HHH-17030 Rework the initializer interactions and polish the interfac…

…e design

hibernate-core/src/main/java/org/hibernate/action/internal/AbstractEntityInsertAction.java

@@ -178,10 +178,13 @@ private void visitEmbeddedAttributeMapping(
 			PersistenceContext persistenceContext) {
 		if ( object != null ) {
 			final EmbeddableMappingType descriptor = attributeMapping.getEmbeddableTypeDescriptor();
+			final EmbeddableMappingType.ConcreteEmbeddableType concreteEmbeddableType = descriptor.findSubtypeBySubclass(
+					object.getClass().getName()
+			);
 			final AttributeMappingsList attributeMappings = descriptor.getAttributeMappings();
 			for ( int i = 0; i < attributeMappings.size(); i++ ) {
 				final AttributeMapping attribute = attributeMappings.get( i );
-				if ( descriptor.declaresAttribute( object.getClass().getName(), attributeMapping ) ) {
+				if ( concreteEmbeddableType.declaresAttribute( attribute ) ) {
 					if ( attribute.isPluralAttributeMapping() ) {
 						addCollectionKey(
 								attribute.asPluralAttributeMapping(),

hibernate-core/src/main/java/org/hibernate/collection/spi/CollectionInitializerProducer.java

@@ -14,6 +14,7 @@
 import org.hibernate.sql.results.graph.DomainResult;
 import org.hibernate.sql.results.graph.DomainResultAssembler;
 import org.hibernate.sql.results.graph.FetchParentAccess;
+import org.hibernate.sql.results.graph.InitializerParent;
 import org.hibernate.sql.results.graph.collection.CollectionInitializer;
 
 /**
@@ -41,7 +42,7 @@ public interface CollectionInitializerProducer {
 	 * @param collectionValueKeyAssembler allows creation of a
 	 *        {@link org.hibernate.sql.results.graph.DomainResult} for
 	 *        either side of the collection foreign key
-	 * @deprecated Use {@link #produceInitializer(NavigablePath, PluralAttributeMapping, FetchParentAccess, LockMode, DomainResult, DomainResult, boolean, AssemblerCreationState)} instead
+	 * @deprecated Use {@link #produceInitializer(NavigablePath, PluralAttributeMapping, InitializerParent, LockMode, DomainResult, DomainResult, boolean, AssemblerCreationState)} instead
 	 */
 	@Deprecated(forRemoval = true)
 	CollectionInitializer produceInitializer(
@@ -56,7 +57,7 @@ CollectionInitializer produceInitializer(
 	default CollectionInitializer produceInitializer(
 			NavigablePath navigablePath,
 			PluralAttributeMapping attribute,
-			FetchParentAccess parentAccess,
+			InitializerParent parent,
 			LockMode lockMode,
 			DomainResult<?> collectionKeyResult,
 			DomainResult<?> collectionValueKeyResult,
@@ -67,30 +68,30 @@ default CollectionInitializer produceInitializer(
 		if ( collectionKeyResult == null ) {
 			collectionKeyAssembler = null;
 			collectionValueKeyAssembler = collectionValueKeyResult.createResultAssembler(
-					null,
+					(InitializerParent) null,
 					creationState
 			);
 		}
 		else if ( collectionKeyResult == collectionValueKeyResult ) {
 			collectionKeyAssembler = collectionValueKeyAssembler = collectionKeyResult.createResultAssembler(
-					null,
+					(InitializerParent) null,
 					creationState
 			);
 		}
 		else {
 			collectionKeyAssembler = collectionKeyResult.createResultAssembler(
-					null,
+					(InitializerParent) null,
 					creationState
 			);
 			collectionValueKeyAssembler = collectionValueKeyResult.createResultAssembler(
-					null,
+					(InitializerParent) null,
 					creationState
 			);
 		}
 		return produceInitializer(
 				navigablePath,
 				attribute,
-				parentAccess,
+				(FetchParentAccess) parent,
 				lockMode,
 				collectionKeyAssembler,
 				collectionValueKeyAssembler,

hibernate-core/src/main/java/org/hibernate/engine/spi/BatchFetchQueue.java

@@ -23,6 +23,7 @@
 import org.hibernate.metamodel.mapping.PluralAttributeMapping;
 import org.hibernate.persister.collection.CollectionPersister;
 import org.hibernate.persister.entity.EntityPersister;
+import org.hibernate.type.Type;
 
 import org.jboss.logging.Logger;
 
@@ -271,19 +272,20 @@ public <T> void collectBatchLoadableEntityIds(
 
 		final LinkedHashSet<EntityKey> set =
 				batchLoadableEntityKeys.get( entityDescriptor.getEntityName() );
+		final EntityPersister entityPersister = entityDescriptor.getEntityPersister();
+		final Type identifierType = entityPersister.getIdentifierType();
 		if ( set != null ) {
 			for ( EntityKey key : set ) {
 				if ( checkForEnd && i == end ) {
 					// the first id found after the given id
 					return ids;
 				}
 
-				if ( entityDescriptor.getEntityPersister().getIdentifierType()
-						.isEqual( loadingId, key.getIdentifier() ) ) {
+				if ( identifierType.isEqual( loadingId, key.getIdentifier() ) ) {
 					end = i;
 				}
 				else {
-					if ( !isCached( key, entityDescriptor.getEntityPersister() ) ) {
+					if ( !isCached( key, entityPersister ) ) {
 						ids[i++] = key.getIdentifier();
 					}
 				}

hibernate-core/src/main/java/org/hibernate/internal/FetchingScrollableResultsImpl.java

@@ -25,8 +25,6 @@
  * @author Steve Ebersole
  */
 public class FetchingScrollableResultsImpl<R> extends AbstractScrollableResults<R> {
-	private final EntityInitializer resultInitializer;
-
 	private R currentRow;
 
 	private int currentPosition;
@@ -50,17 +48,10 @@ public FetchingScrollableResultsImpl(
 				persistenceContext
 		);
 
-		resultInitializer = extractResultInitializer( rowReader );
-
 		this.maxPosition = jdbcValuesSourceProcessingState.getQueryOptions().getEffectiveLimit().getMaxRows();
 		beforeFirst = true;
 	}
 
-	private static <R> EntityInitializer extractResultInitializer(RowReader<R> rowReader) {
-		Initializer initializer = rowReader.getInitializers().get( rowReader.getInitializers().size() - 1 );
-		return initializer.asEntityInitializer(); //might return null when it's not an EntityInitializer (intentional)
-	}
-
 	@Override
 	protected R getCurrentRow() {
 		return currentRow;
@@ -332,7 +323,6 @@ private boolean prepareCurrentRow() {
 				if ( rowProcessingState.next() ) {
 					final EntityKey entityKey2 = getEntityKey();
 					if ( !entityKey.equals( entityKey2 ) ) {
-						resultInitializer.finishUpRow( rowProcessingState );
 						resultProcessed = true;
 						last = false;
 					}
@@ -364,9 +354,6 @@ private boolean isResultSetEmpty() {
 	}
 
 	private EntityKey getEntityKey() {
-		resultInitializer.resolveKey( getRowProcessingState() );
-		final EntityKey entityKey = resultInitializer.getEntityKey();
-		resultInitializer.finishUpRow( getRowProcessingState() );
-		return entityKey;
+		return getRowReader().resolveSingleResultEntityKey( getRowProcessingState() );
 	}
 }

hibernate-core/src/main/java/org/hibernate/loader/ast/internal/CacheEntityLoaderHelper.java

@@ -356,6 +356,7 @@ private void makeEntityCircularReferenceSafe(
 		final StatefulPersistenceContext statefulPersistenceContext = (StatefulPersistenceContext) session.getPersistenceContext();
 
 		if ( ( isManagedEntity( entity ) ) ) {
+			statefulPersistenceContext.addEntity( entityKey, entity );
 			statefulPersistenceContext.addReferenceEntry(
 					entity,
 					Status.READ_ONLY

hibernate-core/src/main/java/org/hibernate/metamodel/mapping/EmbeddableMappingType.java

@@ -6,12 +6,15 @@
  */
 package org.hibernate.metamodel.mapping;
 
+import java.util.Collection;
+import java.util.Collections;
 import java.util.function.BiConsumer;
 
 import org.hibernate.internal.util.IndexedConsumer;
 import org.hibernate.internal.util.MutableInteger;
 import org.hibernate.metamodel.mapping.internal.EmbeddedAttributeMapping;
 import org.hibernate.metamodel.mapping.internal.MappingModelCreationProcess;
+import org.hibernate.metamodel.spi.EmbeddableInstantiator;
 import org.hibernate.metamodel.spi.EmbeddableRepresentationStrategy;
 import org.hibernate.property.access.spi.Getter;
 import org.hibernate.spi.NavigablePath;
@@ -52,16 +55,39 @@ default boolean isPolymorphic() {
 		return getDiscriminatorMapping() != null;
 	}
 
+	interface ConcreteEmbeddableType {
+
+		EmbeddableInstantiator getInstantiator();
+
+		int getSubclassId();
+
+		/**
+		 * Returns {@code true} if the provided embeddable class contains the
+		 * specified attribute mapping, {@code false} otherwise.
+		 * @implNote This method always returns {@code true} for non-polymorphic embeddable types
+		 *
+		 * @param attributeMapping the attribute to check
+		 */
+		boolean declaresAttribute(AttributeMapping attributeMapping);
+
+		boolean declaresAttribute(int attributeIndex);
+
+		Object getDiscriminatorValue();
+	}
+
+	default ConcreteEmbeddableType findSubtypeByDiscriminator(Object discriminatorValue) {
+		return null;
+	}
+
+	default ConcreteEmbeddableType findSubtypeBySubclass(String subclassName) {
+		return null;
+	}
+
 	/**
-	 * Returns {@code true} if the provided embeddable class contains the
-	 * specified attribute mapping, {@code false} otherwise.
-	 * @implNote This method always returns {@code true} for non-polymorphic embeddable types
-	 *
-	 * @param embeddableClassName the embeddable subclass in which the attribute must be declared
-	 * @param attributeMapping the attribute to check
+	 * Returns the concrete embeddable subtypes or an empty collection if {@link #isPolymorphic()} is {@code false}.
 	 */
-	default boolean declaresAttribute(String embeddableClassName, AttributeMapping attributeMapping) {
-		return true;
+	default Collection<ConcreteEmbeddableType> getConcreteEmbeddableTypes() {
+		return Collections.emptySet();
 	}
 
 	default SelectableMapping getAggregateMapping() {

hibernate-core/src/main/java/org/hibernate/metamodel/mapping/internal/AbstractEmbeddableMapping.java

@@ -7,8 +7,10 @@
 package org.hibernate.metamodel.mapping.internal;
 
 import java.io.Serializable;
+import java.util.Collection;
 import java.util.List;
 import java.util.Locale;
+import java.util.Set;
 import java.util.function.Consumer;
 
 import org.hibernate.MappingException;
@@ -47,6 +49,7 @@
 import org.hibernate.metamodel.mapping.SelectableMappings;
 import org.hibernate.metamodel.mapping.SelectablePath;
 import org.hibernate.metamodel.model.domain.NavigableRole;
+import org.hibernate.metamodel.spi.EmbeddableInstantiator;
 import org.hibernate.metamodel.spi.EmbeddableRepresentationStrategy;
 import org.hibernate.persister.entity.EntityPersister;
 import org.hibernate.property.access.internal.PropertyAccessStrategyBackRefImpl;
@@ -68,14 +71,40 @@
 /**
  * Base support for EmbeddableMappingType implementations
  */
-public abstract class AbstractEmbeddableMapping implements EmbeddableMappingType {
+public abstract class AbstractEmbeddableMapping implements EmbeddableMappingType,
+		EmbeddableMappingType.ConcreteEmbeddableType {
 	final protected MutableAttributeMappingList attributeMappings;
 	protected SelectableMappings selectableMappings;
 
 	public AbstractEmbeddableMapping(MutableAttributeMappingList attributeMappings) {
 		this.attributeMappings = attributeMappings;
 	}
 
+	@Override
+	public EmbeddableInstantiator getInstantiator() {
+		return getRepresentationStrategy().getInstantiator();
+	}
+
+	@Override
+	public int getSubclassId() {
+		return 0;
+	}
+
+	@Override
+	public boolean declaresAttribute(AttributeMapping attributeMapping) {
+		return true;
+	}
+
+	@Override
+	public boolean declaresAttribute(int attributeIndex) {
+		return true;
+	}
+
+	@Override
+	public Object getDiscriminatorValue() {
+		return null;
+	}
+
 	@Override
 	public JavaType<?> getMappedJavaType() {
 		return getRepresentationStrategy().getMappedJavaType();

hibernate-core/src/main/java/org/hibernate/metamodel/mapping/internal/CompoundNaturalIdMapping.java

@@ -47,6 +47,7 @@
 import org.hibernate.sql.results.graph.Fetchable;
 import org.hibernate.sql.results.graph.FetchableContainer;
 import org.hibernate.sql.results.graph.Initializer;
+import org.hibernate.sql.results.graph.InitializerParent;
 import org.hibernate.sql.results.graph.internal.ImmutableFetchList;
 import org.hibernate.sql.results.jdbc.spi.JdbcValuesSourceProcessingOptions;
 import org.hibernate.sql.results.jdbc.spi.RowProcessingState;
@@ -572,6 +573,13 @@ public String getResultVariable() {
 		public DomainResultAssembler<Object[]> createResultAssembler(
 				FetchParentAccess parentAccess,
 				AssemblerCreationState creationState) {
+			return createResultAssembler( (InitializerParent) parentAccess, creationState );
+		}
+
+		@Override
+		public DomainResultAssembler<Object[]> createResultAssembler(
+				InitializerParent parent,
+				AssemblerCreationState creationState) {
 			return new AssemblerImpl(
 					fetches,
 					navigablePath,
@@ -591,7 +599,7 @@ public JavaType<Object[]> getResultJavaType() {
 		// FetchParent
 
 		@Override
-		public Initializer createInitializer(FetchParentAccess parentAccess, AssemblerCreationState creationState) {
+		public Initializer createInitializer(InitializerParent parent, AssemblerCreationState creationState) {
 			throw new UnsupportedOperationException( "Compound natural id mappings should not use an initializer" );
 		}
 
@@ -647,7 +655,7 @@ private AssemblerImpl(
 			this.subAssemblers = new DomainResultAssembler[fetches.size()];
 			int i = 0;
 			for ( Fetch fetch : fetches ) {
-				subAssemblers[i++] = fetch.createAssembler( null, creationState );
+				subAssemblers[i++] = fetch.createAssembler( (InitializerParent) null, creationState );
 			}
 		}
 
@@ -669,6 +677,18 @@ public void resolveState(RowProcessingState rowProcessingState) {
 			}
 		}
 
+		@Override
+		public <X> void forEachResultAssembler(BiConsumer<Initializer, X> consumer, X arg) {
+			for ( DomainResultAssembler<?> subAssembler : subAssemblers ) {
+				final Initializer initializer = subAssembler.getInitializer();
+				// In case of natural id mapping selection every initializer is a "result initializer",
+				// regardless of what Initializer#isResultInitializer reports
+				if ( initializer != null ) {
+					consumer.accept( initializer, arg );
+				}
+			}
+		}
+
 		@Override
 		public JavaType<Object[]> getAssembledJavaType() {
 			return jtd;