/**
* 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.HashMap;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.LinkedBlockingQueue;
import org.apache.jute.Record;
import org.apache.log4j.Logger;
import org.apache.zookeeper.jmx.MBeanRegistry;
import org.apache.zookeeper.server.DataTreeBean;
import org.apache.zookeeper.server.FinalRequestProcessor;
import org.apache.zookeeper.server.Request;
import org.apache.zookeeper.server.RequestProcessor;
import org.apache.zookeeper.server.ServerCnxn;
import org.apache.zookeeper.server.SyncRequestProcessor;
import org.apache.zookeeper.server.ZooKeeperServer;
import org.apache.zookeeper.server.persistence.FileTxnSnapLog;
import org.apache.zookeeper.txn.TxnHeader;
/**
* Just like the standard ZooKeeperServer. We just replace the request
* processors: FollowerRequestProcessor -> CommitProcessor ->
* FinalRequestProcessor
*
* A SyncRequestProcessor is also spawn off to log proposals from the leader.
*/
public class FollowerZooKeeperServer extends ZooKeeperServer {
private static final Logger LOG = Logger.getLogger(FollowerZooKeeperServer.class);
private QuorumPeer self;
CommitProcessor commitProcessor;
SyncRequestProcessor syncProcessor;
/*
* Pending sync requests
*/
ConcurrentLinkedQueue<Request> pendingSyncs;
/**
* @param port
* @param dataDir
* @throws IOException
*/
FollowerZooKeeperServer(FileTxnSnapLog logFactory,QuorumPeer self,
DataTreeBuilder treeBuilder) throws IOException {
super(logFactory, self.tickTime,treeBuilder);
this.self = self;
this.pendingSyncs = new ConcurrentLinkedQueue<Request>();
}
public Follower getFollower(){
return self.follower;
}
@Override
protected void createSessionTracker() {
sessionTracker = new FollowerSessionTracker(this, sessionsWithTimeouts,
self.getId());
}
@Override
protected void setupRequestProcessors() {
RequestProcessor finalProcessor = new FinalRequestProcessor(this);
commitProcessor = new CommitProcessor(finalProcessor,
Long.toString(getServerId()), true);
commitProcessor.start();
firstProcessor = new FollowerRequestProcessor(this, commitProcessor);
((FollowerRequestProcessor) firstProcessor).start();
syncProcessor = new SyncRequestProcessor(this,
new SendAckRequestProcessor(getFollower()));
syncProcessor.start();
}
@Override
protected void revalidateSession(ServerCnxn cnxn, long sessionId,
int sessionTimeout) throws IOException, InterruptedException {
getFollower().validateSession(cnxn, sessionId, sessionTimeout);
}
public HashMap<Long, Integer> getTouchSnapshot() {
if (sessionTracker != null) {
return ((FollowerSessionTracker) sessionTracker).snapshot();
}
return new HashMap<Long, Integer>();
}
@Override
public long getServerId() {
return self.getId();
}
LinkedBlockingQueue<Request> pendingTxns = new LinkedBlockingQueue<Request>();
public void logRequest(TxnHeader hdr, Record txn) {
Request request = new Request(null, hdr.getClientId(), hdr.getCxid(),
hdr.getType(), null, null);
request.hdr = hdr;
request.txn = txn;
request.zxid = hdr.getZxid();
if ((request.zxid & 0xffffffffL) != 0) {
pendingTxns.add(request);
}
syncProcessor.processRequest(request);
}
public void commit(long zxid) {
if (pendingTxns.size() == 0) {
LOG.warn("Committing " + Long.toHexString(zxid)
+ " without seeing txn");
return;
}
long firstElementZxid = pendingTxns.element().zxid;
if (firstElementZxid != zxid) {
LOG.fatal("Committing zxid 0x" + Long.toHexString(zxid)
+ " but next pending txn 0x"
+ Long.toHexString(firstElementZxid));
System.exit(12);
}
Request request = pendingTxns.remove();
commitProcessor.commit(request);
}
synchronized public void sync(){
if(pendingSyncs.size() ==0){
LOG.warn("Not expecting a sync.");
return;
}
Request r = pendingSyncs.remove();
commitProcessor.commit(r);
}
@Override
public int getGlobalOutstandingLimit() {
return super.getGlobalOutstandingLimit() / (self.getQuorumSize() - 1);
}
/**
* Do not do anything in the follower.
*/
@Override
public void addCommittedProposal(Request r) {
//do nothing
}
@Override
public void shutdown() {
try {
super.shutdown();
} catch (Exception e) {
LOG.warn("Ignoring unexpected exception during shutdown", e);
}
try {
if (syncProcessor != null) {
syncProcessor.shutdown();
}
} catch (Exception e) {
LOG.warn("Ignoring unexpected exception in syncprocessor shutdown",
e);
}
}
@Override
protected void registerJMX() {
// register with JMX
try {
jmxDataTreeBean = new DataTreeBean(dataTree);
MBeanRegistry.getInstance().register(jmxDataTreeBean, jmxServerBean);
} catch (Exception e) {
LOG.warn("Failed to register with JMX", e);
jmxDataTreeBean = null;
}
}
public void registerJMX(FollowerBean followerBean,
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 = followerBean;
MBeanRegistry.getInstance().register(followerBean, 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(Follower follower) {
// 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 "follower";
}
}