package server import ( "heckel.io/ntfy/log" "heckel.io/ntfy/util" "math/rand" "sync" "time" ) const ( // topicExpungeAfter defines how long a topic is active before it is removed from memory. // This must be larger than matrixRejectPushKeyForUnifiedPushTopicWithoutRateVisitorAfter to give // time for more requests to come in, so that we can send a {"rejected":[""]} response back. topicExpungeAfter = 16 * time.Hour ) // topic represents a channel to which subscribers can subscribe, and publishers // can publish a message type topic struct { ID string subscribers map[int]*topicSubscriber rateVisitor *visitor lastAccess time.Time mu sync.RWMutex } type topicSubscriber struct { userID string // User ID associated with this subscription, may be empty subscriber subscriber cancel func() } // subscriber is a function that is called for every new message on a topic type subscriber func(v *visitor, msg *message) error // newTopic creates a new topic func newTopic(id string) *topic { return &topic{ ID: id, subscribers: make(map[int]*topicSubscriber), lastAccess: time.Now(), } } // Subscribe subscribes to this topic func (t *topic) Subscribe(s subscriber, userID string, cancel func()) int { t.mu.Lock() defer t.mu.Unlock() subscriberID := rand.Int() t.subscribers[subscriberID] = &topicSubscriber{ userID: userID, // May be empty subscriber: s, cancel: cancel, } t.lastAccess = time.Now() return subscriberID } func (t *topic) Stale() bool { t.mu.Lock() defer t.mu.Unlock() if t.rateVisitor != nil && !t.rateVisitor.Stale() { return false } return len(t.subscribers) == 0 && time.Since(t.lastAccess) > topicExpungeAfter } func (t *topic) LastAccess() time.Time { t.mu.RLock() defer t.mu.RUnlock() return t.lastAccess } func (t *topic) SetRateVisitor(v *visitor) { t.mu.Lock() defer t.mu.Unlock() t.rateVisitor = v t.lastAccess = time.Now() } func (t *topic) RateVisitor() *visitor { t.mu.Lock() defer t.mu.Unlock() if t.rateVisitor != nil && t.rateVisitor.Stale() { t.rateVisitor = nil } return t.rateVisitor } // Unsubscribe removes the subscription from the list of subscribers func (t *topic) Unsubscribe(id int) { t.mu.Lock() defer t.mu.Unlock() delete(t.subscribers, id) } // Publish asynchronously publishes to all subscribers func (t *topic) Publish(v *visitor, m *message) error { go func() { // We want to lock the topic as short as possible, so we make a shallow copy of the // subscribers map here. Actually sending out the messages then doesn't have to lock. subscribers := t.subscribersCopy() if len(subscribers) > 0 { logvm(v, m).Tag(tagPublish).Debug("Forwarding to %d subscriber(s)", len(subscribers)) for _, s := range subscribers { // We call the subscriber functions in their own Go routines because they are blocking, and // we don't want individual slow subscribers to be able to block others. go func(s subscriber) { if err := s(v, m); err != nil { logvm(v, m).Tag(tagPublish).Err(err).Warn("Error forwarding to subscriber") } }(s.subscriber) } } else { logvm(v, m).Tag(tagPublish).Trace("No stream or WebSocket subscribers, not forwarding") } t.Keepalive() }() return nil } // Stats returns the number of subscribers and last access to this topic func (t *topic) Stats() (int, time.Time) { t.mu.RLock() defer t.mu.RUnlock() return len(t.subscribers), t.lastAccess } // Keepalive sets the last access time and ensures that Stale does not return true func (t *topic) Keepalive() { t.mu.Lock() defer t.mu.Unlock() t.lastAccess = time.Now() } // CancelSubscribers calls the cancel function for all subscribers, forcing func (t *topic) CancelSubscribers(exceptUserID string) { t.mu.Lock() defer t.mu.Unlock() for _, s := range t.subscribers { if s.userID != exceptUserID { log. Tag(tagSubscribe). With(t). Fields(log.Context{ "user_id": s.userID, }). Debug("Canceling subscriber %s", s.userID) s.cancel() } } } func (t *topic) Context() log.Context { t.mu.RLock() defer t.mu.RUnlock() fields := map[string]any{ "topic": t.ID, "topic_subscribers": len(t.subscribers), "topic_last_access": util.FormatTime(t.lastAccess), } if t.rateVisitor != nil { for k, v := range t.rateVisitor.Context() { fields["topic_rate_"+k] = v } } return fields } // subscribersCopy returns a shallow copy of the subscribers map func (t *topic) subscribersCopy() map[int]*topicSubscriber { t.mu.Lock() defer t.mu.Unlock() subscribers := make(map[int]*topicSubscriber) for k, sub := range t.subscribers { subscribers[k] = &topicSubscriber{ userID: sub.userID, subscriber: sub.subscriber, cancel: sub.cancel, } } return subscribers }