@Override public void update(long n){
  DistributionData original;
  do {
    original=value.get();
  }
 while (!value.compareAndSet(original,original.combine(DistributionData.singleton(n))));
  dirty.afterModification();
}

@ Override public void update ( long n ) { DistributionData original ; do { original = value . get ( ) ; } while ( ! value . compareAndSet ( original , original . combine ( DistributionData . singleton ( n ) ) ) ) ; dirty . afterModification ( ) ; }
increment the counter by the given amount .
