1
0
Fork 0
forked from mirrors/ntfy
ntfy/server/topic.go
2022-06-22 13:52:49 -04:00

84 lines
2.3 KiB
Go

package server
import (
"heckel.io/ntfy/log"
"math/rand"
"sync"
)
// topic represents a channel to which subscribers can subscribe, and publishers
// can publish a message
type topic struct {
ID string
subscribers map[int]subscriber
mu sync.Mutex
}
// 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]subscriber),
}
}
// Subscribe subscribes to this topic
func (t *topic) Subscribe(s subscriber) int {
t.mu.Lock()
defer t.mu.Unlock()
subscriberID := rand.Int()
t.subscribers[subscriberID] = s
return subscriberID
}
// 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 {
log.Debug("%s Forwarding to %d subscriber(s)", logMessagePrefix(v, m), 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 {
log.Warn("%s Error forwarding to subscriber", logMessagePrefix(v, m))
}
}(s)
}
} else {
log.Trace("%s No stream or WebSocket subscribers, not forwarding", logMessagePrefix(v, m))
}
}()
return nil
}
// SubscribersCount returns the number of subscribers to this topic
func (t *topic) SubscribersCount() int {
t.mu.Lock()
defer t.mu.Unlock()
return len(t.subscribers)
}
// subscribersCopy returns a shallow copy of the subscribers map
func (t *topic) subscribersCopy() map[int]subscriber {
t.mu.Lock()
defer t.mu.Unlock()
subscribers := make(map[int]subscriber)
for k, v := range t.subscribers {
subscribers[k] = v
}
return subscribers
}