package main

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

var (
	counter int32          //计数器
	wg      sync.WaitGroup //信号量
)

func main() {

	threadNum := 5

	//1. 五个信号量
	wg.Add(threadNum)

	//2.开启5个线程
	for i := 0; i < threadNum; i++ {
		go incCounter(i)
	}

	//3.等待子线程结束
	wg.Wait()
	fmt.Println(counter)
}

func incCounter(index int) {
	defer wg.Done()

	spinNum := 0
	for {
		//2.1原子操作
		old := counter
		ok := atomic.CompareAndSwapInt32(&counter, old, old+1)
		if ok {
			break
		} else {
			spinNum++
		}
	}

	fmt.Printf("thread,%d,spinnum,%d\n", index, spinNum)

}