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 }
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。