package main

import (
	"fmt"
	"os"
	"os/signal"
	"syscall"
	"time"
)

type Limiter struct {
	ch chan struct{}
}

func main() {
	var l = &Limiter{
		ch: make(chan struct{}, 1),
	}

	for i := 1; i <= 5; i++ {
		go l.execute(func() {
			var fName = "task"
			fmt.Printf("Starting Execution of %s\n", fName)
			time.Sleep(time.Second * 5)
			fmt.Printf("Finished Execution of %s\n", fName)
		})
	}

	forever()
}

func forever() {
	s := make(chan os.Signal, 1)
	signal.Notify(s, syscall.SIGTERM, syscall.SIGINT)

	// wait for signal
	sig := <-s
	fmt.Printf("\nstarting shutdown procedure, detected signal: %s\n", sig)
}

func (l *Limiter) execute(f func()) error {
	l.ch <- struct{}{}
	defer func() {
		<-l.ch
	}()

	f()

	return nil
}