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In this article, the editor introduces in detail "how to achieve distributed locks in Redis-based SETNX operations". The content is detailed, the steps are clear, and the details are handled properly. I hope this article "how to achieve distributed locks in Redis-based SETNX operations" can help you solve your doubts.

Import com.jd.jim.cli.Cluster

Import java.io.IOException

Import java.util.concurrent.TimeUnit

/ * *

*

* distributed lock based on SETNX operation of Redis

*

* @ author lzc.java@icloud.com

*

, /

Public class RedisDistributedLock {

Private Cluster redis

/ / name of the lock

Private String lockKey

/ / value of the lock

Private String lockVal = ""

/ / the valid duration of the default lock (milliseconds)

Private long lockExpires

Private boolean locked

/ / the thread that holds the lock in the current jvm (if have one)

Private Thread exclusiveOwnerThread

/ * *

*

* @ param redis

* @ param lockKey lockKey

* @ param lockExpires lockKey expiration time (in milliseconds)

* @ throws IOException

, /

Public RedisDistributedLock (Cluster redis, String lockKey, long lockExpires) {

This.redis = redis

This.lockKey = lockKey

This.lockExpires = lockExpires

}

/ * *

* Block lock is acquired, but there is a timeout. If the lock is not acquired by tryGetLockTime, it will be returned to false directly.

* @ param tryGetLockTime

* @ param tryGetLockUnit

* @ return

* @ throws InterruptedException

, /

Protected boolean lock (long tryGetLockTime, TimeUnit tryGetLockUnit) {

Try {

/ / the time of timeout control can be obtained locally, because it has nothing to do with lock timeout, but only the control of a period of time

Long start = System.currentTimeMillis ()

Long timeout = tryGetLockUnit.toMillis (tryGetLockTime)

/ / int tryTimes=0

While (System.currentTimeMillis ()-start < timeout) {

/ / tryTimes++

/ / Lock timeout

Long lockExpireTime = System.currentTimeMillis () + lockExpires + 1

String stringOfLockExpireTime = String.valueOf (lockExpireTime)

If (setnx (lockKey, stringOfLockExpireTime)) {/ / acquire the lock

/ / successfully acquire the lock and set the relevant identity

Locked = true

ExclusiveOwnerThread = Thread.currentThread ()

/ / System.out.println ("got the lock, :" + tryTimes)

Return true

}

/ / indicates that the lock has not been acquired. Further check whether the lock has timed out.

String lockVal=redis.get (lockKey)

/ / in the case of lockVal=null, the C1 client acquires the lock, and after processing, the DEL drops the lock, before the DEL lock.

/ / C2 sets the timestamp T0 to the lockKey through SETNX and finds that the client has acquired the lock and entered the GET operation.

/ / at this time, the C1 client DEL is unlocked successfully.

/ / C2 sends a GET command to lockKey to get the return value T1 (null).

If (lockValualValidships nullable Long.parseLong (lockVal))

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