public void setupFeUsageAmplificationFactorMetrics(final int frontendUsageReadAmplificationFactor,
      final int frontendUsageWriteAmplificationFactor) {
    frontendUsageReadAmplificationGauge =
        metricRegistry.gauge(MetricRegistry.name(QuotaManager.class, "FrontendUsageReadAmplifcationFactor"),
            () -> (Gauge<Integer>) () -> frontendUsageReadAmplificationFactor);
    frontendUsageWriteAmplificationGauge =
        metricRegistry.gauge(MetricRegistry.name(QuotaManager.class, "FrontendUsageWriteAmplifcationFactor"),
            () -> (Gauge<Integer>) () -> frontendUsageWriteAmplificationFactor);
  }
Setup the {@link Gauge}s for read and write amplification factor.
Frontend usage cost could get amplified because to serve one copy of data, frontend might need to simultaneously
read or write the data over network to multiple storage nodes.
@param frontendUsageReadAmplificationFactor read amplification factor.
@param frontendUsageWriteAmplificationFactor write amplification factor.
ambry-api/src/main/java/com/github/ambry/quota/QuotaMetrics.java