@Override
    public void visit(TtlUpdateRequest ttlUpdateRequest) {
      metrics.updateBlobTtlRequestQueueTimeInMs.update(requestQueueTime);
      metrics.updateBlobTtlRequestRate.mark();
      metrics.updateBlobTtlProcessingTimeInMs.update(requestProcessingTime);
      responseQueueTimeHistogram = metrics.updateBlobTtlResponseQueueTimeInMs;
      responseSendTimeHistogram = metrics.updateBlobTtlSendTimeInMs;
      requestTotalTimeHistogram = metrics.updateBlobTtlTotalTimeInMs;
      if (isRequestDropped) {
        metrics.updateBlobTtlDroppedRate.mark();
        metrics.totalRequestDroppedRate.mark();
      }
    }
Used to update common metrics for the incoming request.
ambry-server/src/main/java/com/github/ambry/server/AmbryRequests.java