private void rescaleIfNeeded() {
final long now = clock.getTick();
final long next = nextScaleTime.get();
if (now >= next) {
rescale(now, next);
}
}
/**
* Creates a new {@link ExponentiallyDecayingReservoir}.
*
* @param size the number of samples to keep in the sampling reservoir
* @param alpha the exponential decay factor; the higher this is, the more biased the reservoir
* will be towards newer values
* @param clock the clock used to timestamp samples and track rescaling
*/
public ExponentiallyDecayingReservoir(int size, double alpha, Clock clock) {
this.values = new ConcurrentSkipListMap<Double, WeightedSample>();
this.lock = new ReentrantReadWriteLock();
this.alpha = alpha;
this.size = size;
this.clock = clock;
this.count = new AtomicLong(0);
this.startTime = currentTimeInSeconds();
this.nextScaleTime = new AtomicLong(clock.getTick() + RESCALE_THRESHOLD);
}