HHH-9727 - Slight redesign to bootstrapping APIs to allow for OGM bootstrapping

documentation/src/main/asciidoc/topical/bootstrap/NativeBootstrapping.adoc

@@ -233,6 +233,7 @@ over the `SessionFactory` building process.
 === ServiceContributor
 === TypeContributor
 === MetadataSourcesContributor
-=== MetadataBuilderContributor
-=== SessionFactoryBuilderContributor (todo)
+=== MetadataBuilderInitializer
+=== SessionFactoryBuilderFactory
+=== SessionFactoryBuilderInitializer (todo)
 === SessionFactoryObserver

hibernate-core/src/main/java/org/hibernate/boot/internal/MetadataImpl.java

@@ -28,10 +28,12 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.UUID;
 
+import org.hibernate.HibernateException;
 import org.hibernate.MappingException;
 import org.hibernate.SessionFactory;
 import org.hibernate.boot.SessionFactoryBuilder;
@@ -39,8 +41,10 @@ import org.hibernate.boot.model.IdentifierGeneratorDefinition;
 import org.hibernate.boot.model.TypeDefinition;
 import org.hibernate.boot.model.relational.Database;
 import org.hibernate.boot.model.relational.Schema;
+import org.hibernate.boot.registry.classloading.spi.ClassLoaderService;
 import org.hibernate.boot.spi.MetadataBuildingOptions;
 import org.hibernate.boot.spi.MetadataImplementor;
+import org.hibernate.boot.spi.SessionFactoryBuilderFactory;
 import org.hibernate.cfg.annotations.NamedEntityGraphDefinition;
 import org.hibernate.cfg.annotations.NamedProcedureCallDefinition;
 import org.hibernate.dialect.function.SQLFunction;
@@ -52,6 +56,7 @@ import org.hibernate.id.factory.IdentifierGeneratorFactory;
 import org.hibernate.id.factory.spi.MutableIdentifierGeneratorFactory;
 import org.hibernate.internal.NamedQueryRepository;
 import org.hibernate.internal.SessionFactoryImpl;
+import org.hibernate.internal.util.StringHelper;
 import org.hibernate.mapping.Collection;
 import org.hibernate.mapping.FetchProfile;
 import org.hibernate.mapping.MappedSuperclass;
@@ -144,6 +149,34 @@ public class MetadataImpl implements MetadataImplementor, Serializable {
 
 	@Override
 	public SessionFactoryBuilder getSessionFactoryBuilder() {
+		final ClassLoaderService cls = metadataBuildingOptions.getServiceRegistry().getService( ClassLoaderService.class );
+		final java.util.Collection<SessionFactoryBuilderFactory> discoveredBuilderFactories = cls.loadJavaServices( SessionFactoryBuilderFactory.class );
+
+		SessionFactoryBuilder builder = null;
+		List<String> activeFactoryNames = null;
+
+		for ( SessionFactoryBuilderFactory discoveredBuilderFactory : discoveredBuilderFactories ) {
+			final SessionFactoryBuilder returnedBuilder = discoveredBuilderFactory.getSessionFactoryBuilder( this );
+			if ( returnedBuilder != null ) {
+				if ( activeFactoryNames == null ) {
+					activeFactoryNames = new ArrayList<String>();
+				}
+				activeFactoryNames.add( discoveredBuilderFactory.getClass().getName() );
+				builder = returnedBuilder;
+			}
+		}
+
+		if ( activeFactoryNames != null && activeFactoryNames.size() > 1 ) {
+			throw new HibernateException(
+					"Multiple active SessionFactoryBuilderFactory definitions were discovered : " +
+							StringHelper.join( ", ", activeFactoryNames )
+			);
+		}
+
+		if ( builder != null ) {
+			return builder;
+		}
+
 		return new SessionFactoryBuilderImpl( this );
 	}
 

hibernate-core/src/main/java/org/hibernate/boot/spi/SessionFactoryBuilderFactory.java

@@ -0,0 +1,44 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * Copyright (c) 2015, 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.boot.spi;
+
+import org.hibernate.boot.SessionFactoryBuilder;
+
+/**
+ * An extension point for integrators that wish to hook into the process of how a SessionFactory
+ * is built.  Intended as a "discoverable service" ({@link java.util.ServiceLoader}).  There can
+ * be at most one implementation discovered that returns a non-null SessionFactoryBuilder.
+ *
+ * @author Steve Ebersole
+ */
+public interface SessionFactoryBuilderFactory {
+	/**
+	 * The contract method.  Return the SessionFactoryBuilder.  May return {@code null}
+	 *
+	 * @param metadata The metadata from which we will be building a SessionFactory.
+	 *
+	 * @return The SessionFactoryBuilder, or {@code null}
+	 */
+	public SessionFactoryBuilder getSessionFactoryBuilder(MetadataImplementor metadata);
+}