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/*
 * 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.Externalizable;
import java.io.IOException;
import java.io.NotSerializableException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.security.Principal;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionContext;

import org.apache.catalina.Manager;
import org.apache.catalina.SessionListener;
import org.apache.catalina.ha.ClusterManager;
import org.apache.catalina.ha.CatalinaCluster;
import org.apache.catalina.ha.ClusterSession;
import org.apache.catalina.ha.ClusterMessage;
import org.apache.catalina.realm.GenericPrincipal;
import org.apache.catalina.session.StandardSession;
import org.apache.catalina.tribes.io.ReplicationStream;
import org.apache.catalina.tribes.tipis.ReplicatedMapEntry;
import org.apache.catalina.util.Enumerator;
import org.apache.tomcat.util.res.StringManager;
import org.apache.catalina.session.StandardManager;
import org.apache.catalina.session.ManagerBase;
import java.util.concurrent.atomic.AtomicInteger;

/**
 *
 * Similar to the StandardSession except that this session will keep
 * track of deltas during a request.
 *
 * @author Filip Hanik
 * @version $Id: DeltaSession.java 939305 2010-04-29 13:43:39Z kkolinko $
 */

public class DeltaSession extends StandardSession implements Externalizable,ClusterSession,ReplicatedMapEntry {

    public static final org.apache.juli.logging.Log log = org.apache.juli.logging.LogFactory.getLog(DeltaSession.class);

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

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

    /**
     * only the primary session will expire, or be able to expire due to
     * inactivity. This is set to false as soon as I receive this session over
     * the wire in a session message. That means that someone else has made a
     * request on another server.
     */
    private transient boolean isPrimarySession = true;

    /**
     * The delta request contains all the action info
     *
     */
    private transient DeltaRequest deltaRequest = null;

    /**
     * Last time the session was replicated, used for distributed expiring of
     * session
     */
    private transient long lastTimeReplicated = System.currentTimeMillis();


    protected final Lock diffLock = new ReentrantReadWriteLock().writeLock();

    private long version;

    // ----------------------------------------------------------- Constructors

    public DeltaSession() {
        this(null);
    }

    /**
     * Construct a new Session associated with the specified Manager.
     *
     * @param manager
     *            The manager with which this Session is associated
     */
    public DeltaSession(Manager manager) {
        super(manager);
        this.resetDeltaRequest();
    }

    // ----------------------------------------------------- ReplicatedMapEntry

    /**
         * Has the object changed since last replication
         * and is not in a locked state
         * @return boolean
         */
        public boolean isDirty() {
            return getDeltaRequest().getSize()>0;
        }

        /**
         * If this returns true, the map will extract the diff using getDiff()
         * Otherwise it will serialize the entire object.
         * @return boolean
         */
        public boolean isDiffable() {
            return true;
        }

        /**
         * Returns a diff and sets the dirty map to false
         * @return byte[]
         * @throws IOException
         */
        public byte[] getDiff() throws IOException {
            try{
                lock();
                return getDeltaRequest().serialize();
            }finally{
                unlock();
            }
        }

        public ClassLoader[] getClassLoaders() {
            if ( manager instanceof BackupManager ) return ((BackupManager)manager).getClassLoaders();
            else if ( manager instanceof ClusterManagerBase ) return ((ClusterManagerBase)manager).getClassLoaders();
            else if ( manager instanceof StandardManager ) {
                StandardManager sm = (StandardManager)manager;
                return ClusterManagerBase.getClassLoaders(sm.getContainer());
            } else if ( manager instanceof ManagerBase ) {
                ManagerBase mb = (ManagerBase)manager;
                return ClusterManagerBase.getClassLoaders(mb.getContainer());
            }//end if
            return null;
        }

        /**
         * Applies a diff to an existing object.
         * @param diff byte[]
         * @param offset int
         * @param length int
         * @throws IOException
         */
        public void applyDiff(byte[] diff, int offset, int length) throws IOException, ClassNotFoundException {
            try {
                lock();
                ReplicationStream stream = ( (ClusterManager) getManager()).getReplicationStream(diff, offset, length);
                ClassLoader contextLoader = Thread.currentThread().getContextClassLoader();
                try {
                    ClassLoader[] loaders = getClassLoaders();
                    if (loaders != null && loaders.length > 0)
                        Thread.currentThread().setContextClassLoader(loaders[0]);
                    getDeltaRequest().readExternal(stream);
                    getDeltaRequest().execute(this, ((ClusterManager)getManager()).isNotifyListenersOnReplication());
                } finally {
                    Thread.currentThread().setContextClassLoader(contextLoader);
                }
            }finally {
                unlock();
            }
        }

        /**
         * Resets the current diff state and resets the dirty flag
         */
        public void resetDiff() {
            resetDeltaRequest();
        }

        /**
         * Lock during serialization
         */
        public void lock() {
            diffLock.lock();
        }

        /**
         * Unlock after serialization
         */
        public void unlock() {
            diffLock.unlock();
        }

        public void setOwner(Object owner) {
            if ( owner instanceof ClusterManager && getManager()==null) {
                ClusterManager cm = (ClusterManager)owner;
                this.setManager(cm);
                this.setValid(true);
                this.setPrimarySession(false);
                this.access();
                this.resetDeltaRequest();
                this.endAccess();
            }
        }
    // ----------------------------------------------------- Session Properties

    /**
     * returns true if this session is the primary session, if that is the case,
     * the manager can expire it upon timeout.
     */
    public boolean isPrimarySession() {
        return isPrimarySession;
    }

    /**
     * Sets whether this is the primary session or not.
     *
     * @param primarySession
     *            Flag value
     */
    public void setPrimarySession(boolean primarySession) {
        this.isPrimarySession = primarySession;
    }

    /**
     * Set the session identifier for this session without notify listeners.
     *
     * @param id
     *            The new session identifier
     */
    public void setIdInternal(String id) {
        this.id = id;
        resetDeltaRequest();
    }

    /**
     * Set the session identifier for this session.
     *
     * @param id
     *            The new session identifier
     */
    @Override
    public void setId(String id) {
        super.setId(id);
        resetDeltaRequest();
    }


    @Override
    public void setMaxInactiveInterval(int interval) {
        this.setMaxInactiveInterval(interval,true);
    }


    public void setMaxInactiveInterval(int interval, boolean addDeltaRequest) {
        super.maxInactiveInterval = interval;
        if (isValid && interval == 0) {
            expire();
        } else {
            if (addDeltaRequest && (deltaRequest != null)) {
                try {
                    lock();
                    deltaRequest.setMaxInactiveInterval(interval);
                }finally{
                    unlock();
                }
            }
        }
    }

    /**
     * Set the isNew flag for this session.
     *
     * @param isNew
     *            The new value for the isNew flag
     */
    @Override
    public void setNew(boolean isNew) {
        setNew(isNew, true);
    }

    public void setNew(boolean isNew, boolean addDeltaRequest) {
        super.setNew(isNew);
        if (addDeltaRequest && (deltaRequest != null)){
            try {
                lock();
                deltaRequest.setNew(isNew);
            }finally{
                unlock();
            }
        }
    }

    /**
     * Set the authenticated Principal that is associated with this Session.
     * This provides an Authenticator with a means to cache a
     * previously authenticated Principal, and avoid potentially expensive
     * Realm.authenticate() calls on every request.
     *
     * @param principal
     *            The new Principal, or null if none
     */
    @Override
    public void setPrincipal(Principal principal) {
        setPrincipal(principal, true);
    }

    public void setPrincipal(Principal principal, boolean addDeltaRequest) {
        try { 
            lock();
            super.setPrincipal(principal);
            if (addDeltaRequest && (deltaRequest != null))
                deltaRequest.setPrincipal(principal);
        } finally {
            unlock();
        }
    }

    /**
     * Return the isValid flag for this session.
     */
    @Override
    public boolean isValid() {
        if (this.expiring) {
            return true;
        }
        if (!this.isValid) {
            return false;
        }
        if (ACTIVITY_CHECK && accessCount.get() > 0) {
            return true;
        }
        if (maxInactiveInterval >= 0) {
            long timeNow = System.currentTimeMillis();
            int timeIdle = (int) ( (timeNow - thisAccessedTime) / 1000L);
            if (isPrimarySession()) {
                if (timeIdle >= maxInactiveInterval) {
                    expire(true);
                }
            } else {
                if (timeIdle >= (2 * maxInactiveInterval)) {
                    //if the session has been idle twice as long as allowed,
                    //the primary session has probably crashed, and no other
                    //requests are coming in. that is why we do this. otherwise
                    //we would have a memory leak
                    expire(true, false);
                }
            }
        }
        return (this.isValid);
    }

    /**
     * End the access and register to ReplicationValve (crossContext support)
     */
    @Override
    public void endAccess() {
    	super.endAccess() ;
    	if(manager instanceof DeltaManager) {
            ((DeltaManager)manager).registerSessionAtReplicationValve(this);   	
    	}
    }
    
    // ------------------------------------------------- Session Public Methods

    /**
     * Perform the internal processing required to invalidate this session,
     * without triggering an exception if the session has already expired.
     *
     * @param notify
     *            Should we notify listeners about the demise of this session?
     */
    @Override
    public void expire(boolean notify) {
        expire(notify, true);
    }

    public void expire(boolean notify, boolean notifyCluster) {
        if (expiring)
            return;
        String expiredId = getIdInternal();

        if(expiredId != null && manager != null &&
           manager instanceof DeltaManager) {
            DeltaManager dmanager = (DeltaManager)manager;
            CatalinaCluster cluster = dmanager.getCluster();
            ClusterMessage msg = dmanager.requestCompleted(expiredId, true);
            if (msg != null) {
                if(dmanager.doDomainReplication()) {
                    cluster.sendClusterDomain(msg);
                } else {
                    cluster.send(msg);
                }
            }
        }

        super.expire(notify);

        if (notifyCluster) {
            if (log.isDebugEnabled())
                log.debug(sm.getString("deltaSession.notifying",
                                       ((ClusterManager)manager).getName(), 
                                       new Boolean(isPrimarySession()), 
                                       expiredId));
            if ( manager instanceof DeltaManager ) {
                ( (DeltaManager) manager).sessionExpired(expiredId);
            }
        }
    }

    /**
     * Release all object references, and initialize instance variables, in
     * preparation for reuse of this object.
     */
    @Override
    public void recycle() {
        try {
            lock();
            super.recycle();
            deltaRequest.clear();
        }finally{
            unlock();
        }
    }


    /**
     * Return a string representation of this object.
     */
    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append("DeltaSession[");
        sb.append(id);
        sb.append("]");
        return (sb.toString());
    }

    // ------------------------------------------------ Session Package Methods

    public void readExternal(ObjectInput in) throws IOException,ClassNotFoundException {
        try {
            lock();
            readObjectData(in);
        }finally{
            unlock();
        }
    }


    /**
     * Read a serialized version of the contents of this session object from the
     * specified object input stream, without requiring that the StandardSession
     * itself have been serialized.
     *
     * @param stream
     *            The object input stream to read from
     *
     * @exception ClassNotFoundException
     *                if an unknown class is specified
     * @exception IOException
     *                if an input/output error occurs
     */
    @Override
    public void readObjectData(ObjectInputStream stream) throws ClassNotFoundException, IOException {
        readObject((ObjectInput)stream);
    }
    public void readObjectData(ObjectInput stream) throws ClassNotFoundException, IOException {
        readObject(stream);
    }

    /**
     * Write a serialized version of the contents of this session object to the
     * specified object output stream, without requiring that the
     * StandardSession itself have been serialized.
     *
     * @param stream
     *            The object output stream to write to
     *
     * @exception IOException
     *                if an input/output error occurs
     */
    @Override
    public void writeObjectData(ObjectOutputStream stream) throws IOException {
        writeObjectData((ObjectOutput)stream);
    }
    public void writeObjectData(ObjectOutput stream) throws IOException {
        writeObject(stream);
    }

    public void resetDeltaRequest() {
        try {
            lock();
            if (deltaRequest == null) {
                deltaRequest = new DeltaRequest(getIdInternal(), false);
            } else {
                deltaRequest.reset();
                deltaRequest.setSessionId(getIdInternal());
            }
        }finally{
            unlock();
        }
    }

    public DeltaRequest getDeltaRequest() {
        if (deltaRequest == null) resetDeltaRequest();
        return deltaRequest;
    }

    // ------------------------------------------------- HttpSession Properties

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



    /**
     * Remove the object bound with the specified name from this session. If the
     * session does not have an object bound with this name, this method does
     * nothing.
     * 

* After this method executes, and if the object implements * HttpSessionBindingListener, the container calls * valueUnbound() on the object. * * @param name * Name of the object to remove from this session. * @param notify * Should we notify interested listeners that this attribute is * being removed? * * @exception IllegalStateException * if this method is called on an invalidated session */ @Override public void removeAttribute(String name, boolean notify) { removeAttribute(name, notify, true); } public void removeAttribute(String name, boolean notify,boolean addDeltaRequest) { // Validate our current state if (!isValid()) throw new IllegalStateException(sm.getString("standardSession.removeAttribute.ise")); removeAttributeInternal(name, notify, addDeltaRequest); } /** * Bind an object to this session, using the specified name. If an object of * the same name is already bound to this session, the object is replaced. *

* After this method executes, and if the object implements * HttpSessionBindingListener, the container calls * valueBound() on the object. * * @param name * Name to which the object is bound, cannot be null * @param value * Object to be bound, cannot be null * * @exception IllegalArgumentException * if an attempt is made to add a non-serializable object in * an environment marked distributable. * @exception IllegalStateException * if this method is called on an invalidated session */ @Override public void setAttribute(String name, Object value) { setAttribute(name, value, true, true); } public void setAttribute(String name, Object value, boolean notify,boolean addDeltaRequest) { // Name cannot be null if (name == null) throw new IllegalArgumentException(sm.getString("standardSession.setAttribute.namenull")); // Null value is the same as removeAttribute() if (value == null) { removeAttribute(name); return; } try { lock(); super.setAttribute(name,value, notify); if (addDeltaRequest && (deltaRequest != null)) deltaRequest.setAttribute(name, value); } finally { unlock(); } } // -------------------------------------------- HttpSession Private Methods /** * Read a serialized version of this session object from the specified * object input stream. *

* IMPLEMENTATION NOTE : The reference to the owning Manager is not * restored by this method, and must be set explicitly. * * @param stream * The input stream to read from * * @exception ClassNotFoundException * if an unknown class is specified * @exception IOException * if an input/output error occurs */ @Override protected void readObject(ObjectInputStream stream) throws ClassNotFoundException, IOException { readObject((ObjectInput)stream); } private void readObject(ObjectInput stream) throws ClassNotFoundException, IOException { // Deserialize the scalar instance variables (except Manager) authType = null; // Transient only creationTime = ( (Long) stream.readObject()).longValue(); lastAccessedTime = ( (Long) stream.readObject()).longValue(); maxInactiveInterval = ( (Integer) stream.readObject()).intValue(); isNew = ( (Boolean) stream.readObject()).booleanValue(); isValid = ( (Boolean) stream.readObject()).booleanValue(); thisAccessedTime = ( (Long) stream.readObject()).longValue(); version = ( (Long) stream.readObject()).longValue(); boolean hasPrincipal = stream.readBoolean(); principal = null; if (hasPrincipal) { principal = SerializablePrincipal.readPrincipal(stream); } // setId((String) stream.readObject()); id = (String) stream.readObject(); if (log.isDebugEnabled()) log.debug(sm.getString("deltaSession.readSession", id)); // Deserialize the attribute count and attribute values if (attributes == null) attributes = new Hashtable(); int n = ( (Integer) stream.readObject()).intValue(); boolean isValidSave = isValid; isValid = true; for (int i = 0; i < n; i++) { String name = (String) stream.readObject(); Object value = stream.readObject(); if ( (value instanceof String) && (value.equals(NOT_SERIALIZED))) continue; attributes.put(name, value); } isValid = isValidSave; if (listeners == null) { ArrayList arrayList = new ArrayList(); listeners = arrayList; } if (notes == null) { notes = new Hashtable(); } activate(); } public void writeExternal(ObjectOutput out ) throws java.io.IOException { try { lock(); writeObject(out); }finally { unlock(); } } /** * Write a serialized version of this session object to the specified object * output stream. *

* IMPLEMENTATION NOTE : The owning Manager will not be stored in the * serialized representation of this Session. After calling * readObject(), you must set the associated Manager * explicitly. *

* IMPLEMENTATION NOTE : Any attribute that is not Serializable will * be unbound from the session, with appropriate actions if it implements * HttpSessionBindingListener. If you do not want any such attributes, be * sure the distributable property of the associated Manager * is set to true. * * @param stream * The output stream to write to * * @exception IOException * if an input/output error occurs */ @Override protected void writeObject(ObjectOutputStream stream) throws IOException { writeObject((ObjectOutput)stream); } private void writeObject(ObjectOutput stream) throws IOException { // Write the scalar instance variables (except Manager) stream.writeObject(new Long(creationTime)); stream.writeObject(new Long(lastAccessedTime)); stream.writeObject(new Integer(maxInactiveInterval)); stream.writeObject(new Boolean(isNew)); stream.writeObject(new Boolean(isValid)); stream.writeObject(new Long(thisAccessedTime)); stream.writeObject(new Long(version)); stream.writeBoolean(getPrincipal() != null); if (getPrincipal() != null) { SerializablePrincipal.writePrincipal((GenericPrincipal) principal,stream); } stream.writeObject(id); if (log.isDebugEnabled()) log.debug(sm.getString("deltaSession.writeSession", id)); // Accumulate the names of serializable and non-serializable attributes String keys[] = keys(); ArrayList saveNames = new ArrayList(); ArrayList saveValues = new ArrayList(); for (int i = 0; i < keys.length; i++) { Object value = null; value = attributes.get(keys[i]); if (value == null || exclude(keys[i])) continue; else if (value instanceof Serializable) { saveNames.add(keys[i]); saveValues.add(value); } } // Serialize the attribute count and the Serializable attributes int n = saveNames.size(); stream.writeObject(new Integer(n)); for (int i = 0; i < n; i++) { stream.writeObject( saveNames.get(i)); try { stream.writeObject(saveValues.get(i)); } catch (NotSerializableException e) { log.error(sm.getString("standardSession.notSerializable",saveNames.get(i), id), e); stream.writeObject(NOT_SERIALIZED); log.error(" storing attribute '" + saveNames.get(i)+ "' with value NOT_SERIALIZED"); } } } // -------------------------------------------------------- Private Methods /** * Return the value of an attribute without a check for validity. */ protected Object getAttributeInternal(String name) { return (attributes.get(name)); } protected void removeAttributeInternal(String name, boolean notify, boolean addDeltaRequest) { try { lock(); // Remove this attribute from our collection Object value = attributes.get(name); if (value == null) return; super.removeAttributeInternal(name,notify); if (addDeltaRequest && (deltaRequest != null)) deltaRequest.removeAttribute(name); }finally { unlock(); } } protected long getLastTimeReplicated() { return lastTimeReplicated; } public long getVersion() { return version; } protected void setLastTimeReplicated(long lastTimeReplicated) { this.lastTimeReplicated = lastTimeReplicated; } public void setVersion(long version) { this.version = version; } protected void setAccessCount(int count) { if ( accessCount == null && ACTIVITY_CHECK ) accessCount = new AtomicInteger(); if ( accessCount != null ) super.accessCount.set(count); } } // -------------------------------------------------------------- Private Class /** * This class is a dummy implementation of the HttpSessionContext * interface, to conform to the requirement that such an object be returned when * HttpSession.getSessionContext() is called. * * @author Craig R. McClanahan * * @deprecated As of Java Servlet API 2.1 with no replacement. The interface * will be removed in a future version of this API. */ @Deprecated final class StandardSessionContext implements HttpSessionContext { private HashMap dummy = new HashMap(); /** * Return the session identifiers of all sessions defined within this * context. * * @deprecated As of Java Servlet API 2.1 with no replacement. This method * must return an empty Enumeration and will be * removed in a future version of the API. */ @Deprecated public Enumeration getIds() { return (new Enumerator(dummy)); } /** * Return the HttpSession associated with the specified * session identifier. * * @param id * Session identifier for which to look up a session * * @deprecated As of Java Servlet API 2.1 with no replacement. This method * must return null and will be removed in a future version of * the API. */ @Deprecated public HttpSession getSession(String id) { return (null); } }