org.apache.catalina.session
Class PersistentManagerBase

java.lang.Object
  org.apache.catalina.session.ManagerBase
      org.apache.catalina.session.PersistentManagerBase

All Implemented Interfaces:

java.beans.PropertyChangeListener, java.util.EventListener, javax.management.MBeanRegistration, Lifecycle, Manager

Direct Known Subclasses:

PersistentManager

public abstract class PersistentManagerBase
extends ManagerBase
implements Lifecycle, java.beans.PropertyChangeListener

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.

Author:

Craig R. McClanahan, Jean-Francois Arcand

lifecycle

protected LifecycleSupport lifecycle

The lifecycle event support for this component.

maxActiveSessions

protected int maxActiveSessions

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

started

protected boolean started

Has this component been started yet?

store

protected Store store

Store object which will manage the Session store.

saveOnRestart

protected boolean saveOnRestart

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

maxIdleBackup

protected int maxIdleBackup

How long a session must be idle before it should be backed up. -1 means sessions won't be backed up.

minIdleSwap

protected int minIdleSwap

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.

maxIdleSwap

protected int maxIdleSwap

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.

rejectedSessions

protected int rejectedSessions

Number of session creations that failed due to maxActiveSessions.

processingTime

protected long processingTime

Processing time during session expiration and passivation.

PersistentManagerBase

public PersistentManagerBase()

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 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.

Parameters:

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

getMaxIdleSwap

public int getMaxIdleSwap()

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.

setMaxIdleSwap

public void setMaxIdleSwap(int max)

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.

getMinIdleSwap

public int getMinIdleSwap()

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.

setMinIdleSwap

public void setMinIdleSwap(int min)

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.

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

isLoaded

public boolean isLoaded(java.lang.String id)

Return true, if the session id is loaded in memory otherwise false is returned

Parameters:

id - The session id for the session to be searched for

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

getRejectedSessions

public int getRejectedSessions()

Number of session creations that failed due to maxActiveSessions.

Specified by:

getRejectedSessions in interface Manager

Returns:

The count

setRejectedSessions

public void setRejectedSessions(int rejectedSessions)

Description copied from interface: Manager

Sets the number of sessions that were not created because the maximum number of active sessions was reached.

Specified by:

setRejectedSessions in interface Manager

Parameters:

rejectedSessions - Number of rejected sessions

getName

public java.lang.String getName()

Return the descriptive short name of this Manager implementation.

Overrides:

getName in class ManagerBase

Returns:

The descriptive short name of this Manager implementation.

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.

Parameters:

saveOnRestart - true if sessions should be saved on restart, false if they should be ignored.

clearStore

public void clearStore()

Clear all sessions from the Store.

processExpires

public void processExpires()

Implements the Manager interface, direct call to processExpires and processPersistenceChecks

Overrides:

processExpires in class ManagerBase

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.

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

removeSuper

public void removeSuper(Session session)

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

Parameters:

session - Session to be removed

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

removeSession

protected void removeSession(java.lang.String id)

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

Parameters:

id - Session's id 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.

Throws:

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.

Throws:

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.

Throws:

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

findLifecycleListeners

public LifecycleListener[] findLifecycleListeners()

Get the lifecycle listeners associated with this lifecycle. If this Lifecycle has no listeners registered, a zero-length array is returned.

Specified by:

findLifecycleListeners in interface Lifecycle

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:

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:

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

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.