@Override
  protected Void callInternal() throws IOException, InterruptedException {
    return ugi.doAs((PrivilegedExceptionAction<Void>) () -> {
      if (state.compareAndSet(STATE_IDLE, STATE_PROCESSING)) {
        long startTime = counters.startTimeCounter();
        try {
          performDataRead();
          consumer.setDone();
        } catch (Throwable t) {
          consumer.setError(t);
          trace.dumpLog(LOG);
        } finally {
          recordReaderTime(startTime);
          if (state.compareAndSet(STATE_PROCESSING, STATE_IDLE)) { // Always true here.
            cleanup();
          }
        }
      }
      return null;
    });
  }
stripeRgs[stripeIx'] => boolean array (could be a bitmask) of rg-s that need to be read.
Contains only stripes that are read, and only columns included. null => read all RGs.
llap-server/src/java/org/apache/hadoop/hive/llap/io/encoded/OrcEncodedDataReader.java