZabState(QuorumPeer.ZabState.BROADCAST);
self.adminServer.setZooKeeperServer(zk);
// Everything is a go, simply start counting the ticks
// WARNING: I couldn't find any wait statement on a synchronized
// block that would be notified by this notifyAll() call, so
// I commented it out
//synchronized (this) {
// notifyAll();
//}
// We ping twice a tick, so we only update the tick every other
// iteration
boolean tickSkip = true;
// If not null then shutdown this leader
String shutdownMessage = null;
while (true) {
synchronized (this) {
long start = Time.currentElapsedTime();
long cur = start;
long end = start + self.tickTime / 2;
while (cur < end) {
wait(end - cur);
cur = Time.currentElapsedTime();
}
if (!tickSkip) {
self.tick.incrementAndGet();
}
// We use an instance of SyncedLearnerTracker to
// track synced learners to make sure we still have a
// quorum of current (and potentially next pending) view.
SyncedLearnerTracker syncedAckSet = new SyncedLearnerTracker();
syncedAckSet.addQuorumVerifier(self.getQuorumVerifier());
if (self.getLastSeenQuorumVerifier() != null
&& self.getLastSeenQuorumVerifier().getVersion() > self.getQuorumVerifier().getVersion()) {
syncedAckSet.addQuorumVerifier(self.getLastSeenQuorumVerifier());
}
syncedAckSet.addAck(self.getId());
for (LearnerHandler f : getLearners()) {
if (f.synced()) {
syncedAckSet.addAck(f.getSid());
}
}
// check leader running status
if (!this.isRunning()) {
// set shutdown flag
shutdownMessage = "Unexpected internal error";
break;
}
if (!tickSkip && !syncedAckSet.hasAllQuorums()) {
// Lost quorum of last committed and/or last proposed
// config, set shutdown flag
shutdownMessage = "Not sufficient followers synced, only synced with sids: [ "
+ syncedAckSet.ackSetsToString()
+ " ]";
break;
}
tickSkip = !tickSkip;
}
for (LearnerHandler f : getLearners()) {
f.ping();
}
}
if (shutdownMessage != null) {
shutdown(shutdownMessage);
// leader goes in looking state
}
} finally {
zk.unregisterJMX(this);
}
}
boolean isShutdown;
/**
* Close down all the LearnerHandlers
*/
void shutdown(String reason) {
LOG.info("Shutting down");
if (isShutdown) {
return;
}
LOG.info("Shutdown called. For the reason {}", reason);
if (cnxAcceptor != null) {
cnxAcceptor.halt();
} else {
closeSockets();
}
// NIO should not accept conenctions
self.setZooKeeperServer(null);
self.adminServer.setZooKeeperServer(null);
self.closeAllConnections();
// shutdown the previous zk
if (zk != null) {
zk.shutdown();
}
synchronized (learners) {
for (Iterator it = learners.iterator(); it.hasNext(); ) {
LearnerHandler f = it.next();
it.remove();
f.shutdown();
}
}
isShutdown = true;
}
synchronized void closeSockets() {
for (ServerSocket serverSocket : serverSockets) {
if (!serverSocket.isClosed()) {
try {
serverSocket.close();
} catch (IOException e) {
LOG.warn("Ignoring unexpected exception during close {}", serverSocket, e);
}
}
}
}
/** In a reconfig operation, this method attempts to find the best leader for next configuration.
* If the current leader is a voter in the next configuartion, then it remains the leader.
* Otherwise, choose one of the new voters that acked the reconfiguartion, such that it is as
* up-to-date as possible, i.e., acked as many outstanding proposals as possible.
*
* @param reconfigProposal
* @param zxid of the reconfigProposal
* @return server if of the designated leader
*/
private long getDesignatedLeader(Proposal reconfigProposal, long zxid) {
//new configuration
Proposal.QuorumVerifierAcksetPair newQVAcksetPair = reconfigProposal.qvAcksetPairs.get(reconfigProposal.qvAcksetPairs.size() - 1);
//check if I'm in the new configuration with the same quorum address -
// if so, I'll remain the leader
if (newQVAcksetPair.getQuorumVerifier().getVotingMembers().containsKey(self.getId())
&& newQVAcksetPair.getQuorumVerifier().getVotingMembers().get(self.getId()).addr.equals(self.getQuorumAddress())) {
return self.getId();
}
// start with an initial set of candidates that are voters from new config that
// acknowledged the reconfig op (there must be a quorum). Choose one of them as
// current leader candidate
HashSet candidates = new HashSet(newQVAcksetPair.getAckset());
candidates.remove(self.getId()); // if we're here, I shouldn't be the leader
long curCandidate = candidates.iterator().next();
//go over outstanding ops in order, and try to find a candidate that acked the most ops.
//this way it will be the most up-to-date and we'll minimize the number of ops that get dropped
long curZxid = zxid + 1;
Proposal p = outstandingProposals.get(curZxid);
while (p != null && !candidates.isEmpty()) {
for (Proposal.QuorumVerifierAcksetPair qvAckset : p.qvAcksetPairs) {
//reduce the set of candidates to those that acknowledged p
candidates.retainAll(qvAckset.getAckset());
//no candidate acked p, return the best candidate found so far
if (candidates.isEmpty()) {
return curCandidate;
}
//update the current candidate, and if it is the only one remaining, return it
curCandidate = candidates.iterator().next();
if (candidates.size() == 1) {
return curCandidate;
}
}
curZxid++;
p = outstandingProposals.get(curZxid);
}
return curCandidate;
}
/**
* @return True if committed, otherwise false.
**/
public synchronized boolean tryToCommit(Proposal p, long zxid, SocketAddress followerAddr) {
// make sure that ops are committed in order. With reconfigurations it is now possible
// that different operations wait for different sets of acks, and we still want to enforce
// that they are committed in order. Currently we only permit one outstanding reconfiguration
// such that the reconfiguration and subsequent outstanding ops proposed while the reconfig is
// pending all wait for a quorum of old and new config, so it's not possible to get enough acks
// for an operation without getting enough acks for preceding ops. But in the future if multiple
// concurrent reconfigs are allowed, this can happen.
if (outstandingProposals.containsKey(zxid - 1)) {
return false;
}
// in order to be committed, a proposal must be accepted by a quorum.
//
// getting a quorum from all necessary configurations.
if (!p.hasAllQuorums()) {
return false;
}
// commit proposals in order
if (zxid != lastCommitted + 1) {
LOG.warn(
"Commiting zxid 0x{} from {} noy first!",
Long.toHexString(zxid),
followerAddr);
LOG.warn("First is {}", (lastCommitted + 1));
}
outstandingProposals.remove(zxid);
if (p.request != null) {
toBeApplied.add(p);
}
if (p.request == null) {
LOG.warn("Going to commit null: {}", p);
} else if (p.request.getHdr().getType() == OpCode.reconfig) {
LOG.debug("Committing a reconfiguration! {}", outstandingProposals.size());
//if this server is voter in new config with the same quorum address,
//then it will remain the leader
//otherwise an up-to-date follower will be designated as leader. This saves
//leader election time, unless the designated leader fails
Long designatedLeader = getDesignatedLeader(p, zxid);
//LOG.warn("designated leader is: " + designatedLeader);
QuorumVerifier newQV = p.qvAcksetPairs.get(p.qvAcksetPairs.size() - 1).getQuorumVerifier();
self.processReconfig(newQV, designatedLeader, zk.getZxid(), true);
if (designatedLeader != self.getId()) {
allowedToCommit = false;
}
// we're sending the designated leader, and if the leader is changing the followers are
// responsible for closing the connection - this way we are sure that at least a majority of them
// receive the commit message.
commitAndActivate(zxid, designatedLeader);
informAndActivate(p, designatedLeader);
//turnOffFollowers();
} else {
p.request.logLatency(ServerMetrics.getMetrics().QUORUM_ACK_LATENCY);
commit(zxid);
inform(p);
}
zk.commitProcessor.commit(p.request);
if (pendingSyncs.containsKey(zxid)) {
for (LearnerSyncRequest r : pendingSyncs.remove(zxid)) {
sendSync(r);
}
}
return true;
}
/**
* Keep a count of acks that are received by the leader for a particular
* proposal
*
* @param zxid, the zxid of the proposal sent out
* @param sid, the id of the server that sent the ack
* @param followerAddr
*/
@Override
public synchronized void processAck(long sid, long zxid, SocketAddress followerAddr) {
if (!allowedToCommit) {
return; // last op committed was a leader change - from now on
}
// the new leader should commit
if (LOG.isTraceEnabled()) {
LOG.trace("Ack zxid: 0x{}", Long.toHexString(zxid));
for (Proposal p : outstandingProposals.values()) {
long packetZxid = p.packet.getZxid();
LOG.trace("outstanding proposal: 0x{}", Long.toHexString(packetZxid));
}
LOG.trace("outstanding proposals all");
}
if ((zxid & 0xffffffffL) == 0) {
/*
* We no longer process NEWLEADER ack with this method. However,
* the learner sends an ack back to the leader after it gets
* UPTODATE, so we just ignore the message.
*/
return;
}
if (outstandingProposals.size() == 0) {
LOG.debug("outstanding is 0");
return;
}
if (lastCommitted >= zxid) {
LOG.debug(
"proposal has already been committed, pzxid: 0x{} zxid: 0x{}",
Long.toHexString(lastCommitted),
Long.toHexString(zxid));
// The proposal has already been committed
return;
}
Proposal p = outstandingProposals.get(zxid);
if (p == null) {
LOG.warn("Trying to commit future proposal: zxid 0x{} from {}", Long.toHexString(zxid), followerAddr);
return;
}
if (ackLoggingFrequency > 0 && (zxid % ackLoggingFrequency == 0)) {
p.request.logLatency(ServerMetrics.getMetrics().ACK_LATENCY, Long.toString(sid));
}
p.addAck(sid);
boolean hasCommitted = tryToCommit(p, zxid, followerAddr);
// If p is a reconfiguration, multiple other operations may be ready to be committed,
// since operations wait for different sets of acks.
// Currently we only permit one outstanding reconfiguration at a time
// such that the reconfiguration and subsequent outstanding ops proposed while the reconfig is
// pending all wait for a quorum of old and new config, so its not possible to get enough acks
// for an operation without getting enough acks for preceding ops. But in the future if multiple
// concurrent reconfigs are allowed, this can happen and then we need to check whether some pending
// ops may already have enough acks and can be committed, which is what this code does.
if (hasCommitted && p.request != null && p.request.getHdr().getType() == OpCode.reconfig) {
long curZxid = zxid;
while (allowedToCommit && hasCommitted && p != null) {
curZxid++;
p = outstandingProposals.get(curZxid);
if (p != null) {
hasCommitted = tryToCommit(p, curZxid, null);
}
}
}
}
static class ToBeAppliedRequestProcessor implements RequestProcessor {
private final RequestProcessor next;
private final Leader leader;
/**
* This request processor simply maintains the toBeApplied list. For
* this to work next must be a FinalRequestProcessor and
* FinalRequestProcessor.processRequest MUST process the request
* synchronously!
*
* @param next
* a reference to the FinalRequestProcessor
*/
ToBeAppliedRequestProcessor(RequestProcessor next, Leader leader) {
if (!(next instanceof FinalRequestProcessor)) {
throw new RuntimeException(ToBeAppliedRequestProcessor.class.getName()
+ " must be connected to "
+ FinalRequestProcessor.class.getName()
+ " not "
+ next.getClass().getName());
}
this.leader = leader;
this.next = next;
}
/*
* (non-Javadoc)
*
* @see org.apache.zookeeper.server.RequestProcessor#processRequest(org.apache.zookeeper.server.Request)
*/
public void processRequest(Request request) throws RequestProcessorException {
next.processRequest(request);
// The only requests that should be on toBeApplied are write
// requests, for which we will have a hdr. We can't simply use
// request.zxid here because that is set on read requests to equal
// the zxid of the last write op.
if (request.getHdr() != null) {
long zxid = request.getHdr().getZxid();
Iterator iter = leader.toBeApplied.iterator();
if (iter.hasNext()) {
Proposal p = iter.next();
if (p.request != null && p.request.zxid == zxid) {
iter.remove();
return;
}
}
LOG.error("Committed request not found on toBeApplied: {}", request);
}
}
/*
* (non-Javadoc)
*
* @see org.apache.zookeeper.server.RequestProcessor#shutdown()
*/
public void shutdown() {
LOG.info("Shutting down");
next.shutdown();
}
}
/**
* send a packet to all the followers ready to follow
*
* @param qp
* the packet to be sent
*/
void sendPacket(QuorumPacket qp) {
synchronized (forwardingFollowers) {
for (LearnerHandler f : forwardingFollowers) {
f.queuePacket(qp);
}
}
}
/**
* send a packet to all observers
*/
void sendObserverPacket(QuorumPacket qp) {
for (LearnerHandler f : getObservingLearners()) {
f.queuePacket(qp);
}
}
long lastCommitted = -1;
/**
* Create a commit packet and send it to all the members of the quorum
*
* @param zxid
*/
public void commit(long zxid) {
synchronized (this) {
lastCommitted = zxid;
}
QuorumPacket qp = new QuorumPacket(Leader.COMMIT, zxid, null, null);
sendPacket(qp);
ServerMetrics.getMetrics().COMMIT_COUNT.add(1);
}
//commit and send some info
public void commitAndActivate(long zxid, long designatedLeader) {
synchronized (this) {
lastCommitted = zxid;
}
byte[] data = new byte[8];
ByteBuffer buffer = ByteBuffer.wrap(data);
buffer.putLong(designatedLeader);
QuorumPacket qp = new QuorumPacket(Leader.COMMITANDACTIVATE, zxid, data, null);
sendPacket(qp);
}
/**
* Create an inform packet and send it to all observers.
*/
public void inform(Proposal proposal) {
QuorumPacket qp = new QuorumPacket(Leader.INFORM, proposal.request.zxid, proposal.packet.getData(), null);
sendObserverPacket(qp);
}
public static QuorumPacket buildInformAndActivePacket(long zxid, long designatedLeader, byte[] proposalData) {
byte[] data = new byte[proposalData.length + 8];
ByteBuffer buffer = ByteBuffer.wrap(data);
buffer.putLong(designatedLeader);
buffer.put(proposalData);
return new QuorumPacket(Leader.INFORMANDACTIVATE, zxid, data, null);
}
/**
* Create an inform and activate packet and send it to all observers.
*/
public void informAndActivate(Proposal proposal, long designatedLeader) {
sendObserverPacket(buildInformAndActivePacket(proposal.request.zxid, designatedLeader, proposal.packet.getData()));
}
long lastProposed;
@Override
public synchronized long getLastProposed() {
return lastProposed;
}
/**
* Returns the current epoch of the leader.
*
* @return
*/
public long getEpoch() {
return ZxidUtils.getEpochFromZxid(lastProposed);
}
@SuppressWarnings("serial")
public static class XidRolloverException extends Exception {
public XidRolloverException(String message) {
super(message);
}
}
/**
* create a proposal and send it out to all the members
*
* @param request
* @return the proposal that is queued to send to all the members
*/
public Proposal propose(Request request) throws XidRolloverException {
/**
* Address the rollover issue. All lower 32bits set indicate a new leader
* election. Force a re-election instead. See ZOOKEEPER-1277
*/
if ((request.zxid & 0xffffffffL) == 0xffffffffL) {
String msg = "zxid lower 32 bits have rolled over, forcing re-election, and therefore new epoch start";
shutdown(msg);
throw new XidRolloverException(msg);
}
byte[] data = SerializeUtils.serializeRequest(request);
proposalStats.setLastBufferSize(data.length);
QuorumPacket pp = new QuorumPacket(Leader.PROPOSAL, request.zxid, data, null);
Proposal p = new Proposal();
p.packet = pp;
p.request = request;
synchronized (this) {
p.addQuorumVerifier(self.getQuorumVerifier());
if (request.getHdr().getType() == OpCode.reconfig) {
self.setLastSeenQuorumVerifier(request.qv, true);
}
if (self.getQuorumVerifier().getVersion() < self.getLastSeenQuorumVerifier().getVersion()) {
p.addQuorumVerifier(self.getLastSeenQuorumVerifier());
}
LOG.debug("Proposing:: {}", request);
lastProposed = p.packet.getZxid();
outstandingProposals.put(lastProposed, p);
sendPacket(pp);
}
ServerMetrics.getMetrics().PROPOSAL_COUNT.add(1);
return p;
}
/**
* Process sync requests
*
* @param r the request
*/
public synchronized void processSync(LearnerSyncRequest r) {
if (outstandingProposals.isEmpty()) {
sendSync(r);
} else {
List l = pendingSyncs.get(lastProposed);
if (l == null) {
l = new ArrayList();
}
l.add(r);
pendingSyncs.put(lastProposed, l);
}
}
/**
* Sends a sync message to the appropriate server
*/
public void sendSync(LearnerSyncRequest r) {
QuorumPacket qp = new QuorumPacket(Leader.SYNC, 0, null, null);
r.fh.queuePacket(qp);
}
/**
* lets the leader know that a follower is capable of following and is done
* syncing
*
* @param handler handler of the follower
* @return last proposed zxid
*/
@Override
public synchronized long startForwarding(LearnerHandler handler, long lastSeenZxid) {
// Queue up any outstanding requests enabling the receipt of
// new requests
if (lastProposed > lastSeenZxid) {
for (Proposal p : toBeApplied) {
if (p.packet.getZxid() <= lastSeenZxid) {
continue;
}
handler.queuePacket(p.packet);
// Since the proposal has been committed we need to send the
// commit message also
QuorumPacket qp = new QuorumPacket(Leader.COMMIT, p.packet.getZxid(), null, null);
handler.queuePacket(qp);
}
// Only participant need to get outstanding proposals
if (handler.getLearnerType() == LearnerType.PARTICIPANT) {
List zxids = new ArrayList(outstandingProposals.keySet());
Collections.sort(zxids);
for (Long zxid : zxids) {
if (zxid <= lastSeenZxid) {
continue;
}
handler.queuePacket(outstandingProposals.get(zxid).packet);
}
}
}
if (handler.getLearnerType() == LearnerType.PARTICIPANT) {
addForwardingFollower(handler);
} else {
addObserverLearnerHandler(handler);
}
return lastProposed;
}
@Override
public void waitForStartup() throws InterruptedException {
synchronized (zk) {
while (!zk.isRunning() && !Thread.currentThread().isInterrupted()) {
zk.wait(20);
}
}
}
// VisibleForTesting
protected final Set connectingFollowers = new HashSet();
private volatile boolean quitWaitForEpoch = false;
private volatile long timeStartWaitForEpoch = -1;
private volatile SyncedLearnerTracker voteSet;
public static final String MAX_TIME_TO_WAIT_FOR_EPOCH = "zookeeper.leader.maxTimeToWaitForEpoch";
private static int maxTimeToWaitForEpoch;
static {
maxTimeToWaitForEpoch = Integer.getInteger(MAX_TIME_TO_WAIT_FOR_EPOCH, -1);
LOG.info("{} = {}ms", MAX_TIME_TO_WAIT_FOR_EPOCH, maxTimeToWaitForEpoch);
}
// visible for test
public static void setMaxTimeToWaitForEpoch(int maxTimeToWaitForEpoch) {
Leader.maxTimeToWaitForEpoch = maxTimeToWaitForEpoch;
LOG.info("Set {} to {}ms", MAX_TIME_TO_WAIT_FOR_EPOCH, Leader.maxTimeToWaitForEpoch);
}
/**
* Quit condition:
*
* 1 voter goes to looking again and time waitForEpoch > maxTimeToWaitForEpoch
*
* Note: the voter may go to looking again in case of:
* 1. change mind in the last minute when received a different notification
* 2. the leader hadn't started leading when it tried to connect to it
* 3. connection broken between the voter and leader
* 4. voter being shutdown or restarted
*/
private void quitLeading() {
synchronized (connectingFollowers) {
quitWaitForEpoch = true;
connectingFollowers.notifyAll();
}
ServerMetrics.getMetrics().QUIT_LEADING_DUE_TO_DISLOYAL_VOTER.add(1);
LOG.info("Quit leading due to voter changed mind.");
}
public void setLeadingVoteSet(SyncedLearnerTracker voteSet) {
this.voteSet = voteSet;
}
public void reportLookingSid(long sid) {
if (maxTimeToWaitForEpoch < 0 || timeStartWaitForEpoch < 0 || !waitingForNewEpoch) {
return;
}
if (voteSet == null || !voteSet.hasSid(sid)) {
return;
}
if (Time.currentElapsedTime() - timeStartWaitForEpoch > maxTimeToWaitForEpoch) {
quitLeading();
}
}
@Override
public long getEpochToPropose(long sid, long lastAcceptedEpoch) throws InterruptedException, IOException {
synchronized (connectingFollowers) {
if (!waitingForNewEpoch) {
return epoch;
}
if (lastAcceptedEpoch >= epoch) {
epoch = lastAcceptedEpoch + 1;
}
if (isParticipant(sid)) {
connectingFollowers.add(sid);
}
QuorumVerifier verifier = self.getQuorumVerifier();
if (connectingFollowers.contains(self.getId()) && verifier.containsQuorum(connectingFollowers)) {
waitingForNewEpoch = false;
self.setAcceptedEpoch(epoch);
connectingFollowers.notifyAll();
} else {
long start = Time.currentElapsedTime();
if (sid == self.getId()) {
timeStartWaitForEpoch = start;
}
long cur = start;
long end = start + self.getInitLimit() * self.getTickTime();
while (waitingForNewEpoch && cur < end && !quitWaitForEpoch) {
connectingFollowers.wait(end - cur);
cur = Time.currentElapsedTime();
}
if (waitingForNewEpoch) {
throw new InterruptedException("Timeout while waiting for epoch from quorum");
}
}
return epoch;
}
}
@Override
public ZKDatabase getZKDatabase() {
return zk.getZKDatabase();
}
// VisibleForTesting
protected final Set electingFollowers = new HashSet();
// VisibleForTesting
protected boolean electionFinished = false;
@Override
public void waitForEpochAck(long id, StateSummary ss) throws IOException, InterruptedException {
synchronized (electingFollowers) {
if (electionFinished) {
return;
}
if (ss.getCurrentEpoch() != -1) {
if (ss.isMoreRecentThan(leaderStateSummary)) {
throw new IOException("Follower is ahead of the leader, leader summary: "
+ leaderStateSummary.getCurrentEpoch()
+ " (current epoch), "
+ leaderStateSummary.getLastZxid()
+ " (last zxid)");
}
if (ss.getLastZxid() != -1 && isParticipant(id)) {
electingFollowers.add(id);
}
}
QuorumVerifier verifier = self.getQuorumVerifier();
if (electingFollowers.contains(self.getId()) && verifier.containsQuorum(electingFollowers)) {
electionFinished = true;
electingFollowers.notifyAll();
} else {
long start = Time.currentElapsedTime();
long cur = start;
long end = start + self.getInitLimit() * self.getTickTime();
while (!electionFinished && cur < end) {
electingFollowers.wait(end - cur);
cur = Time.currentElapsedTime();
}
if (!electionFinished) {
throw new InterruptedException("Timeout while waiting for epoch to be acked by quorum");
}
}
}
}
/**
* Return a list of sid in set as string
*/
private String getSidSetString(Set sidSet) {
StringBuilder sids = new StringBuilder();
Iterator iter = sidSet.iterator();
while (iter.hasNext()) {
sids.append(iter.next());
if (!iter.hasNext()) {
break;
}
sids.append(",");
}
return sids.toString();
}
/**
* Start up Leader ZooKeeper server and initialize zxid to the new epoch
*/
private synchronized void startZkServer() {
// Update lastCommitted and Db's zxid to a value representing the new epoch
lastCommitted = zk.getZxid();
LOG.info("Have quorum of supporters, sids: [{}]; starting up and setting last processed zxid: 0x{}",
newLeaderProposal.ackSetsToString(),
Long.toHexString(zk.getZxid()));
/*
* ZOOKEEPER-1324. the leader sends the new config it must complete
* to others inside a NEWLEADER message (see LearnerHandler where
* the NEWLEADER message is constructed), and once it has enough
* acks we must execute the following code so that it applies the
* config to itself.
*/
QuorumVerifier newQV = self.getLastSeenQuorumVerifier();
Long designatedLeader = getDesignatedLeader(newLeaderProposal, zk.getZxid());
self.processReconfig(newQV, designatedLeader, zk.getZxid(), true);
if (designatedLeader != self.getId()) {
allowedToCommit = false;
}
leaderStartTime = Time.currentElapsedTime();
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(getEpoch());
zk.getZKDatabase().setlastProcessedZxid(zk.getZxid());
}
/**
* Process NEWLEADER ack of a given sid and wait until the leader receives
* sufficient acks.
*
* @param sid
* @throws InterruptedException
*/
@Override
public void waitForNewLeaderAck(long sid, long zxid) throws InterruptedException {
synchronized (newLeaderProposal.qvAcksetPairs) {
if (quorumFormed) {
return;
}
long currentZxid = newLeaderProposal.packet.getZxid();
if (zxid != currentZxid) {
LOG.error(
"NEWLEADER ACK from sid: {} is from a different epoch - current 0x{} received 0x{}",
sid,
Long.toHexString(currentZxid),
Long.toHexString(zxid));
return;
}
/*
* Note that addAck already checks that the learner
* is a PARTICIPANT.
*/
newLeaderProposal.addAck(sid);
if (newLeaderProposal.hasAllQuorums()) {
quorumFormed = true;
newLeaderProposal.qvAcksetPairs.notifyAll();
} else {
long start = Time.currentElapsedTime();
long cur = start;
long end = start + self.getInitLimit() * self.getTickTime();
while (!quorumFormed && cur < end) {
newLeaderProposal.qvAcksetPairs.wait(end - cur);
cur = Time.currentElapsedTime();
}
if (!quorumFormed) {
throw new InterruptedException("Timeout while waiting for NEWLEADER to be acked by quorum");
}
}
}
}
/**
* Get string representation of a given packet type
* @param packetType
* @return string representing the packet type
*/
public static String getPacketType(int packetType) {
switch (packetType) {
case DIFF:
return "DIFF";
case TRUNC:
return "TRUNC";
case SNAP:
return "SNAP";
case OBSERVERINFO:
return "OBSERVERINFO";
case NEWLEADER:
return "NEWLEADER";
case FOLLOWERINFO:
return "FOLLOWERINFO";
case UPTODATE:
return "UPTODATE";
case LEADERINFO:
return "LEADERINFO";
case ACKEPOCH:
return "ACKEPOCH";
case REQUEST:
return "REQUEST";
case PROPOSAL:
return "PROPOSAL";
case ACK:
return "ACK";
case COMMIT:
return "COMMIT";
case COMMITANDACTIVATE:
return "COMMITANDACTIVATE";
case PING:
return "PING";
case REVALIDATE:
return "REVALIDATE";
case SYNC:
return "SYNC";
case INFORM:
return "INFORM";
case INFORMANDACTIVATE:
return "INFORMANDACTIVATE";
default:
return "UNKNOWN";
}
}
private boolean isRunning() {
return self.isRunning() && zk.isRunning();
}
private boolean isParticipant(long sid) {
return self.getQuorumVerifier().getVotingMembers().containsKey(sid);
}
@Override
public int getCurrentTick() {
return self.tick.get();
}
@Override
public int syncTimeout() {
return self.tickTime * self.syncLimit;
}
@Override
public int getTickOfNextAckDeadline() {
return self.tick.get() + self.syncLimit;
}
@Override
public int getTickOfInitialAckDeadline() {
return self.tick.get() + self.initLimit + self.syncLimit;
}
@Override
public long getAndDecrementFollowerCounter() {
return followerCounter.getAndDecrement();
}
@Override
public void touch(long sess, int to) {
zk.touch(sess, to);
}
@Override
public void submitLearnerRequest(Request si) {
zk.submitLearnerRequest(si);
}
@Override
public long getQuorumVerifierVersion() {
return self.getQuorumVerifier().getVersion();
}
@Override
public String getPeerInfo(long sid) {
QuorumPeer.QuorumServer server = self.getView().get(sid);
return server == null ? "" : server.toString();
}
@Override
public byte[] getQuorumVerifierBytes() {
return self.getLastSeenQuorumVerifier().toString().getBytes();
}
@Override
public QuorumAuthServer getQuorumAuthServer() {
return (self == null) ? null : self.authServer;
}
@Override
public void revalidateSession(QuorumPacket qp, LearnerHandler learnerHandler) throws IOException {
ByteArrayInputStream bis = new ByteArrayInputStream(qp.getData());
DataInputStream dis = new DataInputStream(bis);
long id = dis.readLong();
int to = dis.readInt();
ByteArrayOutputStream bos = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(bos);
dos.writeLong(id);
boolean valid = zk.checkIfValidGlobalSession(id, to);
if (valid) {
try {
// set the session owner as the follower that owns the session
zk.setOwner(id, learnerHandler);
} catch (KeeperException.SessionExpiredException e) {
LOG.error(
"Somehow session 0x{} expired right after being renewed! (impossible)",
Long.toHexString(id),
e);
}
}
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(
LOG,
ZooTrace.SESSION_TRACE_MASK,
"Session 0x" + Long.toHexString(id) + " is valid: " + valid);
}
dos.writeBoolean(valid);
qp.setData(bos.toByteArray());
learnerHandler.queuePacket(qp);
}
@Override
public void registerLearnerHandlerBean(final LearnerHandler learnerHandler, Socket socket) {
LearnerHandlerBean bean = new LearnerHandlerBean(learnerHandler, socket);
if (zk.registerJMX(bean)) {
connectionBeans.put(learnerHandler, bean);
}
}
@Override
public void unregisterLearnerHandlerBean(final LearnerHandler learnerHandler) {
LearnerHandlerBean bean = connectionBeans.remove(learnerHandler);
if (bean != null) {
MBeanRegistry.getInstance().unregister(bean);
}
}
}
