void trackAgeAtAccess(long creationTimeMs) {
      long ageInMs = SystemTime.getInstance().milliseconds() - creationTimeMs;
      this.ageInMs.update(ageInMs);
      if (ageInMs < TimeUnit.MINUTES.toMillis(1)) {
        lessThanMinuteOld.inc();
      } else if (ageInMs < TimeUnit.HOURS.toMillis(1)) {
        betweenMinuteAndHourOld.inc();
      } else if (ageInMs < TimeUnit.DAYS.toMillis(1)) {
        betweenHourAndDayOld.inc();
      } else if (ageInMs < TimeUnit.DAYS.toMillis(7)) {
        betweenDayAndWeekOld.inc();
      } else if (ageInMs < TimeUnit.DAYS.toMillis(30)) {
        betweenWeekAndMonthOld.inc();
      } else if (ageInMs < TimeUnit.DAYS.toMillis(30 * 3)) {
        betweenMonthAndThreeMonthsOld.inc();
      } else if (ageInMs < TimeUnit.DAYS.toMillis(30 * 6)) {
        betweenThreeMonthsAndSixMonthsOld.inc();
      } else if (ageInMs < TimeUnit.DAYS.toMillis(30 * 12)) {
        betweenSixMonthsAndYearOld.inc();
      } else {
        moreThanYearOld.inc();
      }
    }
Tracks the age of the time of access.
@param creationTimeMs the time of creation of the blob.
ambry-router/src/main/java/com/github/ambry/router/NonBlockingRouterMetrics.java