定义错误常量：
const ( NewLeaseErr = 101 LeasTtlErr = 102 KeepAliveErr = 103 PutErr = 104 GetErr = 105 RevokeErr = 106)
创建client:
var conf = clientv3.Config{
Endpoints: []string{"172.16.196.129:2380", "192.168.50.250:2380"},
DialTimeout: 5 * time.Second,
}
client, err := clientv3.New(conf)
defer client.Close()if err != nil {
fmt.Printf("创建client失败:\n", err.Error())
os.Exit(NewLeaseErr)
}创建租约：
//创建租约lease := clientv3.NewLease(client)//设置租约时间leaseResp, err := lease.Grant(context.TODO(), 10)if err != nil {
fmt.Printf("设置租约时间失败:%s\n", err.Error())
os.Exit(LeasTtlErr)
}设置续租：
//设置续租leaseID := leaseResp.ID
ctx, cancelFunc := context.WithCancel(context.TODO())
leaseRespChan, err := lease.KeepAlive(ctx, leaseID)if err != nil {
fmt.Printf("续租失败:%s\n", err.Error())
os.Exit(KeepAliveErr)
}监听租约：
go func() { for {
select { case leaseKeepResp := <-leaseRespChan: if leaseKeepResp == nil {
fmt.Printf("已经关闭续租功能\n") return
} else {
fmt.Printf("续租成功\n") goto END
}
}
END:
time.Sleep(500*time.Millisecond)
}
}()监听某个key的变化
//ctx1, _ := context.WithTimeout(context.TODO(),20) //设置超时ctx传入Watch里会使watch监听失败，可能是watch是个永久监听，不支持设置timeCtx(我也不太清楚)go func() {
wc := client.Watch(context.TODO(), "/job/v3/1", clientv3.WithPrevKV()) for v := range wc { for _, e := range v.Events {
fmt.Printf("type:%v kv:%v prevKey:%v \n ", e.Type, string(e.Kv.Key), e.PrevKv)
}
}
}()put操作：
kv := clientv3.NewKV(client)
time.Sleep(3*time.Second)//通过租约putputResp, err := kv.Put(context.TODO(), "/job/v3/1", "koock",clientv3.WithLease(leaseID))if err != nil {
fmt.Printf("put 失败：%s", err.Error())
os.Exit(PutErr)
}
fmt.Printf("%v\n",putResp.Header)取消续租以及撤销租约：
撤销租约会使当前租约的所关联的key-value失效
//关闭续租cancelFunc()
//撤销租约_, err = lease.Revoke(context.TODO(), leaseID) if err != nil {
fmt.Printf("撤销租约失败:%s\n",err.Error())
os.Exit(RevokeErr)
}
fmt.Printf("撤销租约成功")完整代码段：
package main
import ( "context"
"fmt"
"go.etcd.io/etcd/clientv3"
"os"
"time")const (
NewLeaseErr = 101
LeasTtlErr = 102
KeepAliveErr = 103
PutErr = 104
GetErr = 105
RevokeErr = 106)
func main() { var conf = clientv3.Config{
Endpoints: []string{"172.16.196.129:2380", "192.168.50.250:2380"},
DialTimeout: 5 * time.Second,
}
client, err := clientv3.New(conf)
defer client.Close() if err != nil {
fmt.Printf("创建client失败:\n", err.Error())
os.Exit(NewLeaseErr)
} //创建租约
lease := clientv3.NewLease(client) //设置租约时间
leaseResp, err := lease.Grant(context.TODO(), 10) if err != nil {
fmt.Printf("设置租约时间失败:%s\n", err.Error())
os.Exit(LeasTtlErr)
} //设置续租
leaseID := leaseResp.ID
ctx, cancelFunc := context.WithCancel(context.TODO())
leaseRespChan, err := lease.KeepAlive(ctx, leaseID) if err != nil {
fmt.Printf("续租失败:%s\n", err.Error())
os.Exit(KeepAliveErr)
} //监听租约
go func() { for {
select { case leaseKeepResp := <-leaseRespChan: if leaseKeepResp == nil {
fmt.Printf("已经关闭续租功能\n") return
} else {
fmt.Printf("续租成功\n") goto END
}
}
END:
time.Sleep(500*time.Millisecond)
}
}() //监听某个key的变化
//ctx1, _ := context.WithTimeout(context.TODO(),20)
go func() {
wc := client.Watch(context.TODO(), "/job/v3/1", clientv3.WithPrevKV()) for v := range wc { for _, e := range v.Events {
fmt.Printf("type:%v kv:%v prevKey:%v \n ", e.Type, string(e.Kv.Key), e.PrevKv)
}
}
}()
kv := clientv3.NewKV(client) //通过租约put
putResp, err := kv.Put(context.TODO(), "/job/v3/1", "koock",clientv3.WithLease(leaseID)) if err != nil {
fmt.Printf("put 失败：%s", err.Error())
os.Exit(PutErr)
}
fmt.Printf("%v\n",putResp.Header)
cancelFunc()
time.Sleep(2*time.Second)
_, err = lease.Revoke(context.TODO(), leaseID) if err != nil {
fmt.Printf("撤销租约失败:%s\n",err.Error())
os.Exit(RevokeErr)
}
fmt.Printf("撤销租约成功")
getResp,err := kv.Get(context.TODO(),"/job/v3/1") if err != nil{
fmt.Printf("get 失败：%s",err.Error())
os.Exit(GetErr)
}
fmt.Printf("%v",getResp.Kvs)
time.Sleep(20 * time.Second)
}在put操作时，watch会监听到操作，打印出：type:PUT kv:/job/v3/1 prevKey:<nil>
撤销租约后，watch会监听到delete操作，打印出：type:DELETE kv:/job/v3/1 prevKey:key:"/job/v3/1"
作者：我的饭卡呢
链接：https://www.jianshu.com/p/9bd1ab83b220
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