Double signal.NotifyContext

main.go

package main

import (
	"context"
	"log"
	"os"
	"os/signal"
	"sync"
	"time"
)

type namedContext struct {
	ame string
	ctx context.Context
}

func waitAll(ctxs []namedContext) chan struct{} {
	var wg sync.WaitGroup
	ret := make(chan struct{})

	for _, n := range ctxs {
		wg.Add(1)
		n := n
		go func() {
			defer wg.Done()
			<-n.ctx.Done()
			log.Printf("%s.Done()", n.ame)
		}()
	}
	go func() {
		wg.Wait()
		close(ret)
	}()
	return ret
}

func main() {

	ctx1, cancel1 := signal.NotifyContext(context.Background(), os.Interrupt)
	defer func() {
		log.Printf("cancel1()")
		cancel1()
	}()
	ctx2, cancel2 := signal.NotifyContext(ctx1, os.Interrupt)
	defer func() {
		log.Printf("cancel2()")
		cancel2()
	}()

	go func() {
		log.Printf("INFO: waiting before killing myself")
		time.Sleep(2 * time.Second)
		me, err := os.FindProcess(os.Getpid())
		if err != nil {
			log.Fatal(err)
		}
		log.Printf("INFO: kill %d", os.Getpid())
		me.Signal(os.Interrupt)
	}()

	ctxs := []namedContext{
		{"ctx1", ctx1},
		{"ctx2", ctx2},
	}

	select {
	case <-context.TODO().Done():
		log.Printf("context.TODO().Done()")
	case <-waitAll(ctxs):
		log.Printf("ctx1.Done(), ctx2.Done()")
	}

	log.Println("fini")
}

Output when running:

2022/02/28 13:54:23 INFO: waiting before killing myself
2022/02/28 13:54:25 INFO: kill 6084
2022/02/28 13:54:25 ctx2.Done()
2022/02/28 13:54:25 ctx1.Done()
2022/02/28 13:54:25 ctx1.Done(), ctx2.Done()
2022/02/28 13:54:25 fini
2022/02/28 13:54:25 cancel2()
2022/02/28 13:54:25 cancel1()

BTW: you can't run this in Go playground 🤷