@Override
  public void updateHistogram(String name, long value) {
    MutableHistogram histo = metricsRegistry.getHistogram(name);
    histo.add(value);
  }
Increment a named counter by some value.
@param key   the name of the counter
@param delta the ammount to increment
hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/metrics/BaseSourceImpl.java