Struct EventSubscriptions 

pub struct EventSubscriptions<E> { /* private fields */ }

Cancellable, optionally filtered registry for event-hook observers.

Synchronous best-effort notification semantics match dispatch_event_callbacks: observers run inline on the emitter path, each isolated with catch_unwind. Observers must return quickly, must not hold locks across the call, and must not call back into the emitting subsystem.

Reentrancy: dispatch snapshots the subscription list, releases the internal lock, then evaluates filters and invokes callbacks. A filter or callback may therefore register or remove observers without deadlocking; registrations made during dispatch do not affect the in-flight dispatch. A panicking filter skips its observer and is counted the same as a panicking callback.

Implementations

impl<E> EventSubscriptions<E>

pub fn new() -> Self

pub fn add(&self, callback: Arc<dyn Fn(&E) + Send + Sync>) -> SubscriptionId

Register an observer, returning its subscription id.

pub fn add_filtered( &self, callback: Arc<dyn Fn(&E) + Send + Sync>, filter: Option<EventFilter<E>>, ) -> SubscriptionId

Register an observer with an optional filter predicate.

pub fn remove(&self, id: SubscriptionId) -> bool

Remove a previously registered observer. Returns true if present.

pub fn clear(&self)

Remove all registered observers.

pub fn subscribe( &self, callback: Arc<dyn Fn(&E) + Send + Sync>, ) -> SubscriptionGuard<'_, E>

Register an observer and receive an RAII guard that unsubscribes on drop. Useful for scoped subscriptions in tests and request handlers where manual remove is easy to forget.

pub fn len(&self) -> usize

Number of registered observers.

pub fn is_empty(&self) -> bool

Whether any observer is registered.

pub fn dispatch(&self, owner: &str, event: &E) -> usize

Dispatch an event to matching observers with panic isolation.

Returns the number of observers that panicked.

pub fn dispatch_detailed(&self, owner: &str, event: &E) -> DispatchOutcome

Dispatch with a full outcome breakdown.

pub fn dispatch_timed( &self, owner: &str, event: &E, slow_threshold: Duration, ) -> TimedDispatchOutcome

Timed dispatch: like dispatch_detailed, additionally measuring each callback’s wall time. Callbacks reaching slow_threshold are counted in slow, contribute to slowest_ms, and emit a log::warn so slow observers are visible without affecting delivery.

Timing costs one Instant::now() pair per delivered callback, so hot paths should keep using dispatch/dispatch_detailed and opt into this only for diagnostics or slow-path emission points.

Trait Implementations

impl<E> Default for EventSubscriptions<E>

fn default() -> Self

Returns the “default value” for a type.