private byte[] tryInsert(byte[] x) {
    byte[] temp;

    for(int i = 0; i != n; i++) {
      int hash1 = h1(x, 0, x.length);
      if (t1[hash1] == null) {
        t1[hash1] = x;
        return null;
      }

      // swap x and t1[h1(x)]
      temp = t1[hash1];
      t1[hash1] = x;
      x = temp;

      int hash2 = h2(x, 0, x.length);
      if (t2[hash2] == null) {
        t2[hash2] = x;
        return null;
      }

      // swap x and t2[h2(x)]
      temp = t2[hash2];
      t2[hash2] = x;
      x = temp;
      if (x == null) {
        break;
      }
    }
    return x;
  }
Try to insert with up to n value's "poked out". Return the last value poked out.
If the value is not blank then we assume there was a cycle.
Don't try to insert the same value twice. This is for use in rehash only,
so you won't see the same value twice.
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/CuckooSetBytes.java