#pragma once #include <cstdint> #include <cstddef> /* * Author: Konstantin Oblakov * * Maps random ui64 x (in fact hash of some string) to n baskets/shards. * Output value is id of a basket. 0 <= ConsistentHashing(x, n) < n. * Probability of all baskets must be equal. Also, it should be consistent * in terms, that with different n_1 < n_2 probability of * ConsistentHashing(x, n_1) != ConsistentHashing(x, n_2) must be equal to * (n_2 - n_1) / n_2 - the least possible with previous conditions. * It requires O(1) memory and cpu to calculate. So, it is faster than classic * consistent hashing algos with points on circle. */ std::size_t ConsistentHashing(std::uint64_t x, std::size_t n); // Works for n <= 32768 std::size_t ConsistentHashing(std::uint64_t lo, std::uint64_t hi, std::size_t n); // Works for n <= 2^31