Java tutorial
/* * 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.indexer; import java.util.List; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.compass.core.CompassSession; import org.compass.gps.device.hibernate.HibernateGpsDevice; import org.compass.gps.device.hibernate.HibernateGpsDeviceException; import org.compass.gps.device.hibernate.entities.EntityInformation; import org.compass.gps.device.support.parallel.IndexEntity; import org.hibernate.CacheMode; import org.hibernate.Criteria; import org.hibernate.Query; import org.hibernate.Session; import org.hibernate.Transaction; /** * A Hibernate indexer uses Hibernate pagination using <code>setFirstResult</code> * and <code>setMaxResults</code>. * * @author kimchy */ public class PaginationHibernateIndexEntitiesIndexer implements HibernateIndexEntitiesIndexer { private static final Log log = LogFactory.getLog(PaginationHibernateIndexEntitiesIndexer.class); private HibernateGpsDevice device; public void setHibernateGpsDevice(HibernateGpsDevice device) { this.device = device; } public void performIndex(CompassSession session, IndexEntity[] entities) { for (IndexEntity entity : entities) { EntityInformation entityInfo = (EntityInformation) entity; int fetchCount = device.getFetchCount(); int current = 0; while (true) { if (!device.isRunning()) { return; } Session hibernateSession = device.getSessionFactory().openSession(); hibernateSession.setCacheMode(CacheMode.IGNORE); Transaction hibernateTransaction = null; try { hibernateTransaction = hibernateSession.beginTransaction(); if (log.isDebugEnabled()) { log.debug(device.buildMessage("Indexing entity [" + entityInfo.getName() + "] range [" + current + "-" + (current + fetchCount) + "]")); } List values; Criteria criteria = entityInfo.getQueryProvider().createCriteria(hibernateSession, entityInfo); if (criteria != null) { criteria.setFetchSize(device.getFetchCount()); criteria.setFirstResult(current); criteria.setMaxResults(fetchCount); values = criteria.list(); } else { Query query = entityInfo.getQueryProvider().createQuery(hibernateSession, entityInfo) .setFirstResult(current).setMaxResults(fetchCount); values = query.list(); } for (Object value : values) { session.create(value); } session.evictAll(); hibernateTransaction.commit(); session.close(); current += fetchCount; if (values.size() < fetchCount) { break; } } catch (Exception e) { log.error(device.buildMessage("Failed to index the database"), e); if (hibernateTransaction != null) { try { hibernateTransaction.rollback(); } catch (Exception e1) { log.warn("Failed to rollback Hibernate", e1); } } if (!(e instanceof HibernateGpsDeviceException)) { throw new HibernateGpsDeviceException(device.buildMessage("Failed to index the database"), e); } throw (HibernateGpsDeviceException) e; } finally { hibernateSession.close(); } } } } }