org.apache.zookeeper.server.quorum.ReadOnlyZooKeeperServer Maven / Gradle / Ivy
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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.io.PrintWriter;
import java.util.Objects;
import java.util.stream.Collectors;
import org.apache.zookeeper.ZooDefs.OpCode;
import org.apache.zookeeper.jmx.MBeanRegistry;
import org.apache.zookeeper.server.DataTreeBean;
import org.apache.zookeeper.server.FinalRequestProcessor;
import org.apache.zookeeper.server.PrepRequestProcessor;
import org.apache.zookeeper.server.Request;
import org.apache.zookeeper.server.RequestProcessor;
import org.apache.zookeeper.server.ServerCnxn;
import org.apache.zookeeper.server.ZKDatabase;
import org.apache.zookeeper.server.ZooKeeperServer;
import org.apache.zookeeper.server.ZooKeeperServerBean;
import org.apache.zookeeper.server.persistence.FileTxnSnapLog;
/**
* A ZooKeeperServer which comes into play when peer is partitioned from the
* majority. Handles read-only clients, but drops connections from not-read-only
* ones.
*
* The very first processor in the chain of request processors is a
* ReadOnlyRequestProcessor which drops state-changing requests.
*/
public class ReadOnlyZooKeeperServer extends ZooKeeperServer {
protected final QuorumPeer self;
private volatile boolean shutdown = false;
ReadOnlyZooKeeperServer(FileTxnSnapLog logFactory, QuorumPeer self, ZKDatabase zkDb) {
super(
logFactory,
self.tickTime,
self.minSessionTimeout,
self.maxSessionTimeout,
self.clientPortListenBacklog,
zkDb,
self.getInitialConfig(),
self.isReconfigEnabled());
this.self = self;
}
@Override
protected void setupRequestProcessors() {
RequestProcessor finalProcessor = new FinalRequestProcessor(this);
RequestProcessor prepProcessor = new PrepRequestProcessor(this, finalProcessor);
((PrepRequestProcessor) prepProcessor).start();
firstProcessor = new ReadOnlyRequestProcessor(this, prepProcessor);
((ReadOnlyRequestProcessor) firstProcessor).start();
}
@Override
public synchronized void startup() {
// check to avoid startup follows shutdown
if (shutdown) {
LOG.warn("Not starting Read-only server as startup follows shutdown!");
return;
}
registerJMX(new ReadOnlyBean(this), self.jmxLocalPeerBean);
super.startup();
self.setZooKeeperServer(this);
self.adminServer.setZooKeeperServer(this);
LOG.info("Read-only server started");
}
@Override
public void createSessionTracker() {
sessionTracker = new LearnerSessionTracker(
this, getZKDatabase().getSessionWithTimeOuts(),
this.tickTime, self.getMyId(), self.areLocalSessionsEnabled(),
getZooKeeperServerListener());
}
@Override
protected void startSessionTracker() {
((LearnerSessionTracker) sessionTracker).start();
}
@Override
protected void setLocalSessionFlag(Request si) {
switch (si.type) {
case OpCode.createSession:
if (self.areLocalSessionsEnabled()) {
si.setLocalSession(true);
}
break;
case OpCode.closeSession:
if (((UpgradeableSessionTracker) sessionTracker).isLocalSession(si.sessionId)) {
si.setLocalSession(true);
} else {
LOG.warn("Submitting global closeSession request for session 0x{} in ReadOnly mode",
Long.toHexString(si.sessionId));
}
break;
default:
break;
}
}
@Override
protected void validateSession(ServerCnxn cnxn, long sessionId) throws IOException {
if (((LearnerSessionTracker) sessionTracker).isGlobalSession(sessionId)) {
String msg = "Refusing global session reconnection in RO mode " + cnxn.getRemoteSocketAddress();
LOG.info(msg);
throw new ServerCnxn.CloseRequestException(msg, ServerCnxn.DisconnectReason.RENEW_GLOBAL_SESSION_IN_RO_MODE);
}
}
@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
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(ZooKeeperServer zks) {
// 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 String getState() {
return "read-only";
}
/**
* 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 synchronized void shutdown(boolean fullyShutDown) {
if (!canShutdown()) {
LOG.debug("ZooKeeper server is not running, so not proceeding to shutdown!");
} else {
shutdown = true;
unregisterJMX(this);
// set peer's server to null
self.setZooKeeperServer(null);
// clear all the connections
self.closeAllConnections();
self.adminServer.setZooKeeperServer(null);
}
// shutdown the server itself
super.shutdown(fullyShutDown);
}
@Override
public void dumpConf(PrintWriter pwriter) {
super.dumpConf(pwriter);
pwriter.print("initLimit=");
pwriter.println(self.getInitLimit());
pwriter.print("syncLimit=");
pwriter.println(self.getSyncLimit());
pwriter.print("electionAlg=");
pwriter.println(self.getElectionType());
pwriter.print("electionPort=");
pwriter.println(self.getElectionAddress().getAllPorts()
.stream().map(Objects::toString).collect(Collectors.joining("|")));
pwriter.print("quorumPort=");
pwriter.println(self.getQuorumAddress().getAllPorts()
.stream().map(Objects::toString).collect(Collectors.joining("|")));
pwriter.print("peerType=");
pwriter.println(self.getLearnerType().ordinal());
}
@Override
protected void setState(State state) {
this.state = state;
}
}