private synchronized SourceInfo getSourceInfo(String srcName) {
    SourceInfo sourceInfo = sourceInfoMap.get(srcName);
    if (sourceInfo == null) {
      sourceInfo = new SourceInfo();
      sourceInfoMap.put(srcName, sourceInfo);
    }
    return sourceInfo;
  }
Constructs FragmentRuntimeInfo for scheduling within LLAP daemons.
Also caches state based on state updates.
@param vertexName
@param fragmentNumber
@param priority
@return
llap-tez/src/java/org/apache/hadoop/hive/llap/tezplugins/helpers/SourceStateTracker.java