package main

import (
	"fmt"
	"sync/atomic"
	"time"
)

func ParallelPrintOrderdNum() {
	var count uint32

	trigger := func(i uint32, fn func()) {
		for {
			if n := atomic.LoadUint32(&count); n == i {
				fn()
				atomic.AddUint32(&count, 1)
				break
			}
			// sleep 等代，让此 goroutine 有被调度的机会
			time.Sleep(time.Nanosecond)
		}
	}

	for i := uint32(0); i < 10; i++ {
		go func(i uint32) {
			fn := func() {
				fmt.Println(i)
			}
			trigger(i, fn)
		}(i)
	}

    // 主 goroutine 也需要等待
	trigger(10, func() {})
}

func main() {
	ParallelPrintOrderdNum()
}