Improved the HandlerComparator to ensure it is transitive

Depending on the order in which the methods were found, it was possible that a more generic handler could end up before a more specific one.

This fixes issue AxonFramework#248

core/src/main/java/org/axonframework/messaging/annotation/HandlerComparator.java

@@ -55,7 +55,20 @@ private static int compareHierarchy(Class<?> o1, Class<?> o2) {
         } else if (o2.isAssignableFrom(o1)) {
             return -1;
         }
-        return 0;
+        return Integer.compare(depthOf(o2), depthOf(o1));
+    }
+
+    private static int depthOf(Class<?> o1) {
+        int depth = 0;
+        Class<?> type = o1;
+        while (type != null && !Object.class.equals(type)) {
+            depth++;
+            type = type.getSuperclass();
+        }
+        if (o1.isAnnotation()) {
+            depth += 1000;
+        }
+        return depth;
     }
 
 }

core/src/test/java/org/axonframework/commandhandling/model/ModelInspectorTest.java

@@ -180,7 +180,6 @@ private void testCollectionIsModifiedDuringIterationInRecursiveHierarchy(Supplie
     public void testEventIsPublishedThroughoutHierarchy() throws Exception {
         AggregateModel<SomeSubclass> inspector = ModelInspector.inspectAggregate(SomeSubclass.class);
 
-        CommandMessage<?> message = asCommandMessage("sub");
         AtomicLong payload = new AtomicLong();
 
         inspector.publish(new GenericEventMessage<>(payload), new SomeSubclass());
@@ -195,13 +194,6 @@ public void testExpectCommandToBeForwardedToEntity() throws Exception {
         SomeSubclass target = new SomeSubclass();
         MessageHandlingMember<? super SomeSubclass> handler = inspector.commandHandler(message.getCommandName());
         assertEquals("1", handler.handle(message, target));
-
-        long startTime = System.currentTimeMillis();
-        for (int i = 0; i < 1_000_000; i++) {
-            inspector.commandHandler(message.getCommandName()).handle(message, target);
-        }
-        long endTime = System.currentTimeMillis();
-        System.out.println("Time taken: " + (endTime - startTime) + "ms");
     }
 
     @Test

core/src/test/java/org/axonframework/messaging/annotation/HandlerComparatorTest.java

@@ -21,18 +21,16 @@
 import org.junit.Test;
 
 import java.lang.annotation.Annotation;
-import java.util.Comparator;
-import java.util.Map;
-import java.util.Optional;
+import java.util.*;
 
 import static org.junit.Assert.*;
 
 public class HandlerComparatorTest {
 
-    private MessageHandlingMember stringHandler;
-    private MessageHandlingMember objectHandler;
-    private MessageHandlingMember longHandler;
-    private MessageHandlingMember numberHandler;
+    private MessageHandlingMember<?> stringHandler;
+    private MessageHandlingMember<?> objectHandler;
+    private MessageHandlingMember<?> longHandler;
+    private MessageHandlingMember<?> numberHandler;
 
     private Comparator<MessageHandlingMember<?>> testSubject;
 
@@ -75,6 +73,15 @@ public void testHandlersIsEqualWithItself() throws Exception {
         assertNotEquals(0, testSubject.compare(objectHandler, numberHandler));
     }
 
+    @Test
+    public void testHandlersSortedCorrectly() {
+        List<MessageHandlingMember<?>> members = new ArrayList<>(Arrays.asList(objectHandler, numberHandler, stringHandler, longHandler));
+
+        members.sort(this.testSubject);
+        assertTrue(members.indexOf(longHandler) < members.indexOf(numberHandler));
+        assertEquals(3, members.indexOf(objectHandler));
+    }
+
     @Test
     public void testNotInSameHierarchyUsesPriorityBasedEvaluation() throws Exception {
         assertTrue("Number should appear before String based on priority", testSubject.compare(numberHandler, stringHandler) < 0);