static int optimalNumOfHashFunctions(long n, long m) {
    return Math.max(1, (int) Math.round((double) m / n * Math.log(2)));
  }
A constructor to support rebuilding the BloomFilter from a serialized representation.
@param bits BloomK sketch data in form of array of longs.
@param numFuncs  Number of functions called as K.
storage-api/src/java/org/apache/hive/common/util/BloomKFilter.java