AbstractHibernateGpsDevice.java

/*
 * Copyright 2004-2009 the original author or authors.
 * 
 * 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 org.compass.gps.device.hibernate.dep;

import java.util.Iterator;
import java.util.List;

import org.compass.core.CompassSession;
import org.compass.gps.CompassGpsException;
import org.compass.gps.device.hibernate.HibernateGpsDeviceException;
import org.compass.gps.device.support.parallel.AbstractParallelGpsDevice;
import org.compass.gps.device.support.parallel.IndexEntitiesIndexer;
import org.compass.gps.device.support.parallel.IndexEntity;

/**
 * <p>An abstract hibernate device support. Aimed to provide the base operations
 * required by both Hiberante 2 and Hibernate 3 - the index operation.
 *
 * <p>Extends the abstract parallel gps device providing parallel index execution
 * support.
 *
 * @author kimchy
 */
public abstract class AbstractHibernateGpsDevice extends AbstractParallelGpsDevice {

    public static interface HibernateSessionWrapper {
        void open() throws HibernateGpsDeviceException;

        void close();

        void closeOnError();
    }

    protected int fetchCount = 200;

    public void setFetchCount(int fetchCount) {
        this.fetchCount = fetchCount;
    }


    protected IndexEntity[] doGetIndexEntities() throws CompassGpsException {
        return doGetHibernateEntitiesInfo();
    }

    protected IndexEntitiesIndexer doGetIndexEntitiesIndexer() {
        return new HibernateIndexEntitiesIndexer();
    }

    /**
     * Returns all the hibernate entity info. Called when the device starts up.
     *
     * @return Hibernate class informtion
     * @throws HibernateGpsDeviceException
     */
    protected abstract HibernateEntityInfo[] doGetHibernateEntitiesInfo() throws HibernateGpsDeviceException;

    /**
     * Returns the data that maps to the given class info, paginated with from
     * and count.
     */
    protected abstract List doGetObjects(HibernateEntityInfo info, int from, int count,
                                         HibernateSessionWrapper sessionWrapper) throws HibernateGpsDeviceException;

    protected abstract HibernateSessionWrapper doGetHibernateSessionWrapper();

    private class HibernateIndexEntitiesIndexer implements IndexEntitiesIndexer {

        public void performIndex(CompassSession session, IndexEntity[] entities) {

            for (int i = 0; i < entities.length; i++) {
                HibernateEntityInfo entityInfo = (HibernateEntityInfo) entities[i];
                int current = 0;
                while (true) {
                    if (!isRunning()) {
                        return;
                    }
                    HibernateSessionWrapper sessionWrapper = doGetHibernateSessionWrapper();
                    try {
                        sessionWrapper.open();
                        final List values = doGetObjects(entityInfo, current, fetchCount, sessionWrapper);
                        if (log.isDebugEnabled()) {
                            log.debug(buildMessage("Indexing entity [" + entityInfo.getName() + "] range ["
                                    + current + "-" + (current + fetchCount) + "]"));
                        }
                        current += fetchCount;
                        for (Iterator it = values.iterator(); it.hasNext();) {
                            session.create(it.next());
                        }
                        session.evictAll();
                        sessionWrapper.close();
                        if (values.size() < fetchCount) {
                            break;
                        }
                    } catch (Exception e) {
                        log.error(buildMessage("Failed to index the database"), e);
                        sessionWrapper.closeOnError();
                        if (!(e instanceof HibernateGpsDeviceException)) {
                            throw new HibernateGpsDeviceException(buildMessage("Failed to index the database"), e);
                        }
                        throw (HibernateGpsDeviceException) e;
                    }
                }
            }

        }
    }
}