HHH-15878 Micro optimisations of StatefulPersistenceContext#clear

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

@@ -9,9 +9,12 @@ package org.hibernate.engine.internal;
 import org.hibernate.HibernateException;
 import org.hibernate.LockMode;
 import org.hibernate.boot.registry.classloading.spi.ClassLoaderService;
+import org.hibernate.bytecode.enhance.spi.interceptor.LazyAttributeLoadingInterceptor;
 import org.hibernate.engine.spi.EntityEntry;
 import org.hibernate.engine.spi.ManagedEntity;
 import org.hibernate.engine.spi.PersistenceContext;
+import org.hibernate.engine.spi.PersistentAttributeInterceptable;
+import org.hibernate.engine.spi.PersistentAttributeInterceptor;
 import org.hibernate.internal.CoreLogging;
 import org.hibernate.internal.CoreMessageLogger;
 
@@ -25,6 +28,7 @@ import java.util.Map;
 import java.util.function.Consumer;
 
 import static org.hibernate.engine.internal.ManagedTypeHelper.asManagedEntity;
+import static org.hibernate.engine.internal.ManagedTypeHelper.asPersistentAttributeInterceptableOrNull;
 import static org.hibernate.engine.internal.ManagedTypeHelper.isManagedEntity;
 
 /**
@@ -329,18 +333,6 @@ public class EntityEntryContext {
 		return reentrantSafeEntries;
 	}
 
-	/**
-	 * Not reentrant like #reentrantSafeEntityEntries but most likely
-	 * the more efficient choice, when reentrant safety isn't required.
-	 */
-	public void processEachEntity(final Consumer<Object> entityProcessor) {
-		ManagedEntity managedEntity = head;
-		while ( managedEntity != null ) {
-			entityProcessor.accept( managedEntity.$$_hibernate_getEntityInstance() );
-			managedEntity = managedEntity.$$_hibernate_getNextManagedEntity();
-		}
-	}
-
 	private void processEachManagedEntity(final Consumer<ManagedEntity> action) {
 		ManagedEntity node = head;
 		while ( node != null ) {
@@ -350,13 +342,37 @@ public class EntityEntryContext {
 		}
 	}
 
+	// Could have used #processEachManagedEntity but avoided because of measurable overhead.
+	// Careful, this needs to be very efficient as we potentially iterate quite a bit!
+	// Also: we perform two operations at once, so to not iterate on the list twice;
+	// being a linked list, multiple iterations are not cache friendly at all.
+	private void clearAllReferencesFromManagedEntities() {
+		ManagedEntity nextManagedEntity = head;
+		while ( nextManagedEntity != null ) {
+			final ManagedEntity current = nextManagedEntity;
+			nextManagedEntity = current.$$_hibernate_getNextManagedEntity();
+			Object toProcess = current.$$_hibernate_getEntityInstance();
+			unsetSession( asPersistentAttributeInterceptableOrNull( toProcess ) );
+			clearManagedEntity( current );//careful this also unlinks from the "next" entry in the list
+		}
+	}
+
+	private static void unsetSession(PersistentAttributeInterceptable persistentAttributeInterceptable) {
+		if ( persistentAttributeInterceptable != null ) {
+			final PersistentAttributeInterceptor interceptor = persistentAttributeInterceptable.$$_hibernate_getInterceptor();
+			if ( interceptor instanceof LazyAttributeLoadingInterceptor ) {
+				( (LazyAttributeLoadingInterceptor) interceptor ).unsetSession();
+			}
+		}
+	}
+
 	/**
 	 * Clear this context of all managed entities
 	 */
 	public void clear() {
 		dirty = true;
 
-		processEachManagedEntity( EntityEntryContext::clearManagedEntity );
+		clearAllReferencesFromManagedEntities();
 
 		if ( immutableManagedEntityXref != null ) {
 			immutableManagedEntityXref.clear();

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

@@ -272,6 +272,14 @@ public final class ManagedTypeHelper {
 		throw new ClassCastException( "Object of type '" + entity.getClass() + "' can't be cast to PersistentAttributeInterceptable" );
 	}
 
+	public static PersistentAttributeInterceptable asPersistentAttributeInterceptableOrNull(final Object entity) {
+		if ( entity instanceof PrimeAmongSecondarySupertypes ) {
+			PrimeAmongSecondarySupertypes t = (PrimeAmongSecondarySupertypes) entity;
+			return t.asPersistentAttributeInterceptable();
+		}
+		return null;
+	}
+
 	/**
 	 * Cast the object to HibernateProxy
 	 * (using this is highly preferrable over a direct cast)

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

@@ -35,7 +35,6 @@ import org.hibernate.PersistentObjectException;
 import org.hibernate.TransientObjectException;
 import org.hibernate.bytecode.enhance.spi.interceptor.BytecodeLazyAttributeInterceptor;
 import org.hibernate.bytecode.enhance.spi.interceptor.EnhancementAsProxyLazinessInterceptor;
-import org.hibernate.bytecode.enhance.spi.interceptor.LazyAttributeLoadingInterceptor;
 import org.hibernate.collection.spi.PersistentCollection;
 import org.hibernate.engine.spi.AssociationKey;
 import org.hibernate.engine.spi.BatchFetchQueue;
@@ -44,7 +43,6 @@ import org.hibernate.engine.spi.CollectionKey;
 import org.hibernate.engine.spi.EntityEntry;
 import org.hibernate.engine.spi.EntityKey;
 import org.hibernate.engine.spi.EntityUniqueKey;
-import org.hibernate.engine.spi.ManagedEntity;
 import org.hibernate.engine.spi.NaturalIdResolutions;
 import org.hibernate.engine.spi.PersistenceContext;
 import org.hibernate.engine.spi.PersistentAttributeInterceptable;
@@ -71,7 +69,6 @@ import org.jboss.logging.Logger;
 import static org.hibernate.engine.internal.ManagedTypeHelper.asHibernateProxy;
 import static org.hibernate.engine.internal.ManagedTypeHelper.asManagedEntity;
 import static org.hibernate.engine.internal.ManagedTypeHelper.asPersistentAttributeInterceptable;
-import static org.hibernate.engine.internal.ManagedTypeHelper.isHibernateProxy;
 import static org.hibernate.engine.internal.ManagedTypeHelper.isPersistentAttributeInterceptable;
 
 /**
@@ -236,8 +233,6 @@ public class StatefulPersistenceContext implements PersistenceContext {
 			}
 		}
 
-		entityEntryContext.processEachEntity( StatefulPersistenceContext::processEntityOnClear );
-
 		final SharedSessionContractImplementor session = getSession();
 		if ( collectionEntries != null ) {
 			IdentityMap.onEachKey( collectionEntries, k -> k.unsetSession( session ) );
@@ -267,18 +262,6 @@ public class StatefulPersistenceContext implements PersistenceContext {
 		naturalIdResolutions = null;
 	}
 
-	private static void processEntityOnClear(final Object entity) {
-		//type-cache-pollution agent: it's crucial to use the ManagedTypeHelper rather than attempting a direct cast
-		ManagedTypeHelper.processIfPersistentAttributeInterceptable( entity, StatefulPersistenceContext::unsetSession, null );
-	}
-
-	private static void unsetSession(PersistentAttributeInterceptable persistentAttributeInterceptable, Object ignoredParam) {
-		final PersistentAttributeInterceptor interceptor = persistentAttributeInterceptable.$$_hibernate_getInterceptor();
-		if ( interceptor instanceof LazyAttributeLoadingInterceptor ) {
-			( (LazyAttributeLoadingInterceptor) interceptor ).unsetSession();
-		}
-	}
-
 	@Override
 	public boolean isDefaultReadOnly() {
 		return defaultReadOnly;