golang使用etcd实现分布式锁

package main

import (
    "context"
    "fmt"
    "time"

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

func main() {
    var (
        client *clientv3.Client
        cfg    clientv3.Config
        err    error
        lease clientv3.Lease
        ctx context.Context
        cancelFunc context.CancelFunc
        leaseId clientv3.LeaseID
        leaseGrantResponse *clientv3.LeaseGrantResponse
        leaseKeepAliveChan <-chan *clientv3.LeaseKeepAliveResponse
        leaseKeepAliveResponse *clientv3.LeaseKeepAliveResponse
        txn clientv3.Txn
        txnResponse *clientv3.TxnResponse
        kv clientv3.KV
    )

    cfg = clientv3.Config{
        Endpoints:   []string{"youwebsite:2379"},
        DialTimeout: time.Second * 5,
    }
    if client, err = clientv3.New(cfg); err != nil {
        fmt.Println(err)
        return
    }

    lease = clientv3.NewLease(client)
    if leaseGrantResponse,err = lease.Grant(context.TODO(),5);err!=nil{
        fmt.Println(err)
        return
    }
    leaseId = leaseGrantResponse.ID

    //租约自动过期，立刻过期。//cancelfunc 取消续租，而revoke 则是立即过期
    ctx,cancelFunc = context.WithCancel(context.TODO())
    defer cancelFunc()
    defer lease.Revoke(context.TODO(),leaseId)

    if leaseKeepAliveChan,err = lease.KeepAlive(ctx,leaseId);err!=nil{
        fmt.Println(err)
        return
    }
    //启动续租协程，每秒续租一次
    go func() {
        for {
            select {
            case leaseKeepAliveResponse = <-leaseKeepAliveChan:
                if leaseKeepAliveResponse != nil{
                    fmt.Println("续租成功,leaseID :",leaseKeepAliveResponse.ID)
                }else {
                    fmt.Println("续租失败")
                }

            }
            time.Sleep(time.Second*1)
        }
    }()
    //锁逻辑。
    kv = clientv3.NewKV(client)
    txn = kv.Txn(context.TODO())

    txn.If(clientv3.Compare(clientv3.CreateRevision("/dev/lock"),"=",0)).Then(
        clientv3.OpPut("/dev/lock","占用",clientv3.WithLease(leaseId))).Else(
            clientv3.OpGet("/dev/lock"))
    if txnResponse,err = txn.Commit();err!=nil{
        fmt.Println(err)
        return
    }
    if txnResponse.Succeeded {
        fmt.Println("抢到锁了")
    }else {
        fmt.Println("没抢到锁",txnResponse.Responses[0].GetResponseRange().Kvs[0].Value)
    }
    time.Sleep(time.Second * 10 )
}