jump_consistent_hashing.rb

def jump_consistent_hash(key, num_buckets)
  b = -1
  j = 0

  while j < num_buckets
    b = j
    key = (key * 2862933555777941757 + 1) % (2 ** 64)
    j = ((b + 1) * (2 ** 31) / ((key >> 33) + 1)) % (2 ** 31)
  end

  b
end