DiskPagedSessionHome

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com.lutris.appserver.server.session
Class DiskPagedSessionHome

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

All Implemented Interfaces:: StandardSessionHome

public class DiskPagedSessionHome
extends PagedSessionHome

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}
Sessions are paged if the total number of sessions exceeds PageThreshold. If not set, defaults to 100.
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: 1.2.14.1 $

Field Summary

private java.lang.String PAGE_DIR_KEY
          Configuration keys.

private java.util.Hashtable pagedCache
          The paged cache contains handles to passive sessions that have been paged to disk.

private com.lutris.util.PersistentStore store
          The persistent storage interface.

Fields inherited from class com.lutris.appserver.server.session.PagedSessionHome

loader, sessionMgr

Constructor Summary

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


Method Summary

protected boolean cleanupNewPagedSession()
          Removes a session that is new and paged.

protected void deleteSession(java.lang.String sessionKey)
          Deletes a paged session.

protected int getPagedSessionCount()
          Returns the number of paged sessions.

protected java.util.Enumeration getPagedSessionKeys()
          Returns an enumeration of the keys of all the sessions that have been paged out to persistent storage.

protected PagedSession newSession(StandardSessionManager mgr, java.lang.String sessionKey)
          Creates a new session object.

protected boolean pagedSessionKeyExists(java.lang.String sessionKey)
          Returns true if the specified session key is in use by a session that has been paged out.

protected PagedSession pageIn(java.lang.String sessionKey)
          Reads a paged session from disk.

protected void pageOut(PagedSession s)
          Pages a session to disk.

void shutdown()
          Shuts dows the session home.

Methods inherited from class com.lutris.appserver.server.session.PagedSessionHome

checkPassiveSessions, containsKey, createSession, debug, debug, getSession, getSession, keys, pagedSize, passivateSession, removeSession, size

Methods inherited from class java.lang.Object

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

Field Detail

pagedCache

private java.util.Hashtable pagedCache

The paged cache contains handles to passive sessions that have been paged to disk.

store

private com.lutris.util.PersistentStore store

The persistent storage interface.

PAGE_DIR_KEY

private final java.lang.String PAGE_DIR_KEY

Configuration keys.

See Also:: Constant Field Values

Constructor Detail