Stop multiple goroutine

stop_multiple_goroutine.go

// play at https://play.golang.org/p/lHRnRJHPheY
package main

import (
	"context"
	"errors"
	"log"
	"sync"
	"time"
)

type FN func(context.Context) error

func doSomething(ctx context.Context) error {
	for i := 0; i < 3; i++ {
		select {
		case <-ctx.Done():
			return nil
		default:
		}

		log.Print("doSomething...")
		time.Sleep(time.Second)
	}

	return nil
}

func doSomethingError(ctx context.Context) error {
	return errors.New("Error on doSomething")
}

func run(fns []FN) error {
	wg := sync.WaitGroup{}

	ctxs := make([]struct {
		ctx    context.Context
		cancel context.CancelFunc
	}, len(fns))

	stop := func() {
		for _, ctx := range ctxs {
			ctx.cancel()
		}
	}

	var retError error
	for i, fn := range fns {
		wg.Add(1)

		ctx, cancel := context.WithCancel(context.Background())
		ctxs[i].ctx = ctx
		ctxs[i].cancel = cancel

		go func(ctx context.Context, fn FN) {
			defer wg.Done()
			if err := fn(ctx); err != nil {
				// if error occurred then stop all go routines..
				log.Print(err)
				retError = err
				stop()
			}
		}(ctx, fn)
	}

	// give some time to stop
	wg.Wait()

	return retError
}

func main() {
	for _, test := range []struct {
		fns      []FN
		hasError bool
	}{
		{
			fns: []FN{
				doSomething,
				doSomething,
			},
			hasError: false,
		},
		{
			fns: []FN{
				doSomething,
				doSomethingError,
			},
			hasError: true,
		},
	} {
		err := run(test.fns)

		if test.hasError {
			if err == nil {
				log.Printf("ERR: error expected but nil")
			}
		} else {
			if err != nil {
				log.Printf("ERR: no error expected but err: %s", err)
			}

		}
	}
}