HHH-5562 - Improve how event listeners are handled and introduce a service pattern for integrators to leverage

hibernate-core/src/main/java/org/hibernate/impl/Integrator.java

@@ -0,0 +1,44 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * Copyright (c) 2011, Red Hat Inc. or third-party contributors as
+ * indicated by the @author tags or express copyright attribution
+ * statements applied by the authors.  All third-party contributions are
+ * distributed under license by Red Hat Inc.
+ *
+ * This copyrighted material is made available to anyone wishing to use, modify,
+ * copy, or redistribute it subject to the terms and conditions of the GNU
+ * Lesser General Public License, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this distribution; if not, write to:
+ * Free Software Foundation, Inc.
+ * 51 Franklin Street, Fifth Floor
+ * Boston, MA  02110-1301  USA
+ */
+package org.hibernate.impl;
+
+import org.hibernate.cfg.Configuration;
+import org.hibernate.engine.SessionFactoryImplementor;
+import org.hibernate.service.spi.SessionFactoryServiceRegistry;
+
+/**
+ * Contract for stuff that integrates with Hibernate.
+ *
+ * @todo : obviously, come up with a better name :)
+ *
+ * @author Steve Ebersole
+ * @since 4.0
+ * @jira HHH-5562
+ */
+public interface Integrator {
+	public void integrate(
+			Configuration configuration,
+			SessionFactoryImplementor sessionFactory,
+			SessionFactoryServiceRegistry serviceRegistry);
+}

hibernate-core/src/main/java/org/hibernate/impl/SessionFactoryImpl.java

@@ -27,11 +27,13 @@ import javax.naming.NamingException;
 import javax.naming.Reference;
 import javax.naming.StringRefAddr;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.InvalidObjectException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.io.ObjectStreamException;
 import java.io.Serializable;
+import java.net.URL;
 import java.sql.Connection;
 import java.util.ArrayList;
 import java.util.Collections;
@@ -39,6 +41,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Properties;
 import java.util.Set;
@@ -117,9 +120,11 @@ import org.hibernate.persister.spi.PersisterFactory;
 import org.hibernate.pretty.MessageHelper;
 import org.hibernate.proxy.EntityNotFoundDelegate;
 import org.hibernate.service.ServiceRegistry;
+import org.hibernate.service.classloading.spi.ClassLoaderService;
 import org.hibernate.service.jdbc.connections.spi.ConnectionProvider;
 import org.hibernate.service.jta.platform.spi.JtaPlatform;
 import org.hibernate.service.spi.ServiceRegistryImplementor;
+import org.hibernate.service.spi.SessionFactoryServiceRegistry;
 import org.hibernate.service.spi.SessionFactoryServiceRegistryFactory;
 import org.hibernate.stat.Statistics;
 import org.hibernate.stat.internal.ConcurrentStatisticsImpl;
@@ -209,6 +214,7 @@ public final class SessionFactoryImpl
 			SessionFactoryObserver observer) throws HibernateException {
         LOG.buildingSessionFactory();
 
+		// todo : move stats building to SF service reg building
 		this.statistics = buildStatistics( settings, serviceRegistry );
 
 		this.properties = new Properties();
@@ -239,6 +245,12 @@ public final class SessionFactoryImpl
 		settings.getRegionFactory().start( settings, properties );
 		this.queryPlanCache = new QueryPlanCache( this );
 
+		// todo : everything above here consider implementing as standard SF service.  specifically: stats, caches, types, function-reg
+
+		for ( Integrator integrator : locateIntegrators( this.serviceRegistry ) ) {
+			integrator.integrate( cfg, this, (SessionFactoryServiceRegistry) this.serviceRegistry );
+		}
+
 		//Generators:
 
 		identifierGenerators = new HashMap();
@@ -477,6 +489,46 @@ public final class SessionFactoryImpl
 		this.observer.sessionFactoryCreated( this );
 	}
 
+	private Iterable<Integrator> locateIntegrators(ServiceRegistryImplementor serviceRegistry) {
+		List<Integrator> integrators = new ArrayList<Integrator>();
+
+		// todo : add "known" integrators -> BV, hibernate validation, search, envers
+
+		final Properties properties = new Properties();
+
+		ClassLoaderService classLoader = serviceRegistry.getService( ClassLoaderService.class );
+		List<URL> urls = classLoader.locateResources( "META-INF/hibernate/org.hibernate.impl.Integrator" );
+		for ( URL url : urls ) {
+			try {
+				final InputStream propertyStream = url.openStream();
+				try {
+					properties.clear();
+					properties.load( propertyStream );
+					// for now we only understand 'implClass' as key
+					final String implClass = properties.getProperty( "implClass" );
+					Class integratorClass = classLoader.classForName( implClass );
+					try {
+						integrators.add( (Integrator) integratorClass.newInstance() );
+					}
+					catch (Exception e) {
+						throw new HibernateException( "Unable to instantiate specified Integrator class [" + implClass + "]", e );
+					}
+				}
+				finally {
+					try {
+						propertyStream.close();
+					}
+					catch (IOException ignore) {
+					}
+				}
+			}
+			catch ( IOException ioe ) {
+				LOG.debugf( ioe, "Unable to process Integrator service file [%s], skipping" , url.toExternalForm() );
+			}
+		}
+		return integrators;
+	}
+
 	@Override
 	public void addObserver(SessionFactoryObserver observer) {
 		this.observer.addObserver( observer );