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 * ,
     }
     if client, err = clientv3.New(cfg); err != nil {
         fmt.Println(err)
         return
     }

     lease = clientv3.NewLease(client)
     if leaseGrantResponse,err = lease.Grant(context.TODO(),);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*)
         }
     }()
     //锁逻辑。
     kv = clientv3.NewKV(client)
     txn = kv.Txn(context.TODO())

     txn.If(clientv3.Compare(clientv3.CreateRevision("/dev/lock"),"=",)).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[].GetResponseRange().Kvs[].Value)
     }
     time.Sleep(time.Second *  )
 }