etcd租約及監聽key

package main

import (
	"context"
	"log"
	"time"

	"go.etcd.io/etcd/clientv3"
)

func main() {
	var conf = clientv3.Config{
		Endpoints:   []string{"127.0.0.1:2380"},
		DialTimeout: 5 * time.Second,
	}
    
    //創建clinetv3
	client, err := clientv3.New(conf)
	defer client.Close()

	if err != nil {
		log.Fatal(err.Error())
	}

	//創建租約
	lease := clientv3.NewLease(client)

	//設置租約時間
	leaseResp, err := lease.Grant(context.TODO(), 30)
	if err != nil {
		log.Fatal(err.Error())
	}

	//設置續租
	leaseID := leaseResp.ID
	ctx, _ := context.WithCancel(context.TODO())
	leaseRespChan, err := lease.KeepAlive(ctx, leaseID)
	if err != nil {
		log.Fatal(err.Error()) //設置續租失敗 續期之後向leaseRespChan通知
	}

	//監聽租約
	go func() {
		for {
			select {
			case resp := <-leaseRespChan:
				if resp == nil {
					log.Println("租約已經到期關閉")
					goto LEASE_OVER
				} else {
					log.Println("續租成功")
					goto END
				}
			}
		LEASE_OVER:
			log.Println("lease 監聽結束")
			break
		END:
			time.Sleep(500 * time.Millisecond)
		}
	}()

	//監聽某個key的變化
	//ctx1, _ := context.WithTimeout(context.TODO(),20)
	go func() {
		wc := client.Watch(context.TODO(), "/job/v3/1", clientv3.WithPrevKV()) //創建監聽
		for v := range wc {                                                    //range 監聽事件
			for _, e := range v.Events {
				log.Printf("type:%v kv:%v  prevKey:%v \n ", e.Type, string(e.Kv.Key), e.PrevKv)
			}
		}
	}()

	//key授權租約
	kv := clientv3.NewKV(client)

	//通過租約put
	putResp, err := kv.Put(context.TODO(), "/job/v3/1", "koock", clientv3.WithLease(leaseID))
	if err != nil {
		log.Printf("put 失敗：%s", err.Error())
	}
	log.Printf("%v\n", putResp.Header)

	time.Sleep(10 * time.Second)

	//撤銷租約
	_, err = lease.Revoke(context.TODO(), leaseID)
	if err != nil {
		log.Fatalf("撤銷租約失敗:%s\n", err.Error())
	}
	log.Println("撤銷租約成功")
	//cancelFunc()

	//查詢key
	getResp, err := kv.Get(context.TODO(), "/job/v3/1")
	if err != nil {
		log.Fatalf("get 失敗：%s", err.Error())
	}
	log.Printf("%v", getResp.Kvs)
	time.Sleep(20 * time.Second)
}