From ea859736c2f847ed8396ff105308210ec4e39097 Mon Sep 17 00:00:00 2001
From: Guillaume Smet <guillaume.smet@gmail.com>
Date: Wed, 8 Aug 2018 16:22:18 +0200
Subject: [PATCH] HHH-12896 Minor memory improvements in HQLQueryPlan

---
 .../engine/query/spi/HQLQueryPlan.java        | 28 +++++++++++--------
 .../internal/classic/QueryTranslatorImpl.java |  7 ++++-
 2 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/hibernate-core/src/main/java/org/hibernate/engine/query/spi/HQLQueryPlan.java b/hibernate-core/src/main/java/org/hibernate/engine/query/spi/HQLQueryPlan.java
index 704d8ff4b9..05b7f0152a 100644
--- a/hibernate-core/src/main/java/org/hibernate/engine/query/spi/HQLQueryPlan.java
+++ b/hibernate-core/src/main/java/org/hibernate/engine/query/spi/HQLQueryPlan.java
@@ -48,11 +48,10 @@ import org.hibernate.type.Type;
 public class HQLQueryPlan implements Serializable {
 	private static final CoreMessageLogger LOG = CoreLogging.messageLogger( HQLQueryPlan.class );
 
-    // TODO : keep separate notions of QT[] here for shallow/non-shallow queries...
+	// TODO : keep separate notions of QT[] here for shallow/non-shallow queries...
 
 	private final String sourceQuery;
 	private final QueryTranslator[] translators;
-	private final String[] sqlStrings;
 
 	private final ParameterMetadataImpl parameterMetadata;
 	private final ReturnMetadata returnMetadata;
@@ -60,7 +59,6 @@ public class HQLQueryPlan implements Serializable {
 
 	private final Set<String> enabledFilterNames;
 	private final boolean shallow;
-	private final SessionFactoryImplementor factory;
 
 	/**
 	* We'll check the trace level only once per instance
@@ -79,7 +77,7 @@ public class HQLQueryPlan implements Serializable {
 			SessionFactoryImplementor factory) {
 		this( hql, null, shallow, enabledFilters, factory, null );
 	}
-	
+
 	public HQLQueryPlan(String hql, boolean shallow, Map<String,Filter> enabledFilters,
 			SessionFactoryImplementor factory, EntityGraphQueryHint entityGraphQueryHint) {
 		this( hql, null, shallow, enabledFilters, factory, entityGraphQueryHint );
@@ -95,17 +93,18 @@ public class HQLQueryPlan implements Serializable {
 			EntityGraphQueryHint entityGraphQueryHint) {
 		this.sourceQuery = hql;
 		this.shallow = shallow;
-		this.factory = factory;
 
-		final Set<String> copy = new HashSet<>();
-		copy.addAll( enabledFilters.keySet() );
-		this.enabledFilterNames = java.util.Collections.unmodifiableSet( copy );
+		if ( enabledFilters.isEmpty() ) {
+			this.enabledFilterNames = Collections.emptySet();
+		}
+		else {
+			this.enabledFilterNames = Collections.unmodifiableSet( new HashSet<>( enabledFilters.keySet() ) );
+		}
 
 		final String[] concreteQueryStrings = QuerySplitter.concreteQueries( hql, factory );
 		final int length = concreteQueryStrings.length;
 		this.translators = new QueryTranslator[length];
 
-		final List<String> sqlStringList = new ArrayList<>();
 		final Set<Serializable> combinedQuerySpaces = new HashSet<>();
 
 		final Map querySubstitutions = factory.getSessionFactoryOptions().getQuerySubstitutions();
@@ -124,10 +123,8 @@ public class HQLQueryPlan implements Serializable {
 				( (FilterTranslator) translators[i] ).compile( collectionRole, querySubstitutions, shallow );
 			}
 			combinedQuerySpaces.addAll( translators[i].getQuerySpaces() );
-			sqlStringList.addAll( translators[i].collectSqlStrings() );
 		}
 
-		this.sqlStrings = ArrayHelper.toStringArray( sqlStringList );
 		this.querySpaces = combinedQuerySpaces;
 
 		if ( length == 0 ) {
@@ -166,8 +163,15 @@ public class HQLQueryPlan implements Serializable {
 		return enabledFilterNames;
 	}
 
+	/**
+	 * This method should only be called for debugging purposes as it regenerates a new array every time.
+	 */
 	public String[] getSqlStrings() {
-		return sqlStrings;
+		List<String> sqlStrings = new ArrayList<>();
+		for ( int i = 0; i < translators.length; i++ ) {
+			sqlStrings.addAll( translators[i].collectSqlStrings() );
+		}
+		return ArrayHelper.toStringArray( sqlStrings );
 	}
 
 	public Set getUtilizedFilterNames() {
diff --git a/hibernate-core/src/main/java/org/hibernate/hql/internal/classic/QueryTranslatorImpl.java b/hibernate-core/src/main/java/org/hibernate/hql/internal/classic/QueryTranslatorImpl.java
index 24126fe58d..9ed4be7538 100644
--- a/hibernate-core/src/main/java/org/hibernate/hql/internal/classic/QueryTranslatorImpl.java
+++ b/hibernate-core/src/main/java/org/hibernate/hql/internal/classic/QueryTranslatorImpl.java
@@ -268,10 +268,12 @@ public class QueryTranslatorImpl extends BasicLoader implements FilterTranslator
 		return sqlString;
 	}
 
+	@Override
 	public List<String> collectSqlStrings() {
-		return ArrayHelper.toList( new String[] {sqlString} );
+		return Collections.singletonList( sqlString );
 	}
 
+	@Override
 	public String getQueryString() {
 		return queryString;
 	}
@@ -291,15 +293,18 @@ public class QueryTranslatorImpl extends BasicLoader implements FilterTranslator
 	 *
 	 * @return an array of <tt>Type</tt>s.
 	 */
+	@Override
 	public Type[] getReturnTypes() {
 		return actualReturnTypes;
 	}
 
+	@Override
 	public String[] getReturnAliases() {
 		// return aliases not supported in classic translator!
 		return NO_RETURN_ALIASES;
 	}
 
+	@Override
 	public String[][] getColumnNames() {
 		return scalarColumnNames;
 	}