Golang基于Redis的分布式锁
我理解的分布式锁:
一、为了不单持有锁的进程奔溃而没法释放锁,因此必须可以为锁设定过时时间自动释放锁资源 二、使用TTL检查锁是否成功的被设置过时时间,若是返回-1(未被设置)的话,使用Expire为其设定过时时间 三、在释放锁的时候须要使用Watch命令,确保监测的值在事务执行时时未被改变,若是其余进程修改了锁,会触发事务异常,而后从新执行Watch。git
分享一个我写的Redis封装类,仅实现了链接和锁github
package dao import ( "time" "github.com/go-redis/redis/v7" uuid "github.com/satori/go.uuid" ) type Rds struct { Client *redis.Client AcquireTimeout int32 LockTimeout int32 } func NewRds(host, passwd string, db int) (rds *Rds, err error) { rdsOpt := &redis.Options{ Addr: host, Password: passwd, DB: db, } client := redis.NewClient(rdsOpt) _, err = client.Ping().Result() if err != nil { return } rds = &Rds{Client: client, AcquireTimeout: 10, LockTimeout: 10} return } func (r *Rds) AcquireLockWithTimeout(key string) (identifier string, b bool) { identifier = uuid.NewV4().String() lockname := "lock:" + key end := time.Now().Add(time.Second * time.Duration(r.AcquireTimeout)) for time.Now().Before(end) { if r.Client.SetNX(lockname, identifier, time.Second*time.Duration(r.LockTimeout)).Val() { // 若是key不存在,并成功设置了key b = true return } else if r.Client.TTL(lockname).Val() == -1 { // 若是key存在,可是没有剩余时间 r.Client.Expire(lockname, time.Second*time.Duration(r.LockTimeout)) } time.Sleep(time.Microsecond) } return } func (r *Rds) ReleaseLock(key, identifier string) (b bool) { lockname := "lock:" + key txf := func(tx *redis.Tx) error { v, err := tx.Get(lockname).Result() if err != nil { return err } _, err = tx.Pipelined(func(pipe redis.Pipeliner) error { if v == identifier { pipe.Del(lockname) b = true } return nil }) return err } for { err := r.Client.Watch(txf, lockname) if err == nil { break } else if err == redis.TxFailedErr { glog.Error(err) } } return }