@Override
    public void visit(FileCopyGetChunkRequest fileCopyGetChunkRequest) {
      metrics.fileCopyGetChunkRequestQueueTimeInMs.update(requestQueueTime);
      metrics.fileCopyGetChunkRequestRate.mark();
      metrics.fileCopyGetChunkProcessingTimeInMs.update(requestProcessingTime);
      responseQueueTimeHistogram = metrics.fileCopyGetChunkResponseQueueTimeInMs;
      responseSendTimeHistogram = metrics.fileCopyGetChunkSendTimeInMs;
      requestTotalTimeHistogram = metrics.fileCopyGetChunkTotalTimeInMs;
      if (isRequestDropped) {
        metrics.fileCopyGetChunkDroppedRate.mark();
        metrics.totalRequestDroppedRate.mark();
      }
    }
Used to update common metrics for the incoming request.
ambry-server/src/main/java/com/github/ambry/server/AmbryRequests.java