Stream live server logs over SSE

platform/service/log_events.go

@@ -0,0 +1,87 @@
+package service
+
+import (
+	"strings"
+
+	"browser.local/platform/domain"
+)
+
+const logEventSubscriberBuffer = 512
+
+type LogEventSubscription struct {
+	Events <-chan domain.LogStreamEvent
+	Close  func()
+}
+
+type logEventSubscriber struct {
+	serverInstanceID string
+	events           chan domain.LogStreamEvent
+}
+
+func (svc *CoreService) SubscribeLogEvents(serverInstanceID string) (LogEventSubscription, error) {
+	serverInstanceID = strings.TrimSpace(serverInstanceID)
+	if serverInstanceID == "" {
+		return LogEventSubscription{}, validationError("serverInstanceId is required")
+	}
+	if _, err := svc.store.ServerInstances().Get(serverInstanceID); err != nil {
+		return LogEventSubscription{}, err
+	}
+	events := make(chan domain.LogStreamEvent, logEventSubscriberBuffer)
+	svc.logEventMu.Lock()
+	svc.logEventSubscriberSeq++
+	id := svc.logEventSubscriberSeq
+	svc.logEventSubscribers[id] = logEventSubscriber{serverInstanceID: serverInstanceID, events: events}
+	svc.logEventMu.Unlock()
+	closeOnce := func() {
+		svc.logEventMu.Lock()
+		if subscriber, ok := svc.logEventSubscribers[id]; ok {
+			delete(svc.logEventSubscribers, id)
+			close(subscriber.events)
+		}
+		svc.logEventMu.Unlock()
+	}
+	return LogEventSubscription{Events: events, Close: closeOnce}, nil
+}
+
+func (svc *CoreService) SubscribeLogEventsForSession(sessionID string, serverInstanceID string) (LogEventSubscription, error) {
+	instance, err := svc.GetServerInstanceForSession(sessionID, serverInstanceID)
+	if err != nil {
+		return LogEventSubscription{}, err
+	}
+	return svc.SubscribeLogEvents(instance.ID)
+}
+
+func (svc *CoreService) publishLogEvents(stream domain.LogStream, entries []domain.LogEntry) {
+	if len(entries) == 0 {
+		return
+	}
+	events := make([]domain.LogStreamEvent, len(entries))
+	for index, entry := range entries {
+		events[index] = domain.CopyLogStreamEvent(domain.LogStreamEvent{
+			ServerInstanceID: stream.ServerInstanceID,
+			Stream:           stream,
+			Entry:            entry,
+			LatestSeq:        stream.LatestSeq,
+		})
+	}
+	svc.logEventMu.Lock()
+	for id, subscriber := range svc.logEventSubscribers {
+		if subscriber.serverInstanceID != stream.ServerInstanceID {
+			continue
+		}
+		dropped := false
+		for _, event := range events {
+			select {
+			case subscriber.events <- event:
+			default:
+				delete(svc.logEventSubscribers, id)
+				close(subscriber.events)
+				dropped = true
+			}
+			if dropped {
+				break
+			}
+		}
+	}
+	svc.logEventMu.Unlock()
+}