package main

import (
	"fmt"
	"strconv"
	"sync"
	"time"
)

var wg sync.WaitGroup

// test1 不传递wg，用匿名函数运行
func test1() {
	wg.Add(2)
	go func() {
		defer wg.Done()
		Info("task1")
	}()
	go func() {
		defer wg.Done()
		Info("task2")
	}()
	wg.Wait()

}

//test2 for循环并发
func test2() {
	for i := 0; i <= 10; i++ {
		wg.Add(1)
		go func(a int) {
			defer wg.Done()
			Info("test" + strconv.Itoa(a+1))
		}(i)
	}
	wg.Wait()
}
//test3 并发限速
func test3() {
	limit := make(chan struct{}, 2)
	for i := 0; i < 100; i++ {
		wg.Add(1)
		limit <- struct{}{}
		go func(a int) {
			defer func() {
				wg.Done()
				<-limit
			}()
			Info("test" + strconv.Itoa(i+1))
		}(i)

	}
	wg.Wait()
}

func Info(name string) {
	time.Sleep(time.Second)
	fmt.Printf("this is a %v task...->%v\n", name, time.Now())
}