slight improvements to instantiation of MultiTenantConnectionProvider + doc

Author: gavinking

hibernate-core/src/main/java/org/hibernate/cfg/MultiTenancySettings.java

@@ -13,8 +13,14 @@
 public interface MultiTenancySettings {
 
 	/**
-	 * Specifies a {@link MultiTenantConnectionProvider}
-	 * to use. Since {@code MultiTenantConnectionProvider} is also a service, it may be configured
+	 * Specifies a {@link MultiTenantConnectionProvider} to use, either:
+	 * <ul>
+	 *     <li>an instance of {@code MultiTenantConnectionProvider},
+	 *     <li>a {@link Class} representing a class that implements {@code MultiTenantConnectionProvider}, or
+	 *     <li>the name of a class that implements {@code MultiTenantConnectionProvider}.
+	 * </ul>
+	 *
+	 * Since {@code MultiTenantConnectionProvider} is also a service, it may be configured
 	 * directly via the {@link org.hibernate.boot.registry.StandardServiceRegistryBuilder}.
 	 *
 	 * @since 4.1

hibernate-core/src/main/java/org/hibernate/engine/jdbc/connections/internal/ConnectionProviderInitiator.java

@@ -118,7 +118,7 @@ private static Class<? extends ConnectionProvider> connectionProviderClass(Class
 			throw new ConnectionProviderConfigurationException( "Class '" + providerClass.getName()
 																+ "' does not implement 'ConnectionProvider'" );
 		}
-		@SuppressWarnings("unchecked")
+		@SuppressWarnings("unchecked") // Safe, we just checked
 		final var connectionProviderClass = (Class<? extends ConnectionProvider>) providerClass;
 		return connectionProviderClass;
 	}

hibernate-core/src/main/java/org/hibernate/engine/jdbc/connections/internal/MultiTenantConnectionProviderInitiator.java

@@ -10,14 +10,13 @@
 import org.hibernate.boot.registry.classloading.spi.ClassLoaderService;
 import org.hibernate.boot.registry.classloading.spi.ClassLoadingException;
 import org.hibernate.cfg.JdbcSettings;
+import org.hibernate.engine.jdbc.connections.spi.ConnectionProviderConfigurationException;
 import org.hibernate.engine.jdbc.connections.spi.DataSourceBasedMultiTenantConnectionProviderImpl;
 import org.hibernate.engine.jdbc.connections.spi.MultiTenantConnectionProvider;
 import org.hibernate.resource.beans.internal.Helper;
 import org.hibernate.service.spi.ServiceException;
 import org.hibernate.service.spi.ServiceRegistryImplementor;
 
-import org.jboss.logging.Logger;
-
 import static org.hibernate.cfg.MultiTenancySettings.MULTI_TENANT_CONNECTION_PROVIDER;
 
 /**
@@ -26,7 +25,6 @@
  * @author Steve Ebersole
  */
 public class MultiTenantConnectionProviderInitiator implements StandardServiceInitiator<MultiTenantConnectionProvider<?>> {
-	private static final Logger log = Logger.getLogger( MultiTenantConnectionProviderInitiator.class );
 
 	/**
 	 * Singleton access
@@ -64,23 +62,26 @@ else if ( configValue instanceof MultiTenantConnectionProvider<?> multiTenantCon
 			return multiTenantConnectionProvider;
 		}
 		else {
-			final var implClass = multiTenantConnectionProviderClass( registry, configValue );
+			final var providerClass = providerClass( registry, configValue );
 			try {
-				return implClass.newInstance();
+				return providerClass.newInstance();
 			}
 			catch (Exception e) {
-				log.warn( "Unable to instantiate specified class [" + implClass.getName() + "]", e );
-				throw new ServiceException( "Unable to instantiate specified multi-tenant connection provider [" + implClass.getName() + "]" );
+				throw new ServiceException( "Unable to instantiate specified multi-tenant connection provider [" + providerClass.getName() + "]", e );
 			}
 		}
 	}
 
-	private static Class<MultiTenantConnectionProvider<?>> multiTenantConnectionProviderClass(
+	private static Class<? extends MultiTenantConnectionProvider<?>> providerClass(
 			ServiceRegistryImplementor registry, Object configValue) {
-		if ( configValue instanceof Class ) {
-			@SuppressWarnings("unchecked")
-			final var clazz = (Class<MultiTenantConnectionProvider<?>>) configValue;
-			return clazz;
+		if ( configValue instanceof Class<?> configType ) {
+			if ( !MultiTenantConnectionProvider.class.isAssignableFrom( configType ) ) {
+				throw new ConnectionProviderConfigurationException( "Class '" + configType.getName()
+								+ "' does not implement 'MultiTenantConnectionProvider'" );
+			}
+			@SuppressWarnings("unchecked") // Safe, we just checked
+			final var providerClass = (Class<? extends MultiTenantConnectionProvider<?>>) configType;
+			return providerClass;
 		}
 		else {
 			final String className = configValue.toString();
@@ -89,8 +90,7 @@ private static Class<MultiTenantConnectionProvider<?>> multiTenantConnectionProv
 				return classLoaderService.classForName( className );
 			}
 			catch (ClassLoadingException cle) {
-				log.warn( "Unable to locate specified class [" + className + "]", cle );
-				throw new ServiceException( "Unable to locate specified multi-tenant connection provider [" + className + "]" );
+				throw new ServiceException( "Unable to locate specified multi-tenant connection provider [" + className + "]", cle );
 			}
 		}
 	}