HHH-9512: Avoid creation of invalid managed -> managed entity mapping in MergeContext when traversing cascade loop

(cherry picked from commit 816c97613d)

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

@@ -231,6 +231,17 @@ class MergeContext implements Map {
 			throw new NullPointerException( "null merge and managed entities are not supported by " + getClass().getName() );
 		}
 
+		// Detect invalid 'managed entity' -> 'managed entity' mappings where key != value
+		if ( managedToMergeEntityXref.containsKey( mergeEntity ) ) {
+			if ( managedToMergeEntityXref.get( mergeEntity ) != mergeEntity ) {
+				throw new IllegalStateException(
+						"MergeContext#attempt to create managed -> managed mapping with different entities: "
+								+ printEntity( mergeEntity ) + "; " + printEntity(
+								managedEntity )
+				);
+			}
+		}
+
 		Object oldManagedEntity = mergeToManagedEntityXref.put( mergeEntity, managedEntity );
 		Boolean oldOperatedOn = mergeEntityToOperatedOnFlagMap.put( mergeEntity, isOperatedOn );
 		// If managedEntity already corresponds with a different merge entity, that means

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

@@ -296,6 +296,13 @@ public abstract class EntityType extends AbstractType implements AssociationType
 			return null;
 		}
 		Object cached = copyCache.get( original );
+		if ( cached == null ) {
+			// Avoid creation of invalid managed -> managed mapping in copyCache when traversing
+			// cascade loop (@OneToMany(cascade=ALL) with associated @ManyToOne(cascade=ALL)) in entity graph
+			if ( copyCache.containsValue( original ) ) {
+				cached = original;
+			}
+		}
 		if ( cached != null ) {
 			return cached;
 		}

hibernate-core/src/test/java/org/hibernate/test/cascade/circle/CascadeManagedAndTransient.hbm.xml

@@ -0,0 +1,121 @@
+<?xml version="1.0"?>
+<!--
+~ 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>.
+-->
+<!DOCTYPE hibernate-mapping SYSTEM "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd" >
+
+<hibernate-mapping package="org.hibernate.test.cascade.circle">
+
+    <class name="Route" table="HB_Route">
+
+        <id name="routeID" type="long"><generator class="native"/></id>
+        <version name="version" column="VERS" type="long" />
+
+        <property name="name" type="string" not-null="true"/>
+
+        <set name="nodes" inverse="true" cascade="persist,merge,refresh,save-update">
+            <key column="routeID"/>
+            <one-to-many class="Node"/>
+        </set>
+        <set name="vehicles" inverse="true" cascade="persist,merge,refresh,save-update">
+            <key column="routeID"/>
+            <one-to-many class="Vehicle"/>
+        </set>
+    </class>
+
+    <class name="Tour" table="HB_Tour">
+
+        <id name="tourID" type="long"><generator class="native"/></id>
+        <version name="version" column="VERS" type="long" />
+
+        <property name="name" type="string" not-null="true"/>
+
+        <set name="nodes" inverse="true" lazy="true" cascade="merge,refresh,persist,save-update">
+            <key column="tourID"/>
+            <one-to-many class="Node"/>
+        </set>
+    </class>
+
+    <class name="Transport" table="HB_Transport">
+
+        <id name="transportID" type="long"><generator class="native"/></id>
+        <version name="version" column="VERS" type="long" />
+
+        <property name="name" type="string" not-null="true"/>
+
+        <many-to-one name="pickupNode"
+                     column="pickupNodeID"
+                     unique="true"
+                     not-null="true"
+                     cascade="merge,refresh,persist,save-update"
+                     lazy="false"/>
+
+        <many-to-one name="deliveryNode"
+                     column="deliveryNodeID"
+                     unique="true"
+                     not-null="true"
+                     cascade="merge,refresh,persist,save-update"
+                     lazy="false"/>
+
+        <many-to-one name="vehicle"
+                     column="vehicleID"
+                     unique="false"
+                     not-null="true"
+                     cascade="merge,refresh,persist,save-update"
+                     lazy="false"/>
+    </class>
+
+    <class name="Vehicle" table="HB_Vehicle">
+        <id name="vehicleID" type="long"><generator class="native"/></id>
+        <version name="version" column="VERS" type="long" />
+
+        <property name="name"/>
+        <set name="transports" inverse="false" lazy="true" cascade="merge,refresh,persist,save-update">
+            <key column="vehicleID"/>
+            <one-to-many class="Transport" not-found="exception"/>
+        </set>
+        <many-to-one name="route"
+                     column="routeID"
+                     unique="false"
+                     not-null="false"
+                     cascade="merge,refresh,persist,save-update,save-update"
+                     lazy="false"/>
+    </class>
+
+
+    <class name="Node" table="HB_Node">
+
+        <id name="nodeID" type="long"><generator class="native"/></id>
+        <version name="version" column="VERS" type="long" />
+
+        <property name="name" type="string" not-null="true"/>
+
+        <set name="deliveryTransports" inverse="true" lazy="true" cascade="merge,refresh,persist,save-update">
+            <key column="deliveryNodeID"/>
+            <one-to-many class="Transport"/>
+        </set>
+
+        <set name="pickupTransports" inverse="true" lazy="true" cascade="merge,refresh,persist,save-update">
+            <key column="pickupNodeID"/>
+            <one-to-many class="Transport"/>
+        </set>
+
+        <many-to-one name="route"
+                     column="routeID"
+                     unique="false"
+                     not-null="true"
+                     cascade="merge,refresh,persist,save-update"
+                     lazy="false"/>
+
+        <many-to-one name="tour"
+                     column="tourID"
+                     unique="false"
+                     not-null="true"
+                     cascade="merge,refresh,persist,save-update"
+                     lazy="false"/>
+    </class>
+
+</hibernate-mapping>

hibernate-core/src/test/java/org/hibernate/test/cascade/circle/CascadeManagedAndTransientTest.java

@@ -0,0 +1,164 @@
+/*
+ * 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.test.cascade.circle;
+
+import org.hibernate.Session;
+import org.hibernate.cfg.Configuration;
+import org.hibernate.cfg.Environment;
+import org.hibernate.testing.junit4.BaseCoreFunctionalTestCase;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+
+/**
+ * The test case uses the following model:
+ *
+ *                          <-    ->
+ *                      -- (N : 0,1) -- Tour
+ *                      |    <-   ->
+ *                      | -- (1 : N) -- (pickup) ----
+ *          <-   ->     | |                          |
+ * Route -- (1 : N) -- Node                      Transport
+ *                      |  <-   ->                |
+ *                      -- (1 : N) -- (delivery) --
+ *
+ *  Arrows indicate the direction of cascade-merge, cascade-save, cascade-refresh and cascade-save-or-update
+ *
+ * It reproduces the following issues:
+ * https://hibernate.atlassian.net/browse/HHH-9512
+ * <p/>
+ * This tests that cascades are done properly from each entity.
+ *
+ * @author Alex Belyaev (based on code by Pavol Zibrita and Gail Badner)
+ */
+public class CascadeManagedAndTransientTest extends BaseCoreFunctionalTestCase  {
+
+    @Override
+    public String[] getMappings() {
+        return new String[] {
+                "cascade/circle/CascadeManagedAndTransient.hbm.xml"
+        };
+    }
+
+    @Override
+    public void configure(Configuration cfg) {
+        super.configure( cfg );
+        cfg.setProperty( Environment.CHECK_NULLABILITY, "true" );
+    }
+
+    @Override
+    protected void cleanupTest() {
+        Session s = openSession();
+        s.beginTransaction();
+        s.createQuery( "delete from Transport" );
+        s.createQuery( "delete from Tour" );
+        s.createQuery( "delete from Node" );
+        s.createQuery( "delete from Route" );
+        s.createQuery( "delete from Vehicle" );
+    }
+
+    private void checkNewVehicle(Vehicle newVehicle) {
+        assertEquals("Bus", newVehicle.getName());
+        assertEquals(1, newVehicle.getTransports().size());
+        Transport t = (Transport) newVehicle.getTransports().iterator().next();
+        assertEquals("Transport 2 -> 3", t.getName());
+        assertEquals("Node 2", t.getPickupNode().getName());
+        assertEquals("Node 3", t.getDeliveryNode().getName());
+    }
+
+    @Test
+    public void testAttachedChildInMerge() {
+        fillInitialData();
+
+        Session s = openSession();
+        s.beginTransaction();
+
+        Route route = (Route) s.createQuery("FROM Route WHERE name = :name").setString("name", "Route 1").uniqueResult();
+        Node n2 = (Node) s.createQuery("FROM Node WHERE name = :name").setString("name", "Node 2").uniqueResult();
+        Node n3 = (Node) s.createQuery("FROM Node WHERE name = :name").setString("name", "Node 3").uniqueResult();
+
+        Vehicle vehicle = new Vehicle();
+        vehicle.setName("Bus");
+        vehicle.setRoute(route);
+
+        Transport $2to3 = new Transport();
+        $2to3.setName("Transport 2 -> 3");
+        $2to3.setPickupNode(n2); n2.getPickupTransports().add($2to3);
+        $2to3.setDeliveryNode(n3); n3.getDeliveryTransports().add($2to3);
+        $2to3.setVehicle(vehicle);
+
+        vehicle.setTransports(new HashSet<Transport>(Arrays.asList($2to3)));
+
+        // Try to save graph of transient entities (vehicle, transport) which contains attached entities (node2, node3)
+        Vehicle managedVehicle = (Vehicle) s.merge(vehicle);
+        checkNewVehicle(managedVehicle);
+
+        s.flush();
+        s.clear();
+
+        assertEquals(3, s.createQuery("FROM Transport").list().size());
+        assertEquals(2, s.createQuery("FROM Vehicle").list().size());
+        assertEquals(4, s.createQuery("FROM Node").list().size());
+
+        Vehicle newVehicle = (Vehicle) s.createQuery("FROM Vehicle WHERE name = :name").setParameter("name", "Bus").uniqueResult();
+        checkNewVehicle(newVehicle);
+
+        s.getTransaction().commit();
+        s.close();
+    }
+
+    private void fillInitialData() {
+        Tour tour = new Tour();
+        tour.setName("Tour 1");
+
+        Route route = new Route();
+        route.setName("Route 1");
+
+        ArrayList<Node> nodes = new ArrayList<Node>();
+        for (int i = 0; i < 4; i++) {
+            Node n = new Node();
+            n.setName("Node " + i);
+            n.setTour(tour);
+            n.setRoute(route);
+            nodes.add(n);
+        }
+
+        tour.setNodes(new HashSet<Node>(nodes));
+        route.setNodes(new HashSet<Node>(Arrays.asList(nodes.get(0), nodes.get(1), nodes.get(2))));
+
+        Vehicle vehicle = new Vehicle();
+        vehicle.setName("Car");
+        route.setVehicles(new HashSet<Vehicle>(Arrays.asList(vehicle)));
+        vehicle.setRoute(route);
+
+        Transport $0to1 = new Transport();
+        $0to1.setName("Transport 0 -> 1");
+        $0to1.setPickupNode(nodes.get(0));
+        $0to1.setDeliveryNode(nodes.get(1));
+        $0to1.setVehicle(vehicle);
+
+        Transport $1to2 = new Transport();
+        $1to2.setName("Transport 1 -> 2");
+        $1to2.setPickupNode(nodes.get(1));
+        $1to2.setDeliveryNode(nodes.get(2));
+        $1to2.setVehicle(vehicle);
+
+        vehicle.setTransports(new HashSet<Transport>(Arrays.asList($0to1, $1to2)));
+
+        Session s = openSession();
+        s.beginTransaction();
+
+        s.persist(tour);
+
+        s.getTransaction().commit();
+        s.close();
+    }
+}