136 lines
3.7 KiB
Go
136 lines
3.7 KiB
Go
package server
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import (
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"math/rand"
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"sync"
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"time"
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"heckel.io/ntfy/log"
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)
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// topic represents a channel to which subscribers can subscribe, and publishers
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// can publish a message
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type topic struct {
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ID string
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subscribers map[int]*topicSubscriber
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lastVisitor *visitor
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lastVisitorExpires time.Time
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mu sync.Mutex
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}
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type topicSubscriber struct {
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subscriber subscriber
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visitor *visitor // User ID associated with this subscription, may be empty
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cancel func()
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}
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// subscriber is a function that is called for every new message on a topic
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type subscriber func(v *visitor, msg *message) error
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// newTopic creates a new topic
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func newTopic(id string) *topic {
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return &topic{
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ID: id,
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subscribers: make(map[int]*topicSubscriber),
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}
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}
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// Subscribe subscribes to this topic
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func (t *topic) Subscribe(s subscriber, visitor *visitor, cancel func()) int {
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t.mu.Lock()
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defer t.mu.Unlock()
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subscriberID := rand.Int()
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t.subscribers[subscriberID] = &topicSubscriber{
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visitor: visitor, // May be empty
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subscriber: s,
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cancel: cancel,
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}
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return subscriberID
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}
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func (t *topic) Stale() bool {
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return t.getBillee() == nil
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}
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func (t *topic) getBillee() *visitor {
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for _, this_subscriber := range t.subscribers {
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return this_subscriber.visitor
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}
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if t.lastVisitor != nil && t.lastVisitorExpires.After(time.Now()) {
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t.lastVisitor = nil
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}
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return t.lastVisitor
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}
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// Unsubscribe removes the subscription from the list of subscribers
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func (t *topic) Unsubscribe(id int) {
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t.mu.Lock()
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defer t.mu.Unlock()
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if len(t.subscribers) == 1 {
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t.lastVisitor = t.subscribers[id].visitor
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t.lastVisitorExpires = time.Now().Add(subscriberBilledValidity)
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}
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delete(t.subscribers, id)
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}
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// Publish asynchronously publishes to all subscribers
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func (t *topic) Publish(v *visitor, m *message) error {
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go func() {
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// We want to lock the topic as short as possible, so we make a shallow copy of the
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// subscribers map here. Actually sending out the messages then doesn't have to lock.
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subscribers := t.subscribersCopy()
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if len(subscribers) > 0 {
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logvm(v, m).Tag(tagPublish).Debug("Forwarding to %d subscriber(s)", len(subscribers))
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for _, s := range subscribers {
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// We call the subscriber functions in their own Go routines because they are blocking, and
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// we don't want individual slow subscribers to be able to block others.
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go func(s subscriber) {
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if err := s(v, m); err != nil {
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logvm(v, m).Tag(tagPublish).Err(err).Warn("Error forwarding to subscriber")
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}
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}(s.subscriber)
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}
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} else {
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logvm(v, m).Tag(tagPublish).Trace("No stream or WebSocket subscribers, not forwarding")
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}
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}()
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return nil
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}
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// SubscribersCount returns the number of subscribers to this topic
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func (t *topic) SubscribersCount() int {
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t.mu.Lock()
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defer t.mu.Unlock()
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return len(t.subscribers)
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}
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// CancelSubscribers calls the cancel function for all subscribers, forcing
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func (t *topic) CancelSubscribers(exceptUserID string) {
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t.mu.Lock()
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defer t.mu.Unlock()
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for _, s := range t.subscribers {
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if s.visitor.MaybeUserID() != exceptUserID {
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// TODO: Shouldn't this log the IP for anonymous visitors? It was s.userID before my change.
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log.Tag(tagSubscribe).Field("topic", t.ID).Debug("Canceling subscriber %s", s.visitor.MaybeUserID())
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s.cancel()
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}
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}
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}
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// subscribersCopy returns a shallow copy of the subscribers map
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func (t *topic) subscribersCopy() map[int]*topicSubscriber {
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t.mu.Lock()
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defer t.mu.Unlock()
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subscribers := make(map[int]*topicSubscriber)
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for k, sub := range t.subscribers {
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subscribers[k] = &topicSubscriber{
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visitor: sub.visitor,
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subscriber: sub.subscriber,
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cancel: sub.cancel,
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}
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}
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return subscribers
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}
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