# pingora-ketama
A Rust port of the nginx consistent hashing algorithm.
This crate provides a consistent hashing algorithm which is identical in
behavior to [nginx consistent hashing](https://www.nginx.com/resources/wiki/modules/consistent_hash/).
Using a consistent hash strategy like this is useful when one wants to
minimize the amount of requests that need to be rehashed to different nodes
when a node is added or removed.
Here's a simple example of how one might use it:
```
use pingora_ketama::{Bucket, Continuum};
# #[allow(clippy::needless_doctest_main)]
fn main() {
// Set up a continuum with a few nodes of various weight.
let mut buckets = vec![];
buckets.push(Bucket::new("127.0.0.1:12345".parse().unwrap(), 1));
buckets.push(Bucket::new("127.0.0.2:12345".parse().unwrap(), 2));
buckets.push(Bucket::new("127.0.0.3:12345".parse().unwrap(), 3));
let ring = Continuum::new(&buckets);
// Let's see what the result is for a few keys:
for key in &["some_key", "another_key", "last_key"] {
let node = ring.node(key.as_bytes()).unwrap();
println!("{}: {}:{}", key, node.ip(), node.port());
}
}
```
```bash
# Output:
some_key: 127.0.0.3:12345
another_key: 127.0.0.3:12345
last_key: 127.0.0.2:12345
```
We've provided a health-aware example in
`pingora-ketama/examples/health_aware_selector.rs`.
For a carefully crafted real-world example, see the [`pingora-load-balancing`](https://docs.rs/pingora-load-balancing)
crate.