HHH-16052 EntityKey and CollectionKey equality optimisation

hibernate-core/src/main/java/org/hibernate/engine/spi/CollectionKey.java

@@ -11,6 +11,7 @@ import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
 import java.io.Serializable;
 
+import org.hibernate.AssertionFailure;
 import org.hibernate.persister.collection.CollectionPersister;
 import org.hibernate.pretty.MessageHelper;
 import org.hibernate.type.Type;
@@ -42,6 +43,9 @@ public final class CollectionKey implements Serializable {
 			Type keyType,
 			SessionFactoryImplementor factory) {
 		this.role = role;
+		if ( key == null ) {
+			throw new AssertionFailure( "null identifier for collection of role (" + role + ")" );
+		}
 		this.key = key;
 		this.keyType = keyType;
 		this.factory = factory;
@@ -73,17 +77,18 @@ public final class CollectionKey implements Serializable {
 	}
 
 	@Override
-	public boolean equals(Object other) {
+	public boolean equals(final Object other) {
 		if ( this == other ) {
 			return true;
 		}
-		if ( other == null || getClass() != other.getClass() ) {
+		if ( other == null || CollectionKey.class != other.getClass() ) {
 			return false;
 		}
 
 		final CollectionKey that = (CollectionKey) other;
 		return that.role.equals( role )
-				&& keyType.isEqual( that.key, key, factory );
+				&& ( this.key == that.key ||
+					keyType.isEqual( this.key, that.key, factory ) );
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/engine/spi/EntityKey.java

@@ -97,7 +97,8 @@ public final class EntityKey implements Serializable {
 	}
 
 	private boolean sameIdentifier(final EntityKey otherKey) {
-		return persister.getIdentifierType().isEqual( otherKey.identifier, this.identifier, persister.getFactory() );
+		return this.identifier == otherKey.identifier ||
+			persister.getIdentifierType().isEqual( otherKey.identifier, this.identifier, persister.getFactory() );
 	}
 
 	private boolean samePersistentType(final EntityKey otherKey) {

hibernate-core/src/main/java/org/hibernate/event/internal/DefaultFlushEntityEventListener.java

@@ -82,6 +82,13 @@ public class DefaultFlushEntityEventListener implements FlushEntityEventListener
 					+ " entry (don't flush the Session after an exception occurs)" );
 		}
 
+		//Small optimisation: always try to avoid getIdentifierType().isEqual(..) when possible.
+		//(However it's not safe to invoke the equals() method as it might trigger side-effects)
+		if ( id == oid ) {
+			//No further checks necessary:
+			return;
+		}
+
 		if ( !persister.getIdentifierType().isEqual( id, oid, session.getFactory() ) ) {
 			throw new HibernateException( "identifier of an instance of " + persister.getEntityName()
 					+ " was altered from " + oid + " to " + id );

hibernate-core/src/main/java/org/hibernate/type/AbstractStandardBasicType.java

@@ -165,7 +165,8 @@ public abstract class AbstractStandardBasicType<T>
 	@Override
 	@SuppressWarnings("unchecked")
 	public boolean isEqual(Object one, Object another) {
-		return javaType.areEqual( (T) one, (T) another );
+		return ( one == another ) //optimisation to attempt avoid the need for the method on javaType:
+				|| javaType.areEqual( (T) one, (T) another );
 	}
 
 	@Override

hibernate-core/src/main/java/org/hibernate/type/EntityType.java

@@ -363,6 +363,9 @@ public abstract class EntityType extends AbstractType implements AssociationType
 		if ( x == null || y == null ) {
 			return x == y;
 		}
+		if ( x == y ) {
+			return true;
+		}
 
 		final EntityPersister persister = getAssociatedEntityPersister( factory );
 		final Class<?> mappedClass = persister.getMappedClass();
@@ -396,8 +399,8 @@ public abstract class EntityType extends AbstractType implements AssociationType
 			}
 		}
 
-		return persister.getIdentifierType()
-				.isEqual( xid, yid, factory );
+		// Check for reference equality first as the type-specific checks by IdentifierType are sometimes non-trivial
+		return ( xid == yid ) || persister.getIdentifierType().isEqual( xid, yid, factory );
 	}
 
 	/**