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The core jetty server artifact.
//
// ========================================================================
// Copyright (c) 1995-2018 Mort Bay Consulting Pty. Ltd.
// ------------------------------------------------------------------------
// All rights reserved. This program and the accompanying materials
// are made available under the terms of the Eclipse Public License v1.0
// and Apache License v2.0 which accompanies this distribution.
//
// The Eclipse Public License is available at
// http://www.eclipse.org/legal/epl-v10.html
//
// The Apache License v2.0 is available at
// http://www.opensource.org/licenses/apache2.0.php
//
// You may elect to redistribute this code under either of these licenses.
// ========================================================================
//
package org.eclipse.jetty.server.session;
import java.util.Set;
import javax.servlet.http.HttpServletRequest;
import org.eclipse.jetty.util.component.LifeCycle;
/**
* SessionCache
*
* A working set of {@link Session} objects for a context.
*
* Ideally, multiple requests for the same session id in the same context will always
* share the same Session object from the SessionCache, but it would be possible
* for implementations of SessionCache to create a fresh object for each request.
*
* The SessionData pertaining to the Session objects is obtained from/written to a SessionDataStore.
* The SessionDataStore is the authoritative source of session data:
*
* - if the session data is not present in the SessionDataStore the session does not exist.
* - if the session data is present in the SessionDataStore but its expiry time has passed then
* the session is deemed to have expired and is therefore invalid
*
*
* A SessionCache can passivate a valid Session to the SessionDataStore and
* evict it from the cache according to various strategies:
*
* - whenever the last request exits a Session
* - whenever the Session has not been accessed for a configurable number of seconds
*
.
*
* Eviction can save memory, and can also help mitigate
* some of the problems of a non-sticky load balancer by forcing the session data to
* be re-read from the SessionDataStore more frequently.
*
*/
public interface SessionCache extends LifeCycle
{
public static final int NEVER_EVICT = -1;
public static final int EVICT_ON_SESSION_EXIT = 0;
public static final int EVICT_ON_INACTIVITY = 1; //any number equal or greater is time in seconds
/**
* @param context the {@link SessionContext} to use for this cache
*/
void initialize(SessionContext context);
void shutdown ();
SessionHandler getSessionHandler();
/**
* Create an entirely new Session.
*
* @param request the request
* @param id the unique id associated to the session
* @param time the timestamp of the session creation
* @param maxInactiveMs the max inactive time in milliseconds
* @return a new Session
*/
Session newSession (HttpServletRequest request, String id, long time, long maxInactiveMs);
/**
* Re-materialize a Session that has previously existed.
* @param data the data associated with the session
* @return a Session object for the data supplied
*/
Session newSession (SessionData data);
/**
* Change the id of a Session.
*
* @param oldId the current session id
* @param newId the new session id
* @return the Session after changing its id
* @throws Exception if any error occurred
*/
Session renewSessionId (String oldId, String newId) throws Exception;
/**
* Get an existing Session. If necessary, the cache will load the data for
* the session from the configured SessionDataStore.
*
* @param id the session id
* @return the Session if one exists, null otherwise
* @throws Exception if any error occurred
*/
Session get(String id) throws Exception;
/**
* Finish using a Session. This is called by the SessionHandler
* once a request is finished with a Session. SessionCache
* implementations may want to delay writing out Session contents
* until the last request exits a Session.
*
* @param id the session id
* @param session the current session object
* @throws Exception if any error occurred
*/
void put(String id, Session session) throws Exception;
/**
* Check to see if a Session is in the cache. Does NOT consult
* the SessionDataStore.
*
* @param id the session id
* @return true if a Session object matching the id is present
* in the cache, false otherwise
* @throws Exception if any error occurred
*/
boolean contains (String id) throws Exception;
/**
* Check to see if a session exists: WILL consult the
* SessionDataStore.
*
* @param id the session id
* @return true if the session exists, false otherwise
* @throws Exception if any error occurred
*/
boolean exists (String id) throws Exception;
/**
* Remove a Session completely: from both this
* cache and the SessionDataStore.
*
* @param id the session id
* @return the Session that was removed, null otherwise
* @throws Exception if any error occurred
*/
Session delete (String id) throws Exception;
/**
* Check a list of session ids that belong to potentially expired
* sessions. The Session in the cache should be checked,
* but also the SessionDataStore, as that is the authoritative
* source of all session information.
*
* @param candidates the session ids to check
* @return the set of session ids that have actually expired: this can
* be a superset of the original candidate list.
*/
Set checkExpiration (Set candidates);
/**
* Check a Session to see if it might be appropriate to
* evict or expire.
*
* @param session the session to check
*/
void checkInactiveSession(Session session);
/**
* A SessionDataStore that is the authoritative source
* of session information.
* @param sds the {@link SessionDataStore} to use
*/
void setSessionDataStore(SessionDataStore sds);
/**
*
* @return the {@link SessionDataStore} used
*/
SessionDataStore getSessionDataStore();
/**
* Sessions in this cache can be:
*
* - never evicted
* - evicted once the last request exits
* - evicted after a configurable period of inactivity
*
*
* @param policy -1 is never evict; 0 is evict-on-exit; and any other positive
* value is the time in seconds that a session can be idle before it can
* be evicted.
*/
void setEvictionPolicy (int policy);
/**
*
* @return the eviction policy
*/
int getEvictionPolicy ();
/**
* Whether or not a a session that is about to be evicted should
* be saved before being evicted.
*
* @param saveOnEvict true if the session should be saved before being evicted
*/
void setSaveOnInactiveEviction (boolean saveOnEvict);
/**
*
* @return true if the session should be saved before being evicted
*/
boolean isSaveOnInactiveEviction ();
/**
* Whether or not a session that is newly created should be
* immediately saved. If false, a session that is created and
* invalidated within a single request is never persisted.
*
* @param saveOnCreate true to immediately save the newly created session
*/
void setSaveOnCreate(boolean saveOnCreate);
/**
*
* @return if true the newly created session will be saved immediately
*/
boolean isSaveOnCreate();
/**
* If the data for a session exists but is unreadable,
* the SessionCache can instruct the SessionDataStore to delete it.
*
* @param removeUnloadableSessions true to delete session which cannot be loaded
*/
void setRemoveUnloadableSessions(boolean removeUnloadableSessions);
/**
*
* @return if true unloadable session will be deleted
*/
boolean isRemoveUnloadableSessions();
}