6

Broadcast a signal on a channel

 4 years ago
source link: https://yourbasic.org/golang/broadcast-channel/
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Broadcast a signal on a channel

yourbasic.org/golang

All readers receive zero values on a closed channel.

phonograph.jpg

In this example the Publish function returns a channel, which is used to broadcast a signal when a message has been published.

// Print text after the given time has expired.
// When done, the wait channel is closed.
func Publish(text string, delay time.Duration) (wait <-chan struct{}) {
    ch := make(chan struct{})
    go func() {
        time.Sleep(delay)
        fmt.Println("BREAKING NEWS:", text)
        close(ch) // Broadcast to all receivers.
    }()
    return ch
}

Notice that we use a channel of empty structs: struct{}. This clearly indicates that the channel will only be used for signalling, not for passing data.

This is how you may use the function.

func main() {
    wait := Publish("Channels let goroutines communicate.", 5*time.Second)
    fmt.Println("Waiting for news...")
    <-wait
    fmt.Println("Time to leave.")
}
Waiting for news...
BREAKING NEWS: Channels let goroutines communicate.
Time to leave.

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