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Quit Channel

Quit Channel

In this lesson, we'll study a pattern related to quitting from a select statement.

You will notice that you have probably seen the quit channel pattern in the coding examples before. Let’s discover more about it!

So we’ll set up a car race competition. In the code below, we launch three goroutines by calling the Race function in a for-loop. Now we are only interested in the race until one of the cars reaches the finishing line. Let’s see how it’s done:

Go (1.6.2)
package main
import ( "fmt"
         "math/rand" 
         "time")
func Race(channel, quit chan string, i int) {
  
  channel <- fmt.Sprintf("Car %d started!", i)  
    for{
      rand.Seed(time.Now().UnixNano())
      time.Sleep(time.Duration(rand.Intn(500)+500) * time.Millisecond)
      quit <- fmt.Sprintf("Car %d reached the finishing line!", i)
    }
}
func main() {
  
  channel := make(chan string)
  quit := make(chan string)
  
  for i:=0; i < 3; i++{
    go Race(channel,quit,i)
  }
  for{
    select{
      case raceUpdates := <-channel:
        fmt.Println(raceUpdates)
      case winnerAnnoucement := <-quit:
        fmt.Println(winnerAnnoucement)  
       return
      
    }
  }
}

After the goroutines start concurrently, we have a select statement from line 27 to line 34.

for{
    select{
      case raceUpdates := <-channel:
        fmt.Println(raceUpdates)
      case winnerAnnoucement := <-quit:
        fmt.Println(winnerAnnoucement)  
       return
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