HHH-12835 Fix an incorrect assertion in BatchFetchQueueHelper

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

@@ -54,11 +54,12 @@ public class BatchFetchQueueHelper {
 		}
 		LOG.debug( "Not all entities were loaded." );
 		Set<Serializable> idSet = new HashSet<>( Arrays.asList( ids ) );
+		int originalIdSetSize = idSet.size();
 		for ( Object result : results ) {
 			// All results should be in the PersistenceContext
 			idSet.remove( session.getContextEntityIdentifier( result ) );
 		}
-		assert idSet.size() == ids.length - results.size();
+		assert idSet.size() == originalIdSetSize - results.size();
 		if ( LOG.isDebugEnabled() ) {
 			LOG.debug( "Entities of type [" + persister.getEntityName() + "] not found; IDs: " + idSet );
 		}

hibernate-core/src/test/java/org/hibernate/test/batchfetch/City.java

@@ -0,0 +1,72 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.test.batchfetch;
+
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.FetchType;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.JoinColumn;
+import javax.persistence.ManyToOne;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "city")
+public class City {
+
+	@Id
+	@GeneratedValue(strategy = GenerationType.AUTO)
+	@Column(name = "id")
+	private Integer id;
+
+	@Column(name = "name")
+	private String name;
+
+	@ManyToOne(fetch = FetchType.LAZY)
+	@JoinColumn(name = "country_id")
+	private Country country;
+
+	public City() {
+	}
+
+	public City(String name, Country country) {
+		super();
+		this.name = name;
+		this.country = country;
+	}
+
+	public Integer getId() {
+		return id;
+	}
+
+	public void setId(Integer id) {
+		this.id = id;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public Country getCountry() {
+		return country;
+	}
+
+	public void setCountry(Country country) {
+		this.country = country;
+	}
+
+	@Override
+	public String toString() {
+		return name + " (" + ( country == null ? "?" : country.getName() ) + ")";
+	}
+}

hibernate-core/src/test/java/org/hibernate/test/batchfetch/Country.java

@@ -0,0 +1,66 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.test.batchfetch;
+
+import java.util.List;
+
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "country")
+public class Country {
+
+	@Id
+	@GeneratedValue(strategy = GenerationType.AUTO)
+	@Column(name = "id")
+	private Integer id;
+
+	@Column(name = "name")
+	private String name;
+
+	@OneToMany(mappedBy = "country")
+	private List<City> cities;
+
+	public Country() {
+	}
+
+	public Country(String name) {
+		super();
+		this.name = name;
+	}
+
+	public Integer getId() {
+		return id;
+	}
+
+	public void setId(Integer id) {
+		this.id = id;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public List<City> getCities() {
+		return cities;
+	}
+
+	@Override
+	public String toString() {
+		return name;
+	}
+}

hibernate-core/src/test/java/org/hibernate/test/batchfetch/PaddedBatchFetchTestCase.java

@@ -0,0 +1,64 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later.
+ * See the lgpl.txt file in the root directory or <http://www.gnu.org/licenses/lgpl-2.1.html>.
+ */
+package org.hibernate.test.batchfetch;
+
+import static org.hibernate.testing.transaction.TransactionUtil.doInHibernate;
+import static org.junit.Assert.assertNotNull;
+
+import java.util.List;
+import java.util.stream.IntStream;
+
+import org.hibernate.cfg.AvailableSettings;
+import org.hibernate.cfg.Configuration;
+import org.hibernate.loader.BatchFetchStyle;
+import org.hibernate.testing.TestForIssue;
+import org.hibernate.testing.junit4.BaseCoreFunctionalTestCase;
+import org.junit.Test;
+
+public class PaddedBatchFetchTestCase extends BaseCoreFunctionalTestCase {
+
+	@Override
+	protected Class<?>[] getAnnotatedClasses() {
+		return new Class<?>[]{ Country.class, City.class };
+	}
+
+	@Override
+	protected void configure(Configuration configuration) {
+		super.configure( configuration );
+
+		configuration.setProperty( AvailableSettings.SHOW_SQL, Boolean.TRUE.toString() );
+		configuration.setProperty( AvailableSettings.FORMAT_SQL, Boolean.TRUE.toString() );
+
+		configuration.setProperty( AvailableSettings.BATCH_FETCH_STYLE, BatchFetchStyle.PADDED.name() );
+		configuration.setProperty( AvailableSettings.DEFAULT_BATCH_FETCH_SIZE, "15" );
+	}
+
+	@Test
+	@TestForIssue(jiraKey = "HHH-12835")
+	public void paddedBatchFetchTest() throws Exception {
+		doInHibernate( this::sessionFactory, session -> {
+			// Having DEFAULT_BATCH_FETCH_SIZE=15
+			// results in batchSizes = [15, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
+			// Let's create 11 countries so batch size 15 will be used with padded values,
+			// this causes to have to remove 4 elements from list
+			int numberOfCountries = 11;
+
+			IntStream.range( 0, numberOfCountries ).forEach( i -> {
+				Country c = new Country( "Country " + i );
+				session.save( c );
+				session.save( new City( "City " + i, c ) );
+			} );
+		} );
+
+		doInHibernate( this::sessionFactory, session -> {
+			List<City> allCities = session.createQuery( "from City", City.class ).list();
+
+			// this triggers countries to be fetched in batch
+			assertNotNull( allCities.get( 0 ).getCountry().getName() );
+		} );
+	}
+}