HRW (hrw v0.1.0)

HRW (Highest Random Weight), also known as rendezvous hashing, maps a key to a node out of a set in a way that stays stable when nodes are added or removed.

This module is stateless. For O(log n) lookups over large node sets, see HRW.Skeleton.

Summary

Functions

owner(key, nodes, opts \\ [])

Returns the node responsible for key.

owners(key, nodes, count, opts \\ [])

Returns the top count nodes responsible for key, in descending weight order.

Functions

owner(key, nodes, opts \\ [])

@spec owner(term(), [term()], keyword()) :: term()

Returns the node responsible for key.

Each node is hashed together with the key; the highest-scoring node wins.

Options

:hash_fn - a function term -> integer. Defaults to &:erlang.phash2/1.

Examples

iex> HRW.owner("192.168.0.1", ["server1", "server2", "server3"])
"server2"

owners(key, nodes, count, opts \\ [])

@spec owners(term(), [term()], non_neg_integer(), keyword()) :: [term()]

Returns the top count nodes responsible for key, in descending weight order.

Options

:hash_fn - a function term -> integer. Defaults to &:erlang.phash2/1.

Examples

iex> HRW.owners("192.168.0.1", ["server1", "server2", "server3"], 2)
["server2", "server3"]