Redis Golang分布式锁
为什么要使用分布式锁？
- 多个进程或服务竞争资源，而这些进程或服务又部署在多台机器，此时需要使用分布式锁，确保资源被正确地使用，否则可能出现副作用。
- 避免重复执行某一个动作，多台机器部署的同一个服务上都有相同定时任务，而定时任务只需执行一次，此时需要使用分布式锁，确保效率。
具体业务：电商业务避免重复支付，微服务上多副本服务的夜间定时统计。
分布式锁支持：
- 单机模式的 Redis。
- 哨兵模式的 Redis。说明：该模式也是属于单机，Redis 是一主（Master）多从（Slave），只不过有哨兵机制，主挂掉后哨兵发现后可以将从提升到主。
单机和哨兵模式的 Redis 无法做到锁的高可用，比如 Redis 挂掉了可能导致服务不可用（单机），锁混乱（哨兵），但对可靠性要求没那么高的，我们还是可以使用单机 Redis，毕竟大多数情况都比较稳定。
对可靠性要求较高，要求高可用，官方给出了 Redlock 算法，利用多台主（Redis Master）来逐一加锁，半数加锁成功就认为成功，因为要维护多套 Redis，略显繁琐。真真需要高可用，我建议使用 etcd 官方实现的分布式锁 。
如何使用
很简单，执行：
go get -v github.com/hunterhug/gorlock本库支持无感知锁续命，你只要开启 KeepAlive，可以解决业务处理时间过长，导致锁超时，而被其他人抢占重入的问题:
// LockFactory is main interface
type LockFactory interface {
SetRetryCount(c int64) LockFactory
GetRetryCount() int64
SetUnLockRetryCount(c int64) LockFactory
GetUnLockRetryCount() int64
SetKeepAlive(isKeepAlive bool) LockFactory
IsKeepAlive() bool
SetRetryMillSecondDelay(c int64) LockFactory
GetRetryMillSecondDelay() int64
SetUnLockRetryMillSecondDelay(c int64) LockFactory
GetUnLockRetryMillSecondDelay() int64
LockFactoryCore
}
// LockFactoryCore is core interface
type LockFactoryCore interface {
// Lock lock resource default keepAlive depend on LockFactory
Lock(ctx context.Context, resourceName string, lockMillSecond int) (lock *Lock, err error)
// LockForceKeepAlive lock resource force keepAlive
LockForceKeepAlive(ctx context.Context, resourceName string, lockMillSecond int) (lock *Lock, err error)
// LockForceNotKeepAlive lock resource force not keepAlive
LockForceNotKeepAlive(ctx context.Context, resourceName string, lockMillSecond int) (lock *Lock, err error)
// UnLock unlock resource
UnLock(ctx context.Context, lock *Lock) (isUnLock bool, err error)
// Done asynchronous see lock whether is release
Done(lock *Lock) chan struct{}
}核心操作，就是建一个锁工厂，然后使用接口契约中的方法来生成锁，并操作这把锁。
例子
package main
import (
"context"
"fmt"
"github.com/hunterhug/gorlock"
"time"
)
func main() {
gorlock.SetDebug()
// 1. 配置Redis
redisHost := "127.0.0.1:6379"
redisDb := 0
redisPass := "hunterhug" // may redis has password
config := gorlock.NewRedisSingleModeConfig(redisHost, redisDb, redisPass)
pool, err := gorlock.NewRedisPool(config)
if err != nil {
fmt.Println("redis init err:", err.Error())
return
}
// 2. 新建一个锁工厂
lockFactory := gorlock.New(pool)
// 设置锁重试次数和尝试等待时间，表示加锁不成功等200毫秒再尝试，总共尝试3次，设置负数表示一直尝试，会堵住
lockFactory.SetRetryCount(3).SetRetryMillSecondDelay(200)
// 自动续命锁
lockFactory.SetKeepAlive(true)
// 3. 锁住资源，资源名为myLock
resourceName := "myLock"
// 过期时间10秒
expireMillSecond := 10 * 1000
lock, err := lockFactory.Lock(context.Background(), resourceName, expireMillSecond)
if err != nil {
fmt.Println("lock err:", err.Error())
return
}
// 锁为空，表示加锁失败
if lock == nil {
fmt.Println("lock err:", "can not lock")
return
}
// 加锁成功
fmt.Printf("add lock success:%#v\n", lock)
// 可以等待锁被释放
//<-lockFactory.Done(lock)
time.Sleep(3 * time.Second)
// 4. 解锁
isUnlock, err := lockFactory.UnLock(context.Background(), lock)
if err != nil {
fmt.Println("lock err:", err.Error())
return
}
fmt.Printf("lock unlock: %v, %#v\n", isUnlock, lock)
// 上面已经解锁了，可以多次解锁
isUnlock, err = lockFactory.UnLock(context.Background(), lock)
if err != nil {
fmt.Println("lock err:", err.Error())
return
}
fmt.Println("lock unlock:", isUnlock)
}结果：
add lock success:&gorlock.Lock{CreateMillSecondTime:1627543007573, LiveMillSecondTime:10001, LastKeepAliveMillSecondTime:0, UnlockMillSecondTime:0, ResourceName:"myLock", RandomKey:"a6f438bd9b1f4d759e818dbc78e890f4", IsUnlock:false, isUnlockChan:(chan struct {})(0xc00007a1e0), IsClose:false, OpenKeepAlive:true, closeChan:(chan struct {})(0xc00007a240), keepAliveDealCloseChan:(chan bool)(0xc00007a2a0), mutex:sync.Mutex{state:0, sema:0x0}}
2021-07-29 15:16:48.083 github.com/hunterhug/gorlock:(*redisLockFactory).keepAlive [DEBUG]: start in 2021-07-29 15:16:48.079402 +0800 CST m=+0.518137615 keepAlive myLock with random key:a6f438bd9b1f4d759e818dbc78e890f4 doing
2021-07-29 15:16:48.586 github.com/hunterhug/gorlock:(*redisLockFactory).keepAlive [DEBUG]: start in 2021-07-29 15:16:48.583449 +0800 CST m=+1.022178426 keepAlive myLock with random key:a6f438bd9b1f4d759e818dbc78e890f4 doing
2021-07-29 15:16:49.090 github.com/hunterhug/gorlock:(*redisLockFactory).keepAlive [DEBUG]: start in 2021-07-29 15:16:49.087154 +0800 CST m=+1.525877218 keepAlive myLock with random key:a6f438bd9b1f4d759e818dbc78e890f4 doing
2021-07-29 15:16:49.594 github.com/hunterhug/gorlock:(*redisLockFactory).keepAlive [DEBUG]: start in 2021-07-29 15:16:49.590883 +0800 CST m=+2.029599435 keepAlive myLock with random key:a6f438bd9b1f4d759e818dbc78e890f4 doing
2021-07-29 15:16:50.097 github.com/hunterhug/gorlock:(*redisLockFactory).keepAlive [DEBUG]: start in 2021-07-29 15:16:50.094998 +0800 CST m=+2.533708261 keepAlive myLock with random key:a6f438bd9b1f4d759e818dbc78e890f4 doing
2021-07-29 15:16:50.575 github.com/hunterhug/gorlock:(*redisLockFactory).UnLock [DEBUG]: UnLock send signal to keepAlive ask game over
2021-07-29 15:16:50.575 github.com/hunterhug/gorlock:(*redisLockFactory).keepAlive [DEBUG]: start in 2021-07-29 15:16:50.575115 +0800 CST m=+3.013818937 keepAlive myLock with random key:a6f438bd9b1f4d759e818dbc78e890f4 close
2021-07-29 15:16:50.575 github.com/hunterhug/gorlock:(*redisLockFactory).UnLock [DEBUG]: UnLock receive signal to keepAlive response keepAliveHasBeenClose=false
lock unlock: true, &gorlock.Lock{CreateMillSecondTime:1627543007573, LiveMillSecondTime:10001, LastKeepAliveMillSecondTime:1627543010097, UnlockMillSecondTime:1627543010575, ResourceName:"myLock", RandomKey:"a6f438bd9b1f4d759e818dbc78e890f4", IsUnlock:true, isUnlockChan:(chan struct {})(0xc00007a1e0), IsClose:true, OpenKeepAlive:true, closeChan:(chan struct {})(0xc00007a240), keepAliveDealCloseChan:(chan bool)(0xc00007a2a0), mutex:sync.Mutex{state:0, sema:0x0}}
lock unlock: trueLicense
Copyright [2019-2021] [github.com/hunterhug]
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