HHH-19218 use a stronger hashing function for cache keys

Author: ben-manes

hibernate-core/src/main/java/org/hibernate/cache/internal/BasicCacheKeyImplementation.java

@@ -55,7 +55,16 @@ public BasicCacheKeyImplementation(
 	}
 
 	private static int calculateHashCode(Object disassembledKey, Type type) {
-		return type.getHashCode( disassembledKey );
+		return hash( type.getHashCode( disassembledKey ) );
+	}
+
+	@Internal
+	public static int hash(int h) {
+		// Mix the result with the Murmur3 finalising function
+		h = (h ^ (h >>> 16)) * 0x85ebca6b;
+		h = (h ^ (h >>> 13)) * 0xc2b2ae35;
+		h = h ^ (h >>> 16);
+		return h;
 	}
 
 	public Object getId() {

hibernate-core/src/main/java/org/hibernate/cache/internal/CacheKeyImplementation.java

@@ -81,7 +81,7 @@ public CacheKeyImplementation(
 	private static int calculateHashCode(Object id, Type type, String tenantId) {
 		int result = type.getHashCode( id );
 		result = 31 * result + ( tenantId != null ? tenantId.hashCode() : 0 );
-		return result;
+		return BasicCacheKeyImplementation.hash( result );
 	}
 
 	public Object getId() {

hibernate-core/src/test/java/org/hibernate/orm/test/caching/mocked/CacheKeyImplementationHashCodeTest.java

@@ -13,7 +13,6 @@
 import org.hibernate.boot.Metadata;
 import org.hibernate.boot.MetadataSources;
 import org.hibernate.boot.SessionFactoryBuilder;
-import org.hibernate.cache.internal.CacheKeyImplementation;
 import org.hibernate.cache.internal.DefaultCacheKeysFactory;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.persister.entity.EntityPersister;
@@ -24,6 +23,7 @@
 import org.junit.Test;
 
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 /**
  * @author Gail Badner
@@ -32,37 +32,74 @@ public class CacheKeyImplementationHashCodeTest {
 
 	@Test
 	@JiraKey( value = "HHH-12746")
-	public void test() {
+	public void testHashCodeChanges() {
 		try (ServiceRegistryImplementor serviceRegistry = ServiceRegistryUtil.serviceRegistry()) {
 			MetadataSources ms = new MetadataSources( serviceRegistry );
 			ms.addAnnotatedClass( AnEntity.class ).addAnnotatedClass( AnotherEntity.class );
 			Metadata metadata = ms.buildMetadata();
 			final SessionFactoryBuilder sfb = metadata.getSessionFactoryBuilder();
 			try ( SessionFactoryImplementor sessionFactory = (SessionFactoryImplementor) sfb.build()) {
-				CacheKeyImplementation anEntityCacheKey = createCacheKeyImplementation(
+				Object anEntityCacheKey = createCacheKeyImplementation(
 						1,
 						sessionFactory.getRuntimeMetamodels()
 								.getMappingMetamodel()
 								.getEntityDescriptor( AnEntity.class ),
-						sessionFactory
+						sessionFactory,
+						"tenant"
 				);
-				CacheKeyImplementation anotherEntityCacheKey = createCacheKeyImplementation(
+				Object anotherEntityCacheKey = createCacheKeyImplementation(
 						1,
 						sessionFactory.getRuntimeMetamodels()
 								.getMappingMetamodel()
 								.getEntityDescriptor( AnotherEntity.class ),
-						sessionFactory
+						sessionFactory,
+						"tenant"
 				);
 				assertFalse( anEntityCacheKey.equals( anotherEntityCacheKey ) );
 			}
 		}
 	}
 
-	private CacheKeyImplementation createCacheKeyImplementation(
+	@Test
+	@JiraKey( value = "HHH-19218")
+	public void testMixedHashCode() {
+		try (ServiceRegistryImplementor serviceRegistry = ServiceRegistryUtil.serviceRegistry()) {
+			MetadataSources ms = new MetadataSources( serviceRegistry );
+			ms.addAnnotatedClass( AnEntity.class ).addAnnotatedClass( AnotherEntity.class );
+			Metadata metadata = ms.buildMetadata();
+			final SessionFactoryBuilder sfb = metadata.getSessionFactoryBuilder();
+			try ( SessionFactoryImplementor sessionFactory = (SessionFactoryImplementor) sfb.build()) {
+				Object anEntityCacheKey = createCacheKeyImplementation(
+						1,
+						sessionFactory.getRuntimeMetamodels()
+								.getMappingMetamodel()
+								.getEntityDescriptor( AnEntity.class ),
+						sessionFactory,
+			null
+				);
+				assertTrue( (anEntityCacheKey.hashCode() >>> 16) != 0 );
+				assertTrue( (anEntityCacheKey.hashCode() << 16) != 0 );
+
+				Object anotherEntityCacheKey = createCacheKeyImplementation(
+						1,
+						sessionFactory.getRuntimeMetamodels()
+								.getMappingMetamodel()
+								.getEntityDescriptor( AnotherEntity.class ),
+						sessionFactory,
+						"0"
+				);
+				assertTrue( (anotherEntityCacheKey.hashCode() >>> 16) != 0 );
+				assertTrue( (anotherEntityCacheKey.hashCode() << 16) != 0 );
+			}
+		}
+	}
+
+	private Object createCacheKeyImplementation(
 			int id,
 			EntityPersister persister,
-			SessionFactoryImplementor sfi) {
-		return (CacheKeyImplementation) DefaultCacheKeysFactory.staticCreateEntityKey( id, persister, sfi, "tenant" );
+			SessionFactoryImplementor sfi,
+			String tenantIdentifier) {
+		return DefaultCacheKeysFactory.staticCreateEntityKey( id, persister, sfi, tenantIdentifier);
 	}
 
 	@Entity(name = "AnEntity")

hibernate-core/src/test/java/org/hibernate/orm/test/querycache/QueryRestrictedCollectionCachingTests.java

@@ -131,7 +131,7 @@ private static Serializable[] extractCachedCollectionKeys(CacheImplementor cache
 		final CollectionReadWriteAccess authorsRegionAccess = (CollectionReadWriteAccess) cache.getCollectionRegionAccess( navigableRole );
 
 		final MapStorageAccessImpl storageAccess = (MapStorageAccessImpl) authorsRegionAccess.getStorageAccess();
-		final BasicCacheKeyImplementation cacheKey = new BasicCacheKeyImplementation( ownerKey, role, ownerKey );
+		final BasicCacheKeyImplementation cacheKey = new BasicCacheKeyImplementation( ownerKey, role, BasicCacheKeyImplementation.hash( ownerKey ) );
 		final AbstractReadWriteAccess.Item cacheItem = (AbstractReadWriteAccess.Item) storageAccess.getFromData( cacheKey );
 		assertThat( cacheItem ).isNotNull();