org.simpleframework.http.session.Composer Maven / Gradle / Ivy
/*
* Composer.java May 2007
*
* Copyright (C) 2007, Niall Gallagher
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307 USA
*/
package org.simpleframework.http.session;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;
import org.simpleframework.util.lease.Cleaner;
import org.simpleframework.util.lease.Lease;
import org.simpleframework.util.lease.LeaseException;
import org.simpleframework.util.lease.LeaseManager;
/**
* The Composer object is used to create an object that
* is used to create, store, and find session objects. This is also
* used to dispose of sessions once they have expired. Creating a
* new session is done with the compose method. This
* will create a lease for the session for a fixed duration of time.
*
* @author Niall Gallagher
*/
class Composer extends ConcurrentHashMap implements Cleaner {
/**
* This is the lease manager used to maintain the session objects.
*/
private LeaseManager manager;
/**
* This is the controller used to manage all the session leases.
*/
private Controller handler;
/**
* This is the observer used to observe the session activity.
*/
private Observer observer;
/**
* This is used to determine whether the composer has been closed.
*/
private boolean closed;
/**
* Constructor for the Composer object. This is used
* create an object to compose session objects, and to manage the
* leasing of those sessions. This makes use of the existing lease
* framework to manage the lifecycle of the session instances.
*
* @param observer this is used to observe the session manager
* @param duration this is the idle duration for each session
* @param unit this is the duration time unit measurement used
*/
public Composer(Observer observer, long duration, TimeUnit unit) {
this.manager = new LeaseManager(this);
this.handler = new Maintainer(manager, duration, unit);
this.observer = observer;
}
/**
* This is used to acquire an existing session using the unique
* key for the session. If a session has previously been created
* and the idle timeout period for that session has not expired
* then this can be used to acquire and renew the session.
*
* @param key this is the unique key for the session object
*
* @return this returns the session found for the key
*/
public Session lookup(T key) throws LeaseException {
if(closed) {
throw new SessionException("Session creation is closed");
}
return locate(key);
}
/**
* This is used to acquire an existing session using the unique
* key for the session. If a session has previously been created
* and the idle timeout period for that session has not expired
* then this can be used to acquire and renew the session.
*
* @param key this is the unique key for the session object
*
* @return this returns the session found for the key
*/
private Session locate(T key) throws LeaseException {
Session session = get(key);
if(session != null) {
handler.renew(key);
}
return session;
}
/**
* This is used to create a new session using the specified key
* as the unique identifier for that session. The key can be
* any identifier, typically it is a string however it can be
* any comparable object, such as an integer.
*
* @param key this is the unique key for the session object
*
* @return this returns the session created for the key
*/
public Session compose(T key) throws LeaseException {
if(closed) {
throw new SessionException("Session creation is closed");
}
return create(key);
}
/**
* This is used to create a new session using the specified key
* as the unique identifier for that session. The key can be
* any identifier, typically it is a string however it can be
* any comparable object, such as an integer.
*
* @param key this is the unique key for the session object
*
* @return this returns the session created for the key
*/
private Session create(T key) throws LeaseException {
Lease lease = handler.start(key);
if(lease != null) {
return create(key, lease);
}
return null;
}
/**
* This is used to create a new session using the specified key
* as the unique identifier for that session. The key can be
* any identifier, typically it is a string however it can be
* any comparable object, such as an integer.
*
* @param key this is the unique key for the session object
* @param lease this is the lease that is used by the session
*
* @return this returns the session created for the key
*/
private Session create(T key, Lease lease) throws LeaseException {
Session session = new LeaseSession(lease);
if(key != null) {
put(key, session);
}
if(observer != null) {
observer.create(session);
}
return session;
}
/**
* This close method is used to close the provider
* and release all resources associated with it. This includes
* canceling all active sessions. All resources held by this are
* released by this method and all can be garbage collected.
*
* @exception Exception if the composer can not be closed
*/
public void close() throws LeaseException {
if(!closed) {
manager.close();
}
closed = true;
}
/**
* This is used to remove the keyed session from the composer. If
* the session does not exist then this will throw an exception.
* Once this method has been executed the session is no longer
* available and a new one is required for the specified key.
*
* @exception if the session does not exist or has expired
*/
public void clean(T key) throws Exception {
Session session = remove(key);
if(key != null) {
handler.cancel(key);
}
if(observer != null) {
observer.cancel(session);
}
}
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