# HashRing
[](https://travis-ci.org/reset/hash-ring-ex)
A consistent hash-ring implemention leveraging the excellent [C hash-ring lib](https://github.com/chrismoos/hash-ring) by [Chris Moos](https://github.com/chrismoos) for Elixir.
## Requirements
* Elixir 0.13.0 or newer
## Installation
Add HashRing as a dependency in your `mix.exs` file
```elixir
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
```elixir
{: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
```elixir
{:ok, "first_node"} = HashRing.find(pid, "my_key")
```
Nodes can also be easily dropped
```elixir
: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`
```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>)
