Struct EventBus 

pub struct EventBus { /* private fields */ }

Broadcast-based event bus for the framework

Uses tokio::sync::broadcast which allows multiple receivers and is designed for exactly this kind of pub/sub pattern.

The bus is cheap to clone (Arc internally) and can be shared across threads.

EventLog Bridge

When an EventLog is attached via with_event_log(), every published event is also appended to the persistent log. The EventLog becomes the source of truth, while the broadcast channel remains the real-time notification path.

publish(event) ──┬──▶ broadcast channel (real-time, fire-and-forget)
                 └──▶ EventLog.append() (persistent, replayable)

Implementations

impl EventBus

pub fn new(capacity: usize) -> Self

Create a new EventBus with the given channel capacity

The capacity determines how many events can be buffered before slow receivers start losing events (lagged).

Arguments

• capacity - Buffer size for the broadcast channel (recommended: 1024)

pub fn with_event_log(self, event_log: Arc<dyn EventLog>) -> Self

Attach a persistent EventLog to this bus

When set, every publish() call also appends the event to the log. The append is done via tokio::spawn to avoid blocking the publisher.

This enables the event flow system to consume events from the durable log instead of the ephemeral broadcast channel.

pub fn event_log(&self) -> Option<&Arc<dyn EventLog>>

Get a reference to the attached EventLog, if any

pub fn publish(&self, event: FrameworkEvent) -> usize

Publish an event to all subscribers

This is non-blocking and will never fail. If there are no subscribers, the event is simply dropped. If subscribers are lagging, they will receive a Lagged error on their next recv().

If an EventLog is attached, the event is also appended to the log asynchronously (fire-and-forget via tokio::spawn).

Returns the number of broadcast receivers that will receive the event.

pub fn subscribe(&self) -> Receiver<EventEnvelope>

Subscribe to events

Returns a receiver that will get all future events published to the bus. Events published before this call are not received.

pub fn receiver_count(&self) -> usize

Get the current number of active subscribers

Trait Implementations

impl Clone for EventBus

fn clone(&self) -> EventBus

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for EventBus

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

Formats the value using the given formatter.

impl Default for EventBus

fn default() -> Self

Returns the “default value” for a type.