Closing Go Channels

Posted by yhuang
Public (Editable by Users)

Closing a channel indicates that no more values will be sent on it. This can be useful to communicate completion to the channel’s receivers.

Go
Edit 
package main

import "fmt"

func main() {
    jobs := make(chan int, 5)
    done := make(chan bool)

    // Here's the worker goroutine.
    // It repeatedly receives from jobs with j, more := <-jobs.
    // In this special 2-value form of receive, the more value will be false if jobs has been closed and all values in the channel have already been received.
    // We use this to notify on done when we’ve worked all our jobs.
    go func() {
        for {
            j, more := <-jobs
            if more {
                fmt.Println("received job", j)
            } else {
                fmt.Println("received all jobs")
                done <- true
                return
            }
        }
    }()

    for j := 1; j <= 3; j++ {
        jobs <- j
        fmt.Println("sent job", j)
    }
    close(jobs)
    fmt.Println("sent all jobs")

    <-done
}