Ability to subscribe to a publisher #209
Description
I have been experimenting the load balancer/service discovery components for my project and I like the idea of the load balancer keeping track of the latest endpoints. However, I would like the ability to subscribe to a publisher and get a callback when there is a change in the service. I want to control the concurrency at which I talk to the service based on the number of available endpoints. If the service endpoints change, I would like to be able to grow or shrink my pool of worker goroutines. I would like to propose something like this:
type Publisher struct {
sync.RWMutex
// ...
subscribers []chan<- bool
}
/// Subscribe adds the channel to its list of subscribers. The subscribers
// will be notified when there is a change in the service.
func (p *Publisher) Subscribe(ch chan<- bool) {
p.Lock()
defer p.Unlock()
p.subscribers = append(p.subscribers, ch)
}
// notify notifies all subscribers.
func (p *Publisher) notify() {
if len(p.subscribers) == 0 {
return
}
p.RLock()
defer p.RUnlock()
for _, ch := range p.subscribers {
ch <- true
}
}where the notify would be called whenever there is a change in the service.