HADOOP-12173. NetworkTopology::add calls toString always. Contributed by Inigo Goiri

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/net/NetworkTopology.java

@@ -396,14 +396,13 @@ public class NetworkTopology {
     int newDepth = NodeBase.locationToDepth(node.getNetworkLocation()) + 1;
     netlock.writeLock().lock();
     try {
-      String oldTopoStr = this.toString();
       if( node instanceof InnerNode ) {
         throw new IllegalArgumentException(
           "Not allow to add an inner node: "+NodeBase.getPath(node));
       }
       if ((depthOfAllLeaves != -1) && (depthOfAllLeaves != newDepth)) {
         LOG.error("Error: can't add leaf node " + NodeBase.getPath(node) +
-            " at depth " + newDepth + " to topology:\n" + oldTopoStr);
+            " at depth " + newDepth + " to topology:\n" + this.toString());
         throw new InvalidTopologyException("Failed to add " + NodeBase.getPath(node) +
             ": You cannot have a rack and a non-rack node at the same " +
             "level of the network topology.");