public static String getUserSpecifiedDagName(Configuration conf) {
    String name = HiveConf.getVar(conf, HiveConf.ConfVars.HIVE_QUERY_NAME);
    return (name != null) ? name : conf.get("mapred.job.name");
  }
Singleton
@return instance of this class
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/DagUtils.java