public static MaxSamplesPerPeriod withSteadyClock(long periodLengthInNanos, long maxSamplesPerPeriod) {
        // We make a reasonable assumption that System.nanoTime uses the underlying steady clock.
        return new MaxSamplesPerPeriod(System::nanoTime, periodLengthInNanos, maxSamplesPerPeriod);
    }
Very basic sampling strategy which allows for sampling N requests within a fixed
time window. No attempt is made to distribute the samples evenly within the time
period; this is on a first-come, first-serve basis.
vespajlib/src/main/java/ai/vespa/sampling/MaxSamplesPerPeriod.java