Synchronised Task Completion

tasks.go

package main

import (
	"fmt"
	"time"
	"sync"
	"sort"
)

type task struct {
	name string
	duration time.Duration
}

func (t task) exec () {
	start := time.Now()
	fmt.Printf("%s: %s - Starting ...\n", start.Format("15:04:05"), t.name)
	time.Sleep(t.duration * time.Second)
	end := time.Now()
	fmt.Printf("%s: %s - Ended!\n", end.Format("15:04:05"), t.name)
}

func schedule(ts []task) {
	if len(ts) > 0 {
	  var wg sync.WaitGroup
		var i int 
		sort.Slice(ts, func(i, j int) bool {
			return ts[i].duration > ts[j].duration
		})
		fmt.Println(ts)
		wg.Go(func(){ ts[0].exec() })
		for i = 1; i < len(ts); i++ {
			time.Sleep((ts[i-1].duration - ts[i].duration) * time.Second)
			t := ts[i];
			wg.Go(func(){ t.exec() })
		}
		time.Sleep(ts[i-1].duration * time.Second)
		wg.Wait()
	}
}

func main() {
	tasks := []task {
		{"A", 2},
		{"B", 1},
		{"C", 2},
		{"D", 5},
	}
	fmt.Println(tasks)
	schedule(tasks)
}