more work on coercion, casting, and isInstance()

Author: gavinking

hibernate-core/src/main/java/org/hibernate/event/internal/DefaultLoadEventListener.java

@@ -114,7 +114,7 @@ private boolean handleIdType(EntityPersister persister, LoadEvent event, LoadTyp
 							parentIdTargetIdMapping instanceof CompositeIdentifierMapping compositeMapping
 									? compositeMapping.getMappedIdEmbeddableTypeDescriptor()
 									: parentIdTargetIdMapping.getMappedType();
-					if ( parentIdType.getMappedJavaType().getJavaTypeClass().isInstance( event.getEntityId() ) ) {
+					if ( parentIdType.getMappedJavaType().isInstance( event.getEntityId() ) ) {
 						// yep that's what we have...
 						loadByDerivedIdentitySimplePkValue(
 								event,

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

@@ -115,7 +115,7 @@ public void validateInternalForm(Object naturalIdValue) {
 				}
 			}
 
-			if ( !getJavaType().getJavaTypeClass().isInstance( naturalIdValue ) ) {
+			if ( !getJavaType().isInstance( naturalIdValue ) ) {
 				throw new IllegalArgumentException(
 						String.format(
 								Locale.ROOT,

hibernate-core/src/main/java/org/hibernate/query/sqm/sql/BaseSqmToSqlAstConverter.java

@@ -1650,22 +1650,17 @@ public SelectStatement visitSelectStatement(SqmSelectStatement<?> statement) {
 	@Override
 	public DynamicInstantiation<?> visitDynamicInstantiation(SqmDynamicInstantiation<?> sqmDynamicInstantiation) {
 		final var instantiationTarget = sqmDynamicInstantiation.getInstantiationTarget();
-		final var instantiationNature = instantiationTarget.getNature();
-		final var targetTypeDescriptor = interpretInstantiationTarget( instantiationTarget );
-
-		final var dynamicInstantiation = new DynamicInstantiation<>( instantiationNature, targetTypeDescriptor );
-
+		final var dynamicInstantiation =
+				new DynamicInstantiation<>( instantiationTarget.getNature(),
+						interpretInstantiationTarget( instantiationTarget ) );
 		for ( var sqmArgument : sqmDynamicInstantiation.getArguments() ) {
 			if ( sqmArgument.getSelectableNode() instanceof SqmPath<?> sqmPath ) {
 				prepareForSelection( sqmPath );
 			}
-			final var argumentResultProducer = (DomainResultProducer<?>) sqmArgument.accept( this );
-
-			dynamicInstantiation.addArgument( sqmArgument.getAlias(), argumentResultProducer, this );
+			dynamicInstantiation.addArgument( sqmArgument.getAlias(),
+					(DomainResultProducer<?>) sqmArgument.accept( this ) );
 		}
-
 		dynamicInstantiation.complete();
-
 		return dynamicInstantiation;
 	}
 

hibernate-core/src/main/java/org/hibernate/sql/results/graph/basic/BasicResultAssembler.java

@@ -60,7 +60,7 @@ public J assemble(
 		if ( valueConverter != null ) {
 			if ( jdbcValue != null ) {
 				// the raw value type should be the converter's relational-JTD
-				if ( ! valueConverter.getRelationalJavaType().getJavaTypeClass().isInstance( jdbcValue ) ) {
+				if ( ! valueConverter.getRelationalJavaType().isInstance( jdbcValue ) ) {
 					throw new HibernateException(
 							String.format(
 									Locale.ROOT,

hibernate-core/src/main/java/org/hibernate/sql/results/graph/entity/internal/EntityInitializerImpl.java

@@ -1154,6 +1154,8 @@ private void resolveEntity(EntityInitializerData data, Object proxy) {
 	public void resolveInstance(EntityInitializerData data) {
 		if ( data.getState() == State.KEY_RESOLVED ) {
 			final var rowProcessingState = data.getRowProcessingState();
+			final var session = rowProcessingState.getSession();
+			final var persistenceContext = session.getPersistenceContextInternal();
 			data.setState( State.RESOLVED );
 			if ( data.entityKey == null ) {
 				assert identifierAssembler != null;
@@ -1165,7 +1167,7 @@ public void resolveInstance(EntityInitializerData data) {
 				resolveEntityKey( data, id );
 			}
 			data.entityHolder =
-					rowProcessingState.getSession().getPersistenceContextInternal()
+					persistenceContext
 							.claimEntityHolderIfPossible(
 									data.entityKey,
 									null,
@@ -1179,7 +1181,6 @@ public void resolveInstance(EntityInitializerData data) {
 			else {
 				resolveEntityInstance1( data );
 				if ( data.uniqueKeyAttributePath != null ) {
-					final var session = rowProcessingState.getSession();
 					final var concreteDescriptor = getConcreteDescriptor( data );
 					final var entityUniqueKey = new EntityUniqueKey(
 							concreteDescriptor.getEntityName(),
@@ -1188,8 +1189,7 @@ public void resolveInstance(EntityInitializerData data) {
 							data.uniqueKeyPropertyTypes[concreteDescriptor.getSubclassId()],
 							session.getFactory()
 					);
-					session.getPersistenceContextInternal()
-							.addEntity( entityUniqueKey, data.getInstance() );
+					persistenceContext.addEntity( entityUniqueKey, data.getInstance() );
 				}
 			}
 
@@ -1346,7 +1346,10 @@ protected void upgradeLockMode(EntityInitializerData data) {
 	protected boolean isProxyInstance(Object proxy) {
 		return proxy != null
 			&& ( proxy instanceof MapProxy
-				|| entityDescriptor.getJavaType().getJavaTypeClass().isInstance( proxy ) );
+					// do NOT use JavaType.isInstance() here; we're testing if the
+					// proxy itself is an instance of the given entity type, not if
+					// the underlying entity implementation is an instance
+					|| entityDescriptor.getJavaType().getJavaTypeClass().isInstance( proxy ) );
 	}
 
 	private boolean isExistingEntityInitialized(Object existingEntity) {

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/JavaType.java

@@ -100,11 +100,27 @@ default String getTypeName() {
 	 * but some descriptors need specialized semantics, for example, the descriptors for
 	 * {@link JdbcDateJavaType java.sql.Date}, {@link JdbcTimeJavaType java.sql.Time}, and
 	 * {@link JdbcTimestampJavaType java.sql.Timestamp}.
+	 * <p>
+	 * For {@link org.hibernate.type.descriptor.java.spi.EntityJavaType}, this method
+	 * handles proxies in a semantically correct way, by checking the entity instance
+	 * underlying the proxy object.
 	 */
 	default boolean isInstance(Object value) {
 		return getJavaTypeClass().isInstance( value );
 	}
 
+	/**
+	 * Apply a simple type cast to the given value, without attempting any sort of
+	 * {@linkplain #coerce(Object) coercion} or {@linkplain #wrap wrapping}. This
+	 * method is provided as a convenient way to avoid an unchecked cast to a type
+	 * variable. Use {@code javaType.cast(value)} instead of {@code (T) value}
+	 * wherever possible.
+	 * <p>
+	 * Usually just {@link #getJavaTypeClass() getJavaTypeClass().}{@link Class#cast cast(value)},
+	 * but overridden in some cases as an "optimization". This optimization is
+	 * almost certainly unnecessary, and might even indeed be harmful, since
+	 * {@code Class.cast()} is an intrinsic.
+	 */
 	default T cast(Object value) {
 		return getJavaTypeClass().cast( value );
 	}
@@ -322,10 +338,28 @@ interface CoercionContext {
 
 	/**
 	 * Coerce the given value to this type, if possible.
+	 * <p>
+	 * This method differs from {@link #wrap wrap()} in that it allows
+	 * simple, basic, implicit type conversions, and does not require
+	 * {@link WrapperOptions}. The {@code wrap()} method may be thought
+	 * of as offering explicitly requested type conversions driven by a
+	 * choice of {@link JdbcType}.
+	 * <p>
+	 * An implementation of this method reports failure in one of two
+	 * ways, by:
+	 * <ul>
+	 * <li>throwing {@link CoercionException}, or
+	 * <li>simply returning the given uncoerced value.
+	 * </ul>
+	 * <p>
+	 * Therefore, this method is declared to return {@link Object}.
+	 * In case immediate coercion is required, the following idiom
+	 * may be used:
+	 * <pre>javaType.cast(javaType.coerce(value))</pre>
 	 *
 	 * @param value The value to coerce
-	 * @return The coerced value, or the given value
-	 *         if no coercion was possible
+	 * @return The coerced value, or the given value if no coercion was
+	 *         possible
 	 * @throws CoercionException if coercion fails
 	 */
 	@Incubating

hibernate-core/src/main/java/org/hibernate/type/descriptor/java/SerializableJavaType.java

@@ -58,11 +58,6 @@ private static <T> MutabilityPlan<T> createMutabilityPlan(Class<T> type) {
 				: (MutabilityPlan<T>) SerializableMutabilityPlan.INSTANCE;
 	}
 
-	@Override
-	public boolean isInstance(Object value) {
-		return value instanceof Serializable;
-	}
-
 	@Override
 	public JdbcType getRecommendedJdbcType(JdbcTypeIndicators indicators) {
 		final int typeCode = indicators.isLob() ? Types.BLOB : Types.VARBINARY;
@@ -137,7 +132,7 @@ else if (value instanceof Blob blob) {
 				throw new HibernateException( e );
 			}
 		}
-		else if ( getJavaTypeClass().isInstance( value ) ) {
+		else if ( isInstance( value ) ) {
 			return cast( value );
 		}
 		throw unknownWrap( value.getClass() );