Java Code Examples for redis.clients.jedis.Jedis#watch()

/**
 * 乐观锁：watch
 *
 */
public static int doubleAccount(Jedis jedis, String userId) {
    String key = keyFor(userId);
    while (true) {
        jedis.watch(key);
        int value = Integer.parseInt(jedis.get(key));
        value *= 2; // 加倍
        Transaction tx = jedis.multi();
        tx.set(key, String.valueOf(value));
        List<Object> res = tx.exec();
        if (res != null) {
            break; // 成功了
        }
    }
    return Integer.parseInt(jedis.get(key)); // 重新获取余额
}
 

@Override
public boolean unLock(String lockName, String lockSerialNum) {
	boolean result = false;
	String lock = "lock:" + lockName;
	
	Jedis conn = pool.getResource();
	// 循环尝试解锁
	// while循环适用于超时剥夺锁的情况
	while (true) {
		try {
			// 监视锁数据，一旦被人篡改则重试
			conn.watch(lock);
			// 当确认是自己上的锁时，利用实务进行解锁操作
			if (conn.get(lock).equals(lockSerialNum)) {
				Transaction transaction = conn.multi();
				transaction.del(lock);
				// 执行操作可能有隐患
				transaction.exec();
				result = true;
				System.out.println(Thread.currentThread().getName() + "redis锁解锁成功");
				System.out.println("+++++++++++++++++++");
			}
			conn.unwatch();
			break;
		} catch (JedisException e) {
			// conn.watch(lock)触发，重试解锁
			System.out.println(Thread.currentThread().getName() + "redis锁已被篡改，正在重试...");
			System.out.println("+++++++++++++++++++");
			// e.printStackTrace();
		} finally {
			// 关闭redis连接
			conn.close();
		}

	}

	return result;
}
 

/**
 * Add or modify a user's password
 * 
 * @param username unique user name
 * @param password the user's password (will be hashed)
 * @return true iff a new element was inserted
 */
public static boolean setUserPassword( String username, String password )
{
    Jedis jedis = pool.getResource();
    try
    {
        boolean newUser;

        Transaction trans;
        do
        {
            // Can't use intermediate results of a Redis transaction in that transaction, so watch the keys and do
            // the query before opening the transaction. The transaction will fail on exec() call if the keys
            // changed.
            jedis.watch( keyOfPassHash, keyOfPassSaltsHash );
            boolean exists = jedis.hexists( keyOfPassHash, username );

            trans = jedis.multi();
            // Create a salt as well as the new password entry if the user is new
            if ( !exists )
            {
                newUser = true;

                String salt = generateSalt();
                trans.hset( keyOfPassSaltsHash, username, salt );

                String hash = hash( password, salt );
                trans.hset( keyOfPassHash, username, hash );
            }
            else
                newUser = false;
        }
        while ( trans.exec() == null );

        return newUser;
    }
    finally
    {
        pool.returnResource( jedis );
    }
}
 

/**
 * @param seckillId
 * @param userPhone
 * @param md5
 * @return
 * @throws SeckillException
 * @TODO 先在redis里处理，然后发送到mq，最后减库存到数据库
 */
private SeckillExecution handleSeckillAsync(long seckillId, long userPhone, String md5)
        throws SeckillException {
    if (md5 == null || !md5.equals(getMD5(seckillId))) {
        logger.info("seckill_DATA_REWRITE!!!. seckillId={},userPhone={}", seckillId, userPhone);
        throw new SeckillException(SeckillStateEnum.DATA_REWRITE);
    }

    Jedis jedis = jedisPool.getResource();
    String inventoryKey = RedisKeyPrefix.SECKILL_INVENTORY + seckillId;
    if (jedis.sismember(RedisKey.SECKILLED_USER, String.valueOf(userPhone))) {
        //重复秒杀
        logger.info("seckill REPEATED. seckillId={},userPhone={}", seckillId, userPhone);
        throw new SeckillException(SeckillStateEnum.REPEAT_KILL);
    } else {
        String inventoryStr = jedis.get(inventoryKey);
        int inventory = Integer.valueOf(inventoryStr);
        if (inventory <= 0) {
            throw new SeckillException(SeckillStateEnum.SOLD_OUT);
        }
        jedis.watch(inventoryKey);
        Transaction tx = jedis.multi();
        tx.decr(inventoryKey);
        tx.sadd(RedisKey.SECKILLED_USER, String.valueOf(userPhone));
        List<Object> resultList = tx.exec();
        jedis.unwatch();
        if (resultList != null && resultList.size() == 2) {
            // 秒杀成功，后面异步更新到数据库中
            // 发送消息到消息队列
            SeckillMsgBody msgBody = new SeckillMsgBody();
            msgBody.setSeckillId(seckillId);
            msgBody.setUserPhone(userPhone);
            mqProducer.send(JSON.toJSONString(msgBody));

            // 立即返回给客户端，说明秒杀成功了
            SuccessKilled successKilled = new SuccessKilled();
            successKilled.setUserPhone(userPhone);
            successKilled.setSeckillId(seckillId);
            successKilled.setState(SeckillStateEnum.SUCCESS.getState());
            return new SeckillExecution(seckillId, SeckillStateEnum.SUCCESS, successKilled);
        } else {
            throw new SeckillException(SeckillStateEnum.RUSH_FAILED);
        }
    }
}
 

private String watch0(Jedis j, String... keys) {
	String r = j.watch(keys);
	bind(j);
	return r;
}