Redis实现分布式锁(setnx、getset、incr)以及如何处理超时情况

一、通过setnx实现

• 1、setnx key value
• 2、get key
• 3、getset key value
• 小明提出了方案一：
• 小宏说：小明的思想不严谨
• 网上看还有一种方式（B）：

二、通过incr抢占资源实现

• 1、incr

public static Boolean setnx(final String key, final String value, final long seconds) {
        return getShardedJedisClient().execute(new ShardedJedisAction<Boolean>() {
            public Boolean doAction(ShardedJedis shardedJedis) {
                Jedis jedis = (Jedis) shardedJedis.getShard(key);
                String result = jedis.set(key, value, "NX", "EX", seconds);
                return "OK".equalsIgnoreCase(result);
            }
        });
    }

public String get(final String key) {
        this.checkIsInMulti();
        return (String)this.execute(new SmartJedis.Action<String>() {
            public String doAction(Jedis jedis) {
                return jedis.get(key);
            }
        }, SmartJedis.RW.R, key);
    }

public static String getset(final String key, final String value) {
        return getShardedJedisClient().execute(new ShardedJedisAction<String>() {
            @Override
            public String doAction(ShardedJedis shardedJedis) {
                return shardedJedis.getSet(key, value);
            }
        });
    }

RedisUtils.setnx("LOCK_KEY_phone&idNo&name","demo");
JSONObject result = A.request(B);
AssetUtils.notNull(result,ResponseCodeEnum.Success,"拿到结果");
ResultDmo resultDmo = (ResultDmo)BeanUtils.maptoBean(result);
resultDao.insert(resultDmo);
if(result!=0){
  //上一笔同样的请求还未处理完成，轮训等待(具体如何轮训在此不展开)
}else{
  //上一笔同样的请求处理完成，进行查库操作
  resultDao.select("参数");
}

RedisUtils.setnx("LOCK_KEY_phone&idNo&name","demo",200);

RedisUtils.setnx("LOCK_KEY_phone&idNo&name",currentTime,200);
Long old = RedisUtils.get("LOCK_KEY_phone&idNo&name");
Long new = System.currentTimeMillis();
Long time = new - old;
if(time>0){
//处理已经超时
RedisUtils.delete("LOCK_KEY_phone&idNo&name");
}

public static Long incr(final String key) {
        return shardedClient.execute(new ShardedJedisAction<Long>() {
            @Override
            public Long doAction(ShardedJedis shardedJedis) {
                shardedJedis.expire(key, 200);
                return shardedJedis.incr(key);
            }
        });
    }

Long result = RedisUtils.incr("LOCK_KEY_phone&idNo&name");
        if (result > 1) {
            //如果计数器>1,说明已经有请求进来
            throw new AppException(ResponseCode.FAIL.getCode(), "操作频繁");
        }


 JSONObject result = A.request(B);
 Long endTime = System.currentTimeMillis();
 Long time = endTime - startTime;
  //如果处理时间大于incr的key存活时间,说明该笔请求已经超时
  if (time > 200) {
      //全局ID,统计超时次数
      String key = "LOCK_KEY_phone&idNo&name" + source;
      RedisUtils.incr(key);
      int total = Integer.valueOf(RedisUtils.get(key));
      //断言若超时10次,进行报警(报警不在次展开)
      AssertUtils.isTrue(total < 10, ResponseCode.FAIL, "调用" + source + "渠道超时");
  }