// NewMultiNotifyWatcher creates a NotifyWatcher that combines
// each of the NotifyWatchers passed in. Each watcher's initial
// event is consumed, and a single initial event is sent.
// Subsequent events are not coalesced.
func NewMultiNotifyWatcher(w ...state.NotifyWatcher) *MultiNotifyWatcher {
m := &MultiNotifyWatcher{
watchers: w,
changes: make(chan struct{}),
}
var wg sync.WaitGroup
wg.Add(len(w))
staging := make(chan struct{})
for _, w := range w {
// Consume the first event of each watcher.
<-w.Changes()
go func(w state.NotifyWatcher) {
defer wg.Done()
m.tomb.Kill(w.Wait())
}(w)
// Copy events from the watcher to the staging channel.
go copyEvents(staging, w.Changes(), &m.tomb)
}
go func() {
defer m.tomb.Done()
m.loop(staging)
wg.Wait()
}()
return m
}
