# HashRing

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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"}

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 or `start/1`

{: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)

{:ok, pid} = HashRing.start_link(replicas: 5)

And the standard GenServer options can be passed in, too

{:ok, pid} = HashRing.start_link(name: :my_hash_ring)

## Authors

Jamie Winsor (<>)