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com.lutris.appserver.server.session
Class PagedSessionHome  

java.lang.Object
  com.lutris.appserver.server.session.PagedSessionHome

All Implemented Interfaces:

StandardSessionHome

Direct Known Subclasses:

DiskPagedSessionHome

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public abstract class PagedSessionHome

extends java.lang.Object

implements StandardSessionHome

The StandardSessionManager uses PagedSessionHome to manage a collection of sessions that can be paged to disk.

PagedSessionHome will page sessions to disk as soon as a pre-configured threshold of sessions has been reached. Only sessions in the 'passive' state will be paged to disk. If all sessions are in the 'active' state and the threshold has been reached, then a request to create a new session will block until one of the 'active' sessions goes into the 'passive' state. At this point the session that just became 'passive' is paged to disk and a new session is created.

Sessions are paged to disk by serializing the all data (excluding the session manager) that is associated with a session. This requires that the session data and user associated with a session are serializable.

The following parameters can be used to configure the PagedSessionHome. They should be grouped together in a section, normally SessionManager.SessionHome, which is specified to the constructor.

• PageThreshold: {int}

  Specifies the maximum number of session that may reside in memory simultaneously. If set to zero the the paged session home acts as a write through cache. If set to -1, then the page threshold is assumed to be infinite and paging will never take place. If not set, defaults to -1.

• PageTimeThreshold: {long}

  Specifies the amount of time a session may remain in memory before it is paged out to disk. If this parameter is not set, or, it is set to -1, then the session will not be paged out unless the PageThreshold is reached.

• PageWait: {int}

  Specifies the maximum time (in milliseconds) that a thread will wait for a session to be created or retrieved. If the page threshold has been reached, then a thread has to wait for an existing session to be paged before a new session can be created or a pre-existing session (that has been paged to disk) can be activated. If not set, defaults to 1 minute. If this time is exceeded then an exception is thrown - this prevents a possible deadlock situation.

• PageDir: {String}

  The directory where sessions will be paged. This setting is required.

• MaxSessions: {int}

  Specifies the maximum number of in use concurrent sessions. If this value is exceeded then CreateSession() will throw a CreateSessionException. -1 indicates unlimited session. If MaxSessions is not set in the application's configuration then MaxSessions defaults to unlimited sessions.

Version:

$Revision: 1.5.14.1 $

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Field Summary
private  java.util.Hashtable	activeCache           The active cache contains sessions that are actively in use (associated with) by a request.
private  java.util.Hashtable	activeThreadCache           The active thread cache holds all the association between active sessions and the threads that have checked them out.
private  com.lutris.util.Config	config           Config options for paged session home.
protected  java.lang.ClassLoader	loader           The class loader to use when reading in paged data.
private  java.lang.String	MAX_SESSIONS_KEY           Configuration keys.
private  long	maxSessions           Maximum number of allowed sessions.
private  java.lang.String	PAGE_THRESHOLD_KEY
private  java.lang.String	PAGE_TIME_THRESHOLD_KEY
private  java.lang.String	PAGE_WAIT_KEY
private  long	pageThreshold           The threshold where paging beings.
private  long	pageTimeThreshold           The amount of time a session may remain in memory unused before it is paged out.
private  long	pageWait           If a thread has to wait for a session to be paged before it can retrieve (get) or create a session then pageWait specifies that maximum amount of time that the thread will wait before an exception is thrown.
private  java.util.Hashtable	passiveCache           The passive cache contains sessions that aren't currently associated with a request.
protected  StandardSessionManager	sessionMgr           The session manager associated with the session home.
private  PagedSessionThresholdTimer	thresholdTimer           The pageTimeThreshold timer.
private  long	UNDEFINED_MAX_SESSIONS

 

Constructor Summary

PagedSessionHome(StandardSessionManager sessionMgr, com.lutris.util.Config config, java.lang.ClassLoader loader)

 

Method Summary
private  PagedSession	activateSession(java.lang.String sessionKey)           Puts a session into the 'active' state.
(package private)  long	checkPassiveSessions()           Pages out any sessions that are passive and have exceeded the page time threshold.
private  long	checkPassiveSessions(long threshold)           Pages out any sessions that are passive and have exceeded the page time threshold.
protected abstract  boolean	cleanupNewPagedSession()           Removes a session that is new and paged.
private  void	cleanupNewSession()           Cleans up (removes) the oldest unused (new) session from the passive cache.
boolean	containsKey(java.lang.String sessionKey)           Specifies if a key is currently in use.
StandardSession	createSession(java.lang.String sessionKey)           Creates a new session instance in the cache.
protected  void	debug(int level, java.lang.String msg)           Prints debug information under Logger.DEBUG.
protected  void	debug(java.lang.String msg)           Prints debug information under Logger.DEBUG.
protected abstract  void	deleteSession(java.lang.String sessionKey)           Deletes a paged session.
private  void	ensureNewSession()           Ensures that a new session can be put into the list in-core sessions that are being managed.
protected abstract  int	getPagedSessionCount()           Returns the number of paged sessions.
protected abstract  java.util.Enumeration	getPagedSessionKeys()           Returns an enumeration of the keys of all the sessions that have been paged out to persistent storage.
StandardSession	getSession(java.lang.String sessionKey)           Returns the session associated with the session key.
StandardSession	getSession(java.lang.Thread thread, java.lang.String sessionKey)           Returns the session associated with the session key.
private  boolean	isWriteThroughCache()           Returns true if the current configuration is for a write trhough cache.
java.util.Enumeration	keys()           Returns an enumeration of keys for the cached sessions.
protected abstract  PagedSession	newSession(StandardSessionManager mgr, java.lang.String sessionKey)           Creates a new session object.
protected abstract  boolean	pagedSessionKeyExists(java.lang.String sessionKey)           Returns true if the specified session key is in use by a session that has been paged out.
int	pagedSize()           Returns the current number of sessions that are paged to persistent store.
protected abstract  PagedSession	pageIn(java.lang.String sessionKey)           Reads a paged session from disk.
protected abstract  void	pageOut(PagedSession s)           Pages a session to disk.
void	passivateSession(java.lang.Thread thread, java.lang.String sessionKey)           Puts an 'active' session into the 'passive' state.
void	removeSession(java.lang.String sessionKey)           Removes the session associated with the session key.
void	shutdown()           Shuts down the session home.
int	size()           Returns the current number of sessions.

 

Methods inherited from class java.lang.Object

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

 

Field Detail

activeCache

private java.util.Hashtable activeCache

The active cache contains sessions that are actively in use (associated with) by a request.

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activeThreadCache

private java.util.Hashtable activeThreadCache

The active thread cache holds all the association between active sessions and the threads that have checked them out.

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passiveCache

private java.util.Hashtable passiveCache

The passive cache contains sessions that aren't currently associated with a request.

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config

private com.lutris.util.Config config

Config options for paged session home.

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maxSessions

private long maxSessions

Maximum number of allowed sessions.

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pageThreshold

private long pageThreshold

The threshold where paging beings.

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pageTimeThreshold

private long pageTimeThreshold

The amount of time a session may remain in memory unused before it is paged out. In seconds.

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thresholdTimer

private PagedSessionThresholdTimer thresholdTimer

The pageTimeThreshold timer.

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pageWait

private long pageWait

If a thread has to wait for a session to be paged before it can retrieve (get) or create a session then pageWait specifies that maximum amount of time that the thread will wait before an exception is thrown.

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MAX_SESSIONS_KEY

private final java.lang.String MAX_SESSIONS_KEY

Configuration keys.

See Also:

Constant Field Values

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PAGE_THRESHOLD_KEY

private final java.lang.String PAGE_THRESHOLD_KEY

See Also:

Constant Field Values

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PAGE_TIME_THRESHOLD_KEY

private final java.lang.String PAGE_TIME_THRESHOLD_KEY

See Also:

Constant Field Values

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PAGE_WAIT_KEY

private final java.lang.String PAGE_WAIT_KEY

See Also:

Constant Field Values

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UNDEFINED_MAX_SESSIONS

private final long UNDEFINED_MAX_SESSIONS

See Also:

Constant Field Values

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loader

protected java.lang.ClassLoader loader

The class loader to use when reading in paged data.

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sessionMgr

protected StandardSessionManager sessionMgr

The session manager associated with the session home.

Constructor Detail

PagedSessionHome

public PagedSessionHome(StandardSessionManager sessionMgr,
                        com.lutris.util.Config config,
                        java.lang.ClassLoader loader)
                 throws SessionException,
                        com.lutris.util.ConfigException

Method Detail

createSession

public StandardSession createSession(java.lang.String sessionKey)
                              throws CreateSessionException,
                                     DuplicateKeyException,
                                     SessionException

Creates a new session instance in the cache. The session is associated with the session key and the current thread.

Specified by:

createSession in interface StandardSessionHome

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newSession

protected abstract PagedSession newSession(StandardSessionManager mgr,
                                           java.lang.String sessionKey)
                                    throws SessionException

Creates a new session object. This method is intended to be overriden by classes that extend PagedSessionHome.

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deleteSession

protected abstract void deleteSession(java.lang.String sessionKey)
                               throws SessionException

Deletes a paged session. If the session doesn't exist then this is a noop.

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getSession

public StandardSession getSession(java.lang.String sessionKey)
                           throws SessionException

Returns the session associated with the session key. The session must already be associated with the current thread otherwize null is returned.

Specified by:

getSession in interface StandardSessionHome

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getSession

public StandardSession getSession(java.lang.Thread thread,
                                  java.lang.String sessionKey)
                           throws SessionException

Returns the session associated with the session key. The session is associated with the specified thread. The session is put into the 'active' state.

Specified by:

getSession in interface StandardSessionHome

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removeSession

public void removeSession(java.lang.String sessionKey)
                   throws SessionException

Removes the session associated with the session key.

Specified by:

removeSession in interface StandardSessionHome

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passivateSession

public void passivateSession(java.lang.Thread thread,
                             java.lang.String sessionKey)
                      throws SessionException

Puts an 'active' session into the 'passive' state.

Specified by:

passivateSession in interface StandardSessionHome

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pageOut

protected abstract void pageOut(PagedSession s)
                         throws SessionException

Pages a session to disk.

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pageIn

protected abstract PagedSession pageIn(java.lang.String sessionKey)
                                throws SessionException

Reads a paged session from disk.

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getPagedSessionCount

protected abstract int getPagedSessionCount()
                                     throws SessionException

Returns the number of paged sessions.

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activateSession

private PagedSession activateSession(java.lang.String sessionKey)
                              throws SessionException

Puts a session into the 'active' state. Reads paged version if necessary.

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containsKey

public boolean containsKey(java.lang.String sessionKey)
                    throws SessionException

Specifies if a key is currently in use.

Specified by:

containsKey in interface StandardSessionHome

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pagedSessionKeyExists

protected abstract boolean pagedSessionKeyExists(java.lang.String sessionKey)
                                          throws SessionException

Returns true if the specified session key is in use by a session that has been paged out.

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size

public int size()
         throws SessionException

Returns the current number of sessions.

Specified by:

size in interface StandardSessionHome

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pagedSize

public int pagedSize()
              throws SessionException

Returns the current number of sessions that are paged to persistent store.

Specified by:

pagedSize in interface StandardSessionHome

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keys

public java.util.Enumeration keys()
                           throws SessionException

Returns an enumeration of keys for the cached sessions.

Specified by:

keys in interface StandardSessionHome

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getPagedSessionKeys

protected abstract java.util.Enumeration getPagedSessionKeys()
                                                      throws SessionException

Returns an enumeration of the keys of all the sessions that have been paged out to persistent storage.

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cleanupNewSession

private void cleanupNewSession()
                        throws SessionException

Cleans up (removes) the oldest unused (new) session from the passive cache.

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checkPassiveSessions

long checkPassiveSessions()
                    throws SessionException

Pages out any sessions that are passive and have exceeded the page time threshold.

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checkPassiveSessions

private long checkPassiveSessions(long threshold)
                           throws SessionException

Pages out any sessions that are passive and have exceeded the page time threshold.

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cleanupNewPagedSession

protected abstract boolean cleanupNewPagedSession()
                                           throws SessionException

Removes a session that is new and paged.

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ensureNewSession

private void ensureNewSession()
                       throws SessionException

Ensures that a new session can be put into the list in-core sessions that are being managed. If necessary, this method will page a passive session disk in in order to guarantee that another session can be read into memory (or created). This method may block if a session first needs to be paged to disk.

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shutdown

public void shutdown()

Shuts down the session home. Pages out all active sessions.

Specified by:

shutdown in interface StandardSessionHome

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isWriteThroughCache

private boolean isWriteThroughCache()

Returns true if the current configuration is for a write trhough cache.

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debug

protected void debug(java.lang.String msg)

Prints debug information under Logger.DEBUG.

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debug

protected void debug(int level,
                     java.lang.String msg)

Prints debug information under Logger.DEBUG.

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> com >> lutris >> appserver >> server >> [ session overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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