HHH-18719 Previous row state reuse can provide detaches entities to the consumer

Author: dreab8

hibernate-core/src/main/java/org/hibernate/engine/internal/StatefulPersistenceContext.java

@@ -78,6 +78,7 @@
 import static org.hibernate.engine.internal.ManagedTypeHelper.asManagedEntity;
 import static org.hibernate.engine.internal.ManagedTypeHelper.asPersistentAttributeInterceptable;
 import static org.hibernate.engine.internal.ManagedTypeHelper.isPersistentAttributeInterceptable;
+import static org.hibernate.proxy.HibernateProxy.extractLazyInitializer;
 
 /**
  * A <em>stateful</em> implementation of the {@link PersistenceContext} contract, meaning that we maintain this
@@ -231,8 +232,14 @@ public void clear() {
 		if ( entitiesByKey != null ) {
 			//Strictly avoid lambdas in this case
 			for ( EntityHolderImpl value : entitiesByKey.values() ) {
-				if ( value != null && value.proxy != null ) {
-					HibernateProxy.extractLazyInitializer( value.proxy ).unsetSession();
+				if ( value != null ) {
+					value.state = EntityHolderState.DETACHED;
+					if ( value.proxy != null ) {
+						final LazyInitializer lazyInitializer = extractLazyInitializer( value.proxy );
+						if ( lazyInitializer != null ) {
+							lazyInitializer.unsetSession();
+						}
+					}
 				}
 			}
 		}
@@ -2243,6 +2250,11 @@ public boolean isEventuallyInitialized() {
 			return state == EntityHolderState.INITIALIZED || entityInitializer != null;
 		}
 
+		@Override
+		public boolean isDetached() {
+			return state == EntityHolderState.DETACHED;
+		}
+
 		public static EntityHolderImpl forProxy(EntityKey entityKey, EntityPersister descriptor, Object proxy) {
 			return new EntityHolderImpl( entityKey, descriptor, null, proxy );
 		}
@@ -2255,7 +2267,8 @@ public static EntityHolderImpl forEntity(EntityKey entityKey, EntityPersister de
 	enum EntityHolderState {
 		UNINITIALIZED,
 		ENHANCED_PROXY,
-		INITIALIZED
+		INITIALIZED,
+		DETACHED
 	}
 
 	// NATURAL ID RESOLUTION HANDLING ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -2271,4 +2284,13 @@ public NaturalIdResolutions getNaturalIdResolutions() {
 		return naturalIdResolutions;
 	}
 
+	@Override
+	public EntityHolder detachEntity(EntityKey key) {
+		final EntityHolderImpl entityHolder = removeEntityHolder( key );
+		if ( entityHolder != null ) {
+			entityHolder.state = EntityHolderState.DETACHED;
+		}
+		return entityHolder;
+	}
+
 }

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

@@ -67,4 +67,9 @@ public interface EntityHolder {
 	 * Whether the entity is already initialized or will be initialized through an initializer eventually.
 	 */
 	boolean isEventuallyInitialized();
+
+	/**
+	 * Whether the entity is detached.
+	 */
+	boolean isDetached();
 }

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

@@ -864,4 +864,12 @@ EntityHolder claimEntityHolderIfPossible(
 	 * @return This persistence context's natural-id helper
 	 */
 	NaturalIdResolutions getNaturalIdResolutions();
+
+	/**
+		Remove the {@link EntityHolder} and set its state to DETACHED
+	 */
+	default @Nullable EntityHolder detachEntity(EntityKey key) {
+		EntityHolder entityHolder = removeEntityHolder( key );
+		return entityHolder;
+	}
 }

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

@@ -59,7 +59,7 @@ public void onEvict(EvictEvent event) throws HibernateException {
 					.getMappingMetamodel()
 					.getEntityDescriptor( lazyInitializer.getEntityName() );
 			final EntityKey key = source.generateEntityKey( id, persister );
-			final EntityHolder holder = persistenceContext.removeEntityHolder( key );
+			final EntityHolder holder = persistenceContext.detachEntity( key );
 			// if the entity has been evicted then its holder is null
 			if ( holder != null && !lazyInitializer.isUninitialized() ) {
 				final Object entity = holder.getEntity();

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

@@ -565,7 +565,7 @@ protected void resolveKey(EntityInitializerData data, boolean entityKeyOnly) {
 		}
 
 		if ( oldEntityKey != null && previousRowReuse && oldEntityInstance != null
-				&& areKeysEqual( oldEntityKey.getIdentifier(), id ) ) {
+				&& areKeysEqual( oldEntityKey.getIdentifier(), id ) && !oldEntityHolder.isDetached() ) {
 			data.setState( State.INITIALIZED );
 			data.entityKey = oldEntityKey;
 			data.setInstance( oldEntityInstance );