HashRing

A consistent hash-ring implemention leveraging the excellent C hash-ring lib by Chris Moos for Elixir.

Requirements

• Elixir 0.13.0 or newer

Installation

Add HashRing as a dependency in your mix.exs file

defp deps do
  [
    {hash_ring: "~> 1.0"}
  ]
end

Then run mix deps.get in your shell to fetch the dependencies.

Usage

Start or supervise a new HashRing with HashRing.start_link/1 or HashRing.start/1 and add some nodes

{:ok, pid} = HashRing.start_link
:ok = HashRing.add(pid, "first_node")
:ok = HashRing.add(pid, "second_node")

Then find the appropriate node for your key

{:ok, "first_node"} = HashRing.find(pid, "my_key")

Nodes can also be easily dropped

:ok = HashRing.drop(pid, "first_node")
{:ok, "second_node"} = HashRing.find(pid, "my_key")

Configuring

Started rings will use an MD5 hash function by default. In tests MD5 is on average about 25% faster. The hashing function to use can be specified as an option sent to start_link/1 orstart/1` elixir {:ok, md5} = HashRing.start_link(hash_func: :md5) {:ok, sha1} = HashRing.start_link(hash_func: :sha1) The number of replicas can be configured, too (default: 128) elixir {:ok, pid} = HashRing.start_link(replicas: 5) And the standard GenServer options can be passed in, too elixir {:ok, pid} = HashRing.start_link(name: :my_hash_ring) ## Authors Jamie Winsor (jamie@vialstudios.com)