fix: Broadcast of post to sse blocks execution (#11)

It seems some issues around the Broadcast functionality was blocking my
entire post db writer causing the feed to go stale as no posts were
being written.

Two fixes have been implemented for this. First the Broadcast receiver
function no longer requests a mutex lock. If it tries to send a post to
a closed or nil channel, we don't really care. Locking for every post
coming in would likely lead to situations where multiple calls to
Broadcast would be waiting for the previous to complete sending channel
events.

Secondly the Broadcast call is called in a go routine (i.e. go
server.Broadcast(post)). This should allow the post subscriber in the
serve command to quickly process the posts regardless of how long the
broadcast function uses to loop over SSE clients.

cmd/serve.go

@@ -55,6 +55,7 @@ func serveCmd() *cli.Command {
 				Value:   3000,
 			},
 		},
+
 		Action: func(ctx *cli.Context) error {
 
 			log.Info("Starting Norsky feed generator")
@@ -100,9 +101,11 @@ func serveCmd() *cli.Command {
 			go func() {
 				for post := range postChan {
 					switch post := post.(type) {
+					// Don't crash if broadcast fails
 					case models.CreatePostEvent:
 						dbPostChan <- post
-						broadcaster.Broadcast(post) // Broadcast new post to SSE clients
+						// Broadcast without blocking
+						go broadcaster.Broadcast(post) // Broadcast new post to SSE clients
 					default:
 						dbPostChan <- post
 					}

server/server.go

@@ -59,9 +59,6 @@ func (b *Broadcaster) Broadcast(post models.CreatePostEvent) {
 	log.WithFields(log.Fields{
 		"clients": len(b.clients),
 	}).Info("Broadcasting post to SSE clients")
-
-	b.Lock()
-	defer b.Unlock()
 	for _, client := range b.clients {
 		client <- post
 	}
@@ -82,8 +79,12 @@ func (b *Broadcaster) AddClient(key string, client chan models.CreatePostEvent)
 func (b *Broadcaster) RemoveClient(key string) {
 	b.Lock()
 	defer b.Unlock()
+	// Check if client channel exists in map
 	if _, ok := b.clients[key]; !ok {
-		close(b.clients[key])
+		// Close the channel unless it's already closed
+		if b.clients[key] != nil {
+			close(b.clients[key])
+		}
 		delete(b.clients, key)
 	}