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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.IOException;
import java.util.Map;
import org.apache.zookeeper.jmx.MBeanRegistry;
import org.apache.zookeeper.server.DataTreeBean;
import org.apache.zookeeper.server.ServerCnxn;
import org.apache.zookeeper.server.SyncRequestProcessor;
import org.apache.zookeeper.server.ZKDatabase;
import org.apache.zookeeper.server.ZooKeeperServerBean;
import org.apache.zookeeper.server.persistence.FileTxnSnapLog;
/**
* Parent class for all ZooKeeperServers for Learners
*/
public abstract class LearnerZooKeeperServer extends QuorumZooKeeperServer {
/*
* Request processors
*/
protected CommitProcessor commitProcessor;
protected SyncRequestProcessor syncProcessor;
public LearnerZooKeeperServer(FileTxnSnapLog logFactory, int tickTime, int minSessionTimeout, int maxSessionTimeout, int listenBacklog, ZKDatabase zkDb, QuorumPeer self) throws IOException {
super(logFactory, tickTime, minSessionTimeout, maxSessionTimeout, listenBacklog, zkDb, self);
}
/**
* Abstract method to return the learner associated with this server.
* Since the Learner may change under our feet (when QuorumPeer reassigns
* it) we can't simply take a reference here. Instead, we need the
* subclasses to implement this.
*/
public abstract Learner getLearner();
/**
* Returns the current state of the session tracker. This is only currently
* used by a Learner to build a ping response packet.
*
*/
protected Map<Long, Integer> getTouchSnapshot() {
if (sessionTracker != null) {
return ((LearnerSessionTracker) sessionTracker).snapshot();
}
Map<Long, Integer> map = Map.of();
return map;
}
/**
* Returns the id of the associated QuorumPeer, which will do for a unique
* id of this server.
*/
@Override
public long getServerId() {
return self.getMyId();
}
@Override
public void createSessionTracker() {
sessionTracker = new LearnerSessionTracker(
this,
getZKDatabase().getSessionWithTimeOuts(),
this.tickTime,
self.getMyId(),
self.areLocalSessionsEnabled(),
getZooKeeperServerListener());
}
@Override
protected void revalidateSession(ServerCnxn cnxn, long sessionId, int sessionTimeout) throws IOException {
if (upgradeableSessionTracker.isLocalSession(sessionId)) {
super.revalidateSession(cnxn, sessionId, sessionTimeout);
} else {
getLearner().validateSession(cnxn, sessionId, sessionTimeout);
}
}
@Override
protected void registerJMX() {
// register with JMX
try {
jmxDataTreeBean = new DataTreeBean(getZKDatabase().getDataTree());
MBeanRegistry.getInstance().register(jmxDataTreeBean, jmxServerBean);
} catch (Exception e) {
LOG.warn("Failed to register with JMX", e);
jmxDataTreeBean = null;
}
}
public void registerJMX(ZooKeeperServerBean serverBean, LocalPeerBean localPeerBean) {
// register with JMX
if (self.jmxLeaderElectionBean != null) {
try {
MBeanRegistry.getInstance().unregister(self.jmxLeaderElectionBean);
} catch (Exception e) {
LOG.warn("Failed to register with JMX", e);
}
self.jmxLeaderElectionBean = null;
}
try {
jmxServerBean = serverBean;
MBeanRegistry.getInstance().register(serverBean, localPeerBean);
} catch (Exception e) {
LOG.warn("Failed to register with JMX", e);
jmxServerBean = null;
}
}
@Override
protected void unregisterJMX() {
// unregister from JMX
try {
if (jmxDataTreeBean != null) {
MBeanRegistry.getInstance().unregister(jmxDataTreeBean);
}
} catch (Exception e) {
LOG.warn("Failed to unregister with JMX", e);
}
jmxDataTreeBean = null;
}
protected void unregisterJMX(Learner peer) {
// unregister from JMX
try {
if (jmxServerBean != null) {
MBeanRegistry.getInstance().unregister(jmxServerBean);
}
} catch (Exception e) {
LOG.warn("Failed to unregister with JMX", e);
}
jmxServerBean = null;
}
@Override
public synchronized void shutdown(boolean fullyShutDown) {
if (!canShutdown()) {
LOG.debug("ZooKeeper server is not running, so not proceeding to shutdown!");
} else {
LOG.info("Shutting down");
try {
if (syncProcessor != null) {
// Shutting down the syncProcessor here, first, ensures queued transactions here are written to
// permanent storage, which ensures that crash recovery data is consistent with what is used for a
// leader election immediately following shutdown, because of the old leader going down; and also
// that any state on its way to being written is also loaded in the potential call to
// fast-forward-from-edits, in super.shutdown(...), so we avoid getting a DIFF from the new leader
// that contains entries we have already written to our transaction log.
syncProcessor.shutdown();
}
} catch (Exception e) {
LOG.warn("Ignoring unexpected exception in syncprocessor shutdown", e);
}
}
try {
super.shutdown(fullyShutDown);
} catch (Exception e) {
LOG.warn("Ignoring unexpected exception during shutdown", e);
}
}
}
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