scala+redis实现分布式锁的示例代码

1、redis的底层是单例模式，意思是同一个脚本同一时刻只能有一个线程来执行，利用redis的这个特性来实现分布式锁。

首先实现工具类

package utils

import CacheManager

/**
 * redis分布式锁
 */
object RedisTool {

 //加锁是否成功标志
 val LOCK_SUCCESS:String = "OK"

 //即当key不存在时，我们进行set操作；若key已经存在，则不做任何操作；
 val SET_IF_NOT_EXIST:String = "NX"

 //意思是我们要给这个key加一个过期的设置，具体时间由第五个参数决定。
 val SET_WITH_EXPIRE_TIME:String = "PX"

 val RELEASE_SUCCESS:String = "1"

 /**
  *
  * @param lockKey   锁
  * @param requestId  请求标识
  * @param expireTime  超期时间
  * @param isPersist  临时缓存或者永久缓存
  */
 def tryGetDistributedLock(lockKey:String, requestId:String, expireTime:Int,isPersist:Boolean=false){
  CacheManager.redisClientPool.withClient(
   client => {
    //val redisKeyPrefix = CacheManager.getRedisKeyPrefix(isPersist)
    client.select(CacheManager.redisDBNum)
    val result = client.set(lockKey, requestId, SET_IF_NOT_EXIST, SET_WITH_EXPIRE_TIME, expireTime)
    var flag = false
    if(LOCK_SUCCESS == result){
     flag = true
    }
    flag
   }
  )
 }

 /**
  *释放分布式锁
  * @param lockKey   锁
  * @param requestId  请求标识
  * @param expireTime  超期时间
  * @param isPersist  临时缓存或者永久缓存
  * @return
  */
 def releaseDistributedLock(lockKey:String, requestId:String,expireTime: Int = 10,isPersist:Boolean=false) ={
  CacheManager.redisClientPool.withClient(
   client => {
    val redisKeyPrefix = CacheManager.getRedisKeyPrefix(isPersist)
    client.select(CacheManager.redisDBNum)
    //lua脚本也是单例模式，同样也可以保证同一时刻只有一个线程执行脚本
    val lua =
     s"""
       |local current = redis.call('incrBy',KEYS[1],ARGV[1]);
       |if current == tonumber(ARGV[1]) then
       |  local t = redis.call('ttl',KEYS[1]);
       |  if t == -1 then
       |    redis.call('expire',KEYS[1],ARGV[2])
       |  end;
       |end;
       |return current;
      """.stripMargin
    val code = client.scriptLoad(lua).get
    val ret = client.evalSHA(code, List(redisKeyPrefix + lockKey),List(requestId,expireTime))
    val result = ret.get.asInstanceOf[Object].toString
    var flag = false
    if(result == RELEASE_SUCCESS){
     flag = true
    }
    flag
   }
  )
 }

}

2、实现CacheManager类

package utils

import com.redis.RedisClientPool
/**
 *
 */
object CacheManager {

 val redisClientPool = "dev".equalsIgnoreCase(System.getenv("SCALA_ENV")) match {
  //开发环境
  case true => new RedisClientPool("127.0.0.1", 6379)
  //其他环境
  case false => new RedisClientPool("10.180.x.y", 6379, 8, 0, Some("root"))
 }

 val redisDBNum = 10

 def getRedisKeyPrefix(isPersist:Boolean) ={
  if(isPersist){
   //永久缓存前缀
   "persist_"
  }else{
   //临时缓存前缀
   "tmp_"
  }
 }

}

3、调用锁操作

def updateTableInfo(param:String) = {
  var resMap = Map[String,Any]()
  val lockKey = "mdms.MdmsUtils.updateTableInfo"
  //val requestId = UUID.randomUUID().toString().replace("-", "").toUpperCase()
  val flag = RedisTool.releaseDistributedLock(lockKey, "1")
  if(flag){
   try{

    //执行你的操作
    resMap = Map("code" -> 200 ,"msg" -> "成功")
   }catch {
    case e:Exception => {

     e.printStackTrace()
     resMap = Map("code" -> 200101 ,"msg" -> "执行失败")
    }
   }

  }else{
   resMap = Map("code" -> 200102 ,"msg" -> "操作冲突，已经被其他人捷足先登啦。")
  }
  resMap
 }

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