I'm trying to use a select in a loop to receive either a message or a timeout signal. If the timeout signal is received, the loop should abort:
package main
import ("fmt"; "time")
func main() {
done := time.After(1*time.Millisecond)
numbers := make(chan int)
go func() {for n:=0;; {numbers <- n; n++}}()
for {
select {
case <-done:
break
case num := <- numbers:
fmt.Println(num)
}
}
}
However, it doesn't seem to be stopping:
$ go run a.go
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[...]
Why? Am I using time.After wrong?
The Go spec says:
A "break" statement terminates execution of the innermost "for", "switch", or "select" statement within the same function.
In your example you're just breaking out of the select statement. If you replace break with a return statement you will see that it's working.
In your example code, a return seems appropriate as Pat says, but for future reference you can use labels:
package main
import (
"fmt"
"time"
)
func main() {
done := time.After(1 * time.Millisecond)
numbers := make(chan int)
// Send to channel
go func() {
for n := 0; ; {
numbers <- n
n++
}
}()
readChannel:
for {
select {
case <-done:
break readChannel
case num := <-numbers:
fmt.Println(num)
}
}
// Additional logic...
fmt.Println("Howdy")
}
The "Go" way for that kind of situations is to use labels and break on the label, for example:
L:
for {
select {
case <-done:
break L
case num := <- numbers:
fmt.Println(num)
}
}
Ref:
I have the following solution, by using a anonymous function.
func() {
for {
select {
case <-time.After(5 * time.Second):
if token := c.Connect(); token.Wait() && token.Error() != nil {
fmt.Println("connect err:", token.Error())
} else {
fmt.Println("breaking")
return
}
}
}
}()