1 package main
2
3 import (
4 "context"
5 "fmt"
6 "time"
7
8 "go.etcd.io/etcd/clientv3"
9 )
10
11 func main() {
12 var (
13 client *clientv3.Client
14 cfg clientv3.Config
15 err error
16 lease clientv3.Lease
17 ctx context.Context
18 cancelFunc context.CancelFunc
19 leaseId clientv3.LeaseID
20 leaseGrantResponse *clientv3.LeaseGrantResponse
21 leaseKeepAliveChan <-chan *clientv3.LeaseKeepAliveResponse
22 leaseKeepAliveResponse *clientv3.LeaseKeepAliveResponse
23 txn clientv3.Txn
24 txnResponse *clientv3.TxnResponse
25 kv clientv3.KV
26 )
27
28 cfg = clientv3.Config{
29 Endpoints: []string{"youwebsite:2379"},
30 DialTimeout: time.Second * 5,
31 }
32 if client, err = clientv3.New(cfg); err != nil {
33 fmt.Println(err)
34 return
35 }
36
37 lease = clientv3.NewLease(client)
38 if leaseGrantResponse,err = lease.Grant(context.TODO(),5);err!=nil{
39 fmt.Println(err)
40 return
41 }
42 leaseId = leaseGrantResponse.ID
43
44 //租约自动过期，立刻过期。//cancelfunc 取消续租，而revoke 则是立即过期
45 ctx,cancelFunc = context.WithCancel(context.TODO())
46 defer cancelFunc()
47 defer lease.Revoke(context.TODO(),leaseId)
48
49 if leaseKeepAliveChan,err = lease.KeepAlive(ctx,leaseId);err!=nil{
50 fmt.Println(err)
51 return
52 }
53 //启动续租协程，每秒续租一次
54 go func() {
55 for {
56 select {
57 case leaseKeepAliveResponse = <-leaseKeepAliveChan:
58 if leaseKeepAliveResponse != nil{
59 fmt.Println("续租成功,leaseID :",leaseKeepAliveResponse.ID)
60 }else {
61 fmt.Println("续租失败")
62 }
63
64 }
65 time.Sleep(time.Second*1)
66 }
67 }()
68 //锁逻辑。
69 kv = clientv3.NewKV(client)
70 txn = kv.Txn(context.TODO())
71
72 txn.If(clientv3.Compare(clientv3.CreateRevision("/dev/lock"),"=",0)).Then(
73 clientv3.OpPut("/dev/lock","占用",clientv3.WithLease(leaseId))).Else(
74 clientv3.OpGet("/dev/lock"))
75 if txnResponse,err = txn.Commit();err!=nil{
76 fmt.Println(err)
77 return
78 }
79 if txnResponse.Succeeded {
80 fmt.Println("抢到锁了")
81 }else {
82 fmt.Println("没抢到锁",txnResponse.Responses[0].GetResponseRange().Kvs[0].Value)
83 }
84 time.Sleep(time.Second * 10 )
85 }
