HHH-18951 Support custom annotation attributes as configuration parameters of Generator

hibernate-core/src/main/java/org/hibernate/boot/model/internal/GeneratorBinder.java

@@ -42,6 +42,7 @@
 import org.hibernate.id.uuid.UuidValueGenerator;
 import org.hibernate.internal.CoreLogging;
 import org.hibernate.internal.CoreMessageLogger;
+import org.hibernate.internal.util.AnnotationUtil;
 import org.hibernate.mapping.GeneratorCreator;
 import org.hibernate.mapping.KeyValue;
 import org.hibernate.mapping.PersistentClass;
@@ -412,7 +413,7 @@ private static GeneratorCreator identifierGeneratorCreator(
 							annotationType
 					);
 			callInitialize( annotation, idAttributeMember, creationContext, generator );
-			callConfigure( creationContext, generator, emptyMap(), identifierValue );
+			callConfigure( annotation, creationContext, generator, emptyMap(), identifierValue );
 			checkIdGeneratorTiming( annotationType, generator );
 			return generator;
 		};
@@ -608,7 +609,8 @@ private static void checkVersionGenerationAlways(MemberDetails property, Generat
 	 * call its {@link Configurable#configure(GeneratorCreationContext, Properties)
 	 * configure()} method.
 	 */
-	public static void callConfigure(
+	public static <A extends Annotation> void callConfigure(
+			A annotation,
 			GeneratorCreationContext creationContext,
 			Generator generator,
 			Map<String, Object> configuration,
@@ -620,6 +622,9 @@ public static void callConfigure(
 					creationContext.getRootClass(),
 					configuration
 			);
+			if ( annotation != null ) {
+				parameters.putAll(AnnotationUtil.getAttributes(annotation));
+			}
 			configurable.configure( creationContext, parameters );
 		}
 		if ( generator instanceof ExportableProducer exportableProducer ) {
@@ -773,7 +778,7 @@ private static void instantiateGeneratorBean(
 		identifierValue.setCustomIdGeneratorCreator( creationContext -> {
 			final Generator identifierGenerator =
 					instantiateGenerator( beanContainer, generatorClass( generatorStrategy, identifierValue ) );
-			callConfigure( creationContext, identifierGenerator, configuration, identifierValue );
+			callConfigure( null, creationContext, identifierGenerator, configuration, identifierValue );
 			if ( identifierGenerator instanceof IdentityGenerator) {
 				identifierValue.setColumnToIdentity();
 			}

hibernate-core/src/main/java/org/hibernate/internal/util/AnnotationUtil.java

@@ -0,0 +1,43 @@
+/*
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.internal.util;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.*;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Utility class for various annotation reflection operations.
+ *
+ * @author Yanming Zhou
+ */
+public final class AnnotationUtil {
+
+	private static final List<String> excludedMethodNames = List.of( "hashCode", "toString", "annotationType" );
+
+	/**
+	 * Retrieve the given annotation's attributes as a {@link Map}, preserving all
+	 * attribute types.
+	 * @param annotation the annotation to retrieve the attributes for
+	 * @return the Map of annotation attributes, with attribute names as keys and
+	 * corresponding attribute values as values (never {@code null})
+	 */
+	public static Map<String, Object> getAttributes( Annotation annotation ) {
+		try {
+			Map<String, Object> attributes = new HashMap<>();
+			for ( Method m : annotation.getClass().getDeclaredMethods() ) {
+				if ( m.getParameterCount() == 0 && !excludedMethodNames.contains( m.getName() ) ) {
+					attributes.put( m.getName(), m.invoke( annotation ) );
+				}
+			}
+			return attributes;
+		}
+		catch ( Exception ex ) {
+			throw new RuntimeException( ex );
+		}
+	}
+}

hibernate-core/src/test/java/org/hibernate/orm/test/idgen/userdefined/IdGeneratorTypeWithBeanContainerTest.java

@@ -38,11 +38,14 @@ public class IdGeneratorTypeWithBeanContainerTest {
 		SimpleEntity entity = new SimpleEntity();
 		scope.inTransaction(s -> s.persist(entity));
 		assertThat(entity.id, is(SimpleBeanContainer.INITIAL_VALUE));
+		SimpleEntity entity2 = new SimpleEntity();
+		scope.inTransaction(s -> s.persist(entity2));
+		assertThat(entity2.id, is(entity.id + 2));
 	}
 
 	@Entity
 	public static class SimpleEntity {
-		@Id @SimpleId
+		@Id @SimpleId(step = 2)
 		long id;
 		String data;
 	}

hibernate-core/src/test/java/org/hibernate/orm/test/idgen/userdefined/SimpleGenerator.java

@@ -5,19 +5,26 @@
 package org.hibernate.orm.test.idgen.userdefined;
 
 import java.util.EnumSet;
+import java.util.Properties;
 import java.util.concurrent.atomic.AtomicLong;
 
+import org.hibernate.MappingException;
 import org.hibernate.engine.spi.SharedSessionContractImplementor;
 import org.hibernate.generator.BeforeExecutionGenerator;
 import org.hibernate.generator.EventType;
+import org.hibernate.id.Configurable;
+import org.hibernate.service.ServiceRegistry;
+import org.hibernate.type.Type;
 
 /**
  * @author Yanming Zhou
  */
-public class SimpleGenerator implements BeforeExecutionGenerator {
+public class SimpleGenerator implements BeforeExecutionGenerator, Configurable {
 
 	private final AtomicLong sequence;
 
+	private long step = 1;
+
 	public SimpleGenerator(AtomicLong sequence) {
 		this.sequence = sequence;
 	}
@@ -28,11 +35,16 @@ public Object generate(
 			Object owner,
 			Object currentValue,
 			EventType eventType) {
-		return sequence.getAndIncrement();
+		return sequence.getAndAdd(step);
 	}
 
 	@Override
 	public EnumSet<EventType> getEventTypes() {
 		return EnumSet.of( EventType.INSERT );
 	}
+
+	@Override
+	public void configure(Type type, Properties parameters, ServiceRegistry serviceRegistry) throws MappingException {
+		this.step = (Long) parameters.get("step");
+	}
 }

hibernate-core/src/test/java/org/hibernate/orm/test/idgen/userdefined/SimpleId.java

@@ -19,4 +19,7 @@
 @Retention(RetentionPolicy.RUNTIME)
 @IdGeneratorType(SimpleGenerator.class)
 public @interface SimpleId {
+
+	long step() default 1;
+
 }