private ReadWriteLock getDagLock(QueryIdentifier queryIdentifier) {
    lock.lock();
    try {
      ReadWriteLock dagLock = dagSpecificLocks.get(queryIdentifier);
      if (dagLock == null) {
        dagLock = ReadWriteLockMetrics.wrap(conf,
                                            new ReentrantReadWriteLock(),
                                            LOCK_METRICS);
        dagSpecificLocks.put(queryIdentifier, dagLock);
      }
      return dagLock;
    } finally {
      lock.unlock();
    }
  }
Register an update to a source within an executing dag
@param queryIdentifier
@param sourceName
@param sourceState
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/QueryTracker.java