Enha: simplify sse (worsened event recieving)

broker/sse.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"log/slog"
 	"net/http"
+	"os"
 	"time"
 )
 
@@ -20,22 +21,18 @@ type (
 	Broker       struct {
 		// Events are pushed to this channel by the main events-gathering routine
 		Notifier NotifierChan
-		// New client connections
-		newClients chan NotifierChan
-		// Closed client connections
-		closingClients chan NotifierChan
-		// Client connections registry
-		clients map[NotifierChan]struct{}
+		log      *slog.Logger
 	}
 )
 
 func NewBroker() (broker *Broker) {
 	// Instantiate a broker
 	return &Broker{
-		Notifier:       make(NotifierChan, 1),
-		newClients:     make(chan NotifierChan),
-		closingClients: make(chan NotifierChan),
-		clients:        make(map[NotifierChan]struct{}),
+		Notifier: make(NotifierChan, 100),
+		log: slog.New(slog.NewJSONHandler(os.Stderr, &slog.HandlerOptions{
+			Level:     slog.LevelDebug,
+			AddSource: true,
+		})),
 	}
 }
 
@@ -44,7 +41,6 @@ var Notifier *Broker
 // for use in different packages
 func init() {
 	Notifier = NewBroker()
-	go Notifier.Listen()
 }
 
 func (broker *Broker) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -59,9 +55,6 @@ func (broker *Broker) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	}
 	w.Header().Set("Access-Control-Allow-Origin", origin)
 	w.Header().Set("Access-Control-Allow-Credentials", "true")
-	messageChan := make(NotifierChan, 10) // Buffered channel
-	broker.newClients <- messageChan
-	defer func() { broker.closingClients <- messageChan }()
 	ctx := r.Context()
 	// browser can close sse on its own; ping every 2s to prevent
 	heartbeat := time.NewTicker(2 * time.Second)
@@ -69,12 +62,14 @@ func (broker *Broker) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	for {
 		select {
 		case <-ctx.Done():
+			broker.log.Debug("broker: got ctx done")
 			// Client disconnected
 			return
-		case event := <-messageChan:
+		case event := <-broker.Notifier:
+			broker.log.Debug("got event", "event", event)
 			_, err := fmt.Fprintf(w, "event: %s\ndata: %s\n\n", event.EventName, event.Payload)
 			if err != nil {
-				fmt.Println(err)
+				broker.log.Error("failed to write event", "error", err)
 				// Client disconnected
 				return
 			}
@@ -82,38 +77,10 @@ func (broker *Broker) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		case <-heartbeat.C:
 			// Send SSE heartbeat comment
 			if _, err := fmt.Fprint(w, ":\n\n"); err != nil {
+				broker.log.Error("failed to write heartbeat", "error", err)
 				return // Client disconnected
 			}
 			w.(http.Flusher).Flush()
 		}
 	}
 }
-
-// Listen for new notifications and redistribute them to clients
-func (broker *Broker) Listen() {
-	for {
-		select {
-		case s := <-broker.newClients:
-			// A new client has connected.
-			// Register their message channel
-			broker.clients[s] = struct{}{}
-			slog.Info("Client added", "clients listening", len(broker.clients))
-		case s := <-broker.closingClients:
-			// A client has dettached and we want to
-			// stop sending them messages.
-			delete(broker.clients, s)
-			slog.Info("Client removed", "clients listening", len(broker.clients))
-		case event := <-broker.Notifier:
-			// We got a new event from the outside!
-			// Send event to all connected clients
-			for clientMessageChan := range broker.clients {
-				select {
-				case clientMessageChan <- event:
-				case <-time.After(patience):
-					delete(broker.clients, clientMessageChan)
-					slog.Info("Client was removed", "clients listening", len(broker.clients))
-				}
-			}
-		}
-	}
-}