基于 go+etcd 实现分布式锁
基于 go+etcd 实现分布式锁,主要使用的是租约机制
本文由 简悦 SimpRead 转码, 原文地址 https://www.jianshu.com/p/d3068d0ac7c1
package main
import (
"context"
"fmt"
"go.etcd.io/etcd/clientv3"
"time"
)
func main() {
var (
config clientv3.Config
client *clientv3.Client
lease clientv3.Lease
leaseResp *clientv3.LeaseGrantResponse
leaseId clientv3.LeaseID
leaseRespChan <-chan *clientv3.LeaseKeepAliveResponse
err error
)
//客户端配置
config = clientv3.Config{
Endpoints: []string{"127.0.0.1:2379"},
DialTimeout: 5 * time.Second,
}
//建立连接
if client, err = clientv3.New(config); err != nil {
fmt.Println(err)
return
}
//上锁(创建租约,自动续租)
lease = clientv3.NewLease(client)
//设置一个ctx取消自动续租
ctx,cancleFunc := context.WithCancel(context.TODO())
//设置10秒租约(过期时间)
if leaseResp,err = lease.Grant(context.TODO(),10);err != nil {
fmt.Println(err)
return
}
//拿到租约id
leaseId = leaseResp.ID
//自动续租(不停地往管道中扔租约信息)
if leaseRespChan,err =lease.KeepAlive(ctx,leaseId);err != nil {
fmt.Println(err)
}
//启动一个协程去监听
go listenLeaseChan(leaseRespChan)
//业务处理
kv := clientv3.NewKV(client)
//创建事务
txn := kv.Txn(context.TODO())
txn.If(clientv3.Compare(clientv3.CreateRevision("/cron/lock/job9"),"=",0)).
Then(clientv3.OpPut("/cron/lock/job9","xxx",clientv3.WithLease(leaseId))).
Else(clientv3.OpGet("/cron/lock/job9"))//否则抢锁失败
//提交事务
if txtResp,err :=txn.Commit();err != nil {
fmt.Println(err)
return
} else {
//判断是否抢锁
if !txtResp.Succeeded {
fmt.Println("锁被占用:",string(txtResp.Responses[0].GetResponseRange().Kvs[0].Value))
return
}
}
fmt.Println("处理任务")
//释放锁(停止续租,终止租约)
defer cancleFunc()//函数退出取消自动续租
defer lease.Revoke(context.TODO(),leaseId) //终止租约(去掉过期时间)
time.Sleep(10 * time.Second)
}
func listenLeaseChan(leaseRespChan <-chan *clientv3.LeaseKeepAliveResponse) {
var (
leaseKeepResp *clientv3.LeaseKeepAliveResponse
)
for {
select {
case leaseKeepResp = <-leaseRespChan:
if leaseKeepResp == nil {
fmt.Println("租约失效了")
goto END
} else {
fmt.Println(leaseKeepResp.ID)
}
}
}
END:
}