HHH-17282 Introduce a specialized Map for NavigablePath to Initializer

Author: Sanne

hibernate-core/src/main/java/org/hibernate/sql/results/internal/InitializersList.java

@@ -9,7 +9,6 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
-import java.util.Map;
 
 import org.hibernate.spi.NavigablePath;
 import org.hibernate.sql.exec.spi.ExecutionContext;
@@ -36,14 +35,14 @@ public final class InitializersList {
 	private final Initializer[] sortedNonCollectionsFirst;
 	private final Initializer[] sortedForResolveInstance;
 	private final boolean hasCollectionInitializers;
-	private final Map<NavigablePath, Initializer> initializerMap;
+	private final NavigablePathMapToInitializer initializerMap;
 
 	private InitializersList(
 			Initializer[] initializers,
 			Initializer[] sortedNonCollectionsFirst,
 			Initializer[] sortedForResolveInstance,
 			boolean hasCollectionInitializers,
-			Map<NavigablePath, Initializer> initializerMap) {
+			NavigablePathMapToInitializer initializerMap) {
 		this.initializers = initializers;
 		this.sortedNonCollectionsFirst = sortedNonCollectionsFirst;
 		this.sortedForResolveInstance = sortedForResolveInstance;
@@ -123,7 +122,7 @@ private static boolean initializeFirst(final Initializer initializer) {
 					&& !(initializer instanceof AbstractBatchEntitySelectFetchInitializer );
 		}
 
-		InitializersList build(final Map<NavigablePath, Initializer> initializerMap) {
+		InitializersList build(final NavigablePathMapToInitializer initializerMap) {
 			final int size = initializers.size();
 			final Initializer[] sortedNonCollectionsFirst = new Initializer[size];
 			final Initializer[] sortedForResolveInstance = new Initializer[size];

hibernate-core/src/main/java/org/hibernate/sql/results/internal/NavigablePathMapToInitializer.java

@@ -0,0 +1,90 @@
+/*
+ * 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.sql.results.internal;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Objects;
+
+import org.hibernate.spi.NavigablePath;
+import org.hibernate.sql.results.ResultsLogger;
+import org.hibernate.sql.results.graph.Initializer;
+
+
+/**
+ * This is in all practical terms a {@code Map<NavigablePath, Initializer>}
+ * but wrapping an HashMap so to keep the client code readable as we need
+ * to:
+ * a) have a way to log all initializers
+ * b) prevent type pollution from happening on Initializer retrieval
+ * I also consider it good practice to only expose the minimal set of
+ * operations the client actually needs.
+ */
+public final class NavigablePathMapToInitializer {
+
+	private HashMap<NavigablePath, InitializerHolder> map = null;
+
+	public Initializer get(final NavigablePath navigablePath) {
+		if ( map != null && navigablePath != null ) {
+			final InitializerHolder h = map.get( navigablePath );
+			if ( h != null ) {
+				return h.initializer;
+			}
+		}
+		return null;
+	}
+
+	public void put(final NavigablePath navigablePath, final Initializer initializer) {
+		Objects.requireNonNull( navigablePath );
+		Objects.requireNonNull( initializer );
+		if ( map == null ) {
+			map = new HashMap<>();
+		}
+		map.put( navigablePath, new InitializerHolder( initializer ) );
+	}
+
+	public void logInitializers() {
+		ResultsLogger logger = ResultsLogger.RESULTS_MESSAGE_LOGGER;
+		if ( !logger.isDebugEnabled() ) {
+			return;
+		}
+		if ( map == null ) {
+			logger.debug( "Initializer list is empty" );
+		}
+		else {
+			//Apparently we want to log this on multiple lines (existing code did this - not sure if that was by design):
+			//using a StringBuilder to avoid potentially interleaving the logs from different operations.
+			final StringBuilder sb = new StringBuilder( "Initializer list:\n" );
+			for ( Map.Entry<NavigablePath, InitializerHolder> holderEntry : map.entrySet() ) {
+				final NavigablePath navigablePath = holderEntry.getKey();
+				final Initializer initializer = holderEntry.getValue().initializer;
+				String formatted = String.format(
+						"  %s -> %s@%s (%s)",
+						navigablePath,
+						initializer,
+						initializer.hashCode(),
+						initializer.getInitializedPart()
+				);
+				sb.append( '\t' );
+				sb.append( formatted );
+				sb.append( '\n' );
+			}
+			logger.debug( sb.toString() );
+		}
+	}
+
+	//Custom holder to avoid type pollution:
+	//we make the type explicit, and this is a concrete class.
+	private static final class InitializerHolder {
+		final Initializer initializer;
+
+		private InitializerHolder(final Initializer init) {
+			this.initializer = init;
+		}
+	}
+
+}

hibernate-core/src/main/java/org/hibernate/sql/results/internal/ResultsHelper.java

@@ -6,9 +6,7 @@
  */
 package org.hibernate.sql.results.internal;
 
-import java.util.LinkedHashMap;
 import java.util.List;
-import java.util.Map;
 import java.util.function.Supplier;
 
 import org.hibernate.CacheMode;
@@ -70,7 +68,8 @@ public static <R> RowReader<R> createRowReader(
 			JdbcValuesMapping jdbcValuesMapping) {
 		final SessionFactoryImplementor sessionFactory = executionContext.getSession().getFactory();
 
-		final Map<NavigablePath, Initializer> initializerMap = new LinkedHashMap<>();
+		//custom Map<NavigablePath, Initializer>
+		final NavigablePathMapToInitializer initializerMap = new NavigablePathMapToInitializer();
 		final InitializersList.Builder initializersBuilder = new InitializersList.Builder();
 
 		final List<DomainResultAssembler<?>> assemblers = jdbcValuesMapping.resolveAssemblers(
@@ -133,30 +132,13 @@ public SqlAstCreationContext getSqlAstCreationContext() {
 				}
 		);
 
-		logInitializers( initializerMap );
+		initializerMap.logInitializers();
 
 		final InitializersList initializersList = initializersBuilder.build( initializerMap );
 
 		return new StandardRowReader<>( assemblers, initializersList, rowTransformer, transformedResultJavaType );
 	}
 
-	private static void logInitializers(Map<NavigablePath, Initializer> initializerMap) {
-		if ( ! ResultsLogger.RESULTS_MESSAGE_LOGGER.isDebugEnabled() ) {
-			return;
-		}
-
-		ResultsLogger.RESULTS_MESSAGE_LOGGER.debug( "Initializer list" );
-		initializerMap.forEach( (navigablePath, initializer) -> {
-			ResultsLogger.RESULTS_MESSAGE_LOGGER.debugf(
-					"    %s -> %s@%s (%s)",
-					navigablePath,
-					initializer,
-					initializer.hashCode(),
-					initializer.getInitializedPart()
-			);
-		} );
-	}
-
 	public static void finalizeCollectionLoading(
 			PersistenceContext persistenceContext,
 			CollectionPersister collectionDescriptor,