Struct ConsistentHashRing 

pub struct ConsistentHashRing { /* private fields */ }

A consistent-hash ring mapping arbitrary byte keys to ShardIds.

Each shard occupies virtual_nodes (default 150) positions on the ring, providing excellent key distribution even with a small number of shards.

Lookup algorithm

1. Hash the key with FNV-1a.
2. Find the first ring position ≥ the hash (wrap-around to the minimum position if none exists — standard consistent-hashing).
3. Return the ShardId at that ring position.

Implementations

impl ConsistentHashRing

pub fn new(virtual_nodes: usize) -> Self

Create a new ring with the given number of virtual nodes per shard.

pub fn add_shard(&mut self, shard_id: ShardId, _peer_id: &str)

Add shard_id to the ring, placing virtual_nodes replicas.

peer_id is accepted for future extensibility (e.g., zone-aware placement) but is not stored inside the ring itself — it lives in VectorShard.

pub fn remove_shard(&mut self, shard_id: ShardId)

Remove shard_id from the ring, deleting all its virtual nodes.

pub fn get_shard(&self, key: &[u8]) -> Option<ShardId>

Find the shard responsible for key.

Returns None only when the ring is empty.

pub fn shard_count(&self) -> usize

Number of distinct shards currently on the ring.

Trait Implementations

impl Clone for ConsistentHashRing

fn clone(&self) -> ConsistentHashRing

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ConsistentHashRing

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ConsistentHashRing

fn default() -> Self

Returns the “default value” for a type.