Struct Engine

pub struct Engine {
    state: RwLock<State>,
    stats: EngineStats,
}

Shared, protocol-neutral pub/sub router.

The engine never parses a payload and never names a protocol. It matches RouteKey values and try_sends Deliverys. Adapters own their sockets, their channels, and any schema work.

Fields

state: RwLock<State>

stats: EngineStats

Implementations

impl Engine

pub fn new() -> Self

Creates an empty engine with zero subscriptions and zero counters.

pub fn stats(&self) -> &EngineStats

Process-lifetime counters. Survives Self::drop_adapter.

pub async fn subscribe( &self, adapter_id: impl Into<AdapterId>, sub_id: impl Into<SubId>, route: RouteKey, tx: Sender<Delivery>, ) -> Result<SubscriberKey, EngineError>

Registers a subscriber. The adapter owns tx and reads Deliverys.

A RouteKey with type_hint: None is a wildcard: every type on that topic. A typed key matches only that hint. The same sub_id may be reused on a different adapter.

Errors

Returns EngineError::DuplicateSub if this adapter already registered sub_id.

pub async fn unsubscribe( &self, adapter_id: impl Into<AdapterId>, sub_id: impl Into<SubId>, ) -> Result<(), EngineError>

Removes one subscription. Further publishes will not reach it.

Errors

Returns EngineError::UnknownSub if this adapter has no subscription with that sub_id.

pub async fn drop_adapter(&self, adapter_id: impl Into<AdapterId>) -> usize

Removes every subscription owned by adapter_id.

Returns how many were removed, or 0 if the adapter had none. Call this on shutdown and when a session restarts, or stale subscriptions keep matching and silently discarding messages.

pub async fn publish(&self, envelope: Envelope) -> PublishOutcome

Fans out envelope to matching subscribers. Never inspects the payload.

Matching is exact-plus-wildcard: a publish with type_hint: Some("Ping") reaches both typed(topic, "Ping") and topic(topic) subscribers. A publish with no type hint reaches wildcards only.

Each send is try_send. A full or closed channel counts as dropped and does not block other subscribers.

pub async fn subscription_count(&self) -> usize

Number of registered subscriptions across every adapter.

Used to wait until a newly spawned adapter has subscribed before publishing test traffic. Not a readiness API for production.

Trait Implementations

impl Default for Engine

fn default() -> Self

Returns the “default value” for a type.