[bufferedchannel]bufferedchannel with waiting group #waiting group #channel

bufferedchannel.go

package main

import (
	"gpool"
	"fmt"
	"net/http"
	"time"
)

func main() {
	links := []string{
		"http://baidu.com",
		"http://qq.com",
		"http://taobao.com",
		"http://jd.com",
		"http://z.cn",
	}

	pool := gpool.New(5)
	for{
		for _,l := range links {
			pool.Add(1)
			go func(link string) {
				checkLink(link)
				time.Sleep(time.Second)
				pool.Done()
			}(l)
		}
	}

	pool.Wait()
}

func checkLink(link string) {
	_, err := http.Get(link)
	if err != nil {
		fmt.Println(link, "might be down!")
		return
	}

	fmt.Println(link, "is up!")
}

gpool.go

package gpool

import (
	"sync"
)

type pool struct {
	queue chan int
	wg    *sync.WaitGroup
}

func New(size int) *pool {
	if size <= 0 {
		size = 1
	}
	return &pool{
		queue: make(chan int, size),
		wg:    &sync.WaitGroup{},
	}
}

func (p *pool) Add(delta int) {
	for i := 0; i < delta; i++ {
		p.queue <- 1
	}
	for i := 0; i > delta; i-- {
		<-p.queue
	}
	p.wg.Add(delta)
}

func (p *pool) Done() {
	<-p.queue
	p.wg.Done()
}

func (p *pool) Wait() {
	p.wg.Wait()
}