com.impetus.kundera.ejb.EntityManagerSession.java Source code

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Here is the source code for com.impetus.kundera.ejb.EntityManagerSession.java

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/*
 * Copyright 2010 Impetus Infotech.
 *
 * 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 com.impetus.kundera.ejb;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.impetus.kundera.cache.Cache;

/**
 * The Class EntityManagerCache.
 */
public class EntityManagerSession {

    /** The Constant log. */
    private static final Log log = LogFactory.getLog(EntityManagerSession.class);

    /** cache is used to store objects retrieved in this EntityManager session. */
    private Map<Object, Object> sessionCache;

    /** The em. */
    private EntityManagerImpl em;

    /**
    * Instantiates a new entity manager cache.
    * 
    * @param em
    *            the em
    */
    public EntityManagerSession(EntityManagerImpl em) {
        this.em = em;
        this.sessionCache = new ConcurrentHashMap<Object, Object>();
    }

    /**
    * Find in cache.
    * 
    * @param <T>
    *            the generic type
    * @param entityClass
    *            the entity class
    * @param id
    *            the id
    * @return the t
    */
    @SuppressWarnings("unchecked")
    protected <T> T lookup(Class<T> entityClass, Object id) {
        String key = cacheKey(entityClass, id);
        log.debug("Reading from L1 >> " + key);
        T o = (T) sessionCache.get(key);

        // go to second-level cache
        if (o == null) {
            log.debug("Reading from L2 >> " + key);
            Cache c = em.getFactory().getCache(entityClass);
            if (c != null) {
                o = (T) c.get(key);
                if (o != null) {
                    log.debug("Found item in second level cache!");
                }
            }
        }
        return o;
    }

    /**
    * Store in L1 only.
    * 
    * @param id
    *            the id
    * @param entity
    *            the entity
    */
    protected void store(Object id, Object entity) {
        store(id, entity, Boolean.FALSE);
    }

    /**
    * Save to cache.
    * 
    * @param id
    *            the id
    * @param entity
    *            the entity
    * @param spillOverToL2
    *            the spill over to l2
    */
    protected void store(Object id, Object entity, boolean spillOverToL2) {
        String key = cacheKey(entity.getClass(), id);
        log.debug("Writing to L1 >> " + key);
        sessionCache.put(key, entity);

        if (spillOverToL2) {
            log.debug("Writing to L2 >>" + key);
            // save to second level cache
            Cache c = em.getFactory().getCache(entity.getClass());
            if (c != null) {
                c.put(key, entity);
            }
        }
    }

    /**
    * Removes the.
    * 
    * @param <T>
    *            the generic type
    * @param entityClass
    *            the entity class
    * @param id
    *            the id
    */
    protected <T> void remove(Class<T> entityClass, Object id) {
        remove(entityClass, id, Boolean.FALSE);
    }

    /**
    * Removes the from cache.
    * 
    * @param <T>
    *            the generic type
    * @param entityClass
    *            the entity class
    * @param id
    *            the id
    * @param spillOverToL2
    *            the spill over to l2
    */
    protected <T> void remove(Class<T> entityClass, Object id, boolean spillOverToL2) {
        String key = cacheKey(entityClass, id);
        log.debug("Removing from L1 >> " + key);
        Object o = sessionCache.remove(key);

        if (spillOverToL2) {
            log.debug("Removing from L2 >> " + key);
            Cache c = em.getFactory().getCache(entityClass);
            if (c != null) {
                Object o2 = c.remove(key);
                if (o == null) {
                    o = o2;
                }
            }
        }
    }

    /**
     * Cache key.
     * 
     * @param clazz
     *            the clazz
     * @param id
     *            the id
     * 
     * @return the string
     */
    private String cacheKey(Class<?> clazz, Object id) {
        return clazz.getName() + "_" + id;
    }

    public final void clear() {
        sessionCache = new ConcurrentHashMap<Object, Object>();
    }
}