State rescale()

in core/src/main/java/com/spotify/metrics/core/LockFreeExponentiallyDecayingReservoir.java [117:135]

• 16 lines of code
• 3 McCabe index (conditional complexity)

        State rescale(long newTick) {
            long durationNanos = newTick - startTick;
            double scalingFactor = Math.exp(-alphaNanos * durationNanos);
            int newCount = 0;
            ConcurrentSkipListMap<Double, WeightedSample> newValues = new ConcurrentSkipListMap<>();
            if (Double.compare(scalingFactor, 0) != 0) {
                RescalingConsumer consumer = new RescalingConsumer(scalingFactor, newValues);
                values.forEach(consumer);
                // make sure the counter is in sync with the number of stored samples.
                newCount = consumer.count;
            }
            // It's possible that more values were added while the map was scanned, those with the
            // minimum priorities are removed.
            while (newCount > size) {
                Objects.requireNonNull(newValues.pollFirstEntry(), "Expected an entry");
                newCount--;
            }
            return new State(alphaNanos, size, newTick, newCount, newValues);
        }