org.apache.catalina.session
Class PersistentManagerBase

java.lang.Object
  |
  +--org.apache.catalina.session.ManagerBase
        |
        +--org.apache.catalina.session.PersistentManagerBase

All Implemented Interfaces:

java.util.EventListener, Lifecycle, Manager, java.beans.PropertyChangeListener, java.lang.Runnable

Direct Known Subclasses:

DistributedManager, PersistentManager

public abstract class PersistentManagerBase

extends ManagerBase

implements Lifecycle, java.beans.PropertyChangeListener, java.lang.Runnable

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

IMPLEMENTATION NOTE: Correct behavior of session storing and reloading depends upon external calls to the start() and stop() methods of this class at the correct times.

Version:

$Revision: 1.6 $ $Date: 2001/08/10 20:12:00 $

Author:

Craig R. McClanahan

Field Summary

protected LifecycleSupport	lifecycle The lifecycle event support for this component.
protected static java.lang.String	name The descriptive name of this Manager implementation (for logging).
protected boolean	threadDone The background thread completion semaphore.

Fields inherited from class org.apache.catalina.session.ManagerBase

algorithm, container, debug, DEFAULT_ALGORITHM, digest, distributable, entropy, maxInactiveInterval, random, randomClass, recycled, SESSION_ID_BYTES, sessions, sm, support

Fields inherited from interface org.apache.catalina.Lifecycle

START_EVENT, STOP_EVENT

Constructor Summary

PersistentManagerBase()

Method Summary

void	addLifecycleListener(LifecycleListener listener) Add a lifecycle event listener to this component.
void	clearStore() Clear all sessions from the Store.
Session	createSession() Return a new session object as long as the number of active sessions does not exceed maxActiveSessions.
Session	findSession(java.lang.String id) Return the active Session, associated with this Manager, with the specified session id (if any); otherwise return null.
int	getCheckInterval() Return the check interval (in seconds) for this Manager.
java.lang.String	getInfo() Return descriptive information about this Manager implementation and the corresponding version number, in the format <description>/<version>.
int	getMaxActiveSessions() Return the maximum number of active Sessions allowed, or -1 for no limit.
int	getMaxIdleBackup() 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.
int	getMaxIdleSwap() The time in seconds after which a session should be swapped out of memory to disk.
int	getMinIdleSwap() The minimum time in seconds that a session must be idle before it can be swapped out of memory, or -1 if it can be swapped out at any time.
java.lang.String	getName() Return the descriptive short name of this Manager implementation.
boolean	getSaveOnRestart() Indicates whether sessions are saved when the Manager is shut down properly.
Store	getStore() Return the Store object which manages persistent Session storage for this Manager.
protected boolean	isSessionStale(Session session, long timeNow) Indicate whether the session has been idle for longer than its expiration date as of the supplied time.
protected boolean	isStarted() Get the started status.
void	load() Load all sessions found in the persistence mechanism, assuming they are marked as valid and have not passed their expiration limit.
protected void	processExpires() Invalidate all sessions that have expired.
protected void	processMaxActiveSwaps() Swap idle sessions out to Store if too many are active
protected void	processMaxIdleBackups() Back up idle sessions.
protected void	processMaxIdleSwaps() Swap idle sessions out to Store if they are idle too long.
void	processPersistenceChecks() Called by the background thread after active sessions have been checked for expiration, to allow sessions to be swapped out, backed up, etc.
void	propertyChange(java.beans.PropertyChangeEvent event) Process property change events from our associated Context.
void	remove(Session session) Remove this Session from the active Sessions for this Manager, and from the Store.
void	removeLifecycleListener(LifecycleListener listener) Remove a lifecycle event listener from this component.
void	run() The background thread that checks for session timeouts and shutdown.
void	setCheckInterval(int checkInterval) Set the check interval (in seconds) for this Manager.
void	setContainer(Container container) Set the Container with which this Manager has been associated.
void	setMaxActiveSessions(int max) Set the maximum number of actives Sessions allowed, or -1 for no limit.
void	setMaxIdleBackup(int backup) Sets the option to back sessions up to the Store after they are used in a request.
void	setMaxIdleSwap(int max) Sets the time in seconds after which a session should be swapped out of memory to disk.
void	setMinIdleSwap(int min) Sets the minimum time in seconds that a session must be idle before it can be swapped out of memory due to maxActiveSession.
void	setSaveOnRestart(boolean saveOnRestart) Set the option to save sessions to the Store when the Manager is shut down, then loaded when the Manager starts again.
protected void	setStarted(boolean started) Set the started flag
void	setStore(Store store) Set the Store object which will manage persistent Session storage for this Manager.
void	start() Prepare for the beginning of active use of the public methods of this component.
void	stop() Gracefully terminate the active use of the public methods of this component.
protected Session	swapIn(java.lang.String id) Look for a session in the Store and, if found, restore it in the Manager's list of active sessions if appropriate.
protected void	swapOut(Session session) Remove the session from the Manager's list of active sessions and write it out to the Store.
protected void	threadSleep() Sleep for the duration specified by the checkInterval property.
protected void	threadStart() Start the background thread that will periodically check for session timeouts.
protected void	threadStop() Stop the background thread that is periodically checking for session timeouts.
void	unload() Save all currently active sessions in the appropriate persistence mechanism, if any.
protected void	writeSession(Session session) Write the provided session to the Store without modifying the copy in memory or triggering passivation events.

Methods inherited from class org.apache.catalina.session.ManagerBase

add, addPropertyChangeListener, findSessions, generateSessionId, getAlgorithm, getContainer, getDebug, getDigest, getDistributable, getEngine, getEntropy, getJvmRoute, getMaxInactiveInterval, getRandom, getRandomClass, removePropertyChangeListener, setAlgorithm, setDebug, setDistributable, setEntropy, setMaxInactiveInterval, setRandomClass

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

lifecycle

protected LifecycleSupport lifecycle

The lifecycle event support for this component.

name

protected static java.lang.String name

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

threadDone

protected boolean threadDone

The background thread completion semaphore.

Constructor Detail

PersistentManagerBase

public PersistentManagerBase()

Method Detail

getCheckInterval

public int getCheckInterval()

Return the check interval (in seconds) for this Manager.

setCheckInterval

public void setCheckInterval(int checkInterval)

Set the check interval (in seconds) for this Manager.

Parameters:

checkInterval - The new check interval

getMaxIdleBackup

public int getMaxIdleBackup()

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.

setMaxIdleBackup

public void setMaxIdleBackup(int backup)

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 checkInterval. 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 + checkInterval seconds, plus the time it takes to handle other session expiration, swapping, etc. tasks.

Parameters:

backup - The number of seconds after their last accessed time when they should be written to the Store.

getMaxIdleSwap

public int getMaxIdleSwap()

The time in seconds after which a session should be swapped out of memory to disk.

setMaxIdleSwap

public void setMaxIdleSwap(int max)

Sets the time in seconds after which a session should be swapped out of memory to disk.

getMinIdleSwap

public int getMinIdleSwap()

The minimum time in seconds that a session must be idle before it can be swapped out of memory, or -1 if it can be swapped out at any time.

setMinIdleSwap

public void setMinIdleSwap(int min)

Sets the minimum time in seconds that a session must be idle before it can be swapped out of memory due to maxActiveSession. Set it to -1 if it can be swapped out at any time.

setContainer

public void setContainer(Container container)

Set the Container with which this Manager has been associated. If it is a Context (the usual case), listen for changes to the session timeout property.

Specified by:

setContainer in interface Manager

Overrides:

setContainer in class ManagerBase

Parameters:

container - The associated Container

getInfo

public java.lang.String getInfo()

Return descriptive information about this Manager implementation and the corresponding version number, in the format <description>/<version>.

Specified by:

getInfo in interface Manager

Overrides:

getInfo in class ManagerBase

getMaxActiveSessions

public int getMaxActiveSessions()

Return the maximum number of active Sessions allowed, or -1 for no limit.

setMaxActiveSessions

public void setMaxActiveSessions(int max)

Set the maximum number of actives Sessions allowed, or -1 for no limit.

Parameters:

max - The new maximum number of sessions

getName

public java.lang.String getName()

Return the descriptive short name of this Manager implementation.

Overrides:

getName in class ManagerBase

isStarted

protected boolean isStarted()

Get the started status.

setStarted

protected void setStarted(boolean started)

Set the started flag

setStore

public void setStore(Store store)

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

Parameters:

store - the associated Store

getStore

public Store getStore()

Return the Store object which manages persistent Session storage for this Manager.

getSaveOnRestart

public boolean getSaveOnRestart()

Indicates whether sessions are saved when the Manager is shut down properly. This requires the unload() method to be called.

setSaveOnRestart

public void setSaveOnRestart(boolean 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.

clearStore

public void clearStore()

Clear all sessions from the Store.

processPersistenceChecks

public void processPersistenceChecks()

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

createSession

public Session createSession()

Return a new session object as long as the number of active sessions does not exceed maxActiveSessions. If there aren't too many active sessions, or if there is no limit, a session is created or retrieved from the recycled pool.

Specified by:

createSession in interface Manager

Overrides:

createSession in class ManagerBase

Throws:

java.lang.IllegalStateException - if a new session cannot be instantiated for any reason

findSession

public Session findSession(java.lang.String id)
                    throws java.io.IOException

Return the active Session, associated with this Manager, with the specified session id (if any); otherwise return null. This method checks the persistence store if persistence is enabled, otherwise just uses the functionality from ManagerBase.

Specified by:

findSession in interface Manager

Overrides:

findSession in class ManagerBase

Parameters:

id - The session id for the session to be returned

Throws:

java.lang.IllegalStateException - if a new session cannot be instantiated for any reason

java.io.IOException - if an input/output error occurs while processing this request

load

public void load()

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.

Specified by:

load in interface Manager

remove

public void remove(Session session)

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

Specified by:

remove in interface Manager

Overrides:

remove in class ManagerBase

Parameters:

session - Session to be removed

unload

public void unload()

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.

Specified by:

unload in interface Manager

swapIn

protected Session swapIn(java.lang.String id)
                  throws java.io.IOException

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.

java.io.IOException

swapOut

protected void swapOut(Session session)
                throws java.io.IOException

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.

Parameters:

session - The Session to write out.

java.io.IOException

writeSession

protected void writeSession(Session session)
                     throws java.io.IOException

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.

java.io.IOException

addLifecycleListener

public void addLifecycleListener(LifecycleListener listener)

Add a lifecycle event listener to this component.

Specified by:

addLifecycleListener in interface Lifecycle

Parameters:

listener - The listener to add

removeLifecycleListener

public void removeLifecycleListener(LifecycleListener listener)

Remove a lifecycle event listener from this component.

Specified by:

removeLifecycleListener in interface Lifecycle

Parameters:

listener - The listener to remove

start

public void start()
           throws LifecycleException

Prepare for the beginning of active use of the public methods of this component. This method should be called after configure(), and before any of the public methods of the component are utilized.

Specified by:

start in interface Lifecycle

Throws:

java.lang.IllegalStateException - if this component has already been started

LifecycleException - if this component detects a fatal error that prevents this component from being used

stop

public void stop()
          throws LifecycleException

Gracefully terminate the active use of the public methods of this component. This method should be the last one called on a given instance of this component.

Specified by:

stop in interface Lifecycle

Throws:

java.lang.IllegalStateException - if this component has not been started

LifecycleException - if this component detects a fatal error that needs to be reported

propertyChange

public void propertyChange(java.beans.PropertyChangeEvent event)

Process property change events from our associated Context.

Specified by:

propertyChange in interface java.beans.PropertyChangeListener

Parameters:

event - The property change event that has occurred

isSessionStale

protected boolean isSessionStale(Session session,
                                 long timeNow)

Indicate whether the session has been idle for longer than its expiration date as of the supplied time. FIXME: Probably belongs in the Session class.

processExpires

protected void processExpires()

Invalidate all sessions that have expired.

processMaxIdleSwaps

protected void processMaxIdleSwaps()

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

processMaxActiveSwaps

protected void processMaxActiveSwaps()

Swap idle sessions out to Store if too many are active

processMaxIdleBackups

protected void processMaxIdleBackups()

Back up idle sessions.

threadSleep

protected void threadSleep()

Sleep for the duration specified by the checkInterval property.

threadStart

protected void threadStart()

Start the background thread that will periodically check for session timeouts.

threadStop

protected void threadStop()

Stop the background thread that is periodically checking for session timeouts.

run

public void run()

The background thread that checks for session timeouts and shutdown.

Specified by:

run in interface java.lang.Runnable