Function listenSessionEventOnce

Subscribes to a single session-specific event on the swarm bus service for a specific client, executing a callback when the event matches a filter.

This function sets up a one-time listener for events on the "session-bus" topic associated with a given client ID, invoking the provided callback with the event data when an event is received and passes the filter condition. It is wrapped in beginContext for a clean execution environment and logs the operation via loggerService. The callback is queued using functools-kit to ensure sequential processing, and the listener unsubscribes after the first matching event. The function supports a wildcard client ID ("*") for listening to all clients or validates a specific client session. It returns an unsubscribe function to cancel the listener prematurely.

Throws

If the clientId is not "*" and no active session exists for it.

Example

const unsubscribe = listenSessionEventOnce(
  "client-123",
  (event) => event.type === "start",
  (event) => console.log(event)
);
// Logs the first "start" session event for "client-123"
unsubscribe(); // Cancels listener if not yet triggered
  • listenSessionEventOnce(
        clientId: string,
        filterFn: (event: IBusEvent) => boolean,
        fn: (event: IBusEvent) => void,
    ): () => void

    Parameters

    • clientId: string

      The ID of the client to subscribe to session events for, or "*" to listen to all clients.

    • filterFn: (event: IBusEvent) => boolean

      A function that filters events, returning true to trigger the callback with that event.

    • fn: (event: IBusEvent) => void

      The callback function to execute once when a matching session event is received, passed the event object.

    Returns () => void

    A function to unsubscribe from the session event listener before it triggers.

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