/*
 * 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.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.Date;

import org.apache.catalina.Engine;
import org.apache.catalina.Host;
import org.apache.catalina.LifecycleException;
import org.apache.catalina.LifecycleState;
import org.apache.catalina.Session;
import org.apache.catalina.ha.ClusterManager;
import org.apache.catalina.ha.ClusterMessage;
import org.apache.catalina.session.ManagerBase;
import org.apache.catalina.tribes.Channel;
import org.apache.catalina.tribes.Member;
import org.apache.catalina.tribes.io.ReplicationStream;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.ExceptionUtils;
import org.apache.tomcat.util.res.StringManager;

/**
 * The DeltaManager manages replicated sessions by only replicating the deltas
 * in data. For applications written to handle this, the DeltaManager is the
 * optimal way of replicating data.
 *
 * This code is almost identical to StandardManager with a difference in how it
 * persists sessions and some modifications to it.
 *
 * <b>IMPLEMENTATION NOTE </b>: Correct behavior of session storing and
 * reloading depends upon external calls to the <code>start()</code> and
 * <code>stop()</code> methods of this class at the correct times.
 *
 * @author Craig R. McClanahan
 * @author Peter Rossbach
 */
public class DeltaManager extends ClusterManagerBase{

    // ---------------------------------------------------- Security Classes
    public final Log log = LogFactory.getLog(DeltaManager.class);

    /**
     * The string manager for this package.
     */
    protected static final StringManager sm = StringManager.getManager(DeltaManager.class);

    // ----------------------------------------------------- Instance Variables

    protected String name = null;

    private boolean expireSessionsOnShutdown = false;
    private boolean notifySessionListenersOnReplication = true;
    private boolean notifyContainerListenersOnReplication  = true;
    private volatile boolean stateTransfered = false ;
    private volatile boolean noContextManagerReceived = false ;
    private int stateTransferTimeout = 60;
    private boolean sendAllSessions = true;
    private int sendAllSessionsSize = 1000 ;

    /**
     * wait time between send session block (default 2 sec)
     */
    private int sendAllSessionsWaitTime = 2 * 1000 ;
    private final ArrayList<SessionMessage> receivedMessageQueue =
            new ArrayList<>();
    private boolean receiverQueue = false ;
    private boolean stateTimestampDrop = true ;
    private volatile long stateTransferCreateSendTime;

    // -------------------------------------------------------- stats attributes

    private long sessionReplaceCounter = 0 ;
    private long counterReceive_EVT_GET_ALL_SESSIONS = 0 ;
    private long counterReceive_EVT_ALL_SESSION_DATA = 0 ;
    private long counterReceive_EVT_SESSION_CREATED = 0 ;
    private long counterReceive_EVT_SESSION_EXPIRED = 0;
    private long counterReceive_EVT_SESSION_ACCESSED = 0 ;
    private long counterReceive_EVT_SESSION_DELTA = 0;
    private int counterReceive_EVT_ALL_SESSION_TRANSFERCOMPLETE = 0 ;
    private long counterReceive_EVT_CHANGE_SESSION_ID = 0 ;
    private long counterReceive_EVT_ALL_SESSION_NOCONTEXTMANAGER = 0 ;
    private long counterSend_EVT_GET_ALL_SESSIONS = 0 ;
    private long counterSend_EVT_ALL_SESSION_DATA = 0 ;
    private long counterSend_EVT_SESSION_CREATED = 0;
    private long counterSend_EVT_SESSION_DELTA = 0 ;
    private long counterSend_EVT_SESSION_ACCESSED = 0;
    private long counterSend_EVT_SESSION_EXPIRED = 0;
    private int counterSend_EVT_ALL_SESSION_TRANSFERCOMPLETE = 0 ;
    private long counterSend_EVT_CHANGE_SESSION_ID = 0;
    private int counterNoStateTransfered = 0 ;


    // ------------------------------------------------------------- Constructor
    public DeltaManager() {
        super();
    }

    // ------------------------------------------------------------- Properties

    @Override
    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String getName() {
        return name;
    }

    /**
     * @return Returns the counterSend_EVT_GET_ALL_SESSIONS.
     */
    public long getCounterSend_EVT_GET_ALL_SESSIONS() {
        return counterSend_EVT_GET_ALL_SESSIONS;
    }

    /**
     * @return Returns the counterSend_EVT_SESSION_ACCESSED.
     */
    public long getCounterSend_EVT_SESSION_ACCESSED() {
        return counterSend_EVT_SESSION_ACCESSED;
    }

    /**
     * @return Returns the counterSend_EVT_SESSION_CREATED.
     */
    public long getCounterSend_EVT_SESSION_CREATED() {
        return counterSend_EVT_SESSION_CREATED;
    }

    /**
     * @return Returns the counterSend_EVT_SESSION_DELTA.
     */
    public long getCounterSend_EVT_SESSION_DELTA() {
        return counterSend_EVT_SESSION_DELTA;
    }

    /**
     * @return Returns the counterSend_EVT_SESSION_EXPIRED.
     */
    public long getCounterSend_EVT_SESSION_EXPIRED() {
        return counterSend_EVT_SESSION_EXPIRED;
    }

    /**
     * @return Returns the counterSend_EVT_ALL_SESSION_DATA.
     */
    public long getCounterSend_EVT_ALL_SESSION_DATA() {
        return counterSend_EVT_ALL_SESSION_DATA;
    }

    /**
     * @return Returns the counterSend_EVT_ALL_SESSION_TRANSFERCOMPLETE.
     */
    public int getCounterSend_EVT_ALL_SESSION_TRANSFERCOMPLETE() {
        return counterSend_EVT_ALL_SESSION_TRANSFERCOMPLETE;
    }

    /**
     * @return Returns the counterSend_EVT_CHANGE_SESSION_ID.
     */
    public long getCounterSend_EVT_CHANGE_SESSION_ID() {
        return counterSend_EVT_CHANGE_SESSION_ID;
    }

    /**
     * @return Returns the counterReceive_EVT_ALL_SESSION_DATA.
     */
    public long getCounterReceive_EVT_ALL_SESSION_DATA() {
        return counterReceive_EVT_ALL_SESSION_DATA;
    }

    /**
     * @return Returns the counterReceive_EVT_GET_ALL_SESSIONS.
     */
    public long getCounterReceive_EVT_GET_ALL_SESSIONS() {
        return counterReceive_EVT_GET_ALL_SESSIONS;
    }

    /**
     * @return Returns the counterReceive_EVT_SESSION_ACCESSED.
     */
    public long getCounterReceive_EVT_SESSION_ACCESSED() {
        return counterReceive_EVT_SESSION_ACCESSED;
    }

    /**
     * @return Returns the counterReceive_EVT_SESSION_CREATED.
     */
    public long getCounterReceive_EVT_SESSION_CREATED() {
        return counterReceive_EVT_SESSION_CREATED;
    }

    /**
     * @return Returns the counterReceive_EVT_SESSION_DELTA.
     */
    public long getCounterReceive_EVT_SESSION_DELTA() {
        return counterReceive_EVT_SESSION_DELTA;
    }

    /**
     * @return Returns the counterReceive_EVT_SESSION_EXPIRED.
     */
    public long getCounterReceive_EVT_SESSION_EXPIRED() {
        return counterReceive_EVT_SESSION_EXPIRED;
    }


    /**
     * @return Returns the counterReceive_EVT_ALL_SESSION_TRANSFERCOMPLETE.
     */
    public int getCounterReceive_EVT_ALL_SESSION_TRANSFERCOMPLETE() {
        return counterReceive_EVT_ALL_SESSION_TRANSFERCOMPLETE;
    }

    /**
     * @return Returns the counterReceive_EVT_CHANGE_SESSION_ID.
     */
    public long getCounterReceive_EVT_CHANGE_SESSION_ID() {
        return counterReceive_EVT_CHANGE_SESSION_ID;
    }

    /**
     * @return Returns the counterReceive_EVT_ALL_SESSION_NOCONTEXTMANAGER.
     */
    public long getCounterReceive_EVT_ALL_SESSION_NOCONTEXTMANAGER() {
        return counterReceive_EVT_ALL_SESSION_NOCONTEXTMANAGER;
    }

    /**
     * @return Returns the processingTime.
     */
    @Override
    public long getProcessingTime() {
        return processingTime;
    }

    /**
     * @return Returns the sessionReplaceCounter.
     */
    public long getSessionReplaceCounter() {
        return sessionReplaceCounter;
    }

    /**
     * @return Returns the counterNoStateTransfered.
     */
    public int getCounterNoStateTransfered() {
        return counterNoStateTransfered;
    }

    public int getReceivedQueueSize() {
        return receivedMessageQueue.size() ;
    }

    /**
     * @return Returns the stateTransferTimeout.
     */
    public int getStateTransferTimeout() {
        return stateTransferTimeout;
    }
    /**
     * @param timeoutAllSession The timeout
     */
    public void setStateTransferTimeout(int timeoutAllSession) {
        this.stateTransferTimeout = timeoutAllSession;
    }

    /**
     * @return <code>true</code> if the state transfer is complete.
     */
    public boolean getStateTransfered() {
        return stateTransfered;
    }

    /**
     * Set that state transferred is complete
     * @param stateTransfered Flag value
     */
    public void setStateTransfered(boolean stateTransfered) {
        this.stateTransfered = stateTransfered;
    }

    public boolean isNoContextManagerReceived() {
        return noContextManagerReceived;
    }

    public void setNoContextManagerReceived(boolean noContextManagerReceived) {
        this.noContextManagerReceived = noContextManagerReceived;
    }

    /**
     * @return the sendAllSessionsWaitTime in msec
     */
    public int getSendAllSessionsWaitTime() {
        return sendAllSessionsWaitTime;
    }

    /**
     * @param sendAllSessionsWaitTime The sendAllSessionsWaitTime to set at msec.
     */
    public void setSendAllSessionsWaitTime(int sendAllSessionsWaitTime) {
        this.sendAllSessionsWaitTime = sendAllSessionsWaitTime;
    }

    /**
     * @return the stateTimestampDrop.
     */
    public boolean isStateTimestampDrop() {
        return stateTimestampDrop;
    }

    /**
     * @param isTimestampDrop The new flag value
     */
    public void setStateTimestampDrop(boolean isTimestampDrop) {
        this.stateTimestampDrop = isTimestampDrop;
    }

    /**
     *
     * @return the sendAllSessions.
     */
    public boolean isSendAllSessions() {
        return sendAllSessions;
    }

    /**
     * @param sendAllSessions The sendAllSessions to set.
     */
    public void setSendAllSessions(boolean sendAllSessions) {
        this.sendAllSessions = sendAllSessions;
    }

    /**
     * @return the sendAllSessionsSize.
     */
    public int getSendAllSessionsSize() {
        return sendAllSessionsSize;
    }

    /**
     * @param sendAllSessionsSize The sendAllSessionsSize to set.
     */
    public void setSendAllSessionsSize(int sendAllSessionsSize) {
        this.sendAllSessionsSize = sendAllSessionsSize;
    }

    /**
     * @return the notifySessionListenersOnReplication.
     */
    public boolean isNotifySessionListenersOnReplication() {
        return notifySessionListenersOnReplication;
    }

    /**
     * @param notifyListenersCreateSessionOnReplication
     *              The notifySessionListenersOnReplication to set.
     */
    public void setNotifySessionListenersOnReplication(
            boolean notifyListenersCreateSessionOnReplication) {
        this.notifySessionListenersOnReplication = notifyListenersCreateSessionOnReplication;
    }


    public boolean isExpireSessionsOnShutdown() {
        return expireSessionsOnShutdown;
    }

    public void setExpireSessionsOnShutdown(boolean expireSessionsOnShutdown) {
        this.expireSessionsOnShutdown = expireSessionsOnShutdown;
    }

    public boolean isNotifyContainerListenersOnReplication() {
        return notifyContainerListenersOnReplication;
    }

    public void setNotifyContainerListenersOnReplication(
            boolean notifyContainerListenersOnReplication) {
        this.notifyContainerListenersOnReplication = notifyContainerListenersOnReplication;
    }


    // --------------------------------------------------------- Public Methods

    @Override
    public Session createSession(String sessionId) {
        return createSession(sessionId, true);
    }

    /**
     * Create new session with check maxActiveSessions and send session creation
     * to other cluster nodes.
     *
     * @param sessionId The session id that should be used for the session
     * @param distribute <code>true</code> to replicate the new session
     * @return The session
     */
    public Session createSession(String sessionId, boolean distribute) {
        DeltaSession session = (DeltaSession) super.createSession(sessionId) ;
        if (distribute) {
            sendCreateSession(session.getId(), session);
        }
        if (log.isDebugEnabled())
            log.debug(sm.getString("deltaManager.createSession.newSession",
                    session.getId(), Integer.valueOf(sessions.size())));
        return session;
    }

    /**
     * Send create session event to all backup node
     * @param sessionId The session id of the session
     * @param session The session object
     */
    protected void sendCreateSession(String sessionId, DeltaSession session) {
        if(cluster.getMembers().length > 0 ) {
            SessionMessage msg =
                new SessionMessageImpl(getName(),
                                       SessionMessage.EVT_SESSION_CREATED,
                                       null,
                                       sessionId,
                                       sessionId + "-" + System.currentTimeMillis());
            if (log.isDebugEnabled()) {
                log.debug(sm.getString("deltaManager.sendMessage.newSession", name, sessionId));
            }
            msg.setTimestamp(session.getCreationTime());
            counterSend_EVT_SESSION_CREATED++;
            send(msg);
        }
    }

    /**
     * Send messages to other backup member (domain or all)
     * @param msg Session message
     */
    protected void send(SessionMessage msg) {
        if(cluster != null) {
            cluster.send(msg);
        }
    }

    /**
     * {@inheritDoc}
     * <p>
     * Creates new DeltaSession instance.
     */
    @Override
    public Session createEmptySession() {
        return getNewDeltaSession() ;
    }

    /**
     * Get new session class to be used in the doLoad() method.
     * @return a new session
     */
    protected DeltaSession getNewDeltaSession() {
        return new DeltaSession(this);
    }

    @Override
    public void changeSessionId(Session session) {
        changeSessionId(session, true);
    }

    @Override
    public void changeSessionId(Session session, String newId) {
        changeSessionId(session, newId, true);
    }

    protected void changeSessionId(Session session, boolean notify) {
        String orgSessionID = session.getId();
        super.changeSessionId(session);
        if (notify) sendChangeSessionId(session.getId(), orgSessionID);
    }

    protected void changeSessionId(Session session, String newId, boolean notify) {
        String orgSessionID = session.getId();
        super.changeSessionId(session, newId);
        if (notify) sendChangeSessionId(session.getId(), orgSessionID);
    }

    protected void sendChangeSessionId(String newSessionID, String orgSessionID) {
        if (cluster.getMembers().length > 0) {
            try {
                // serialize sessionID
                byte[] data = serializeSessionId(newSessionID);
                // notify change sessionID
                SessionMessage msg = new SessionMessageImpl(getName(),
                        SessionMessage.EVT_CHANGE_SESSION_ID, data,
                        orgSessionID, orgSessionID + "-"
                                + System.currentTimeMillis());
                msg.setTimestamp(System.currentTimeMillis());
                counterSend_EVT_CHANGE_SESSION_ID++;
                send(msg);
            } catch (IOException e) {
                log.error(sm.getString("deltaManager.unableSerializeSessionID",
                        newSessionID), e);
            }
        }
    }

    /**
     * serialize sessionID
     * @param sessionId Session id to serialize
     * @return byte array with serialized session id
     * @throws IOException if an input/output error occurs
     */
    protected byte[] serializeSessionId(String sessionId) throws IOException {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(bos);
        oos.writeUTF(sessionId);
        oos.flush();
        oos.close();
        return bos.toByteArray();
    }

    /**
     * Load sessionID
     * @param data serialized session id
     * @return session id
     * @throws IOException if an input/output error occurs
     */
    protected String deserializeSessionId(byte[] data) throws IOException {
        ReplicationStream ois = getReplicationStream(data);
        String sessionId = ois.readUTF();
        ois.close();
        return sessionId;
    }

    /**
     * Load Deltarequest from external node
     * Load the Class at container classloader
     * @see DeltaRequest#readExternal(java.io.ObjectInput)
     * @param session Corresponding session
     * @param data message data
     * @return The request
     * @throws ClassNotFoundException Serialization error
     * @throws IOException IO error with serialization
     */
    protected DeltaRequest deserializeDeltaRequest(DeltaSession session, byte[] data)
            throws ClassNotFoundException, IOException {
        session.lock();
        try {
            ReplicationStream ois = getReplicationStream(data);
            session.getDeltaRequest().readExternal(ois);
            ois.close();
            return session.getDeltaRequest();
        } finally {
            session.unlock();
        }
    }

    /**
     * serialize DeltaRequest
     * @see DeltaRequest#writeExternal(java.io.ObjectOutput)
     *
     * @param session Associated session
     * @param deltaRequest The request to serialize
     * @return serialized delta request
     * @throws IOException IO error with serialization
     */
    protected byte[] serializeDeltaRequest(DeltaSession session, DeltaRequest deltaRequest)
            throws IOException {
        session.lock();
        try {
            return deltaRequest.serialize();
        } finally {
            session.unlock();
        }
    }

    /**
     * Load sessions from other cluster node.
     * FIXME replace currently sessions with same id without notification.
     * FIXME SSO handling is not really correct with the session replacement!
     * @param data Serialized data
     * @exception ClassNotFoundException
     *                if a serialized class cannot be found during the reload
     * @exception IOException
     *                if an input/output error occurs
     */
    protected void deserializeSessions(byte[] data) throws ClassNotFoundException,IOException {

        // Open an input stream to the specified pathname, if any
        // Load the previously unloaded active sessions
        try (ObjectInputStream ois = getReplicationStream(data)) {
            Integer count = (Integer) ois.readObject();
            int n = count.intValue();
            for (int i = 0; i < n; i++) {
                DeltaSession session = (DeltaSession) createEmptySession();
                session.readObjectData(ois);
                session.setManager(this);
                session.setValid(true);
                session.setPrimarySession(false);
                //in case the nodes in the cluster are out of
                //time synch, this will make sure that we have the
                //correct timestamp, isValid returns true, cause
                // accessCount=1
                session.access();
                //make sure that the session gets ready to expire if
                // needed
                session.setAccessCount(0);
                session.resetDeltaRequest();
                // FIXME How inform other session id cache like SingleSignOn
                // increment sessionCounter to correct stats report
                if (findSession(session.getIdInternal()) == null ) {
                    sessionCounter++;
                } else {
                    sessionReplaceCounter++;
                    // FIXME better is to grap this sessions again !
                    if (log.isWarnEnabled()) {
                        log.warn(sm.getString("deltaManager.loading.existing.session",
                                session.getIdInternal()));
                    }
                }
                add(session);
                if (notifySessionListenersOnReplication) {
                    session.tellNew();
                }
            }
        } catch (ClassNotFoundException e) {
            log.error(sm.getString("deltaManager.loading.cnfe", e), e);
            throw e;
        } catch (IOException e) {
            log.error(sm.getString("deltaManager.loading.ioe", e), e);
            throw e;
        }
    }


    /**
     * Save any currently active sessions in the appropriate persistence
     * mechanism, if any. If persistence is not supported, this method returns
     * without doing anything.
     *
     * @param currentSessions Sessions to serialize
     * @return serialized data
     * @exception IOException
     *                if an input/output error occurs
     */
    protected byte[] serializeSessions(Session[] currentSessions) throws IOException {

        // Open an output stream to the specified pathname, if any
        ByteArrayOutputStream fos = new ByteArrayOutputStream();
        try (ObjectOutputStream oos = new ObjectOutputStream(new BufferedOutputStream(fos))) {
            oos.writeObject(Integer.valueOf(currentSessions.length));
            for(int i=0 ; i < currentSessions.length;i++) {
                ((DeltaSession)currentSessions[i]).writeObjectData(oos);
            }
            // Flush and close the output stream
            oos.flush();
        } catch (IOException e) {
            log.error(sm.getString("deltaManager.unloading.ioe", e), e);
            throw e;
        }

        // send object data as byte[]
        return fos.toByteArray();
    }

    /**
     * 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 {

        super.startInternal();

        // Load unloaded sessions, if any
        try {
            if (cluster == null) {
                log.error(sm.getString("deltaManager.noCluster", getName()));
                return;
            } else {
                if (log.isInfoEnabled()) {
                    String type = "unknown" ;
                    if( cluster.getContainer() instanceof Host){
                        type = "Host" ;
                    } else if( cluster.getContainer() instanceof Engine){
                        type = "Engine" ;
                    }
                    log.info(sm.getString("deltaManager.registerCluster",
                            getName(), type, cluster.getClusterName()));
                }
            }
            if (log.isInfoEnabled()) {
                log.info(sm.getString("deltaManager.startClustering", getName()));
            }

            getAllClusterSessions();

        } catch (Throwable t) {
            ExceptionUtils.handleThrowable(t);
            log.error(sm.getString("deltaManager.managerLoad"), t);
        }

        setState(LifecycleState.STARTING);
    }

    /**
     * get from first session master the backup from all clustered sessions
     * @see #findSessionMasterMember()
     */
    public synchronized void getAllClusterSessions() {
        if (cluster != null && cluster.getMembers().length > 0) {
            long beforeSendTime = System.currentTimeMillis();
            Member mbr = findSessionMasterMember();
            if(mbr == null) { // No domain member found
                 return;
            }
            SessionMessage msg = new SessionMessageImpl(this.getName(),
                    SessionMessage.EVT_GET_ALL_SESSIONS, null, "GET-ALL", "GET-ALL-" + getName());
            msg.setTimestamp(beforeSendTime);
            // set reference time
            stateTransferCreateSendTime = beforeSendTime ;
            // request session state
            counterSend_EVT_GET_ALL_SESSIONS++;
            stateTransfered = false ;
            // FIXME This send call block the deploy thread, when sender waitForAck is enabled
            try {
                synchronized(receivedMessageQueue) {
                     receiverQueue = true ;
                }
                cluster.send(msg, mbr, Channel.SEND_OPTIONS_ASYNCHRONOUS);
                if (log.isInfoEnabled())
                    log.info(sm.getString("deltaManager.waitForSessionState",
                            getName(), mbr, Integer.valueOf(getStateTransferTimeout())));
                // FIXME At sender ack mode this method check only the state
                //       transfer and resend is a problem!
                waitForSendAllSessions(beforeSendTime);
            } finally {
                synchronized(receivedMessageQueue) {
                    for (SessionMessage smsg : receivedMessageQueue) {
                        if (!stateTimestampDrop) {
                            messageReceived(smsg, smsg.getAddress());
                        } else {
                            if (smsg.getEventType() != SessionMessage.EVT_GET_ALL_SESSIONS &&
                                    smsg.getTimestamp() >= stateTransferCreateSendTime) {
                                // FIXME handle EVT_GET_ALL_SESSIONS later
                                messageReceived(smsg, smsg.getAddress());
                            } else {
                                if (log.isWarnEnabled()) {
                                    log.warn(sm.getString("deltaManager.dropMessage",
                                            getName(),
                                            smsg.getEventTypeString(),
                                            new Date(stateTransferCreateSendTime),
                                            new Date(smsg.getTimestamp())));
                                }
                            }
                        }
                    }
                    receivedMessageQueue.clear();
                    receiverQueue = false ;
                }
           }
        } else {
            if (log.isInfoEnabled()) log.info(sm.getString("deltaManager.noMembers", getName()));
        }
    }

    /**
     * Find the master of the session state
     * @return master member of sessions
     */
    protected Member findSessionMasterMember() {
        Member mbr = null;
        Member mbrs[] = cluster.getMembers();
        if(mbrs.length != 0 ) mbr = mbrs[0];
        if(mbr == null && log.isWarnEnabled()) {
            log.warn(sm.getString("deltaManager.noMasterMember",getName(), ""));
        }
        if(mbr != null && log.isDebugEnabled()) {
            log.debug(sm.getString("deltaManager.foundMasterMember",getName(), mbr));
        }
        return mbr;
    }

    /**
     * Wait that cluster session state is transferred or timeout after 60 Sec
     * With stateTransferTimeout == -1 wait that backup is transferred (forever mode)
     * @param beforeSendTime Start instant of the operation
     */
    protected void waitForSendAllSessions(long beforeSendTime) {
        long reqStart = System.currentTimeMillis();
        long reqNow = reqStart ;
        boolean isTimeout = false;
        if(getStateTransferTimeout() > 0) {
            // wait that state is transferred with timeout check
            do {
                try {
                    Thread.sleep(100);
                } catch (Exception sleep) {
                    //
                }
                reqNow = System.currentTimeMillis();
                isTimeout = ((reqNow - reqStart) > (1000L * getStateTransferTimeout()));
            } while ((!getStateTransfered()) && (!isTimeout) && (!isNoContextManagerReceived()));
        } else {
            if(getStateTransferTimeout() == -1) {
                // wait that state is transferred
                do {
                    try {
                        Thread.sleep(100);
                    } catch (Exception sleep) {
                    }
                } while ((!getStateTransfered())&& (!isNoContextManagerReceived()));
                reqNow = System.currentTimeMillis();
            }
        }
        if (isTimeout) {
            counterNoStateTransfered++ ;
            log.error(sm.getString("deltaManager.noSessionState", getName(),
                    new Date(beforeSendTime), Long.valueOf(reqNow - beforeSendTime)));
        }else if (isNoContextManagerReceived()) {
            if (log.isWarnEnabled())
                log.warn(sm.getString("deltaManager.noContextManager", getName(),
                        new Date(beforeSendTime), Long.valueOf(reqNow - beforeSendTime)));
        } else {
            if (log.isInfoEnabled())
                log.info(sm.getString("deltaManager.sessionReceived",getName(),
                        new Date(beforeSendTime), Long.valueOf(reqNow - beforeSendTime)));
        }
    }

    /**
     * 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 {

        if (log.isDebugEnabled())
            log.debug(sm.getString("deltaManager.stopped", getName()));

        setState(LifecycleState.STOPPING);

        // Expire all active sessions
        if (log.isInfoEnabled()) log.info(sm.getString("deltaManager.expireSessions", getName()));
        Session sessions[] = findSessions();
        for (int i = 0; i < sessions.length; i++) {
            DeltaSession session = (DeltaSession) sessions[i];
            if (!session.isValid())
                continue;
            try {
                session.expire(true, isExpireSessionsOnShutdown());
            } catch (Throwable t) {
                ExceptionUtils.handleThrowable(t);
            }
        }

        // Require a new random number generator if we are restarted
        super.stopInternal();
    }

    // -------------------------------------------------------- Replication
    // Methods

    /**
     * A message was received from another node, this is the callback method to
     * implement if you are interested in receiving replication messages.
     *
     * @param cmsg -
     *            the message received.
     */
    @Override
    public void messageDataReceived(ClusterMessage cmsg) {
        if (cmsg instanceof SessionMessage) {
            SessionMessage msg = (SessionMessage) cmsg;
            switch (msg.getEventType()) {
                case SessionMessage.EVT_GET_ALL_SESSIONS:
                case SessionMessage.EVT_SESSION_CREATED:
                case SessionMessage.EVT_SESSION_EXPIRED:
                case SessionMessage.EVT_SESSION_ACCESSED:
                case SessionMessage.EVT_SESSION_DELTA:
                case SessionMessage.EVT_CHANGE_SESSION_ID:
                    synchronized(receivedMessageQueue) {
                        if(receiverQueue) {
                            receivedMessageQueue.add(msg);
                            return ;
                        }
                    }
                   break;
                default:
                    //we didn't queue, do nothing
                    break;
            } //switch

            messageReceived(msg, msg.getAddress());
        }
    }

    /**
     * When the request has been completed, the replication valve will notify
     * the manager, and the manager will decide whether any replication is
     * needed or not. If there is a need for replication, the manager will
     * create a session message and that will be replicated. The cluster
     * determines where it gets sent.
     *
     * @param sessionId -
     *            the sessionId that just completed.
     * @return a SessionMessage to be sent,
     */
    @Override
    public ClusterMessage requestCompleted(String sessionId) {
         return requestCompleted(sessionId, false);
    }

    /**
     * When the request has been completed, the replication valve will notify
     * the manager, and the manager will decide whether any replication is
     * needed or not. If there is a need for replication, the manager will
     * create a session message and that will be replicated. The cluster
     * determines where it gets sent.
     *
     * Session expiration also calls this method, but with expires == true.
     *
     * @param sessionId -
     *            the sessionId that just completed.
     * @param expires -
     *            whether this method has been called during session expiration
     * @return a SessionMessage to be sent,
     */
    @SuppressWarnings("null") // session can't be null when it is used
    public ClusterMessage requestCompleted(String sessionId, boolean expires) {
        DeltaSession session = null;
        SessionMessage msg = null;
        try {
            session = (DeltaSession) findSession(sessionId);
            if (session == null) {
                // A parallel request has called session.invalidate() which has
                // removed the session from the Manager.
                return null;
            }
            DeltaRequest deltaRequest = session.getDeltaRequest();
            session.lock();
            if (deltaRequest.getSize() > 0) {
                counterSend_EVT_SESSION_DELTA++;
                byte[] data = serializeDeltaRequest(session,deltaRequest);
                msg = new SessionMessageImpl(getName(),
                                             SessionMessage.EVT_SESSION_DELTA,
                                             data,
                                             sessionId,
                                             sessionId + "-" + System.currentTimeMillis());
                session.resetDeltaRequest();
            }
        } catch (IOException x) {
            log.error(sm.getString("deltaManager.createMessage.unableCreateDeltaRequest",
                    sessionId), x);
            return null;
        } finally {
            if (session!=null) session.unlock();
        }
        if(msg == null) {
            if(!expires && !session.isPrimarySession()) {
                counterSend_EVT_SESSION_ACCESSED++;
                msg = new SessionMessageImpl(getName(),
                                             SessionMessage.EVT_SESSION_ACCESSED,
                                             null,
                                             sessionId,
                                             sessionId + "-" + System.currentTimeMillis());
                if (log.isDebugEnabled()) {
                    log.debug(sm.getString("deltaManager.createMessage.accessChangePrimary",
                            getName(), sessionId));
                }
            }
        } else { // log only outside synch block!
            if (log.isDebugEnabled()) {
                log.debug(sm.getString("deltaManager.createMessage.delta", getName(), sessionId));
            }
        }
        if (!expires) session.setPrimarySession(true);
        //check to see if we need to send out an access message
        if (!expires && (msg == null)) {
            long replDelta = System.currentTimeMillis() - session.getLastTimeReplicated();
            if (session.getMaxInactiveInterval() >=0 &&
                    replDelta > (session.getMaxInactiveInterval() * 1000L)) {
                counterSend_EVT_SESSION_ACCESSED++;
                msg = new SessionMessageImpl(getName(),
                                             SessionMessage.EVT_SESSION_ACCESSED,
                                             null,
                                             sessionId,
                                             sessionId + "-" + System.currentTimeMillis());
                if (log.isDebugEnabled()) {
                    log.debug(sm.getString("deltaManager.createMessage.access",
                            getName(),sessionId));
                }
            }
        }

        //update last replicated time
        if (msg != null) {
           session.setLastTimeReplicated(System.currentTimeMillis());
           msg.setTimestamp(session.getLastTimeReplicated());
        }
        return msg;
    }
    /**
     * Reset manager statistics
     */
    public synchronized void resetStatistics() {
        processingTime = 0 ;
        expiredSessions.set(0);
        synchronized (sessionCreationTiming) {
            sessionCreationTiming.clear();
            while (sessionCreationTiming.size() <
                    ManagerBase.TIMING_STATS_CACHE_SIZE) {
                sessionCreationTiming.add(null);
            }
        }
        synchronized (sessionExpirationTiming) {
            sessionExpirationTiming.clear();
            while (sessionExpirationTiming.size() <
                    ManagerBase.TIMING_STATS_CACHE_SIZE) {
                sessionExpirationTiming.add(null);
            }
        }
        rejectedSessions = 0 ;
        sessionReplaceCounter = 0 ;
        counterNoStateTransfered = 0 ;
        setMaxActive(getActiveSessions());
        sessionCounter = getActiveSessions() ;
        counterReceive_EVT_ALL_SESSION_DATA = 0;
        counterReceive_EVT_GET_ALL_SESSIONS = 0;
        counterReceive_EVT_SESSION_ACCESSED = 0 ;
        counterReceive_EVT_SESSION_CREATED = 0 ;
        counterReceive_EVT_SESSION_DELTA = 0 ;
        counterReceive_EVT_SESSION_EXPIRED = 0 ;
        counterReceive_EVT_ALL_SESSION_TRANSFERCOMPLETE = 0;
        counterReceive_EVT_CHANGE_SESSION_ID = 0;
        counterSend_EVT_ALL_SESSION_DATA = 0;
        counterSend_EVT_GET_ALL_SESSIONS = 0;
        counterSend_EVT_SESSION_ACCESSED = 0 ;
        counterSend_EVT_SESSION_CREATED = 0 ;
        counterSend_EVT_SESSION_DELTA = 0 ;
        counterSend_EVT_SESSION_EXPIRED = 0 ;
        counterSend_EVT_ALL_SESSION_TRANSFERCOMPLETE = 0;
        counterSend_EVT_CHANGE_SESSION_ID = 0;

    }

    //  -------------------------------------------------------- expire

    /**
     * send session expired to other cluster nodes
     *
     * @param id
     *            session id
     */
    protected void sessionExpired(String id) {
        if(cluster.getMembers().length > 0 ) {
            counterSend_EVT_SESSION_EXPIRED++ ;
            SessionMessage msg = new SessionMessageImpl(getName(),
                    SessionMessage.EVT_SESSION_EXPIRED, null, id, id+ "-EXPIRED-MSG");
            msg.setTimestamp(System.currentTimeMillis());
            if (log.isDebugEnabled()) {
                log.debug(sm.getString("deltaManager.createMessage.expire", getName(), id));
            }
            send(msg);
        }
    }

    /**
     * Expire all find sessions.
     */
    public void expireAllLocalSessions()
    {
        long timeNow = System.currentTimeMillis();
        Session sessions[] = findSessions();
        int expireDirect  = 0 ;
        int expireIndirect = 0 ;

        if(log.isDebugEnabled()) {
            log.debug("Start expire all sessions " + getName() + " at " + timeNow +
                    " sessioncount " + sessions.length);
        }
        for (int i = 0; i < sessions.length; i++) {
            if (sessions[i] instanceof DeltaSession) {
                DeltaSession session = (DeltaSession) sessions[i];
                if (session.isPrimarySession()) {
                    if (session.isValid()) {
                        session.expire();
                        expireDirect++;
                    } else {
                        expireIndirect++;
                    }//end if
                }//end if
            }//end if
        }//for
        long timeEnd = System.currentTimeMillis();
        if(log.isDebugEnabled()) {
            log.debug("End expire sessions " + getName() +
                    " expire processingTime " + (timeEnd - timeNow) +
                    " expired direct sessions: " + expireDirect +
                    " expired direct sessions: " + expireIndirect);
        }

    }

    @Override
    public String[] getInvalidatedSessions() {
        return new String[0];
    }

    //  -------------------------------------------------------- message receive

    /**
     * This method is called by the received thread when a SessionMessage has
     * been received from one of the other nodes in the cluster.
     *
     * @param msg -
     *            the message received
     * @param sender -
     *            the sender of the message, this is used if we receive a
     *            EVT_GET_ALL_SESSION message, so that we only reply to the
     *            requesting node
     */
    protected void messageReceived(SessionMessage msg, Member sender) {
        ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
        try {

            ClassLoader[] loaders = getClassLoaders();
            Thread.currentThread().setContextClassLoader(loaders[0]);
            if (log.isDebugEnabled()) {
                log.debug(sm.getString("deltaManager.receiveMessage.eventType",
                        getName(), msg.getEventTypeString(), sender));
            }

            switch (msg.getEventType()) {
                case SessionMessage.EVT_GET_ALL_SESSIONS:
                    handleGET_ALL_SESSIONS(msg,sender);
                    break;
                case SessionMessage.EVT_ALL_SESSION_DATA:
                    handleALL_SESSION_DATA(msg,sender);
                    break;
                case SessionMessage.EVT_ALL_SESSION_TRANSFERCOMPLETE:
                    handleALL_SESSION_TRANSFERCOMPLETE(msg,sender);
                    break;
                case SessionMessage.EVT_SESSION_CREATED:
                    handleSESSION_CREATED(msg,sender);
                    break;
                case SessionMessage.EVT_SESSION_EXPIRED:
                    handleSESSION_EXPIRED(msg,sender);
                    break;
                case SessionMessage.EVT_SESSION_ACCESSED:
                    handleSESSION_ACCESSED(msg,sender);
                    break;
                case SessionMessage.EVT_SESSION_DELTA:
                   handleSESSION_DELTA(msg,sender);
                   break;
                case SessionMessage.EVT_CHANGE_SESSION_ID:
                    handleCHANGE_SESSION_ID(msg,sender);
                    break;
                case SessionMessage.EVT_ALL_SESSION_NOCONTEXTMANAGER:
                    handleALL_SESSION_NOCONTEXTMANAGER(msg,sender);
                    break;
                default:
                    //we didn't recognize the message type, do nothing
                    break;
            } //switch
        } catch (Exception x) {
            log.error(sm.getString("deltaManager.receiveMessage.error",getName()), x);
        } finally {
            Thread.currentThread().setContextClassLoader(contextLoader);
        }
    }

    // -------------------------------------------------------- message receiver handler


    /**
     * handle receive session state is complete transferred
     * @param msg Session message
     * @param sender Member which sent the message
     */
    protected void handleALL_SESSION_TRANSFERCOMPLETE(SessionMessage msg, Member sender) {
        counterReceive_EVT_ALL_SESSION_TRANSFERCOMPLETE++ ;
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("deltaManager.receiveMessage.transfercomplete",
                    getName(), sender.getHost(), Integer.valueOf(sender.getPort())));
        }
        stateTransferCreateSendTime = msg.getTimestamp() ;
        stateTransfered = true ;
    }

    /**
     * handle receive session delta
     * @param msg Session message
     * @param sender Member which sent the message
     * @throws IOException IO error with serialization
     * @throws ClassNotFoundException Serialization error
     */
    protected void handleSESSION_DELTA(SessionMessage msg, Member sender)
            throws IOException, ClassNotFoundException {
        counterReceive_EVT_SESSION_DELTA++;
        byte[] delta = msg.getSession();
        DeltaSession session = (DeltaSession) findSession(msg.getSessionID());
        if (session == null) {
            if (log.isDebugEnabled()) {
                log.debug(sm.getString("deltaManager.receiveMessage.delta.unknown",
                        getName(), msg.getSessionID()));
            }
        } else {
            if (log.isDebugEnabled()) {
                log.debug(sm.getString("deltaManager.receiveMessage.delta",
                        getName(), msg.getSessionID()));
            }
            session.lock();
            try {
                DeltaRequest dreq = deserializeDeltaRequest(session, delta);
                dreq.execute(session, isNotifyListenersOnReplication());
                session.setPrimarySession(false);
            } finally {
                session.unlock();
            }
        }
    }

    /**
     * handle receive session is access at other node ( primary session is now false)
     * @param msg Session message
     * @param sender Member which sent the message
     * @throws IOException Propagated IO error
     */
    protected void handleSESSION_ACCESSED(SessionMessage msg,Member sender) throws IOException {
        counterReceive_EVT_SESSION_ACCESSED++;
        DeltaSession session = (DeltaSession) findSession(msg.getSessionID());
        if (session != null) {
            if (log.isDebugEnabled()) {
                log.debug(sm.getString("deltaManager.receiveMessage.accessed",
                        getName(), msg.getSessionID()));
            }
            session.access();
            session.setPrimarySession(false);
            session.endAccess();
        }
    }

    /**
     * handle receive session is expire at other node ( expire session also here)
     * @param msg Session message
     * @param sender Member which sent the message
     * @throws IOException Propagated IO error
     */
    protected void handleSESSION_EXPIRED(SessionMessage msg,Member sender) throws IOException {
        counterReceive_EVT_SESSION_EXPIRED++;
        DeltaSession session = (DeltaSession) findSession(msg.getSessionID());
        if (session != null) {
            if (log.isDebugEnabled()) {
                log.debug(sm.getString("deltaManager.receiveMessage.expired",
                        getName(), msg.getSessionID()));
            }
            session.expire(notifySessionListenersOnReplication, false);
        }
    }

    /**
     * handle receive new session is created at other node (create backup - primary false)
     * @param msg Session message
     * @param sender Member which sent the message
     */
    protected void handleSESSION_CREATED(SessionMessage msg,Member sender) {
        counterReceive_EVT_SESSION_CREATED++;
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("deltaManager.receiveMessage.createNewSession",
                    getName(), msg.getSessionID()));
        }
        DeltaSession session = (DeltaSession) createEmptySession();
        session.setValid(true);
        session.setPrimarySession(false);
        session.setCreationTime(msg.getTimestamp());
        // use container maxInactiveInterval so that session will expire correctly
        // in case of primary transfer
        session.setMaxInactiveInterval(getContext().getSessionTimeout() * 60, false);
        session.access();
        session.setId(msg.getSessionID(), notifySessionListenersOnReplication);
        session.endAccess();

    }

    /**
     * handle receive sessions from other not ( restart )
     * @param msg Session message
     * @param sender Member which sent the message
     * @throws ClassNotFoundException Serialization error
     * @throws IOException IO error with serialization
     */
    protected void handleALL_SESSION_DATA(SessionMessage msg,Member sender)
            throws ClassNotFoundException, IOException {
        counterReceive_EVT_ALL_SESSION_DATA++;
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("deltaManager.receiveMessage.allSessionDataBegin", getName()));
        }
        byte[] data = msg.getSession();
        deserializeSessions(data);
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("deltaManager.receiveMessage.allSessionDataAfter", getName()));
        }
        //stateTransferred = true;
    }

    /**
     * handle receive that other node want all sessions ( restart )
     * a) send all sessions with one message
     * b) send session at blocks
     * After sending send state is complete transferred
     * @param msg Session message
     * @param sender Member which sent the message
     * @throws IOException IO error sending messages
     */
    protected void handleGET_ALL_SESSIONS(SessionMessage msg, Member sender) throws IOException {
        counterReceive_EVT_GET_ALL_SESSIONS++;
        //get a list of all the session from this manager
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("deltaManager.receiveMessage.unloadingBegin", getName()));
        }
        // Write the number of active sessions, followed by the details
        // get all sessions and serialize without sync
        Session[] currentSessions = findSessions();
        long findSessionTimestamp = System.currentTimeMillis() ;
        if (isSendAllSessions()) {
            sendSessions(sender, currentSessions, findSessionTimestamp);
        } else {
            // send session at blocks
            int remain = currentSessions.length;
            for (int i = 0; i < currentSessions.length; i += getSendAllSessionsSize()) {
                int len = i + getSendAllSessionsSize() > currentSessions.length ?
                        currentSessions.length - i :
                        getSendAllSessionsSize();
                Session[] sendSessions = new Session[len];
                System.arraycopy(currentSessions, i, sendSessions, 0, len);
                sendSessions(sender, sendSessions,findSessionTimestamp);
                remain = remain - len;
                if (getSendAllSessionsWaitTime() > 0 && remain > 0) {
                    try {
                        Thread.sleep(getSendAllSessionsWaitTime());
                    } catch (Exception sleep) {
                    }
                }//end if
            }//for
        }//end if

        SessionMessage newmsg = new SessionMessageImpl(name,
                SessionMessage.EVT_ALL_SESSION_TRANSFERCOMPLETE, null, "SESSION-STATE-TRANSFERRED",
                "SESSION-STATE-TRANSFERRED" + getName());
        newmsg.setTimestamp(findSessionTimestamp);
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("deltaManager.createMessage.allSessionTransfered",getName()));
        }
        counterSend_EVT_ALL_SESSION_TRANSFERCOMPLETE++;
        cluster.send(newmsg, sender);
    }

    /**
     * handle receive change sessionID at other node
     * @param msg Session message
     * @param sender Member which sent the message
     * @throws IOException IO error with serialization
     */
    protected void handleCHANGE_SESSION_ID(SessionMessage msg,Member sender) throws IOException {
        counterReceive_EVT_CHANGE_SESSION_ID++;
        DeltaSession session = (DeltaSession) findSession(msg.getSessionID());
        if (session != null) {
            String newSessionID = deserializeSessionId(msg.getSession());
            session.setPrimarySession(false);
            // change session id
            changeSessionId(session, newSessionID, notifySessionListenersOnReplication,
                    notifyContainerListenersOnReplication);
        }
    }

    /**
     * handle receive no context manager.
     * @param msg Session message
     * @param sender Member which sent the message
     */
    protected void handleALL_SESSION_NOCONTEXTMANAGER(SessionMessage msg, Member sender) {
        counterReceive_EVT_ALL_SESSION_NOCONTEXTMANAGER++ ;
        if (log.isDebugEnabled())
            log.debug(sm.getString("deltaManager.receiveMessage.noContextManager",
                    getName(), sender.getHost(), Integer.valueOf(sender.getPort())));
        noContextManagerReceived = true ;
    }

    /**
     * send a block of session to sender
     * @param sender Sender member
     * @param currentSessions Sessions to send
     * @param sendTimestamp Timestamp
     * @throws IOException IO error sending messages
     */
    protected void sendSessions(Member sender, Session[] currentSessions,long sendTimestamp)
            throws IOException {
        byte[] data = serializeSessions(currentSessions);
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("deltaManager.receiveMessage.unloadingAfter", getName()));
        }
        SessionMessage newmsg = new SessionMessageImpl(name, SessionMessage.EVT_ALL_SESSION_DATA,
                data, "SESSION-STATE", "SESSION-STATE-" + getName());
        newmsg.setTimestamp(sendTimestamp);
        if (log.isDebugEnabled()) {
            log.debug(sm.getString("deltaManager.createMessage.allSessionData", getName()));
        }
        counterSend_EVT_ALL_SESSION_DATA++;
        int sendOptions = Channel.SEND_OPTIONS_SYNCHRONIZED_ACK|Channel.SEND_OPTIONS_USE_ACK;
        cluster.send(newmsg, sender, sendOptions);
    }

    @Override
    public ClusterManager cloneFromTemplate() {
        DeltaManager result = new DeltaManager();
        clone(result);
        result.expireSessionsOnShutdown = expireSessionsOnShutdown;
        result.notifySessionListenersOnReplication = notifySessionListenersOnReplication;
        result.notifyContainerListenersOnReplication = notifyContainerListenersOnReplication;
        result.stateTransferTimeout = stateTransferTimeout;
        result.sendAllSessions = sendAllSessions;
        result.sendAllSessionsSize = sendAllSessionsSize;
        result.sendAllSessionsWaitTime = sendAllSessionsWaitTime ;
        result.stateTimestampDrop = stateTimestampDrop ;
        return result;
    }
}