caster is a dead simple and performant message broadcaster for Go with context support. It uses the publisher and subscriber pattern (pubsub) to broadcast messages from a single or multiple source channels to multiple subscriber channels. Subscribers can dynamically join and leave.
Suppose the Go channel is:
var srcCh <-chan interface{}We can broadcast the messages coming out of it to multiple subscribers:
c := caster.New(nil)
go func() {
// subscriber #1
ch, _ := c.Sub(nil, 1)
for m := range ch {
// do anything to the broadcasted message
}
}()
go func() {
// subscriber #2
ch, _ := c.Sub(nil, 1)
for m := range ch {
// do anything to the broadcasted message
}
}()
go func() {
// publisher
for m := range srcCh {
c.Pub(m)
}
c.Close()
}()Subscribers can join and leave at any time:
// join
ch1, _ := c.Sub(nil, 1)
// leave
c.Unsub(ch1)
// join with context and automatically leave when the context is canceled
ch2, _ := c.Sub(ctx, 1)
// join with 10 subscriber channel buffer
ch3, _ := c.Sub(ctx, 10)caster can associate with a context as well:
// `c` will be closed when the `ctx` is canceled
c := caster.New(ctx)A boolean value is returned to indicate whether the caster is still running or not:
_, ok := c.Sub(nil, 1)
if !ok {
// the caster has been closed, do something else
}