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

README.md

@@ -43,7 +43,8 @@ if _, v, err := nip19.Decode(npub); err == nil {
 	panic(err)
 }
 
-sub := relay.Subscribe(context.Background(), filters)
+ctx, cancel := context.WithCancel(context.Background())
+sub := relay.Subscribe(ctx, filters)
 
 go func() {
 	<-sub.EndOfStoredEvents
@@ -52,7 +53,9 @@ go func() {
 
 for ev := range sub.Events {
 	// handle returned event.
-	// channel will stay open until sub.Unsub() is called
+	// channel will stay open until the ctx is cancelled (in this case, by calling cancel())
+	
+	fmt.Println(ev.ID)
 }
 ```
 

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()"))

subscription.go

@@ -24,6 +24,8 @@ type EventMessage struct {
 	Relay string
 }
 
+// Unsub closes the subscription, sending "CLOSE" to relay as in NIP-01
+// Unsub() also closes the channel sub.Events
 func (sub *Subscription) Unsub() {
 	sub.mutex.Lock()
 	defer sub.mutex.Unlock()
@@ -35,11 +37,14 @@ func (sub *Subscription) Unsub() {
 	sub.stopped = true
 }
 
+// Sub sets sub.Filters and then calls sub.Fire(ctx)
 func (sub *Subscription) Sub(ctx context.Context, filters Filters) {
 	sub.Filters = filters
 	sub.Fire(ctx)
 }
 
+// Fire sends the "REQ" command to the relay
+// when ctx is cancelled, sub.Unsub() is called, closing the subscription
 func (sub *Subscription) Fire(ctx context.Context) {
 	message := []interface{}{"REQ", sub.id}
 	for _, filter := range sub.Filters {