Struct HashRing

Source

pub struct HashRing<N, B> { /* private fields */ }

Expand description

A hash ring for consistent hashing.

§Examples

use hulahoop::HashRing;
let mut ring: HashRing<&str, _> = HashRing::new();

ring.insert("10.0.0.1:1234", 1);
assert_eq!(ring.get("Some key"), Some(&"10.0.0.1:1234"));

Implementations§

Source §

impl<N> HashRing<N, BuildHasherDefault<DefaultHasher>>

Source

pub fn new() -> Self

Creates a new HashRing with the default hasher.

§Examples

use hulahoop::HashRing;

let mut ring: HashRing<&str, _> = HashRing::new();

ring.insert("10.0.0.1:1234", 1);
assert_eq!(ring.get("Some key"), Some(&"10.0.0.1:1234"));

Source §

impl<N, B> HashRing<N, B>
where N: Hash, B: BuildHasher,

Source

pub fn with_hasher(hash_builder: B) -> Self

Creates an empty HashRing which will use the given hash_builder to hash nodes and keys.

§Examples

use std::hash::BuildHasherDefault;
use rustc_hash::FxHasher;
use hulahoop::HashRing;

let mut ring: HashRing<&str, BuildHasherDefault<FxHasher>> = HashRing::with_hasher(BuildHasherDefault::<FxHasher>::default());

ring.insert("10.0.0.1:1234", 1);
assert_eq!(ring.get("Some key"), Some(&"10.0.0.1:1234"));

Source

pub fn hasher(&self) -> &B

Returns a reference to the ring’s BuildHasher.

§Examples

use hulahoop::HashRing;
use std::collections::hash_map::RandomState;

let hasher = RandomState::new();
let ring: HashRing<&str, _> = HashRing::with_hasher(hasher);
let hasher: &RandomState = ring.hasher();

Source

pub fn insert(&mut self, node: N, weight: u64) -> Option<N>

Inserts a node to the HashRing.

A weight, representing the number of virtual nodes for the given node, must be provided.

There can be hash collisions resulting in fewer than weight virtual nodes added. If the ring did not have this node present or weight is 0, None is returned. If the ring did have this node present, the virtual nodes are updated, and the old node is returned.

§Examples

use hulahoop::HashRing;

let mut ring: HashRing<&str, _> = HashRing::default();

assert_eq!(ring.insert("10.0.0.1:1234", 1), None);
assert_eq!(ring.insert("10.0.0.1:1234", 1), Some("10.0.0.1:1234"));

Source

pub fn get<K>(&self, key: K) -> Option<&N>
where K: Hash,

Returns a reference to the node with a hash closest to the hash of the key.

§Examples

use hulahoop::HashRing;

let mut ring: HashRing<&str, _> = HashRing::default();

ring.insert("10.0.0.1:1234", 1);
assert_eq!(ring.get("Some key"), Some(&"10.0.0.1:1234"));
assert_eq!(ring.get(12345), Some(&"10.0.0.1:1234"));

Source

pub fn len(&self) -> usize

Returns the number of nodes in the Hashring.

It does not return the number of virtual nodes (as specified with weight in the insert method).

§Examples

use hulahoop::HashRing;

let mut ring: HashRing<&str, _> = HashRing::default();

ring.insert("10.0.0.1:1234", 10);
ring.insert("10.0.0.2:1234", 10);
assert_eq!(ring.len(), 2);

Source

pub fn is_empty(&self) -> bool

Returns true if the ring contains no elements.

§Examples

use hulahoop::HashRing;

let mut ring: HashRing<&str, _> = HashRing::default();
assert!(ring.is_empty());

ring.insert("10.0.0.1:1234", 10);
assert!(!ring.is_empty());

Source

pub fn contains_node(&self, node: &N) -> bool

Returns true if the ring contains the specified node.

§Examples

use hulahoop::HashRing;

let mut ring: HashRing<&str, _> = HashRing::default();

ring.insert("10.0.0.1:1234", 10);
assert_eq!(ring.contains_node(&"10.0.0.1:1234"), true);
assert_eq!(ring.contains_node(&"10.0.0.2:1234"), false);

Source

pub fn iter(&self) -> Iter<'_, N> ⓘ

An iterator visiting all node-weight pairs in arbitrary order. The iterator element type is (&'a N, u64).

The weight is the actual number of virtual nodes. It may be lower than the weight provided when inserting a node in case of hash collisions.

§Examples

use hulahoop::HashRing;

let mut ring: HashRing<&str, _> = HashRing::default();

ring.insert("10.0.0.1:1234", 10);
ring.insert("10.0.0.2:1234", 5);

for (node, weight) in ring.iter() {
    println!("node: {node} weight: {weight}");
}

Source

pub fn remove(&mut self, node: &N) -> u64

Removes a node from the HashRing, returning the number of virtual nodes (weight) of the removed node.

The returned number is the actual number of virtual nodes. It may be lower than the weight provided when inserting a node in case of hash collisions.

§Examples

use hulahoop::HashRing;

let mut ring: HashRing<&str, _> = HashRing::default();

ring.insert("10.0.0.1:1234", 10);
assert_eq!(ring.remove(&"10.0.0.1:1234"), 10);
assert_eq!(ring.remove(&"10.0.0.1:1234"), 0);