added sub.mutex handling in the relay Connect() function (#37)

relay.go

@@ -46,6 +46,9 @@ type Relay struct {
 	okCallbacks s.MapOf[string, func(bool)]
 }
 
+// RelayConnect returns a relay object connected to url
+// Once successfully connected, cancelling ctx has no effect 
+// To close the connection, call r.Close()
 func RelayConnect(ctx context.Context, url string) (*Relay, error) {
 	r := &Relay{URL: NormalizeURL(url)}
 	err := r.Connect(ctx)
@@ -141,13 +144,14 @@ func (r *Relay) Connect(ctx context.Context) error {
 					}
 
 					// check if the event matches the desired filter, ignore otherwise
-					if !subscription.Filters.Match(&event) {
-						continue
-					}
-
-					if !subscription.stopped {
+					func() {
+						subscription.mutex.Lock()
+						defer subscription.mutex.Unlock()
+						if !subscription.Filters.Match(&event) || subscription.stopped {
+							return
+						}
 						subscription.Events <- event
-					}
+					}()
 				}
 			case "EOSE":
 				if len(jsonMessage) < 2 {
@@ -181,6 +185,8 @@ func (r *Relay) Connect(ctx context.Context) error {
 	return nil
 }
 
+// Publish sends an "EVENT" command to the relay r as in NIP-01
+// status can be: success, failed, or sent (no response from relay before ctx times out)
 func (r *Relay) Publish(ctx context.Context, event Event) Status {
 	status := PublishStatusFailed
 
@@ -236,6 +242,9 @@ func (r *Relay) Publish(ctx context.Context, event Event) Status {
 	}
 }
 
+// Subscribe sends a "REQ" command to the relay r as in NIP-01
+// Events are returned through the channel sub.Events
+// the subscription is closed when context ctx is cancelled ("CLOSE" in NIP-01)
 func (r *Relay) Subscribe(ctx context.Context, filters Filters) *Subscription {
 	if r.Connection == nil {
 		panic(fmt.Errorf("must call .Connect() first before calling .Subscribe()"))