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 - bits are used as such for bitset and are NOT copied, any changes to bits will affect bloom filter
@param numFuncs - number of hash functions
storage-api/src/java/org/apache/hive/common/util/BloomFilter.java