Struct Subscription

Source

pub struct Subscription { /* private fields */ }

Expand description

Handle representing an active listener or middleware registration.

Returned by the subscribe_* and add_*middleware* methods on EventBus. The listener remains registered as long as the bus is running — dropping a Subscription does not unsubscribe it.

To automatically unsubscribe when a scope exits, convert this into a SubscriptionGuard with into_guard.

§Cloning

Subscription is Clone. All clones refer to the same underlying registration; calling unsubscribe on any clone removes the listener.

Implementations§

Source §

impl Subscription

Source

pub const fn id(&self) -> SubscriptionId

Return the unique SubscriptionId for this registration.

The id can be passed to EventBus::unsubscribe to remove the listener without consuming this handle.

Source

pub const fn name(&self) -> Option<&'static str>

Return the listener name, if one was provided by the handler.

Named handlers expose their name through this getter, making it possible to identify a subscription without querying EventBus::stats. Middleware subscriptions always return None.

Source

pub async fn unsubscribe(self) -> Result<bool, EventBusError>

Remove this listener from the bus.

Returns Ok(true) if the listener was found and removed, Ok(false) if it was already removed, or Err if the bus has shut down.

Source

pub fn into_guard(self) -> SubscriptionGuard

Convert this subscription into a guard that automatically unsubscribes when dropped.

The guard sends a fire-and-forget unsubscribe message in its Drop impl, so no .await is needed. If the bus has already shut down the message is silently discarded.

§Examples

use jaeb::{EventBus, SyncEventHandler, HandlerResult};

#[derive(Clone)]
struct Evt;

struct H;
impl SyncEventHandler<Evt> for H {
    fn handle(&self, _: &Evt) -> HandlerResult { Ok(()) }
}

let bus = EventBus::builder().buffer_size(64).build().await.expect("valid config");
{
    let _guard = bus.subscribe::<Evt, _, _>(H).await.unwrap().into_guard();
    // listener is active inside this scope
}
// guard dropped → listener automatically unsubscribed
bus.shutdown().await.unwrap();