standard/etcd/study/main.go

package main

import (
	"context"
	"fmt"
	"go.etcd.io/etcd/client/v3"
	"time"
)
func main() {
	cli, err := clientv3.New(clientv3.Config{
		Endpoints:   []string{"192.168.1.7:2379"},
		DialTimeout: 5 * time.Second,
	})
	if err != nil {
		// handle error!
		fmt.Printf("connect to etcd failed, err:%v\n", err)
		return
	}
	fmt.Println("connect to etcd success")
	defer cli.Close()
	// put
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	_, err = cli.Put(ctx, "name", "shuaimei")
	cancel()
	if err != nil {
		fmt.Printf("put to etcd failed, err:%v\n", err)
		return
	}

	// get
	ctx, cancel = context.WithTimeout(context.Background(), time.Second)
	resp, err := cli.Get(ctx, "name")
	cancel()
	if err != nil {
		fmt.Printf("get from etcd failed, err:%v\n", err)
		return
	}
	for _, ev := range resp.Kvs {
		fmt.Printf("%s:%s\n", ev.Key, ev.Value)
	}

	//申请租约 Grant()
	var leaseGrantResp *clientv3.LeaseGrantResponse
	lease := clientv3.NewLease(cli)
	if leaseGrantResp, err = lease.Grant(context.TODO(), 10); err != nil {
		fmt.Println(err)
		return
	}
	leaseId := leaseGrantResp.ID

	// 获得kv API子集
	kv := clientv3.NewKV(cli)

	if _, err = kv.Put(context.TODO(), "/school/class/students", "h", clientv3.WithLease(leaseId)); err != nil {
		fmt.Println(err)
		return
	}

	//for {
	//	var getResp *clientv3.GetResponse
	//	if getResp, err = kv.Get(context.TODO(), "/school/class/students"); err != nil {
	//		fmt.Println(err)
	//		return
	//	}
	//	if getResp.Count == 0 {
	//		fmt.Println("kv过期了")
	//		break
	//	}
	//	fmt.Println("还没过期:", getResp.Kvs)
	//	time.Sleep(2 * time.Second)
	//}

	//自动续租 KeepAlive()
	var keepRespChan  <-chan *clientv3.LeaseKeepAliveResponse
	fmt.Println(leaseId)
	if keepRespChan, err = lease.KeepAlive(context.TODO(), leaseId); err != nil {
		fmt.Println(err)
		return
	}
	go func() {
		for {
			select {
			case keepResp := <- keepRespChan:
				if keepRespChan == nil {
					fmt.Println("租约已经失效了")
					goto END
				} else {    // 每秒会续租一次, 所以就会受到一次应答
					fmt.Println("收到自动续租应答:", keepResp.ID)
				}
			}
		}
	END:
	}()

}