package com.today.commons.lock

import com.today.service.commons.help.BizHelp.withJedis
import com.today.service.purchase.PurchaseDataSource.jedisPool

import scala.collection.convert.ImplicitConversionsToJava._

/**
  * Created by cjl at 2018-09-02
  * Description:
  * Changed:
  */
object RedisLock {

  //NX -- Only set the key if it does not already exist. XX -- Only set the key if it already exist
  private val SET_IF_NOT_EXIST: String = "NX"
  //expire time units: EX = seconds; PX = milliseconds
  private val SET_WITH_EXPIRE_TIME: String = "PX"

  private val LOCK_SUCCESS: String = "OK"
  private val RELEASE_SUCCESS: Long = 1L

  /**
    * 尝试获取分布式锁
    *
    * @param lockKey    锁
    * @param requestId  请求标识
    * @param expireTime 超期时间  单位:毫秒
    * @return 是否获取成功
    */
  def tryLock(lockKey: String, requestId: String, expireTime: Long): Boolean = {
    val res = withJedis(jedisPool)( j =>
      j.set(lockKey, requestId, SET_IF_NOT_EXIST, SET_WITH_EXPIRE_TIME, expireTime)
    )
    res.isDefined && res.get == LOCK_SUCCESS
  }

  /**
    * 释放分布式锁
    *
    * @param lockKey   锁
    * @param requestId 请求标识 防止开别人的锁
    * @return 是否释放成功
    */
  def releaseLock(lockKey: String, requestId: String): Boolean = {
    // 原子性 eval命令执行lua代码的时候，lua代码将被当成一个命令去执行，并且直到eval命令执行完成，Redis才会执行其他命令
    val script: String = "if redis.call('get', KEYS[1]) == ARGV[1] then return redis.call('del', KEYS[1]) else return 0 end"
    val res = withJedis(jedisPool)(
      _.eval(script, List(lockKey), List(requestId))
    )
    res.isDefined && res.get == RELEASE_SUCCESS
  }
}