private void updateHashSalt() {
    for (int i = 0; i != 6; i++) {
      salt[i] = gen.nextInt(0x7FFFFFFF);
    }
  }
In case of rehash, hash function h2 is changed by updating the
entries in the salt array with new random values.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/CuckooSetLong.java