Fixed listener registry to eject listeners only if they indeed exceed the limit.

Change-Id: Ic9453b5b1eabc3d9c92af01e6817612e710bfba8

@@ -30,6 +30,8 @@ import static org.slf4j.LoggerFactory.getLogger;
 public class ListenerRegistry<E extends Event, L extends EventListener<E>>
         implements EventSink<E> {
 
+    private static final long LIMIT = 1_800; // ms
+
     private final Logger log = getLogger(getClass());
 
     private long lastStart;
@@ -80,10 +82,13 @@ public class ListenerRegistry<E extends Event, L extends EventListener<E>>
     @Override
     public void onProcessLimit() {
         if (lastStart > 0) {
+            long duration = System.currentTimeMillis() - lastStart;
+            if (duration > LIMIT) {
                 log.error("Listener {} exceeded execution time limit: {} ms; ejected",
                           lastListener.getClass().getName(),
-                      System.currentTimeMillis() - lastStart);
+                          duration);
                 removeListener(lastListener);
+            }
             lastStart = 0;
         }
     }

@@ -19,11 +19,11 @@
         <step name="Ping-1"
               exec="onos-mininet sendAndExpect h1 ping -c1 h4 --expect \ 0% packet loss"/>
         <step name="Link-1-Down" requires="Ping-1"
-              exec="onos-mininet sendAndExpect link s4 s5 down --expect ."/>
+              exec="onos-mininet sendAndExpect link s4 s7 down --expect ."/>
         <step name="Ping-2" requires="Link-1-Down"
               exec="onos-mininet sendAndExpect h1 ping -c1 h4 --expect \ 0% packet loss"/>
         <step name="Link-2-Down" requires="Ping-2"
-              exec="onos-mininet sendAndExpect link s4 s7 down --expect ."/>
+              exec="onos-mininet sendAndExpect link s4 s5 down --expect ."/>
         <step name="Ping-3" requires="Link-2-Down"
               exec="onos-mininet sendAndExpect h1 ping -c1 h4 --expect 100% packet loss"/>
         <step name="Link-1-Up" requires="Ping-3"