Why doesn't this Golang code to select among multiple time.After channels work?

Question

Why doesn't this Golang code to select among multiple time.After channels work?

See code below. The 'timeout' message is never issued. Why?

package main

import (
    "fmt"
    "time"
)

func main() {
    count := 0
    for {
        select {
        case <-time.After(1 * time.Second):
            count++
            fmt.Printf("tick %d\n", count)
            if count >= 5 {
                fmt.Printf("ugh\n")
                return
            }
        case <-time.After(3 * time.Second):
            fmt.Printf("timeout\n")
            return
        }
    }
}

Run it on Playground: http://play.golang.org/p/1gku-CWVAh

Output:

tick 1
tick 2
tick 3
tick 4
tick 5
ugh

Answer 1

Because time.After is a function, so on every iteration it returns a new channel. If you want this channel to be the same for all iterations, you should save it before the loop:

timeout := time.After(3 * time.Second)
for {
    select {
    //...
    case <-timeout:
        fmt.Printf("timeout\n")
        return
    }
}

Playground: http://play.golang.org/p/muWLgTxpNf.

Answer 2

Even @Ainar-G has already provided the answer, another possibility is to use time.Tick(1e9) to generate a time tick on every second and then listen for timeAfterchannel after the specified period.

package main

import (
    "fmt"
    "time"
)

func main() {
    count := 0
    timeTick := time.Tick(1 * time.Second)
    timeAfter := time.After(5 * time.Second)

    for {
        select {
        case <-timeTick:
            count++
            fmt.Printf("tick %d\n", count)
            if count >= 5 {
                fmt.Printf("ugh\n")
                return
            }
        case <-timeAfter:
            fmt.Printf("timeout\n")
            return
        }
    }
}