go-rendezvous

This package provides a simplistic implementation of Rendezvous Hashing with a pluggable hash.Hash function.

From Wikipedia:

Rendezvous or highest random weight (HRW) hashing is an algorithm that allows clients to achieve distributed agreement on a set of k options out of a possible set of n options.

A typical application is when clients need to agree on which sites (or proxies) objects are assigned to.

Rendezvous Hashing is simple in principle, but wide-reaching in application.

For example, to determine ownership of an item:

h := rendezvous.NewHasher(
    rendezvous.WithMembers("node1", "node2", "node3", "node4", "node5"),
)

fmt.Printf("The owner of item is %s\n", h.Owner("item"))
// Output: The owner of item is node3

Or to fairly place replicas of a file in a storage cluster:

h := rendezvous.NewHasher(
    rendezvous.WithMembers("node1", "node2", "node3", "node4", "node5"),
)

fmt.Printf("the nodes to replicate data to are: %v\n", h.Place("item", 3))
// Output: the nodes to replicate data to are: [node3 node5 node1]

Or maybe to implement a priority list:

h := rendezvous.NewHasher(
    rendezvous.WithMembers("node1", "node2", "node3", "node4", "node5"),
)

fmt.Printf("priority list: %v\n", h.Prioritise("item"))
// Output: priority list: [node3 node5 node1 node2 node4]