fix unique logic (move it to a helper function, we can't return two channels because that will break if the caller doesn't read from both.)

relaypool.go

@@ -60,14 +60,18 @@ func NewRelayPool() *RelayPool {
 
 // Add adds a new relay to the pool, if policy is nil, it will be a simple
 // read+write policy.
-func (r *RelayPool) Add(url string, policy RelayPoolPolicy) error {
+func (r *RelayPool) Add(url string, policy RelayPoolPolicy) chan error {
 	if policy == nil {
 		policy = SimplePolicy{Read: true, Write: true}
 	}
 
+	cherr := make(chan error)
+
+	go func() {
 		relay, err := RelayConnect(url)
 		if err != nil {
-		return err
+			cherr <- fmt.Errorf("failed to connect to %s: %w", url, err)
+			return
 		}
 
 		r.Policies.Store(relay.URL, policy)
@@ -86,7 +90,11 @@ func (r *RelayPool) Add(url string, policy RelayPoolPolicy) error {
 			return true
 		})
 
-	return nil
+		cherr <- nil
+		close(cherr)
+	}()
+
+	return cherr
 }
 
 // Remove removes a relay from the pool.
@@ -101,7 +109,7 @@ func (r *RelayPool) Remove(url string) {
 	}
 }
 
-func (r *RelayPool) Sub(filters Filters) (string, chan EventMessage, chan Event) {
+func (r *RelayPool) Sub(filters Filters) (string, chan EventMessage) {
 	random := make([]byte, 7)
 	rand.Read(random)
 	id := hex.EncodeToString(random)
@@ -109,8 +117,6 @@ func (r *RelayPool) Sub(filters Filters) (string, chan EventMessage, chan Event)
 	r.subscriptions.Store(id, filters)
 	eventStream := make(chan EventMessage)
 	r.eventStreams.Store(id, eventStream)
-	uniqueEvents := make(chan Event)
-	emittedAlready := s.MapOf[string, struct{}]{}
 
 	r.Relays.Range(func(_ string, relay *Relay) bool {
 		sub := relay.subscribe(id, filters)
@@ -118,16 +124,28 @@ func (r *RelayPool) Sub(filters Filters) (string, chan EventMessage, chan Event)
 		go func(sub *Subscription) {
 			for evt := range sub.Events {
 				eventStream <- EventMessage{Relay: relay.URL, Event: evt}
-				if _, ok := emittedAlready.LoadOrStore(evt.ID, struct{}{}); !ok {
-					uniqueEvents <- evt
-				}
 			}
 		}(sub)
 
 		return true
 	})
 
-	return id, eventStream, uniqueEvents
+	return id, eventStream
+}
+
+func Unique(all chan EventMessage) chan Event {
+	uniqueEvents := make(chan Event)
+	emittedAlready := s.MapOf[string, struct{}]{}
+
+	go func() {
+		for eventMessage := range all {
+			if _, ok := emittedAlready.LoadOrStore(eventMessage.Event.ID, struct{}{}); !ok {
+				uniqueEvents <- eventMessage.Event
+			}
+		}
+	}()
+
+	return uniqueEvents
 }
 
 func (r *RelayPool) PublishEvent(evt *Event) (*Event, chan PublishStatus, error) {