Fixes failing ThreeBrokerVirtualTopicNetwork test associated /w AMQ-4296

git-svn-id: https://svn.apache.org/repos/asf/activemq/trunk@1483878 13f79535-47bb-0310-9956-ffa450edef68

activemq-leveldb-store/src/main/scala/org/apache/activemq/leveldb/LevelDBStore.scala

@@ -255,6 +255,14 @@ class LevelDBStore extends LockableServiceSupport with BrokerServiceAware with P
         }
       }
     }
+
+    // Remove topics that don't have subs..
+    for( (name, topic) <- topics.toArray ) {
+      if( topic.subscription_count == 0 ) {
+        removeTopicMessageStore(name)
+      }
+    }
+
     debug("started")
   }
 
@@ -754,6 +762,10 @@ class LevelDBStore extends LockableServiceSupport with BrokerServiceAware with P
       super.asyncAddQueueMessage(context, message, false)
     }
 
+    def subscription_count = subscriptions.synchronized {
+      subscriptions.size
+    }
+
     def gcPosition:Option[(Long, Long)] = {
       var pos = lastSeq.get()
       subscriptions.synchronized {