public void seekFirst(final TNode root) {
      current = root;
      height = 0;
      if (root != null) {
        while (current.avlLeft != null) {
          stack[height++] = current;
          current = (TNode) current.avlLeft;
        }
      }
    }
Reset the iterator, and seeks to the first (min) node of the tree
@param root the current root of the tree
hbase-common/src/main/java/org/apache/hadoop/hbase/util/AvlUtil.java