broadcast.go
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package util
type Broadcast struct {
listeners []chan interface{}
reg chan (chan interface{})
unreg chan (chan interface{})
in chan interface{}
}
func NewBroadcast() *Broadcast {
b := &Broadcast{
listeners: make([]chan interface{}, 0),
reg: make(chan (chan interface{})),
unreg: make(chan (chan interface{})),
in: make(chan interface{}),
}
go func() {
for {
select {
case l := <-b.unreg:
// remove L from b.listeners
// this operation is slow: O(n) but not used frequently
// unlike iterating over listeners
oldListeners := b.listeners
b.listeners = make([]chan interface{}, 0, len(oldListeners))
for _, oldL := range oldListeners {
if l != oldL {
b.listeners = append(b.listeners, oldL)
}
}
case l := <-b.reg:
b.listeners = append(b.listeners, l)
case item := <-b.in:
for _, l := range b.listeners {
l <- item
}
}
}
}()
return b
}
func (b *Broadcast) In() chan interface{} {
return b.in
}
func (b *Broadcast) Reg() chan interface{} {
listener := make(chan interface{})
b.reg <- listener
return listener
}
func (b *Broadcast) UnReg(listener chan interface{}) {
b.unreg <- listener
}