Priority in Go select statement workaround

The language supports this natively and no workaround is required. It’s very simple: the quit channel should only be visible to the producer. On quit, the producer closes the channel. Only when the channel is empty and closed does the consumer quit. This is made possible by ranging over the channel.

Here is an example to illustrate:

package main

import (
    "fmt"
    "math/rand"
    "time"
)

var (
    produced  = 0
    processed = 0
)

func produceEndlessly(out chan int, quit chan bool) {
    defer close(out)
    for {
        select {
        case <-quit:
            fmt.Println("RECV QUIT")
            return
        default:
            out <- rand.Int()
            time.Sleep(time.Duration(rand.Int63n(5e6)))
            produced++
        }
    }
}

func quitRandomly(quit chan bool) {
    d := time.Duration(rand.Int63n(5e9))
    fmt.Println("SLEEP", d)
    time.Sleep(d)
    fmt.Println("SEND QUIT")
    quit <- true
}

func main() {
    vals, quit := make(chan int, 10), make(chan bool)
    go produceEndlessly(vals, quit)
    go quitRandomly(quit)
    for x := range vals {
        fmt.Println(x)
        processed++
        time.Sleep(time.Duration(rand.Int63n(5e8)))
    }
    fmt.Println("Produced:", produced)
    fmt.Println("Processed:", processed)
}