From 6c4643f265355fc54bc47d5e3f339906e3421e35 Mon Sep 17 00:00:00 2001
From: Gail Badner <gbadner@redhat.com>
Date: Fri, 23 Aug 2019 22:40:36 -0700
Subject: [PATCH] HHH-13586 : ClassCastException when using a single region
 name for both entity and query results

(cherry picked from commit 2076c68ddff5dc39055e90e162a34c99c72261cb)
---
 .../cache/internal/EnabledCaching.java        | 40 +++++++++++++------
 .../hibernate/cache/spi/CacheImplementor.java |  4 +-
 2 files changed, 30 insertions(+), 14 deletions(-)

diff --git a/hibernate-core/src/main/java/org/hibernate/cache/internal/EnabledCaching.java b/hibernate-core/src/main/java/org/hibernate/cache/internal/EnabledCaching.java
index e7257ed0d0..9ce34807a3 100644
--- a/hibernate-core/src/main/java/org/hibernate/cache/internal/EnabledCaching.java
+++ b/hibernate-core/src/main/java/org/hibernate/cache/internal/EnabledCaching.java
@@ -48,6 +48,7 @@ import org.hibernate.pretty.MessageHelper;
 /**
  * @author Steve Ebersole
  * @author Strong Liu
+ * @author Gail Badner
  */
 public class EnabledCaching implements CacheImplementor, DomainDataRegionBuildingContext {
 	private static final CoreMessageLogger LOG = CoreLogging.messageLogger( EnabledCaching.class );
@@ -57,6 +58,10 @@ public class EnabledCaching implements CacheImplementor, DomainDataRegionBuildin
 
 	private final Map<String,Region> regionsByName = new ConcurrentHashMap<>();
 
+	// A map by name for QueryResultsRegion instances that have the same name as a Region
+	// in #regionsByName.
+	private final Map<String, QueryResultsRegion> queryResultsRegionsByDuplicateName = new ConcurrentHashMap<>();
+
 	private final Map<NavigableRole,EntityDataAccess> entityAccessMap = new ConcurrentHashMap<>();
 	private final Map<NavigableRole,NaturalIdDataAccess> naturalIdAccessMap = new ConcurrentHashMap<>();
 	private final Map<NavigableRole,CollectionDataAccess> collectionAccessMap = new ConcurrentHashMap<>();
@@ -204,6 +209,8 @@ public class EnabledCaching implements CacheImplementor, DomainDataRegionBuildin
 
 	@Override
 	public Region getRegion(String regionName) {
+		// The Region in regionsByName has precedence over the
+		// QueryResultsRegion in #queryResultsRegionsByDuplicateName
 		return regionsByName.get( regionName );
 	}
 
@@ -488,12 +495,23 @@ public class EnabledCaching implements CacheImplementor, DomainDataRegionBuildin
 	}
 
 	protected QueryResultsCache makeQueryResultsRegionAccess(String regionName) {
-		final QueryResultsRegion region = (QueryResultsRegion) regionsByName.computeIfAbsent(
+		final Region region = regionsByName.computeIfAbsent(
 				regionName,
 				this::makeQueryResultsRegion
 		);
+		final QueryResultsRegion queryResultsRegion;
+		if ( QueryResultsRegion.class.isInstance( region ) ) {
+			queryResultsRegion = (QueryResultsRegion) region;
+		}
+		else {
+			// There was already a different type of Region with the same name.
+			queryResultsRegion = queryResultsRegionsByDuplicateName.computeIfAbsent(
+					regionName,
+					this::makeQueryResultsRegion
+			);
+		}
 		final QueryResultsCacheImpl regionAccess = new QueryResultsCacheImpl(
-				region,
+				queryResultsRegion,
 				timestampsCache
 		);
 		namedQueryResultsCacheMap.put( regionName, regionAccess );
@@ -502,20 +520,9 @@ public class EnabledCaching implements CacheImplementor, DomainDataRegionBuildin
 	}
 
 	protected QueryResultsRegion makeQueryResultsRegion(String regionName) {
-		// make sure there is not an existing domain-data region with that name..
-		final Region existing = regionsByName.get( regionName );
-		if ( existing != null ) {
-			if ( !QueryResultsRegion.class.isInstance( existing ) ) {
-				throw new IllegalStateException( "Cannot store both domain-data and query-result-data in the same region [" + regionName );
-			}
-
-			throw new IllegalStateException( "Illegal call to create QueryResultsRegion - one already existed" );
-		}
-
 		return regionFactory.buildQueryResultsRegion( regionName, getSessionFactory() );
 	}
 
-
 	@Override
 	public Set<String> getCacheRegionNames() {
 		return regionsByName.keySet();
@@ -524,6 +531,10 @@ public class EnabledCaching implements CacheImplementor, DomainDataRegionBuildin
 	@Override
 	public void evictRegion(String regionName) {
 		getRegion( regionName ).clear();
+		final QueryResultsRegion queryResultsRegionWithDuplicateName = queryResultsRegionsByDuplicateName.get( regionName );
+		if ( queryResultsRegionWithDuplicateName != null ) {
+			queryResultsRegionWithDuplicateName.clear();
+		}
 	}
 
 	@Override
@@ -545,6 +556,9 @@ public class EnabledCaching implements CacheImplementor, DomainDataRegionBuildin
 		for ( Region region : regionsByName.values() ) {
 			region.destroy();
 		}
+		for ( Region region : queryResultsRegionsByDuplicateName.values() ) {
+			region.destroy();
+		}
 	}
 
 
diff --git a/hibernate-core/src/main/java/org/hibernate/cache/spi/CacheImplementor.java b/hibernate-core/src/main/java/org/hibernate/cache/spi/CacheImplementor.java
index 00a28c7b99..c77b13db7b 100644
--- a/hibernate-core/src/main/java/org/hibernate/cache/spi/CacheImplementor.java
+++ b/hibernate-core/src/main/java/org/hibernate/cache/spi/CacheImplementor.java
@@ -52,7 +52,9 @@ public interface CacheImplementor extends Service, Cache, org.hibernate.engine.s
 	void prime(Set<DomainDataRegionConfig> cacheRegionConfigs);
 
 	/**
-	 * Get a cache Region by name
+	 * Get a cache Region by name. If there is both a {@link DomainDataRegion}
+	 * and a {@link QueryResultsRegion} with the specified name, then the
+	 * {@link DomainDataRegion} will be returned.
 	 *
 	 * @apiNote It is only valid to call this method after {@link #prime} has
 	 * been performed