org.eiichiro.gig.heroku.HerokuPostgresJPAEntityManagerFactoryComponent Maven / Gradle / Ivy

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/*
 * Copyright (C) 2012 Eiichiro Uchiumi. All Rights Reserved.
 * 
 * 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.eiichiro.gig.heroku;

import java.net.URI;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.PersistenceException;

import org.eiichiro.jaguar.Component;
import org.eiichiro.jaguar.inject.Name;
import org.eiichiro.jaguar.lifecycle.Constructed;
import org.eiichiro.jaguar.lifecycle.Passivated;
import org.eiichiro.jaguar.scope.Singleton;
import org.eiichiro.reverb.system.Environment;
import org.postgresql.Driver;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * {@code HerokuPostgresJPAEntityManagerFactoryComponent} is a representing JPA 2.0 
 * {@code EntityManagerFactory} for PostgreSQL-based Heroku database service.
 * 
 * @author Eiichiro Uchiumi
 */
@Name("org.eiichiro.gig.heroku.HerokuPostgresJPAEntityManagerFactory")
@Singleton
@Heroku
public class HerokuPostgresJPAEntityManagerFactoryComponent extends Component {

	private static final String DATABASE_URL = "DATABASE_URL";
	
	private static final String JDBC_DRIVER = "javax.persistence.jdbc.driver";
	
	private static final String JDBC_URL = "javax.persistence.jdbc.url";
	
	private static final String JDBC_USER = "javax.persistence.jdbc.user";
	
	private static final String JDBC_PASSWORD = "javax.persistence.jdbc.password";
	
	private Logger logger = LoggerFactory.getLogger(getClass());
	
	private Map properties = new HashMap();
	
	private List persistenceUnits = new ArrayList();
	
	private Map factories = new ConcurrentHashMap();
	
	/**
	 * Configures JPA's JDBC connection properties from the environment variable 
	 * 'DATABASE_URL' and gets the persistence units to be connected from a 
	 * {@code PersistenceXMLProcessor}.
	 */
	@Constructed
	public void configure() {
		String database = Environment.getenv(DATABASE_URL);
		
		if (database == null) {
			logger.warn("Environment variable [$" + DATABASE_URL + "] has not been specified; " +
					"So you don't have access to the database service in this application");
		} else {
			logger.info("$DATABASE_URL is [" + database + "]");
			
			try {
				URI uri = new URI(database);
				Map properties = new HashMap();
				properties.put(JDBC_DRIVER, Driver.class.getName());
				properties.put(JDBC_URL, "jdbc:postgresql://" + uri.getHost() + uri.getPath());
				properties.put(JDBC_USER, uri.getUserInfo().split(":")[0]);
				properties.put(JDBC_PASSWORD, uri.getUserInfo().split(":")[1]);
				PersistenceXMLProcessor processor = new PersistenceXMLProcessor();
				processor.process();
				persistenceUnits = processor.persistenceUnits();
				this.properties = properties;
			} catch (Exception e) {
				logger.error("Failed to configure JPA's JDBC connection properties: " +
						"$DATABASE_URL is [" + database + "]", e);
			}
		}
	}
	
	/** Lifecycle callback to close the {@code EntityManagerFactory} set. */
	@Passivated
	public void close() {
		for (EntityManagerFactory factory : factories.values()) {
			factory.close();
		}
		
		persistenceUnits.clear();
		properties.clear();
	}
	
	/**
	 * Returns the {@code EntityManagerFactory} instance corresponding to the 
	 * persistence unit the current application connects.
	 * If the {@code PersistenceXMLProcessor} detects multiple persistence unit 
	 * declarations, this class connects the first-detected one (Index 0 of the 
	 * persistence unit list that the {@code PersistenceXMLProcessor#persistenceUnits()} 
	 * returns).
	 * If the current application cannot access to the database service for any 
	 * reasons, this method returns null.
	 * 
	 * Note: In the future, the implementation will be improved for 
	 * multitenant applications. The persistence unit set on the current thread 
	 * via something like "Namespaces API" will be used for the 
	 * {@code EntityManagerFactory} creation.
	 * 
	 * @return The {@code EntityManagerFactory} instance corresponding to the 
	 * persistence unit the current application connects.
	 */
	@Override
	public EntityManagerFactory instance() {
		if (!persistenceUnits.isEmpty()) {
			EntityManagerFactory factory = factories.get(persistenceUnits.get(0));
			
			if (factory == null) {
				try {
					factory = Persistence.createEntityManagerFactory(persistenceUnits.get(0), properties);
					factories.put(persistenceUnits.get(0), factory);
					logger.info("EntityManagerFactory for persistence unit ["
							+ persistenceUnits.get(0) + "] created");
				} catch (PersistenceException e) {
					logger.error("Failed to create EntityManagerFactory", e);
				}
			}
			
			return factory;
		}
		
		logger.warn("Cannot access to the database service in this application; " +
				"Returned 'EntityManagerFactory' instance is null");
		return null;
	}
	
	public Map properties() {
		return properties;
	}
	
	public List persistenceUnits() {
		return persistenceUnits;
	}
	
}