private synchronized void resetQuotaUsage() {
    cuUsage.replaceAll((k, v) -> new CapacityUnit());
    feUsage.set(new CapacityUnit());
  }
Atomically resets the usage of all the resources.
ambry-quota/src/main/java/com/github/ambry/quota/capacityunit/AmbryCUQuotaSource.java