@Override
  public void update(long value) {
    counter.increment();
    histogram.add(value, 1);
  }
Custom histogram implementation based on FastLongHistogram. Dropwizard-based histograms are slow
compared to this implementation, so we are using our implementation here. See HBASE-15222.
hbase-metrics/src/main/java/org/apache/hadoop/hbase/metrics/impl/HistogramImpl.java