datarace.go

package main

import (
	"fmt"
	"time"

	"github.com/thejerf/suture"
)

func main() {
	// We have a main supervisor at the top of the tree.
	mainSup := suture.NewSimple("main")
	mainSup.ServeBackground()

	// It has a child supervisor that also has some services on it at creation
	// time.
	s := newSomeService()
	mainSup.Add(s)

	// We can add more stuff at run time without issues.
	mainSup.Add(newChildService("three"))

	// However we cannot add stuff to the child supervisor, or we get a data
	// race.
	s.AddChild("four")

	time.Sleep(5 * time.Second)
}

// someService does more than one thing, so it embeds a Supervisor and adds
// some services at creation time.
type someService struct {
	*suture.Supervisor
	// other stuff
}

func newSomeService() *someService {
	s := &someService{
		Supervisor: suture.NewSimple("someService"),
	}
	s.Add(newChildService("one"))
	s.Add(newChildService("two"))
	return s
}

func (s *someService) AddChild(name string) {
	s.Add(newChildService(name))
}

// childService is just something that does stuff.
type childService struct {
	name string
	stop chan struct{}
}

func newChildService(name string) *childService {
	return &childService{
		name: name,
		stop: make(chan struct{}),
	}
}

func (c *childService) Serve() {
	ticker := time.NewTicker(time.Second)
	for {
		select {
		case <-c.stop:
			return
		case <-ticker.C:
			fmt.Println("tick on", c.name)
		}
	}
}

func (c *childService) Stop() {
	close(c.stop)
}