protected @Override boolean removeEldestEntry(Map.Entry<Point, TimeStampedMetric> eldest) {
                    return size() > pointsToKeep;
                }
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