Safe shutdown in Go.

example.go

package main
 
import (
    	"log"
	"shutdown"
)
 
func main() {
	ch := shutdown.Add("test")
	ch2 := shutdown.Add("test2")
 
	go func() {
		for {
			select {
			case <-ch2:
				log.Printf("Received the signal")
				shutdown.Done("test2")
			case <-ch:
				log.Printf("Received the signal")
				shutdown.Done("test")
			}
		}
	}()
 
	shutdown.Shutdown(1000)
}

shutdown.go

package shutdown
 
import (
    	"log"
	"time"
)
 
var waitingList map[string]chan bool
var waitCh chan string
 
func init() {
	waitingList = make(map[string]chan bool)
	waitCh = make(chan string)
}
 
func Add(name string) chan bool {
	if ch, ok := waitingList[name]; ok {
		return ch
	}
 
	log.Printf("Shutdown: registering <%s>.", name)
 
	waitingList[name] = make(chan bool)
	return waitingList[name]
}
 
func Done(name string) {
	log.Printf("Shutdown: <%s> finished.", name)
 
	go func() {
		waitCh <- name
	}()
}
 
func Shutdown(timeout int) {
	for name, ch := range waitingList {
		log.Printf("Notifying <%s>.", name)
		ch <- true
	}
 
	var timeoutCh <-chan time.Time
 
	if timeout > 0 {
		timeoutCh = time.After(time.Duration(timeout) * time.Millisecond)
	} else {
		timeoutCh = make(chan time.Time)
	}
 
	for {
		select {
		case name := <-waitCh:
			delete(waitingList, name)
			if len(waitingList) == 0 {
				log.Printf("All done.")
				return
			}
		case <-timeoutCh:
			log.Printf("Timeout expired... unfinished processes:")
			for name, _ := range waitingList {
				log.Printf(name)
			}
			return
		}
	}
}