Struct Engine 

pub struct Engine { /* private fields */ }

The sharded engine. Owns handles to all shard tasks and routes requests by key hash.

Clone is cheap — it just clones the Vec<ShardHandle> (which are mpsc senders under the hood).

Implementations

impl Engine

pub fn new(shard_count: usize) -> Self

Creates an engine with shard_count shards using default config.

Each shard is spawned as a tokio task immediately. Panics if shard_count is zero.

pub fn with_config(shard_count: usize, config: EngineConfig) -> Self

Creates an engine with shard_count shards and the given config.

Panics if shard_count is zero.

pub fn with_available_cores() -> Self

Creates an engine with one shard per available CPU core.

Falls back to a single shard if the core count can’t be determined.

pub fn with_available_cores_config(config: EngineConfig) -> Self

Creates an engine with one shard per available CPU core and the given config.

pub fn shard_count(&self) -> usize

Returns the number of shards.

pub async fn send_to_shard( &self, shard_idx: usize, request: ShardRequest, ) -> Result<ShardResponse, ShardError>

Sends a request to a specific shard by index.

Used by SCAN to iterate through shards sequentially.

pub async fn route( &self, key: &str, request: ShardRequest, ) -> Result<ShardResponse, ShardError>

Routes a request to the shard that owns key.

pub async fn broadcast<F>( &self, make_req: F, ) -> Result<Vec<ShardResponse>, ShardError>

where F: Fn() -> ShardRequest,

Sends a request to every shard and collects all responses.

Dispatches to all shards first (so they start processing in parallel), then collects the replies. Used for commands like DBSIZE and INFO that need data from all shards.

pub async fn route_multi<F>( &self, keys: &[String], make_req: F, ) -> Result<Vec<ShardResponse>, ShardError>

where F: Fn(String) -> ShardRequest,

Routes requests for multiple keys concurrently.

Dispatches all requests without waiting, then collects responses. The response order matches the key order. Used for multi-key commands like DEL and EXISTS.

Trait Implementations

impl Clone for Engine

fn clone(&self) -> Engine

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Engine

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

Formats the value using the given formatter.