de.xwic.sandbox.security.etrack.EntityLifeKeeper.java Source code

Introduction

Here is the source code for de.xwic.sandbox.security.etrack.EntityLifeKeeper.java

Source

/*******************************************************************************
 * Copyright 2015 xWic group (http://www.xwic.de)
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software 
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and 
 * limitations under the License.
 *******************************************************************************/

package de.xwic.sandbox.security.etrack;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpSession;

import org.hibernate.LockMode;
import org.hibernate.Session;

import de.xwic.appkit.core.dao.IEntity;
import de.xwic.appkit.core.dao.impl.hbn.HibernateUtil;
import de.xwic.sandbox.security.SessionRequestFilter;

/**
 * Tracks a list of entities that is being "used" by the current session
 * an needs to be re-bound to the HibernateSession on each request.
 * One instance of the life keeper will be bound to each HttpSession.
 * @author Lippisch
 */
public class EntityLifeKeeper {

    public static final String SESSION_KEY = "EntityLifeKeeper";

    public Map<String, EntityRefTrack> entities = new HashMap<String, EntityRefTrack>();

    /**
     * 
     * @param entity
     */
    public static void registerEntity(IEntity entity) {

        getEntityLifeKeeper()._registerEntity(entity);
    }

    /**
     * @param entity
     */
    private void _registerEntity(IEntity entity) {

        getEntityRefTrak(entity).addReference();

    }

    /**
     * 
     * @param entity
     */
    public static void deregisterEntity(IEntity entity) {

        getEntityLifeKeeper()._deregisterEntity(entity);

    }

    /**
     * @param entity
     */
    private void _deregisterEntity(IEntity entity) {

        EntityRefTrack et = getEntityRefTrak(entity);
        if (et.removeReference() == 0) {
            // no longer referenced - remove
            String key = entity.getClass().getName() + "#" + entity.getId();
            entities.remove(key);
        }

    }

    /**
     * Return the EntityRefTrak for this entity. It will be created if it
     * does not exist yet.
     * @param entity
     * @return
     */
    private EntityRefTrack getEntityRefTrak(IEntity entity) {

        String key = entity.getClass().getName() + "#" + entity.getId();
        EntityRefTrack et = entities.get(key);
        if (et == null) {
            et = new EntityRefTrack(entity);
            entities.put(key, et);
        }
        return et;

    }

    /**
     * Retrieve the instance from the session.
     * @return
     */
    private static EntityLifeKeeper getEntityLifeKeeper() {
        HttpSession session = SessionRequestFilter.getSession();
        if (session == null) {
            throw new IllegalStateException("HttpSession is not available");
        }

        EntityLifeKeeper self = (EntityLifeKeeper) session.getAttribute(SESSION_KEY);
        if (self == null) {
            self = new EntityLifeKeeper();
            session.setAttribute(SESSION_KEY, self);
        }
        return self;
    }

    /**
     * @param session
     */
    public static void refreshEntities(HttpSession session) {
        EntityLifeKeeper self = (EntityLifeKeeper) session.getAttribute(SESSION_KEY);
        if (self != null) {
            self._refreshEntities();
        }

    }

    /**
     * Refresh entities.
     */
    private void _refreshEntities() {

        if (entities.size() > 0) {
            Session session = HibernateUtil.currentSession();
            for (EntityRefTrack et : entities.values()) {
                session.lock(et.getEntity(), LockMode.NONE);
            }
        }
    }
}