/*
* 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.catalina.ha.session;
import java.io.IOException;
import javax.servlet.ServletException;
import org.apache.catalina.Container;
import org.apache.catalina.Context;
import org.apache.catalina.Engine;
import org.apache.catalina.Host;
import org.apache.catalina.LifecycleException;
import org.apache.catalina.Manager;
import org.apache.catalina.Session;
import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.ha.CatalinaCluster;
import org.apache.catalina.ha.ClusterManager;
import org.apache.catalina.ha.ClusterValve;
import org.apache.catalina.session.ManagerBase;
import org.apache.catalina.session.PersistentManager;
import org.apache.catalina.valves.ValveBase;
import org.apache.tomcat.util.res.StringManager;
/**
* Valve to handle Tomcat jvmRoute takeover using mod_jk module after node
* failure. After a node crashes, subsequent requests go to other cluster nodes.
* That incurs a drop in performance. When this Valve is enabled on a backup
* node and sees a request, which was intended for another (thus failed) node,
* it will rewrite the cookie jsessionid information to use the route to this
* backup cluster node, that answered the request. After the response is
* delivered to the client, all subsequent client requests will go directly to
* the backup node. The change of sessionid is also sent to all other cluster
* nodes. After all that, the session stickiness will work directly to the
* backup node and the traffic will not go back to the failed node after it is
* restarted!
*
* <p>
* For this valve to function correctly, so that all nodes of the cluster
* receive the sessionid change notifications that it generates, the following
* ClusterListener MUST be configured at all nodes of the cluster:
* {@link org.apache.catalina.ha.session.JvmRouteSessionIDBinderListener
* JvmRouteSessionIDBinderListener} since Tomcat 5.5.10, and both
* JvmRouteSessionIDBinderListener and JvmRouteSessionIDBinderLifecycleListener
* for earlier versions of Tomcat.
*
* <p>
* Add this Valve to your host definition at conf/server.xml .
*
* Since 5.5.10 as direct cluster valve:<br/>
*
* <pre>
* <Cluster>
* <Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve" />
* </Cluster>
* </pre>
*
* <br />
* Before 5.5.10 as Host element:<br/>
*
* <pre>
* <Host>
* <Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve" />
* </Host>
* </pre>
*
* <em>A Trick:</em><br/>
* You can enable this mod_jk turnover mode via JMX before you drop a node to
* all backup nodes! Set enable true on all JvmRouteBinderValve backups, disable
* worker at mod_jk and then drop node and restart it! Then enable mod_jk worker
* and disable JvmRouteBinderValves again. This use case means that only
* requested sessions are migrated.
*
* @author Peter Rossbach
*/
public class JvmRouteBinderValve extends ValveBase implements ClusterValve {
/*--Static Variables----------------------------------------*/
public static final org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory
.getLog(JvmRouteBinderValve.class);
/**
* The descriptive information about this implementation.
*/
protected static final String info = "org.apache.catalina.ha.session.JvmRouteBinderValve/1.2";
//------------------------------------------------------ Constructor
public JvmRouteBinderValve() {
super(true);
}
/*--Instance Variables--------------------------------------*/
/**
* the cluster
*/
protected CatalinaCluster cluster;
/**
* The string manager for this package.
*/
protected static final StringManager sm = StringManager.getManager(Constants.Package);
/**
* enabled this component
*/
protected boolean enabled = true;
/**
* number of session that no at this tomcat instance hosted
*/
protected long numberOfSessions = 0;
protected String sessionIdAttribute = "org.apache.catalina.ha.session.JvmRouteOrignalSessionID";
/*--Logic---------------------------------------------------*/
/**
* Return descriptive information about this implementation.
*/
@Override
public String getInfo() {
return (info);
}
/**
* set session id attribute to failed node for request.
*
* @return Returns the sessionIdAttribute.
*/
public String getSessionIdAttribute() {
return sessionIdAttribute;
}
/**
* get name of failed request session attribute
*
* @param sessionIdAttribute
* The sessionIdAttribute to set.
*/
public void setSessionIdAttribute(String sessionIdAttribute) {
this.sessionIdAttribute = sessionIdAttribute;
}
/**
* @return Returns the number of migrated sessions.
*/
public long getNumberOfSessions() {
return numberOfSessions;
}
/**
* @return Returns the enabled.
*/
public boolean getEnabled() {
return enabled;
}
/**
* @param enabled
* The enabled to set.
*/
public void setEnabled(boolean enabled) {
this.enabled = enabled;
}
/**
* Detect possible the JVMRoute change at cluster backup node..
*
* @param request
* tomcat request being processed
* @param response
* tomcat response being processed
* @exception IOException
* if an input/output error has occurred
* @exception ServletException
* if a servlet error has occurred
*/
@Override
public void invoke(Request request, Response response) throws IOException,
ServletException {
if (getEnabled() &&
request.getContext() != null &&
request.getContext().getDistributable() &&
!request.isAsyncDispatching()) {
// valve cluster can access manager - other cluster handle turnover
// at host level - hopefully!
Manager manager = request.getContext().getManager();
if (manager != null && (
(manager instanceof ClusterManager
&& getCluster() != null
&& getCluster().getManager(((ClusterManager)manager).getName()) != null)
||
(manager instanceof PersistentManager)))
handlePossibleTurnover(request);
}
// Pass this request on to the next valve in our pipeline
getNext().invoke(request, response);
}
/**
* handle possible session turn over.
*
* @see JvmRouteBinderValve#handleJvmRoute(Request, String, String)
* @param request current request
*/
protected void handlePossibleTurnover(Request request) {
String sessionID = request.getRequestedSessionId() ;
if (sessionID != null) {
long t1 = System.currentTimeMillis();
String jvmRoute = getLocalJvmRoute(request);
if (jvmRoute == null) {
if (log.isDebugEnabled())
log.debug(sm.getString("jvmRoute.missingJvmRouteAttribute"));
return;
}
handleJvmRoute( request, sessionID, jvmRoute);
if (log.isDebugEnabled()) {
long t2 = System.currentTimeMillis();
long time = t2 - t1;
log.debug(sm.getString("jvmRoute.turnoverInfo", Long.valueOf(time)));
}
}
}
/**
* get jvmroute from engine
*
* @param request current request
* @return return jvmRoute from ManagerBase or null
*/
protected String getLocalJvmRoute(Request request) {
Manager manager = getManager(request);
if(manager instanceof ManagerBase)
return ((ManagerBase) manager).getJvmRoute();
return null ;
}
/**
* get ClusterManager
*
* @param request current request
* @return manager or null
*/
protected Manager getManager(Request request) {
Manager manager = request.getContext().getManager();
if (log.isDebugEnabled()) {
if(manager != null)
log.debug(sm.getString("jvmRoute.foundManager", manager, request.getContext().getName()));
else
log.debug(sm.getString("jvmRoute.notFoundManager", request.getContext().getName()));
}
return manager;
}
/**
* @return Returns the cluster.
*/
@Override
public CatalinaCluster getCluster() {
return cluster;
}
/**
* @param cluster The cluster to set.
*/
@Override
public void setCluster(CatalinaCluster cluster) {
this.cluster = cluster;
}
/**
* Handle jvmRoute stickiness after tomcat instance failed. After this
* correction a new Cookie send to client with new jvmRoute and the
* SessionID change propagate to the other cluster nodes.
*
* @param request current request
* @param sessionId
* request SessionID from Cookie
* @param localJvmRoute
* local jvmRoute
*/
protected void handleJvmRoute(
Request request, String sessionId, String localJvmRoute) {
// get requested jvmRoute.
String requestJvmRoute = null;
int index = sessionId.indexOf('.');
if (index > 0) {
requestJvmRoute = sessionId
.substring(index + 1, sessionId.length());
}
if (requestJvmRoute != null && !requestJvmRoute.equals(localJvmRoute)) {
if (log.isDebugEnabled()) {
log.debug(sm.getString("jvmRoute.failover", requestJvmRoute,
localJvmRoute, sessionId));
}
Session catalinaSession = null;
try {
catalinaSession = getManager(request).findSession(sessionId);
} catch (IOException e) {
// Hups!
}
String id = sessionId.substring(0, index);
String newSessionID = id + "." + localJvmRoute;
// OK - turnover the session and inform other cluster nodes
if (catalinaSession != null) {
changeSessionID(request, sessionId, newSessionID,
catalinaSession);
numberOfSessions++;
} else {
try {
catalinaSession = getManager(request).findSession(newSessionID);
} catch (IOException e) {
// Hups!
}
if (catalinaSession != null) {
// session is rewrite at other request, rewrite this also
changeRequestSessionID(request, sessionId, newSessionID);
} else {
if (log.isDebugEnabled()) {
log.debug(sm.getString("jvmRoute.cannotFindSession",sessionId));
}
}
}
}
}
/**
* change session id and send to all cluster nodes
*
* @param request current request
* @param sessionId
* original session id
* @param newSessionID
* new session id for node migration
* @param catalinaSession
* current session with original session id
*/
protected void changeSessionID(Request request, String sessionId,
String newSessionID, Session catalinaSession) {
fireLifecycleEvent("Before session migration", catalinaSession);
catalinaSession.setId(newSessionID, false);
// FIXME: Why we remove change data from other running request?
// setId also trigger resetDeltaRequest!!
if (catalinaSession instanceof DeltaSession)
((DeltaSession) catalinaSession).resetDeltaRequest();
changeRequestSessionID(request, sessionId, newSessionID);
// now sending the change to all other clusternodes!
sendSessionIDClusterBackup(request,sessionId, newSessionID);
fireLifecycleEvent("After session migration", catalinaSession);
if (log.isDebugEnabled()) {
log.debug(sm.getString("jvmRoute.changeSession", sessionId,
newSessionID));
}
}
/**
* Change Request Session id
* @param request current request
* @param sessionId
* original session id
* @param newSessionID
* new session id for node migration
*/
protected void changeRequestSessionID(Request request, String sessionId, String newSessionID) {
request.changeSessionId(newSessionID);
// set original sessionid at request, to allow application detect the
// change
if (sessionIdAttribute != null && !"".equals(sessionIdAttribute)) {
if (log.isDebugEnabled()) {
log.debug(sm.getString("jvmRoute.set.orignalsessionid",sessionIdAttribute,sessionId));
}
request.setAttribute(sessionIdAttribute, sessionId);
}
}
/**
* Send the changed Sessionid to all clusternodes.
*
* @see JvmRouteSessionIDBinderListener#messageReceived(
* org.apache.catalina.ha.ClusterMessage)
* @param sessionId
* current failed sessionid
* @param newSessionID
* new session id, bind to the new cluster node
*/
protected void sendSessionIDClusterBackup(Request request, String sessionId,
String newSessionID) {
CatalinaCluster c = getCluster();
if (c != null && !(getManager(request) instanceof BackupManager)) {
SessionIDMessage msg = new SessionIDMessage();
msg.setOrignalSessionID(sessionId);
msg.setBackupSessionID(newSessionID);
Context context = request.getContext();
msg.setContextName(context.getName());
msg.setHost(context.getParent().getName());
c.send(msg);
}
}
/**
* Start this component and implement the requirements
* of {@link org.apache.catalina.util.LifecycleBase#startInternal()}.
*
* @exception LifecycleException if this component detects a fatal error
* that prevents this component from being used
*/
@Override
protected synchronized void startInternal() throws LifecycleException {
if (cluster == null) {
Container hostContainer = getContainer();
// compatibility with JvmRouteBinderValve version 1.1
// ( setup at context.xml or context.xml.default )
if (!(hostContainer instanceof Host)) {
if (log.isWarnEnabled())
log.warn(sm.getString("jvmRoute.configure.warn"));
hostContainer = hostContainer.getParent();
}
if (hostContainer instanceof Host
&& ((Host) hostContainer).getCluster() != null) {
cluster = (CatalinaCluster) ((Host) hostContainer).getCluster();
} else {
Container engine = hostContainer.getParent() ;
if (engine instanceof Engine
&& ((Engine) engine).getCluster() != null) {
cluster = (CatalinaCluster) ((Engine) engine).getCluster();
}
}
}
if (log.isInfoEnabled()) {
log.info(sm.getString("jvmRoute.valve.started"));
if (cluster == null)
log.info(sm.getString("jvmRoute.noCluster"));
}
super.startInternal();
}
/**
* Stop this component and implement the requirements
* of {@link org.apache.catalina.util.LifecycleBase#stopInternal()}.
*
* @exception LifecycleException if this component detects a fatal error
* that prevents this component from being used
*/
@Override
protected synchronized void stopInternal() throws LifecycleException {
super.stopInternal();
cluster = null;
numberOfSessions = 0;
if (log.isInfoEnabled())
log.info(sm.getString("jvmRoute.valve.stopped"));
}
}