api/redis/subscriber.go: adding some comments.

api/redis/subscriber.go

@@ -11,8 +11,10 @@ import (
 )
 
 type Subscriber struct {
-	sub      *redis.PubSub
-	ctx      context.Context
+	sub *redis.PubSub
+	ctx context.Context
+
+	// Mutex for channels map.
 	mu       sync.RWMutex
 	timeout  time.Duration
 	channels map[string]chan []byte
@@ -94,11 +96,15 @@ func (s *Subscriber) Read(channel api.Channel) ([]byte, error) {
 }
 
 func (s *Subscriber) Close() error {
+	// Close redis pubsub.
 	err := s.sub.Close()
 
+	// Close all go channels, this will make Read() unblock.
 	for _, ch := range s.channels {
 		close(ch)
 	}
+
+	// Clear the channel map of old channels.
 	s.mu.Lock()
 	s.channels = make(map[string]chan []byte)
 	s.mu.Unlock()