simpletcpreplicationmanager.java

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/*
 * Copyright 1999,2004 The Apache Software Foundation.
 * 
 * Licensed 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 org.apache.catalina.LifecycleException;
import org.apache.catalina.Session;
import org.apache.catalina.ha.CatalinaCluster;
import org.apache.catalina.ha.ClusterManager;
import org.apache.catalina.ha.ClusterMessage;
import org.apache.catalina.tribes.Member;
import org.apache.catalina.realm.GenericPrincipal;
import org.apache.catalina.session.StandardManager;
import org.apache.catalina.tribes.io.ReplicationStream;
import java.io.ByteArrayInputStream;
import org.apache.catalina.Loader;

/**
 * Title:        Tomcat Session Replication for Tomcat 4.0 <BR>
 * Description:  A very simple straight forward implementation of
 *               session replication of servers in a cluster.<BR>
 *               This session replication is implemented "live". By live
 *               I mean, when a session attribute is added into a session on Node A
 *               a message is broadcasted to other messages and setAttribute is called on the
 *               replicated sessions.<BR>
 *               A full description of this implementation can be found under
 *               <href="http://www.filip.net/tomcat/">Filip's Tomcat Page</a><BR>
 *
 * Copyright:    See apache license
 * Company:      www.filip.net
 * @author  <a href="mailto:[e-mail]">Filip Hanik</a>
 * @author Bela Ban (modifications for synchronous replication)
 * @version 1.0 for TC 4.0
 * Description: The InMemoryReplicationManager is a session manager that replicated
 * session information in memory. It uses <a href="www.javagroups.com">JavaGroups</a> as
 * a communication protocol to ensure guaranteed and ordered message delivery.
 * JavaGroups also provides a very flexible protocol stack to ensure that the replication
 * can be used in any environment.
 * <BR><BR>
 * The InMemoryReplicationManager extends the StandardManager hence it allows for us
 * to inherit all the basic session management features like expiration, session listeners etc
 * <BR><BR>
 * To communicate with other nodes in the cluster, the InMemoryReplicationManager sends out 7 different type of multicast messages
 * all defined in the SessionMessage class.<BR>
 * When a session is replicated (not an attribute added/removed) the session is serialized into
 * a byte array using the StandardSession.readObjectData, StandardSession.writeObjectData methods.
 */
public class SimpleTcpReplicationManager extends StandardManager implements ClusterManager
{
    public static org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory.getLog( SimpleTcpReplicationManager.class );

    //the channel configuration
    protected String mChannelConfig = null;

    //the group name
    protected String mGroupName = "TomcatReplication";

    //somehow start() gets called more than once
    protected boolean mChannelStarted = false;

    //log to screen
    protected boolean mPrintToScreen = true;

    protected boolean defaultMode = false;

    protected boolean mManagerRunning = false;

    /** Use synchronous rather than asynchronous replication. Every session modification (creation, change, removal etc)
     * will be sent to all members. The call will then wait for max milliseconds, or forever (if timeout is 0) for
     * all responses.
     */
    protected boolean synchronousReplication=true;

    /** Set to true if we don't want the sessions to expire on shutdown */
    protected boolean mExpireSessionsOnShutdown = true;

    protected boolean useDirtyFlag = false;

    protected String name;

    protected boolean distributable = true;

    protected CatalinaCluster cluster;

    protected java.util.HashMap invalidatedSessions = new java.util.HashMap();

    /**
     * Flag to keep track if the state has been transferred or not
     * Assumes false.
     */
    protected boolean stateTransferred = false;
    private boolean notifyListenersOnReplication;
    private boolean sendClusterDomainOnly = true ;

    /**
     * Constructor, just calls super()
     *
     */
    public SimpleTcpReplicationManager()
    {
        super();
    }

    public boolean isSendClusterDomainOnly() {
        return sendClusterDomainOnly;
    }
    
    /**
     * @param sendClusterDomainOnly The sendClusterDomainOnly to set.
     */
    public void setSendClusterDomainOnly(boolean sendClusterDomainOnly) {
        this.sendClusterDomainOnly = sendClusterDomainOnly;
    }
  
    /**
     * @return Returns the defaultMode.
     */
    public boolean isDefaultMode() {
        return defaultMode;
    }
    /**
     * @param defaultMode The defaultMode to set.
     */
    public void setDefaultMode(boolean defaultMode) {
        this.defaultMode = defaultMode;
    }
    
    public boolean isManagerRunning()
    {
        return mManagerRunning;
    }

    public void setUseDirtyFlag(boolean usedirtyflag)
    {
        this.useDirtyFlag = usedirtyflag;
    }

    public void setExpireSessionsOnShutdown(boolean expireSessionsOnShutdown)
    {
        mExpireSessionsOnShutdown = expireSessionsOnShutdown;
    }

    public void setCluster(CatalinaCluster cluster) {
        if(log.isDebugEnabled())
            log.debug("Cluster associated with SimpleTcpReplicationManager");
        this.cluster = cluster;
    }

    public boolean getExpireSessionsOnShutdown()
    {
        return mExpireSessionsOnShutdown;
    }

    public void setPrintToScreen(boolean printtoscreen)
    {
        if(log.isDebugEnabled())
            log.debug("Setting screen debug to:"+printtoscreen);
        mPrintToScreen = printtoscreen;
    }

    public void setSynchronousReplication(boolean flag)
    {
        synchronousReplication=flag;
    }

    /**
     * Override persistence since they don't go hand in hand with replication for now.
     */
    public void unload() throws IOException {
        if ( !getDistributable() ) {
            super.unload();
        }
    }

    /**
     * Creates a HTTP session.
     * Most of the code in here is copied from the StandardManager.
     * This is not pretty, yeah I know, but it was necessary since the
     * StandardManager had hard coded the session instantiation to the a
     * StandardSession, when we actually want to instantiate a ReplicatedSession<BR>
     * If the call comes from the Tomcat servlet engine, a SessionMessage goes out to the other
     * nodes in the cluster that this session has been created.
     * @param notify - if set to true the other nodes in the cluster will be notified.
     *                 This flag is needed so that we can create a session before we deserialize
     *                 a replicated one
     *
     * @see ReplicatedSession
     */
    protected Session createSession(String sessionId, boolean notify, boolean setId)
    {

        //inherited from the basic manager
        if ((getMaxActiveSessions() >= 0) &&
           (sessions.size() >= getMaxActiveSessions()))
            throw new IllegalStateException(sm.getString("standardManager.createSession.ise"));


        Session session = new ReplicatedSession(this);

        // Initialize the properties of the new session and return it
        session.setNew(true);
        session.setValid(true);
        session.setCreationTime(System.currentTimeMillis());
        session.setMaxInactiveInterval(this.maxInactiveInterval);
        if(sessionId == null)
            sessionId = generateSessionId();
        if ( setId ) session.setId(sessionId);
        if ( notify && (cluster!=null) ) {
            ((ReplicatedSession)session).setIsDirty(true);
        }
        return (session);
    }//createSession

    //=========================================================================
    // OVERRIDE THESE METHODS TO IMPLEMENT THE REPLICATION
    //=========================================================================

    /**
     * Construct and return a new session object, based on the default
     * settings specified by this Manager's properties.  The session
     * id will be assigned by this method, and available via the getId()
     * method of the returned session.  If a new session cannot be created
     * for any reason, return <code>null</code>.
     *
     * @exception IllegalStateException if a new session cannot be
     *  instantiated for any reason
     */
    public Session createSession(String sessionId)
    {
        //create a session and notify the other nodes in the cluster
        Session session =  createSession(sessionId,getDistributable(),true);
        add(session);
        return session;
    }

    public void sessionInvalidated(String sessionId) {
        synchronized ( invalidatedSessions ) {
            invalidatedSessions.put(sessionId, sessionId);
        }
    }

    public String[] getInvalidatedSessions() {
        synchronized ( invalidatedSessions ) {
            String[] result = new String[invalidatedSessions.size()];
            invalidatedSessions.values().toArray(result);
            return result;
        }

    }

    public ClusterMessage requestCompleted(String sessionId)
    {
        if (  !getDistributable() ) {
            log.warn("Received requestCompleted message, although this context["+
                     getName()+"] is not distributable. Ignoring message");
            return null;
        }
        //notify javagroups
        try
        {
            if ( invalidatedSessions.get(sessionId) != null ) {
                synchronized ( invalidatedSessions ) {
                    invalidatedSessions.remove(sessionId);
                    SessionMessage msg = new SessionMessageImpl(name,
                    SessionMessage.EVT_SESSION_EXPIRED,
                    null,
                    sessionId,
                    sessionId);
                return msg;
                }
            } else {
                ReplicatedSession session = (ReplicatedSession) findSession(
                    sessionId);
                if (session != null) {
                    //return immediately if the session is not dirty
                    if (useDirtyFlag && (!session.isDirty())) {
                        //but before we return doing nothing,
                        //see if we should send
                        //an updated last access message so that
                        //sessions across cluster dont expire
                        long interval = session.getMaxInactiveInterval();
                        long lastaccdist = System.currentTimeMillis() -
                            session.getLastAccessWasDistributed();
                        if ( ((interval*1000) / lastaccdist)< 3 ) {
                            SessionMessage accmsg = new SessionMessageImpl(name,
                                SessionMessage.EVT_SESSION_ACCESSED,
                                null,
                                sessionId,
                                sessionId);
                            session.setLastAccessWasDistributed(System.currentTimeMillis());
                            return accmsg;
                        }
                        return null;
                    }

                    session.setIsDirty(false);
                    if (log.isDebugEnabled()) {
                        try {
                            log.debug("Sending session to cluster=" + session);
                        }
                        catch (Exception ignore) {}
                    }
                    SessionMessage msg = new SessionMessageImpl(name,
                        SessionMessage.EVT_SESSION_CREATED,
                        writeSession(session),
                        session.getIdInternal(),
                        session.getIdInternal());
                    return msg;
                } //end if
            }//end if
        }
        catch (Exception x )
        {
            log.error("Unable to replicate session",x);
        }
        return null;
    }

    /**
     * Serialize a session into a byte array<BR>
     * This method simple calls the writeObjectData method on the session
     * and returns the byte data from that call
     * @param session - the session to be serialized
     * @return a byte array containing the session data, null if the serialization failed
     */
    protected byte[] writeSession( Session session )
    {
        try
        {
            java.io.ByteArrayOutputStream session_data = new java.io.ByteArrayOutputStream();
            java.io.ObjectOutputStream session_out = new java.io.ObjectOutputStream(session_data);
            session_out.flush();