Optimize auto flush

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

@@ -588,25 +588,20 @@ public boolean areTablesToBeUpdated(Set<? extends Serializable> tables) {
 				return true;
 			}
 		}
-		if ( unresolvedInsertions == null ) {
-			return false;
-		}
-		return areTablesToBeUpdated( unresolvedInsertions, tables );
+		return unresolvedInsertions != null
+			&& areTablesToBeUpdated( unresolvedInsertions, tables );
 	}
 
 	private static boolean areTablesToBeUpdated(@Nullable ExecutableList<?> queue, Set<? extends Serializable> tableSpaces) {
-		if ( queue == null || queue.isEmpty() ) {
-			return false;
-		}
-		else {
+		if ( queue != null && !queue.isEmpty() ) {
 			for ( var actionSpace : queue.getQuerySpaces() ) {
 				if ( tableSpaces.contains( actionSpace ) ) {
 					ACTION_LOGGER.changesMustBeFlushedToSpace( actionSpace );
 					return true;
 				}
 			}
-			return false;
 		}
+		return false;
 	}
 
 	private static boolean areTablesToBeUpdated(UnresolvedEntityInsertActions actions, Set<? extends Serializable> tableSpaces) {

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

@@ -60,6 +60,7 @@
 import org.hibernate.query.criteria.HibernateCriteriaBuilder;
 import org.hibernate.query.criteria.JpaCriteriaInsert;
 import org.hibernate.query.spi.QueryImplementor;
+import org.hibernate.query.spi.QueryParameterBindings;
 import org.hibernate.query.spi.QueryProducerImplementor;
 import org.hibernate.query.sql.spi.NativeQueryImplementor;
 import org.hibernate.resource.jdbc.spi.JdbcSessionContext;
@@ -418,8 +419,8 @@ public boolean autoFlushIfRequired(Set<String> querySpaces, boolean skipPreFlush
 	}
 
 	@Override
-	public void autoPreFlush() {
-		delegate.autoPreFlush();
+	public boolean autoPreFlushIfRequired(QueryParameterBindings parameterBindings) {
+		return delegate.autoPreFlushIfRequired( parameterBindings );
 	}
 
 	@Override

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

@@ -29,6 +29,7 @@
 import org.hibernate.engine.jdbc.spi.JdbcCoordinator;
 import org.hibernate.engine.jdbc.spi.JdbcServices;
 import org.hibernate.persister.entity.EntityPersister;
+import org.hibernate.query.spi.QueryParameterBindings;
 import org.hibernate.query.spi.QueryProducerImplementor;
 import org.hibernate.resource.jdbc.spi.JdbcSessionOwner;
 import org.hibernate.resource.transaction.spi.TransactionCoordinator;
@@ -535,7 +536,7 @@ default boolean autoFlushIfRequired(Set<String> querySpaces) {
 	 */
 	boolean autoFlushIfRequired(Set<String> querySpaces, boolean skipPreFlush);
 
-	void autoPreFlush();
+	boolean autoPreFlushIfRequired(QueryParameterBindings parameterBindings);
 
 	/**
 	 * Check if there is a Hibernate or JTA transaction in progress and,

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

@@ -40,6 +40,7 @@
 import org.hibernate.query.criteria.HibernateCriteriaBuilder;
 import org.hibernate.query.criteria.JpaCriteriaInsert;
 import org.hibernate.query.spi.QueryImplementor;
+import org.hibernate.query.spi.QueryParameterBindings;
 import org.hibernate.query.spi.QueryProducerImplementor;
 import org.hibernate.query.sql.spi.NativeQueryImplementor;
 import org.hibernate.resource.jdbc.spi.JdbcSessionContext;
@@ -569,8 +570,8 @@ public boolean autoFlushIfRequired(Set<String> querySpaces, boolean skipPreFlush
 	}
 
 	@Override
-	public void autoPreFlush() {
-		delegate.autoPreFlush();
+	public boolean autoPreFlushIfRequired(QueryParameterBindings parameterBindings) {
+		return delegate.autoPreFlushIfRequired( parameterBindings );
 	}
 
 	@Override

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

@@ -113,9 +113,9 @@ protected void logFlushResults(FlushEvent event) {
 	}
 
 	/**
-	 * Process cascade save/update at the start of a flush to discover
-	 * any newly referenced entity that must be passed to saveOrUpdate(),
-	 * and also apply orphan delete
+	 * Process {@link CascadingActions#PERSIST_ON_FLUSH} at the start of a
+	 * flush to discover any newly referenced entity that must be passed to
+	 * {@code persist()}, and also apply orphan delete.
 	 */
 	private void prepareEntityFlushes(EventSource session, PersistenceContext persistenceContext)
 			throws HibernateException {

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

@@ -34,8 +34,7 @@ public void onAutoFlush(AutoFlushEvent event) throws HibernateException {
 		final var partialFlushEvent = eventMonitor.beginPartialFlushEvent();
 		try {
 			eventListenerManager.partialFlushStart();
-
-			if ( flushMightBeNeeded( source ) ) {
+			if ( flushMightBeNeeded( event, source ) ) {
 				// Need to get the number of collection removals before flushing to executions
 				// (because flushing to executions can add collection removal actions to the action queue).
 				final var actionQueue = source.getActionQueue();
@@ -82,32 +81,30 @@ public void onAutoFlush(AutoFlushEvent event) throws HibernateException {
 		}
 	}
 
-	@Override
-	public void onAutoPreFlush(EventSource source) throws HibernateException {
-		final var eventListenerManager = source.getEventListenerManager();
-		eventListenerManager.prePartialFlushStart();
-		final var eventMonitor = source.getEventMonitor();
-		final var diagnosticEvent = eventMonitor.beginPrePartialFlush();
-		try {
-			if ( flushMightBeNeeded( source ) ) {
-				preFlush( source, source.getPersistenceContextInternal() );
-			}
-		}
-		finally {
-			eventMonitor.completePrePartialFlush( diagnosticEvent, source );
-			eventListenerManager.prePartialFlushEnd();
-		}
-	}
-
-	private boolean flushIsReallyNeeded(AutoFlushEvent event, final EventSource source) {
+	private static boolean flushIsReallyNeeded(AutoFlushEvent event, EventSource source) {
 		return source.getHibernateFlushMode() == FlushMode.ALWAYS
 			|| source.getActionQueue().areTablesToBeUpdated( event.getQuerySpaces() );
 	}
 
-	private boolean flushMightBeNeeded(final EventSource source) {
+	private static boolean flushMightBeNeeded(AutoFlushEvent event, EventSource source) {
+		return flushMightBeNeededForMode( event, source )
+			&& nonEmpty( source );
+	}
+
+	private static boolean flushMightBeNeededForMode(AutoFlushEvent event, EventSource source) {
+		return switch ( source.getHibernateFlushMode() ) {
+			case ALWAYS -> true;
+			case AUTO -> {
+				final var querySpaces = event.getQuerySpaces();
+				yield querySpaces == null || !querySpaces.isEmpty();
+			}
+			case MANUAL, COMMIT -> false;
+		};
+	}
+
+	private static boolean nonEmpty(EventSource source) {
 		final var persistenceContext = source.getPersistenceContextInternal();
-		return !source.getHibernateFlushMode().lessThan( FlushMode.AUTO )
-			&& ( persistenceContext.getNumberOfManagedEntities() > 0
-				|| persistenceContext.getCollectionEntriesSize() > 0 );
+		return persistenceContext.getNumberOfManagedEntities() > 0
+			|| persistenceContext.getCollectionEntriesSize() > 0;
 	}
 }

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

@@ -0,0 +1,51 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.event.internal;
+
+import org.hibernate.HibernateException;
+import org.hibernate.event.spi.EventSource;
+import org.hibernate.event.spi.PreFlushEvent;
+import org.hibernate.event.spi.PreFlushEventListener;
+
+public class DefaultPreFlushEventListener extends AbstractFlushingEventListener implements PreFlushEventListener {
+
+	@Override
+	public void onAutoPreFlush(PreFlushEvent event) throws HibernateException {
+		final var source = event.getEventSource();
+		final var eventListenerManager = source.getEventListenerManager();
+		eventListenerManager.prePartialFlushStart();
+		final var eventMonitor = source.getEventMonitor();
+		final var diagnosticEvent = eventMonitor.beginPrePartialFlush();
+		try {
+			if ( preFlushMightBeNeeded( source )
+					&& event.getParameterBindings().hasAnyTransientEntityBindings( source ) ) {
+				preFlush( source, source.getPersistenceContextInternal() );
+			}
+		}
+		finally {
+			eventMonitor.completePrePartialFlush( diagnosticEvent, source );
+			eventListenerManager.prePartialFlushEnd();
+		}
+	}
+
+
+	private static boolean preFlushMightBeNeeded(EventSource source) {
+		return flushMightBeNeededForMode( source )
+			&& nonEmpty( source );
+	}
+
+	private static boolean flushMightBeNeededForMode(EventSource source) {
+		return switch ( source.getHibernateFlushMode() ) {
+			case ALWAYS, AUTO -> true;
+			case MANUAL, COMMIT -> false;
+		};
+	}
+
+	private static boolean nonEmpty(EventSource source) {
+		final var persistenceContext = source.getPersistenceContextInternal();
+		return persistenceContext.getNumberOfManagedEntities() > 0
+			|| persistenceContext.getCollectionEntriesSize() > 0;
+	}
+}

hibernate-core/src/main/java/org/hibernate/event/service/internal/EventListenerRegistryImpl.java

@@ -25,6 +25,7 @@
 import org.hibernate.event.internal.DefaultPersistEventListener;
 import org.hibernate.event.internal.DefaultPersistOnFlushEventListener;
 import org.hibernate.event.internal.DefaultPostLoadEventListener;
+import org.hibernate.event.internal.DefaultPreFlushEventListener;
 import org.hibernate.event.internal.DefaultPreLoadEventListener;
 import org.hibernate.event.internal.DefaultRefreshEventListener;
 import org.hibernate.event.internal.DefaultReplicateEventListener;
@@ -69,6 +70,7 @@
 import static org.hibernate.event.spi.EventType.PRE_COLLECTION_REMOVE;
 import static org.hibernate.event.spi.EventType.PRE_COLLECTION_UPDATE;
 import static org.hibernate.event.spi.EventType.PRE_DELETE;
+import static org.hibernate.event.spi.EventType.PRE_FLUSH;
 import static org.hibernate.event.spi.EventType.PRE_INSERT;
 import static org.hibernate.event.spi.EventType.PRE_LOAD;
 import static org.hibernate.event.spi.EventType.PRE_UPDATE;
@@ -216,6 +218,9 @@ private void applyStandardListeners() {
 			// auto-flush listeners
 			prepareListeners( AUTO_FLUSH, new DefaultAutoFlushEventListener() );
 
+			// pre-flush listeners
+			prepareListeners( PRE_FLUSH, new DefaultPreFlushEventListener() );
+
 			// create listeners
 			prepareListeners( PERSIST, new DefaultPersistEventListener() );
 

hibernate-core/src/main/java/org/hibernate/event/service/spi/EventListenerGroups.java

@@ -31,6 +31,7 @@
 import org.hibernate.event.spi.PreCollectionRemoveEventListener;
 import org.hibernate.event.spi.PreCollectionUpdateEventListener;
 import org.hibernate.event.spi.PreDeleteEventListener;
+import org.hibernate.event.spi.PreFlushEventListener;
 import org.hibernate.event.spi.PreInsertEventListener;
 import org.hibernate.event.spi.PreLoadEventListener;
 import org.hibernate.event.spi.PreUpdateEventListener;
@@ -57,6 +58,7 @@ public final class EventListenerGroups {
 	// All session events need to be iterated frequently;
 	// CollectionAction and EventAction also need most of these very frequently:
 	public final EventListenerGroup<AutoFlushEventListener> eventListenerGroup_AUTO_FLUSH;
+	public final EventListenerGroup<PreFlushEventListener> eventListenerGroup_PRE_FLUSH;
 	public final EventListenerGroup<ClearEventListener> eventListenerGroup_CLEAR;
 	public final EventListenerGroup<DeleteEventListener> eventListenerGroup_DELETE;
 	public final EventListenerGroup<DirtyCheckEventListener> eventListenerGroup_DIRTY_CHECK;
@@ -103,6 +105,7 @@ public EventListenerGroups(ServiceRegistry serviceRegistry) {
 		// Pre-compute all iterators on Event listeners:
 
 		eventListenerGroup_AUTO_FLUSH = listeners( eventListenerRegistry, AUTO_FLUSH );
+		eventListenerGroup_PRE_FLUSH = listeners( eventListenerRegistry, PRE_FLUSH );
 		eventListenerGroup_CLEAR = listeners( eventListenerRegistry, CLEAR );
 		eventListenerGroup_DELETE = listeners( eventListenerRegistry, DELETE );
 		eventListenerGroup_DIRTY_CHECK = listeners( eventListenerRegistry, DIRTY_CHECK );

hibernate-core/src/main/java/org/hibernate/event/spi/AutoFlushEventListener.java

@@ -18,7 +18,4 @@ public interface AutoFlushEventListener {
 	 * @param event The auto-flush event to be handled.
 	 */
 	void onAutoFlush(AutoFlushEvent event) throws HibernateException;
-
-	default void onAutoPreFlush(EventSource source) throws HibernateException {
-	}
 }

hibernate-core/src/main/java/org/hibernate/event/spi/EventType.java

@@ -39,6 +39,7 @@ public final class EventType<T> {
 
 	public static final EventType<FlushEventListener> FLUSH = create( "flush", FlushEventListener.class );
 	public static final EventType<AutoFlushEventListener> AUTO_FLUSH = create( "auto-flush", AutoFlushEventListener.class );
+	public static final EventType<PreFlushEventListener> PRE_FLUSH = create( "pre-flush", PreFlushEventListener.class );
 	public static final EventType<DirtyCheckEventListener> DIRTY_CHECK = create( "dirty-check", DirtyCheckEventListener.class );
 	public static final EventType<FlushEntityEventListener> FLUSH_ENTITY = create( "flush-entity", FlushEntityEventListener.class );
 

hibernate-core/src/main/java/org/hibernate/event/spi/PreFlushEvent.java

@@ -0,0 +1,41 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.event.spi;
+
+import org.hibernate.Incubating;
+import org.hibernate.query.spi.QueryParameterBindings;
+
+/**
+ * An event that occurs just before arguments are bound to JDBC
+ * parameters during execution of HQL. Gives Hibernate a chance
+ * to persist any transient entities used as query parameter
+ * arguments.
+ *
+ * @author Gavin King
+ * @since 7.2
+ */
+@Incubating
+public class PreFlushEvent extends AbstractSessionEvent {
+
+	private boolean preFlushRequired;
+	private final QueryParameterBindings parameterBindings;
+
+	public PreFlushEvent(QueryParameterBindings parameterBindings, EventSource source) {
+		super( source );
+		this.parameterBindings = parameterBindings;
+	}
+
+	public QueryParameterBindings getParameterBindings() {
+		return parameterBindings;
+	}
+
+	public boolean isPreFlushRequired() {
+		return preFlushRequired;
+	}
+
+	public void setPreFlushRequired(boolean preFlushRequired) {
+		this.preFlushRequired = preFlushRequired;
+	}
+}

hibernate-core/src/main/java/org/hibernate/event/spi/PreFlushEventListener.java

@@ -0,0 +1,19 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ * Copyright Red Hat Inc. and Hibernate Authors
+ */
+package org.hibernate.event.spi;
+
+import org.hibernate.HibernateException;
+import org.hibernate.Incubating;
+
+/**
+ * A listener for events of type {@link PreFlushEvent}.
+ *
+ * @author Gavin King
+ * @since 7.2
+ */
+@Incubating
+public interface PreFlushEventListener {
+	void onAutoPreFlush(PreFlushEvent event) throws HibernateException;
+}

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

@@ -61,6 +61,7 @@
 import org.hibernate.query.SelectionQuery;
 import org.hibernate.query.UnknownSqlResultSetMappingException;
 import org.hibernate.query.spi.QueryImplementor;
+import org.hibernate.query.spi.QueryParameterBindings;
 import org.hibernate.resource.jdbc.spi.JdbcSessionOwner;
 import org.hibernate.resource.transaction.spi.TransactionCoordinator;
 import org.hibernate.resource.transaction.spi.TransactionCoordinatorBuilder;
@@ -1437,14 +1438,17 @@ public boolean autoFlushIfRequired(Set<String> querySpaces, boolean skipPreFlush
 	}
 
 	@Override
-	public void autoPreFlush() {
+	public boolean autoPreFlushIfRequired(QueryParameterBindings parameterBindings) {
 		checkOpen();
-		// do not auto-flush while outside a transaction
-		if ( isTransactionInProgress() ) {
-			eventListenerGroups.eventListenerGroup_AUTO_FLUSH
-					.fireEventOnEachListener( this,
-							AutoFlushEventListener::onAutoPreFlush );
+		if ( !isTransactionInProgress() ) {
+			// do not auto-flush while outside a transaction
+			return false;
 		}
+		final var preFlushEvent = new PreFlushEvent( parameterBindings, this );
+		eventListenerGroups.eventListenerGroup_PRE_FLUSH
+				.fireEventOnEachListener( preFlushEvent,
+						PreFlushEventListener::onAutoPreFlush );
+		return preFlushEvent.isPreFlushRequired();
 	}
 
 	@Override

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

@@ -69,6 +69,7 @@
 import org.hibernate.loader.internal.CacheLoadHelper;
 import org.hibernate.persister.collection.CollectionPersister;
 import org.hibernate.persister.entity.EntityPersister;
+import org.hibernate.query.spi.QueryParameterBindings;
 import org.hibernate.stat.spi.StatisticsImplementor;
 
 import java.util.List;
@@ -1325,7 +1326,8 @@ public void afterScrollOperation() {
 	}
 
 	@Override
-	public void autoPreFlush() {
+	public boolean autoPreFlushIfRequired(QueryParameterBindings parameterBindings) {
+		return false;
 	}
 
 	@Override