HashRing

Documentation

A minimal implementation of consistent hashing as described in [Consistent Hashing and Random Trees: Distributed Caching Protocols for Relieving Hot Spots on the World Wide Web] (https://www.akamai.com/es/es/multimedia/documents/technical-publication/consistent-hashing-and-random-trees-distributed-caching-protocols-for-relieving-hot-spots-on-the-world-wide-web-technical-publication.pdf). Clients can use the HashRing struct to add consistent hashing to their applications. HashRing's API consists of three methods: add, remove, and get for adding a node to the ring, removing a node from the ring, and getting the node responsible for the provided key.

Example

Below is a simple example of how an application might use HashRing to make use of consistent hashing. Since HashRing exposes only a minimal API clients can build other abstractions, such as virtual nodes, on top of it. The example below shows one potential implementation of virtual nodes on top of HashRing

```rust extern crate hashring;

use std::net::{IpAddr, SocketAddr}; use std::str::FromStr;

use hashring::HashRing;

[derive(Debug, Copy, Clone)]

struct VNode { id: usize, addr: SocketAddr, }

impl VNode { fn new(ip: &str, port: u16, id: usize) -> Self { let addr = SocketAddr::new(IpAddr::from_str(&ip).unwrap(), port); VNode { id: id, addr: addr, } } }

impl ToString for VNode { fn to_string(&self) -> String { format!("{}|{}", self.addr, self.id) } }

impl PartialEq for VNode { fn eq(&self, other: &VNode) -> bool { self.id == other.id && self.addr == other.addr } }

fn main() { let mut ring: HashRing = HashRing::new();

let mut nodes = vec![];
nodes.push(VNode::new("127.0.0.1", 1024, 1));
nodes.push(VNode::new("127.0.0.1", 1024, 2));
nodes.push(VNode::new("127.0.0.2", 1024, 1));
nodes.push(VNode::new("127.0.0.2", 1024, 2));
nodes.push(VNode::new("127.0.0.2", 1024, 3));
nodes.push(VNode::new("127.0.0.3", 1024, 1));

for node in nodes {
    ring.add(node);
}

println!("{:?}", ring.get("foo"));
println!("{:?}", ring.get("bar"));
println!("{:?}", ring.get("baz"));

} ```