private ConcurrentMap<String, SourceStateProto> getSourceCompletionMap(QueryIdentifier queryIdentifier) {
    ConcurrentMap<String, SourceStateProto> dagMap = sourceCompletionMap.get(queryIdentifier);
    if (dagMap == null) {
      dagMap = new ConcurrentHashMap<>();
      ConcurrentMap<String, SourceStateProto> old =
          sourceCompletionMap.putIfAbsent(queryIdentifier, dagMap);
      dagMap = (old != null) ? old : dagMap;
    }
    return dagMap;
  }
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