Struct hydra::HashRing

pub struct HashRing<T, S = RandomState> { /* private fields */ }

A concurrent, consistent hash ring.

Provides the following features:

• Lookup optimized ring storage.
• Key overrides that allow you to pin a key to a specific node.

In order to call find_node, T must implement Clone, this is to prevent blocking for too long and keep the ring as up to date as possible.

Implementations

impl<T> HashRing<T>

pub fn new() -> Self

Constructs a new instance of HashRing.

pub fn add_node<K: Hash>(&self, key: K, node: T) -> Option<T>

Adds a node to the existing set of nodes in the ring, this will replace an entry if one exists.

pub fn remove_node<K: Hash>(&self, key: K) -> Option<T>

Removes a node from the existing set of nodes.

pub fn add_nodes<K: Hash, I: IntoIterator<Item = (K, T)>>(&self, nodes: I)

Adds a collection of nodes to the existing set of nodes in the ring, replacing any existing entries if they exist.

pub fn set_nodes<K: Hash, I: IntoIterator<Item = (K, T)>>(&self, nodes: I)

Replaces the nodes in the ring with a new set of nodes.

pub fn map_node<K: Hash, F: FnMut(Option<&T>)>(&self, key: K, map: F)

Finds the node responsible for the given key and passes it to map.

pub fn add_override<K: Hash>(&self, key: K, node: T) -> Option<T>

Adds an override to the ring.

pub fn add_overrides<K: Hash, I: IntoIterator<Item = (K, T)>>( &self, overrides: I )

Adds a collection of overrides to the ring.

pub fn set_overrides<K: Hash, I: IntoIterator<Item = (K, T)>>( &self, overrides: I )

Replaces the overrides in the ring with a new set of overrides.

pub fn remove_override<K: Hash>(&self, key: K) -> Option<T>

Removes an existing override from the ring.

pub fn clear(&self)

Clears all of the nodes and overrides from the hash ring.

impl<T> HashRing<T>

where T: Clone,

pub fn find_node<K: Hash>(&self, key: K) -> Option<T>

Returns the node responsible for key. If there are no nodes in the ring, it will return None.

Trait Implementations

impl<T> Default for HashRing<T>

fn default() -> Self

Returns the “default value” for a type.