# SecKillDesign

**Repository Path**: DYZHALIE/SecKillDesign

## Basic Information

- **Project Name**: SecKillDesign
- **Description**: 秒杀与抢购系统架构设计与实现
- **Primary Language**: Java
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2020-06-24
- **Last Updated**: 2020-12-20

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

Java秒杀与抢购模型的架构设计与实现
=======================

开发环境:
-----------------------------------
IntelliJ IDEA + Maven + Workbench
    
压测工具:
-----------------------------------
JMeter

使用框架:
-----------------------------------
Spring Boot + Mybatis + Redis + RabbitMQ
 
具体内容:
-----------------------------------
    对高并发高负载情形下的应用场景进行分析，以高效地处理资源竞争为目的，设计一个秒杀与抢购模型。
    本项目提供了三种解决方案来比较系统的性能：
    1.利用MySQL的update行锁实现悲观锁。
    2.MySQL加字段version实现乐观锁。
    3.使用Redis作为原子计数器（watch事务+decr操作），RabbitMQ作为消息队列记录用户抢购行为，MySQL做异步存储。
    上述三个解决方案均使用了JMeter进行压力与性能测试，分析其吞吐量、平均响应时间、错误率等参数，最后得出相应结论。

备注:
-----------------------------------
    1.此项目包含了sql文件，包括表单创建和添加数据。
    2.包含了JMeter配置图片与实验结果图片
    3.包含了测试数据集：param.txt。第一个参数代表用户ID，第二个参数代表产品ID。

核心代码：
-----------------------------------
### MySQL悲观锁
    @Transactional
    public SecKillEnum handleByPessLockInMySQL(Map<String, Object> paramMap) {
        Jedis jedis = redisCacheHandle.getJedis();
        Record record = null;
        Integer userId = (Integer) paramMap.get("userId");
        Integer productId = (Integer)paramMap.get("productId");
        User user = new User(userId);
        Product product = secKillMapper.getProductById(productId);
        String hasBoughtSetKey = SecKillUtils.getRedisHasBoughtSetKey(product.getProductName());

        //判断是否重复购买
        boolean isBuy = jedis.sismember(hasBoughtSetKey, user.getId().toString());
        if (isBuy){
            //重复秒杀
            throw new SecKillException(SecKillEnum.REPEAT);
        }
        boolean secKillSuccess = secKillMapper.updatePessLockInMySQL(product);
        if (!secKillSuccess){
            //库存不足
            throw new SecKillException(SecKillEnum.LOW_STOCKS);
        }

        //秒杀成功
        record = new Record(null,user,product,SecKillEnum.SUCCESS.getCode(),SecKillEnum.SUCCESS.getMessage(),new Date());
        log.info(record.toString());
        boolean insertFlag =  secKillMapper.insertRecord(record);
        //插入record成功
        if (insertFlag){
            long addResult = jedis.sadd(hasBoughtSetKey,user.getId().toString());
            if (addResult>0){
                log.info("---------秒杀成功");
                return SecKillEnum.SUCCESS;
            }else {
                throw new SecKillException(SecKillEnum.REPEAT);
            }
        }else {
            throw new SecKillException(SecKillEnum.SYSTEM_EXCEPTION);
        }
    }
    
### MySQL乐观锁
    @Transactional
    public SecKillEnum handleByPosiLockInMySQL(Map<String, Object> paramMap){
        Jedis jedis = redisCacheHandle.getJedis();
        Record record = null;
        Integer userId = (Integer) paramMap.get("userId");
        Integer productId = (Integer)paramMap.get("productId");
        User user = new User(userId);
        Product product = secKillMapper.getProductById(productId);
        String hasBoughtSetKey = SecKillUtils.getRedisHasBoughtSetKey(product.getProductName());

        //判断是否重复购买
        boolean isBuy = jedis.sismember(hasBoughtSetKey, user.getId().toString());
        if (isBuy){
            //重复秒杀
            throw new SecKillException(SecKillEnum.REPEAT);
        }
        //库存减一
        int lastStock = product.getStock()-1;
        if (lastStock>=0){
            product.setStock(lastStock);
            boolean secKillSuccess = secKillMapper.updatePosiLockInMySQL(product);
            if (!secKillSuccess){
                //秒杀失败,version被修改
                throw new SecKillException(SecKillEnum.FAIL);
            }
        }else {
            //库存不足
            throw new SecKillException(SecKillEnum.LOW_STOCKS);
        }

        record = new Record(null,user,product,SecKillEnum.SUCCESS.getCode(),SecKillEnum.SUCCESS.getMessage(),new Date());
        log.info(record.toString());
        boolean insertFlag = secKillMapper.insertRecord(record);
        //插入record成功
        if (insertFlag){
            long addResult = jedis.sadd(hasBoughtSetKey,user.getId().toString());
            if (addResult>0){
                //秒杀成功
                return SecKillEnum.SUCCESS;
            }else {
                //重复秒杀
                log.info("---------重复秒杀");
                throw new SecKillException(SecKillEnum.REPEAT);
            }
        }else {
            //系统错误
            throw new SecKillException(SecKillEnum.SYSTEM_EXCEPTION);
        }
    }
    
### redis的watch监控
    public SecKillEnum handleByRedisWatch(Map<String, Object> paramMap) {
        Jedis jedis = redisCacheHandle.getJedis();
        Record record = null;
        Integer userId = (Integer) paramMap.get("userId");
        Integer productId = (Integer)paramMap.get("productId");
        User user = new User(userId);
        String productName = jedis.get("product_"+productId);
        String productStockCacheKey = productName+"_stock";
        String hasBoughtSetKey = SecKillUtils.getRedisHasBoughtSetKey(productName);

        //watch开启监控
        jedis.watch(productStockCacheKey);

        //判断是否重复购买，注意这里高并发情形下并不安全
        boolean isBuy = jedis.sismember(hasBoughtSetKey, user.getId().toString());
        if (isBuy){
            //重复秒杀
            throw new SecKillException(SecKillEnum.REPEAT);
        }

        String stock = jedis.get(productStockCacheKey);
        if (Integer.parseInt(stock)<=0) {
            //库存不足
            throw new SecKillException(SecKillEnum.LOW_STOCKS);
        }

        //开启Redis事务
        Transaction tx = jedis.multi();
        //库存减一
        tx.decrBy(productStockCacheKey,1);
        //执行事务
        List<Object> resultList = tx.exec();

        if (resultList == null || resultList.isEmpty()) {
            jedis.unwatch();
            //watch监控被更改过----物品抢购失败;
            throw new SecKillException(SecKillEnum.FAIL);
        }

        //添加到已买队列
        long addResult = jedis.sadd(hasBoughtSetKey,user.getId().toString());
        if (addResult>0){
            Product product = new Product(productId);
            //秒杀成功
            record =  new Record(null,user,product,SecKillEnum.SUCCESS.getCode(),SecKillEnum.SUCCESS.getMessage(),new Date());
            //添加record到rabbitMQ消息队列
            rabbitMQSender.send(JSON.toJSONString(record));
            //返回秒杀成功
            return SecKillEnum.SUCCESS;
        }else {
            //重复秒杀
            //这里抛出RuntimeException异常，redis的decr操作并不会回滚，所以需要手动incr回去
            jedis.incrBy(productStockCacheKey,1);
            throw new SecKillException(SecKillEnum.REPEAT);
        }
    }
    
JMeter压测图片:
-----------------------------------
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/jmeter/origin.png "github")
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/jmeter/data-config.png "github")

实验结果图片:
-----------------------------------
### MySQL悲观锁
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/stress_test_result/pessLockInMySQL/result_1.png "github")
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/stress_test_result/pessLockInMySQL/result_2.png "github")
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/stress_test_result/pessLockInMySQL/result_3.png "github")
#####################################################################

### MySQL乐观锁
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/stress_test_result/posiLockInMySQL/result_1.png "github")
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/stress_test_result/posiLockInMySQL/result_2.png "github")
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/stress_test_result/posiLockInMySQL/result_3.png "github")
#####################################################################

### redis的watch监控
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/stress_test_result/posiLockInRedis/result_1.png "github")
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/stress_test_result/posiLockInRedis/result_2.png "github")
![github](https://github.com/SkyScraperTwc/SecKillDesign/blob/master/src/main/resources/stress_test_result/posiLockInRedis/result_3.png "github")