diff --git a/event/bus.go b/event/bus.go index 25388397fe6a90bdbc656df8124da0f6ee3ab621..028bde7b9ccc5b4450e1f039c65ac12d9fc99085 100644 --- a/event/bus.go +++ b/event/bus.go @@ -22,27 +22,53 @@ type Emitter interface { Emit(evt interface{}) } +// Subscription represents a subscription to one or multiple event types. +type Subscription interface { + io.Closer + + // Out returns the channel from which to consume events. + Out() <-chan interface{} +} + // Bus is an interface for a type-based event delivery system. type Bus interface { - // Subscribe creates a new subscription. + // Subscribe creates a new Subscription. // - // Failing to drain the channel may cause publishers to block. CancelFunc must return after - // last send to the channel. + // eventType can be either a pointer to a single event type, or a slice of pointers to + // subscribe to multiple event types at once, under a single subscription (and channel). // - // Example: - // ch := make(chan EventT, 10) - // defer close(ch) - // cancel, err := eventbus.Subscribe(ch) - // defer cancel() - Subscribe(typedChan interface{}, opts ...SubscriptionOpt) (CancelFunc, error) + // Failing to drain the channel may cause publishers to block. + // + // Simple example + // + // sub, err := eventbus.Subscribe(new(EventType)) + // defer sub.Close() + // for e := range sub.Out() { + // event := e.(EventType) // guaranteed safe + // [...] + // } + // + // Multi-type example + // + // sub, err := eventbus.Subscribe([]interface{}{new(EventA), new(EventB)}) + // defer sub.Close() + // for e := range sub.Out() { + // select e.(type): + // case EventA: + // [...] + // case EventB: + // [...] + // } + // } + Subscribe(eventType interface{}, opts ...SubscriptionOpt) (Subscription, error) // Emitter creates a new event emitter. // // eventType accepts typed nil pointers, and uses the type information for wiring purposes. // // Example: - // em, err := eventbus.Emitter(new(EventT)) - // defer em.Close() // MUST call this after being done with the emitter - // em.Emit(EventT{}) + // em, err := eventbus.Emitter(new(EventT)) + // defer em.Close() // MUST call this after being done with the emitter + // em.Emit(EventT{}) Emitter(eventType interface{}, opts ...EmitterOpt) (Emitter, error) }