protected synchronized void sendOrQueueEvent(ReaderEvent readerEvent) {
      LlapBaseRecordReader<?> recordReader = getRecordReader();
      if (recordReader != null) {
        recordReader.handleEvent(readerEvent);
      } else {
        if (LOG.isDebugEnabled()) {
          LOG.debug("No registered record reader, queueing event " + readerEvent.getEventType()
              + " with message " + readerEvent.getMessage());
        }

        try {
          queuedEvents.put(readerEvent);
        } catch (Exception err) {
          throw new RuntimeException("Unexpected exception while queueing reader event", err);
        }
      }
    }
Send the ReaderEvents to the record reader, if it is registered to this responder.
If there is no registered record reader, add them to a list of pending reader events
since we don't want to drop these events.
@param readerEvent
llap-ext-client/src/java/org/apache/hadoop/hive/llap/LlapBaseInputFormat.java