CKey

CKey is an experimental consistent hash key library, implemented in Rust.

See the theory about consistent hashing. This library could be used as a brick to implement a Chord ring. It provides 256-bit keys, with some helpers to add, compare, and know their position on the ring. Internally, keys are stored on 4 unsigned integers of 64-bit each.

Status

For now this is a toy project, clearly NOT suitable for production use.

Usage

use ckey::CKey;

let k1 = CKey::rand();
let k2 = k1.next();
let k3 = k2 + 10u8;
assert!(k2.inside(k1, k3));
let k4 = CKey::from(1000u16);
assert_eq!("0.015258789", format!("{}", k4));

Benchmarks

Taken from a random CI job:

running 6 tests
test tests::bench_bytes    ... bench:          28 ns/iter (+/- 0)
test tests::bench_display  ... bench:         204 ns/iter (+/- 3)
test tests::bench_from_f64 ... bench:          10 ns/iter (+/- 0)
test tests::bench_incr     ... bench:           2 ns/iter (+/- 0)
test tests::bench_inside   ... bench:          10 ns/iter (+/- 1)
test tests::bench_serial   ... bench:         468 ns/iter (+/- 106)
test result: ok. 0 passed; 0 failed; 0 ignored; 6 measured; 0 filtered out; finished in 6.37s

This is not the result of extensive, thorough benchmarking, just a random snapshot at some point in development history.

TL;DR relatively fast, though slower than standard integer ops.

The implementation tries to optimize for the speed of operations like incr or inside which are typically repeated a lot of times in a real-world program. OTOH creation and serialization of keys are rather costly.

To run the benchmarks:

cd bench
rustup default nightly
cargo bench

Links

• crate on crates.io
• doc on docs.rs
• source on gitlab.com

License

Ckey is licensed under the MIT license.