https://tomcat.apache.org/: Tomcat Servlet Engine Core Classes and Standard implementations 
/*
 * 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.session;

import java.io.IOException;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.apache.catalina.Lifecycle;
import org.apache.catalina.LifecycleException;
import org.apache.catalina.LifecycleState;
import org.apache.catalina.Session;
import org.apache.catalina.Store;
import org.apache.catalina.StoreManager;
import org.apache.catalina.security.SecurityUtil;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;

Extends the ManagerBase class to implement most of the functionality required by a Manager which supports any kind of persistence, even if only for restarts. 

IMPLEMENTATION NOTE: Correct behavior of session storing and reloading depends upon external calls to the Lifecycle.start() and Lifecycle.stop() methods of this class at the correct times. 
Author:Craig R. McClanahan
/**
 * Extends the {@link ManagerBase} class to implement most of the
 * functionality required by a Manager which supports any kind of
 * persistence, even if only for  restarts.
 * <p>
 * <b>IMPLEMENTATION NOTE</b>:  Correct behavior of session storing and
 * reloading depends upon external calls to the {@link Lifecycle#start()}
 * and {@link Lifecycle#stop()} methods of this class
 * at the correct times.
 *
 * @author Craig R. McClanahan
 */
public abstract class PersistentManagerBase extends ManagerBase
        implements StoreManager {

    private final Log log = LogFactory.getLog(PersistentManagerBase.class); // must not be static

    // ---------------------------------------------------- Security Classes

    private class PrivilegedStoreClear
        implements PrivilegedExceptionAction<Void> {

        PrivilegedStoreClear() {
            // NOOP
        }

        @Override
        public Void run() throws Exception{
           store.clear();
           return null;
        }
    }

    private class PrivilegedStoreRemove
        implements PrivilegedExceptionAction<Void> {

        private String id;

        PrivilegedStoreRemove(String id) {
            this.id = id;
        }

        @Override
        public Void run() throws Exception{
           store.remove(id);
           return null;
        }
    }

    private class PrivilegedStoreLoad
        implements PrivilegedExceptionAction<Session> {

        private String id;

        PrivilegedStoreLoad(String id) {
            this.id = id;
        }

        @Override
        public Session run() throws Exception{
           return store.load(id);
        }
    }

    private class PrivilegedStoreSave
        implements PrivilegedExceptionAction<Void> {

        private Session session;

        PrivilegedStoreSave(Session session) {
            this.session = session;
        }

        @Override
        public Void run() throws Exception{
           store.save(session);
           return null;
        }
    }

    private class PrivilegedStoreKeys
        implements PrivilegedExceptionAction<String[]> {

        PrivilegedStoreKeys() {
            // NOOP
        }

        @Override
        public String[] run() throws Exception{
           return store.keys();
        }
    }

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

    
The descriptive name of this Manager implementation (for logging).

/**
     * The descriptive name of this Manager implementation (for logging).
     */
    private static final String name = "PersistentManagerBase";

    
Key of the note of a session in which the timestamp of last backup is stored.

/**
     * Key of the note of a session in which the timestamp of last backup is stored.
     */
    private static final String PERSISTED_LAST_ACCESSED_TIME =
            "org.apache.catalina.session.PersistentManagerBase.persistedLastAccessedTime";


    
Store object which will manage the Session store.

/**
     * Store object which will manage the Session store.
     */
    protected Store store = null;


    
Whether to save and reload sessions when the Manager unload
and load methods are called.

/**
     * Whether to save and reload sessions when the Manager <code>unload</code>
     * and <code>load</code> methods are called.
     */
    protected boolean saveOnRestart = true;


    
How long a session must be idle before it should be backed up. -1 means sessions won't be backed up. 
/**
     * How long a session must be idle before it should be backed up.
     * {@code -1} means sessions won't be backed up.
     */
    protected int maxIdleBackup = -1;


    
The minimum time in seconds a session must be idle before it is eligible to be swapped to disk to keep the active session count below maxActiveSessions. Setting to -1 means sessions will not be swapped out to keep the active session count down. 
/**
     * The minimum time in seconds a session must be idle before it is eligible
     * to be swapped to disk to keep the active session count below
     * maxActiveSessions. Setting to {@code -1} means sessions will not be
     * swapped out to keep the active session count down.
     */
    protected int minIdleSwap = -1;


    
The maximum time in seconds a session may be idle before it is eligible to be swapped to disk due to inactivity. Setting this to -1 means sessions should not be swapped out just because of inactivity. 
/**
     * The maximum time in seconds a session may be idle before it is eligible
     * to be swapped to disk due to inactivity. Setting this to {@code -1} means
     * sessions should not be swapped out just because of inactivity.
     */
    protected int maxIdleSwap = -1;


    
Sessions currently being swapped in and the associated locks

/**
     * Sessions currently being swapped in and the associated locks
     */
    private final Map<String,Object> sessionSwapInLocks = new HashMap<>();

    /*
     * Session that is currently getting swapped in to prevent loading it more
     * than once concurrently
     */
    private final ThreadLocal<Session> sessionToSwapIn = new ThreadLocal<>();


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


    
Indicates how many seconds old a session can get, after its last use in a request, before it should be backed up to the store. -1 means sessions are not backed up. 
Returns:the timeout after which sessions are ripe for back up
/**
     * Indicates how many seconds old a session can get, after its last use in a
     * request, before it should be backed up to the store. {@code -1} means sessions
     * are not backed up.
     *
     * @return the timeout after which sessions are ripe for back up
     */
    public int getMaxIdleBackup() {

        return maxIdleBackup;

    }


    
Sets the option to back sessions up to the Store after they are used in a request. Sessions remain available in memory after being backed up, so they are not passivated as they are when swapped out. The value set indicates how old a session may get (since its last use) before it must be backed up: -1 means sessions are not backed up. 
 Note that this is not a hard limit: sessions are checked against this age limit periodically according to processExpiresFrequency. This value should be considered to indicate when a session is ripe for backing up. 
 So it is possible that a session may be idle for maxIdleBackup +
processExpiresFrequency * engine.backgroundProcessorDelay seconds, plus the time it takes to handle other session expiration, swapping, etc. tasks. 
Params:
  • backup – The number of seconds after their last accessed
time when they should be written to the Store.
/**
     * Sets the option to back sessions up to the Store after they
     * are used in a request. Sessions remain available in memory
     * after being backed up, so they are not passivated as they are
     * when swapped out. The value set indicates how old a session
     * may get (since its last use) before it must be backed up: {@code -1}
     * means sessions are not backed up.
     * <p>
     * Note that this is not a hard limit: sessions are checked
     * against this age limit periodically according to {@code processExpiresFrequency}.
     * This value should be considered to indicate when a session is
     * ripe for backing up.
     * <p>
     * So it is possible that a session may be idle for {@code maxIdleBackup +
     * processExpiresFrequency * engine.backgroundProcessorDelay} seconds, plus the time it takes to handle other
     * session expiration, swapping, etc. tasks.
     *
     * @param backup The number of seconds after their last accessed
     * time when they should be written to the Store.
     */
    public void setMaxIdleBackup (int backup) {

        if (backup == this.maxIdleBackup)
            return;
        int oldBackup = this.maxIdleBackup;
        this.maxIdleBackup = backup;
        support.firePropertyChange("maxIdleBackup",
                                   Integer.valueOf(oldBackup),
                                   Integer.valueOf(this.maxIdleBackup));

    }


    
Returns:The maximum time in seconds a session may be idle before it is eligible to be swapped to disk due to inactivity. A value of -1 means sessions should not be swapped out just because of inactivity.
/**
     * @return The maximum time in seconds a session may be idle before it is
     * eligible to be swapped to disk due to inactivity. A value of {@code -1}
     * means sessions should not be swapped out just because of inactivity.
     */
    public int getMaxIdleSwap() {
        return maxIdleSwap;
    }


    
Sets the maximum time in seconds a session may be idle before it is eligible to be swapped to disk due to inactivity. Setting this to -1 means sessions should not be swapped out just because of inactivity. 
Params:
  • max – time in seconds to wait for possible swap out
/**
     * Sets the maximum time in seconds a session may be idle before it is
     * eligible to be swapped to disk due to inactivity. Setting this to
     * {@code -1} means sessions should not be swapped out just because of
     * inactivity.
     *
     * @param max time in seconds to wait for possible swap out
     */
    public void setMaxIdleSwap(int max) {

        if (max == this.maxIdleSwap)
            return;
        int oldMaxIdleSwap = this.maxIdleSwap;
        this.maxIdleSwap = max;
        support.firePropertyChange("maxIdleSwap",
                                   Integer.valueOf(oldMaxIdleSwap),
                                   Integer.valueOf(this.maxIdleSwap));
    }


    
Returns:The minimum time in seconds a session must be idle before it is eligible to be swapped to disk to keep the active session count below maxActiveSessions. A value of -1 means sessions will not be swapped out to keep the active session count down.
/**
     * @return The minimum time in seconds a session must be idle before it is
     * eligible to be swapped to disk to keep the active session count below
     * maxActiveSessions. A value of {@code -1} means sessions will not be
     * swapped out to keep the active session count down.
     */
    public int getMinIdleSwap() {
        return minIdleSwap;
    }


    
Sets the minimum time in seconds a session must be idle before it is eligible to be swapped to disk to keep the active session count below maxActiveSessions. Setting to -1 means sessions will not be swapped out to keep the active session count down. 
Params:
  • min – time in seconds before a possible swap out
/**
     * Sets the minimum time in seconds a session must be idle before it is
     * eligible to be swapped to disk to keep the active session count below
     * maxActiveSessions. Setting to {@code -1} means sessions will not be
     * swapped out to keep the active session count down.
     *
     * @param min time in seconds before a possible swap out
     */
    public void setMinIdleSwap(int min) {

        if (this.minIdleSwap == min)
            return;
        int oldMinIdleSwap = this.minIdleSwap;
        this.minIdleSwap = min;
        support.firePropertyChange("minIdleSwap",
                                   Integer.valueOf(oldMinIdleSwap),
                                   Integer.valueOf(this.minIdleSwap));

    }


    
Check, whether a session is loaded in memory

Params:
  • id – The session id for the session to be searched for
Returns:true, if the session id is loaded in memory otherwise false is returned
/**
     * Check, whether a session is loaded in memory
     *
     * @param id The session id for the session to be searched for
     * @return {@code true}, if the session id is loaded in memory
     * otherwise {@code false} is returned
     */
    public boolean isLoaded(String id) {
        try {
            if (super.findSession(id) != null) {
                return true;
            }
        } catch (IOException e) {
            log.error(sm.getString("persistentManager.isLoadedError", id), e);
        }
        return false;
    }


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


    
Set the Store object which will manage persistent Session
storage for this Manager.

Params:
  • store – the associated Store
/**
     * Set the Store object which will manage persistent Session
     * storage for this Manager.
     *
     * @param store the associated Store
     */
    public void setStore(Store store) {
        this.store = store;
        store.setManager(this);
    }


    
Returns:the Store object which manages persistent Session
storage for this Manager.
/**
     * @return the Store object which manages persistent Session
     * storage for this Manager.
     */
    @Override
    public Store getStore() {
        return this.store;
    }


    
Indicates whether sessions are saved when the Manager is shut down properly. This requires the unload() method to be called. 
Returns:true, when sessions should be saved on restart, {code false} otherwise
/**
     * Indicates whether sessions are saved when the Manager is shut down
     * properly. This requires the {@link #unload()} method to be called.
     *
     * @return {@code true}, when sessions should be saved on restart,
     * {code false} otherwise
     */
    public boolean getSaveOnRestart() {

        return saveOnRestart;

    }


    
Set the option to save sessions to the Store when the Manager is
shut down, then loaded when the Manager starts again. If set to
false, any sessions found in the Store may still be picked up when
the Manager is started again.

Params:
  • saveOnRestart – true if sessions should be saved on restart, false if they should be ignored.
/**
     * Set the option to save sessions to the Store when the Manager is
     * shut down, then loaded when the Manager starts again. If set to
     * false, any sessions found in the Store may still be picked up when
     * the Manager is started again.
     *
     * @param saveOnRestart {@code true} if sessions should be saved on restart, {@code false} if
     *     they should be ignored.
     */
    public void setSaveOnRestart(boolean saveOnRestart) {

        if (saveOnRestart == this.saveOnRestart)
            return;

        boolean oldSaveOnRestart = this.saveOnRestart;
        this.saveOnRestart = saveOnRestart;
        support.firePropertyChange("saveOnRestart",
                                   Boolean.valueOf(oldSaveOnRestart),
                                   Boolean.valueOf(this.saveOnRestart));

    }


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


    
Clear all sessions from the Store.

/**
     * Clear all sessions from the Store.
     */
    public void clearStore() {

        if (store == null)
            return;

        try {
            if (SecurityUtil.isPackageProtectionEnabled()) {
                try {
                    AccessController.doPrivileged(new PrivilegedStoreClear());
                } catch (PrivilegedActionException e) {
                    log.error(sm.getString("persistentManager.storeClearError"), e.getException());
                }
            } else {
                store.clear();
            }
        } catch (IOException e) {
            log.error(sm.getString("persistentManager.storeClearError"), e);
        }

    }


    
{@inheritDoc}


Direct call to processExpires and processPersistenceChecks

/**
     * {@inheritDoc}
     * <p>
     * Direct call to processExpires and processPersistenceChecks
     */
    @Override
    public void processExpires() {

        long timeNow = System.currentTimeMillis();
        Session sessions[] = findSessions();
        int expireHere = 0 ;
        if(log.isDebugEnabled())
             log.debug("Start expire sessions " + getName() + " at " + timeNow + " sessioncount " + sessions.length);
        for (Session session : sessions) {
            if (!session.isValid()) {
                expiredSessions.incrementAndGet();
                expireHere++;
            }
        }
        processPersistenceChecks();
        if (getStore() instanceof StoreBase) {
            ((StoreBase) getStore()).processExpires();
        }

        long timeEnd = System.currentTimeMillis();
        if(log.isDebugEnabled())
             log.debug("End expire sessions " + getName() + " processingTime " + (timeEnd - timeNow) + " expired sessions: " + expireHere);
        processingTime += (timeEnd - timeNow);

    }


    
Called by the background thread after active sessions have been checked
for expiration, to allow sessions to be swapped out, backed up, etc.

/**
     * Called by the background thread after active sessions have been checked
     * for expiration, to allow sessions to be swapped out, backed up, etc.
     */
    public void processPersistenceChecks() {

        processMaxIdleSwaps();
        processMaxActiveSwaps();
        processMaxIdleBackups();

    }


    
{@inheritDoc}


This method checks the persistence store if persistence is enabled,
otherwise just uses the functionality from ManagerBase.

/**
     * {@inheritDoc}
     * <p>
     * This method checks the persistence store if persistence is enabled,
     * otherwise just uses the functionality from ManagerBase.
     */
    @Override
    public Session findSession(String id) throws IOException {

        Session session = super.findSession(id);
        // OK, at this point, we're not sure if another thread is trying to
        // remove the session or not so the only way around this is to lock it
        // (or attempt to) and then try to get it by this session id again. If
        // the other code ran swapOut, then we should get a null back during
        // this run, and if not, we lock it out so we can access the session
        // safely.
        if(session != null) {
            synchronized(session){
                session = super.findSession(session.getIdInternal());
                if(session != null){
                   // To keep any external calling code from messing up the
                   // concurrency.
                   session.access();
                   session.endAccess();
                }
            }
        }
        if (session != null)
            return session;

        // See if the Session is in the Store
        session = swapIn(id);
        return session;
    }

    
Remove this Session from the active Sessions for this Manager,
but not from the Store. (Used by the PersistentValve)

Params:
  • session – Session to be removed
/**
     * Remove this Session from the active Sessions for this Manager,
     * but not from the Store. (Used by the PersistentValve)
     *
     * @param session Session to be removed
     */
    @Override
    public void removeSuper(Session session) {
        super.remove(session, false);
    }

    
Load all sessions found in the persistence mechanism, assuming
they are marked as valid and have not passed their expiration
limit. If persistence is not supported, this method returns
without doing anything.


Note that by default, this method is not called by the MiddleManager
class. In order to use it, a subclass must specifically call it,
for example in the start() and/or processPersistenceChecks() methods.

/**
     * Load all sessions found in the persistence mechanism, assuming
     * they are marked as valid and have not passed their expiration
     * limit. If persistence is not supported, this method returns
     * without doing anything.
     * <p>
     * Note that by default, this method is not called by the MiddleManager
     * class. In order to use it, a subclass must specifically call it,
     * for example in the start() and/or processPersistenceChecks() methods.
     */
    @Override
    public void load() {

        // Initialize our internal data structures
        sessions.clear();

        if (store == null)
            return;

        String[] ids = null;
        try {
            if (SecurityUtil.isPackageProtectionEnabled()) {
                try {
                    ids = AccessController.doPrivileged(new PrivilegedStoreKeys());
                } catch (PrivilegedActionException e) {
                    log.error(sm.getString("persistentManager.storeLoadKeysError"),
                            e.getException());
                    return;
                }
            } else {
                ids = store.keys();
            }
        } catch (IOException e) {
            log.error(sm.getString("persistentManager.storeLoadKeysError"), e);
            return;
        }

        int n = ids.length;
        if (n == 0)
            return;

        if (log.isDebugEnabled())
            log.debug(sm.getString("persistentManager.loading", String.valueOf(n)));

        for (String id : ids)
            try {
                swapIn(id);
            } catch (IOException e) {
                log.error(sm.getString("persistentManager.storeLoadError"), e);
            }

    }


    
{@inheritDoc}


Remove this Session from the Store.

/**
     * {@inheritDoc}
     * <p>
     * Remove this Session from the Store.
     */
    @Override
    public void remove(Session session, boolean update) {

        super.remove (session, update);

        if (store != null){
            removeSession(session.getIdInternal());
        }
    }


    
Remove this Session from the active Sessions for this Manager,
and from the Store.

Params:
  • id – Session's id to be removed
/**
     * Remove this Session from the active Sessions for this Manager,
     * and from the Store.
     *
     * @param id Session's id to be removed
     */
    protected void removeSession(String id){
        try {
            if (SecurityUtil.isPackageProtectionEnabled()) {
                try {
                    AccessController.doPrivileged(new PrivilegedStoreRemove(id));
                } catch (PrivilegedActionException e) {
                    log.error(sm.getString("persistentManager.removeError"), e.getException());
                }
            } else {
                store.remove(id);
            }
        } catch (IOException e) {
            log.error(sm.getString("persistentManager.removeError"), e);
        }
    }

    
Save all currently active sessions in the appropriate persistence
mechanism, if any.  If persistence is not supported, this method
returns without doing anything.


Note that by default, this method is not called by the MiddleManager
class. In order to use it, a subclass must specifically call it,
for example in the stop() and/or processPersistenceChecks() methods.

/**
     * Save all currently active sessions in the appropriate persistence
     * mechanism, if any.  If persistence is not supported, this method
     * returns without doing anything.
     * <p>
     * Note that by default, this method is not called by the MiddleManager
     * class. In order to use it, a subclass must specifically call it,
     * for example in the stop() and/or processPersistenceChecks() methods.
     */
    @Override
    public void unload() {

        if (store == null)
            return;

        Session sessions[] = findSessions();
        int n = sessions.length;
        if (n == 0)
            return;

        if (log.isDebugEnabled())
            log.debug(sm.getString("persistentManager.unloading",
                             String.valueOf(n)));

        for (Session session : sessions)
            try {
                swapOut(session);
            } catch (IOException e) {
                // This is logged in writeSession()
            }

    }


    @Override
    public int getActiveSessionsFull() {
        // In memory session count
        int result = getActiveSessions();
        try {
            // Store session count
            result += getStore().getSize();
        } catch (IOException ioe) {
            log.warn(sm.getString("persistentManager.storeSizeException"));
        }
        return result;
    }


    @Override
    public Set<String> getSessionIdsFull() {
        // In memory session ID list
        Set<String> sessionIds = new HashSet<>(sessions.keySet());
        try {
            // Store session ID list
            sessionIds.addAll(Arrays.asList(getStore().keys()));
        } catch (IOException e) {
            log.warn(sm.getString("persistentManager.storeKeysException"));
        }
        return sessionIds;
    }


    // ------------------------------------------------------ Protected Methods

    
Look for a session in the Store and, if found, restore
it in the Manager's list of active sessions if appropriate.
The session will be removed from the Store after swapping
in, but will not be added to the active session list if it
is invalid or past its expiration.

Params:
  • id – The id of the session that should be swapped in
Throws:
Returns:restored session, or null, if none is found
/**
     * Look for a session in the Store and, if found, restore
     * it in the Manager's list of active sessions if appropriate.
     * The session will be removed from the Store after swapping
     * in, but will not be added to the active session list if it
     * is invalid or past its expiration.
     *
     * @param id The id of the session that should be swapped in
     * @return restored session, or {@code null}, if none is found
     * @throws IOException an IO error occurred
     */
    protected Session swapIn(String id) throws IOException {

        if (store == null)
            return null;

        Object swapInLock = null;

        /*
         * The purpose of this sync and these locks is to make sure that a
         * session is only loaded once. It doesn't matter if the lock is removed
         * and then another thread enters this method and tries to load the same
         * session. That thread will re-create a swapIn lock for that session,
         * quickly find that the session is already in sessions, use it and
         * carry on.
         */
        synchronized (this) {
            swapInLock = sessionSwapInLocks.get(id);
            if (swapInLock == null) {
                swapInLock = new Object();
                sessionSwapInLocks.put(id, swapInLock);
            }
        }

        Session session = null;

        synchronized (swapInLock) {
            // First check to see if another thread has loaded the session into
            // the manager
            session = sessions.get(id);

            if (session == null) {
                Session currentSwapInSession = sessionToSwapIn.get();
                try {
                    if (currentSwapInSession == null || !id.equals(currentSwapInSession.getId())) {
                        session = loadSessionFromStore(id);
                        sessionToSwapIn.set(session);

                        if (session != null && !session.isValid()) {
                            log.error(sm.getString("persistentManager.swapInInvalid", id));
                            session.expire();
                            removeSession(id);
                            session = null;
                        }

                        if (session != null) {
                            reactivateLoadedSession(id, session);
                        }
                    }
                } finally {
                    sessionToSwapIn.remove();
                }
            }
        }

        // Make sure the lock is removed
        synchronized (this) {
            sessionSwapInLocks.remove(id);
        }

        return session;

    }

    private void reactivateLoadedSession(String id, Session session) {
        if(log.isDebugEnabled())
            log.debug(sm.getString("persistentManager.swapIn", id));

        session.setManager(this);
        // make sure the listeners know about it.
        ((StandardSession)session).tellNew();
        add(session);
        ((StandardSession)session).activate();
        // endAccess() to ensure timeouts happen correctly.
        // access() to keep access count correct or it will end up
        // negative
        session.access();
        session.endAccess();
    }

    private Session loadSessionFromStore(String id) throws IOException {
        try {
            if (SecurityUtil.isPackageProtectionEnabled()){
                return securedStoreLoad(id);
            } else {
                 return store.load(id);
            }
        } catch (ClassNotFoundException e) {
            String msg = sm.getString(
                    "persistentManager.deserializeError", id);
            log.error(msg, e);
            throw new IllegalStateException(msg, e);
        }
    }


    private Session securedStoreLoad(String id) throws IOException, ClassNotFoundException {
        try {
            return AccessController.doPrivileged(
                    new PrivilegedStoreLoad(id));
        } catch (PrivilegedActionException ex) {
            Exception e = ex.getException();
            log.error(sm.getString(
                    "persistentManager.swapInException", id),
                    e);
            if (e instanceof IOException){
                throw (IOException)e;
            } else if (e instanceof ClassNotFoundException) {
                throw (ClassNotFoundException)e;
            }
        }
        return null;
    }


    
Remove the session from the Manager's list of active
sessions and write it out to the Store. If the session
is past its expiration or invalid, this method does
nothing.

Params:
  • session – The Session to write out
Throws:
/**
     * Remove the session from the Manager's list of active
     * sessions and write it out to the Store. If the session
     * is past its expiration or invalid, this method does
     * nothing.
     *
     * @param session The Session to write out
     * @throws IOException an IO error occurred
     */
    protected void swapOut(Session session) throws IOException {

        if (store == null || !session.isValid()) {
            return;
        }

        ((StandardSession)session).passivate();
        writeSession(session);
        super.remove(session, true);
        session.recycle();

    }


    
Write the provided session to the Store without modifying
the copy in memory or triggering passivation events. Does
nothing if the session is invalid or past its expiration.

Params:
  • session – The session that should be written
Throws:
/**
     * Write the provided session to the Store without modifying
     * the copy in memory or triggering passivation events. Does
     * nothing if the session is invalid or past its expiration.
     * @param session The session that should be written
     * @throws IOException an IO error occurred
     */
    protected void writeSession(Session session) throws IOException {

        if (store == null || !session.isValid()) {
            return;
        }

        try {
            if (SecurityUtil.isPackageProtectionEnabled()){
                try{
                    AccessController.doPrivileged(new PrivilegedStoreSave(session));
                }catch(PrivilegedActionException ex){
                    Exception exception = ex.getException();
                    if (exception instanceof IOException) {
                        throw (IOException) exception;
                    }
                    log.error(sm.getString("persistentManager.serializeError",
                            session.getIdInternal(), exception));
                }
            } else {
                 store.save(session);
            }
        } catch (IOException e) {
            log.error(sm.getString("persistentManager.serializeError", session.getIdInternal(), e));
            throw e;
        }

    }


    
Start this component and implement the requirements of LifecycleBase.startInternal(). 
Throws:
  • LifecycleException – if this component detects a fatal error
 that prevents this component from being used
/**
     * 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();

        if (store == null)
            log.error("No Store configured, persistence disabled");
        else if (store instanceof Lifecycle)
            ((Lifecycle)store).start();

        setState(LifecycleState.STARTING);
    }


    
Stop this component and implement the requirements of LifecycleBase.stopInternal(). 
Throws:
  • LifecycleException – if this component detects a fatal error
 that prevents this component from being used
/**
     * 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("Stopping");

        setState(LifecycleState.STOPPING);

        if (getStore() != null && saveOnRestart) {
            unload();
        } else {
            // Expire all active sessions
            Session sessions[] = findSessions();
            for (Session value : sessions) {
                StandardSession session = (StandardSession) value;
                if (!session.isValid())
                    continue;
                session.expire();
            }
        }

        if (getStore() instanceof Lifecycle) {
            ((Lifecycle)getStore()).stop();
        }

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


    // ------------------------------------------------------ Protected Methods


    
Swap idle sessions out to Store if they are idle too long.

/**
     * Swap idle sessions out to Store if they are idle too long.
     */
    protected void processMaxIdleSwaps() {

        if (!getState().isAvailable() || maxIdleSwap < 0)
            return;

        Session sessions[] = findSessions();

        // Swap out all sessions idle longer than maxIdleSwap
        if (maxIdleSwap >= 0) {
            for (Session value : sessions) {
                StandardSession session = (StandardSession) value;
                synchronized (session) {
                    if (!session.isValid())
                        continue;
                    int timeIdle = (int) (session.getIdleTimeInternal() / 1000L);
                    if (timeIdle >= maxIdleSwap && timeIdle >= minIdleSwap) {
                        if (session.accessCount != null &&
                                session.accessCount.get() > 0) {
                            // Session is currently being accessed - skip it
                            continue;
                        }
                        if (log.isDebugEnabled())
                            log.debug(sm.getString
                                    ("persistentManager.swapMaxIdle",
                                            session.getIdInternal(),
                                            Integer.valueOf(timeIdle)));
                        try {
                            swapOut(session);
                        } catch (IOException e) {
                            // This is logged in writeSession()
                        }
                    }
                }
            }
        }

    }


    
Swap idle sessions out to Store if too many are active

/**
     * Swap idle sessions out to Store if too many are active
     */
    protected void processMaxActiveSwaps() {

        if (!getState().isAvailable() || minIdleSwap < 0 || getMaxActiveSessions() < 0) {
            return;
        }

        Session sessions[] = findSessions();

        // FIXME: Smarter algorithm (LRU)
        int limit = (int) (getMaxActiveSessions() * 0.9);

        if (limit >= sessions.length)
            return;

        if(log.isDebugEnabled())
            log.debug(sm.getString
                ("persistentManager.tooManyActive",
                 Integer.valueOf(sessions.length)));

        int toswap = sessions.length - limit;

        for (int i = 0; i < sessions.length && toswap > 0; i++) {
            StandardSession session =  (StandardSession) sessions[i];
            synchronized (session) {
                int timeIdle = (int) (session.getIdleTimeInternal() / 1000L);
                if (timeIdle >= minIdleSwap) {
                    if (session.accessCount != null &&
                            session.accessCount.get() > 0) {
                        // Session is currently being accessed - skip it
                        continue;
                    }
                    if(log.isDebugEnabled())
                        log.debug(sm.getString
                            ("persistentManager.swapTooManyActive",
                             session.getIdInternal(),
                             Integer.valueOf(timeIdle)));
                    try {
                        swapOut(session);
                    } catch (IOException e) {
                        // This is logged in writeSession()
                    }
                    toswap--;
                }
            }
        }

    }


    
Back up idle sessions.

/**
     * Back up idle sessions.
     */
    protected void processMaxIdleBackups() {

        if (!getState().isAvailable() || maxIdleBackup < 0)
            return;

        Session sessions[] = findSessions();

        // Back up all sessions idle longer than maxIdleBackup
        if (maxIdleBackup >= 0) {
            for (Session value : sessions) {
                StandardSession session = (StandardSession) value;
                synchronized (session) {
                    if (!session.isValid())
                        continue;
                    long lastAccessedTime = session.getLastAccessedTimeInternal();
                    Long persistedLastAccessedTime =
                            (Long) session.getNote(PERSISTED_LAST_ACCESSED_TIME);
                    if (persistedLastAccessedTime != null &&
                            lastAccessedTime == persistedLastAccessedTime.longValue())
                        continue;
                    int timeIdle = (int) (session.getIdleTimeInternal() / 1000L);
                    if (timeIdle >= maxIdleBackup) {
                        if (log.isDebugEnabled())
                            log.debug(sm.getString
                                    ("persistentManager.backupMaxIdle",
                                            session.getIdInternal(),
                                            Integer.valueOf(timeIdle)));

                        try {
                            writeSession(session);
                        } catch (IOException e) {
                            // This is logged in writeSession()
                        }
                        session.setNote(PERSISTED_LAST_ACCESSED_TIME,
                                Long.valueOf(lastAccessedTime));
                    }
                }
            }
        }

    }

}