@SuppressWarnings("serial")
    private LinkedHashMap<Point, TimeStampedMetric> getCachedMetric(String metricName) {
        LinkedHashMap<Point, TimeStampedMetric> points = persistentData.get(metricName);
        if (points == null) {
            points = new LinkedHashMap<>(16, 0.75f, false) {
                protected @Override boolean removeEldestEntry(Map.Entry<Point, TimeStampedMetric> eldest) {
                    return size() > pointsToKeep;
                }
            };
            persistentData.put(metricName, points);
        }
        return points;
    }
The persistence layer for metrics. Both CPU and memory hungry, but
it runs in its own little world.

@author Steinar Knutsen
container-core/src/main/java/com/yahoo/metrics/simple/DimensionCache.java