/**
* 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.PrintWriter;
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.RequestProcessor;
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.
* <p>
* 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, zkDb);
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.cnxnFactory.setZooKeeperServer(this);
self.adminServer.setZooKeeperServer(this);
LOG.info("Read-only server started");
}
@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.getId();
}
@Override
public synchronized void shutdown() {
shutdown = true;
unregisterJMX(this);
// set peer's server to null
self.cnxnFactory.setZooKeeperServer(null);
// clear all the connections
self.cnxnFactory.closeAll();
self.adminServer.setZooKeeperServer(null);
// shutdown the server itself
super.shutdown();
}
@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().getPort());
pwriter.print("quorumPort=");
pwriter.println(self.getQuorumAddress().getPort());
pwriter.print("peerType=");
pwriter.println(self.getLearnerType().ordinal());
}
}