go channel练习

透过 go channel练习

1. 透过goroutine 跑20个job
2. 显示各个job的完成情况
3. 使用errChan job发生错误跳出main func
4. 通过 finishChan 通知全部job完成
5. 设置超时机制

/**
 * @ClassName main
 * @Description //TODO 
 * @Author liwei
 * @Date 2021/4/12 21:30
 * @Version example V1.0
 **/

package main

import (
    "fmt"
    "log"
    "math/rand"
    "sync"
    "time"
)

func main()  {
    outChan:=make(chan  string,100)
    finishChan:=make(chan  struct{})
    errChan:=make(chan error,100)
    wg:=sync.WaitGroup{}
    wg.Add(20)
    for i:=0;i<=20 ;i++  {//透过goroutine 跑20个job
        go func(val int ,wg *sync.WaitGroup,out chan string,err  chan  error) {
            time.Sleep(time.Duration(rand.Int31n(1000))*time.Millisecond)
            out<-fmt.Sprintf("finish job id:%d",val)
            //if val==15{
            //  err<-errors.New("fail job in 15")
            //}
            wg.Done()
        }(i,&wg,outChan,errChan)
    }

    go func() {
        wg.Wait()
        close(finishChan)
    }()

Loop :
    for  {
        select {
        case out:=<-outChan: //显示各个job的完成情况
            log.Print(out)
        case err:=<-errChan://出现错误执行
            log.Print(err)
            break Loop
        case <-finishChan: //完成执行
            log.Print("close finishChan")
            break  Loop
        case <-time.After(100*time.Millisecond): //超时执行
            log.Print("timeOut")
            break Loop
        }
    }

}