redisrua解决库存问题_通过乐观锁解决库存超卖的问题

DROP TABLE IF EXISTS &＃96;goods&＃96;;
CREATE TABLE &＃96;goods&＃96; (&＃96;id&＃96; int(11) NOT NULL AUTO_INCREMENT COMMENT &＃39;商品id&＃39;,&＃96;name&＃96; varchar(30) DEFAULT NULL COMMENT &＃39;商品名称&＃39;,&＃96;stock&＃96; int(11) DEFAULT &＃39;0&＃39; COMMENT &＃39;商品库存&＃39;,&＃96;version&＃96; int(11) DEFAULT &＃39;0&＃39; COMMENT &＃39;并发版本控制&＃39;,PRIMARY KEY (&＃96;id&＃96;)
) ENGINE&＃61;InnoDB DEFAULT CHARSET&＃61;utf8 COMMENT &＃39;商品表&＃39;;INSERT INTO &＃96;goods&＃96; VALUES (1, &＃39;iphone&＃39;, 10, 0);
INSERT INTO &＃96;goods&＃96; VALUES (2, &＃39;huawei&＃39;, 10, 0);DROP TABLE IF EXISTS &＃96;order&＃96;;
CREATE TABLE &＃96;order&＃96; (&＃96;id&＃96; int(11) AUTO_INCREMENT,&＃96;uid&＃96; int(11) COMMENT &＃39;用户id&＃39;,&＃96;gid&＃96; int(11) COMMENT &＃39;商品id&＃39;,PRIMARY KEY (&＃96;id&＃96;)
) ENGINE&＃61;InnoDB DEFAULT CHARSET&＃61;utf8 COMMENT &＃39;订单表&＃39;;

org.springframework.bootspring-boot-starter-weborg.mybatis.spring.bootmybatis-spring-boot-starter2.1.1org.springframework.bootspring-boot-devtoolsruntimetruemysqlmysql-connector-javaruntimeorg.projectlomboklomboktrueorg.springframework.bootspring-boot-starter-testtest

spring:datasource:type: com.zaxxer.hikari.HikariDataSourcedriverClassName: com.mysql.cj.jdbc.Driverurl: jdbc:mysql://localhost:3307/test?allowMultiQueries&＃61;true&useUnicode&＃61;true&characterEncoding&＃61;UTF-8&useSSL&＃61;false&serverTimezone&＃61;UTCusername: rootpassword: root

package com.idcmind.ants.entity;public class Goods {private int id;private String name;private int stock;private int version;...此处省略getter、setter以及 toString方法
}
public class Order {private int id;private int uid;private int gid;...此处省略getter、setter以及 toString方法
}

&＃64;Mapper
public interface GoodsDao {/*** 查询商品库存* &＃64;param id 商品id* &＃64;return*/&＃64;Select("SELECT * FROM goods WHERE id &＃61; #{id}")Goods getStock(&＃64;Param("id") int id);/*** 乐观锁方案扣减库存* &＃64;param id 商品id* &＃64;param version 版本号* &＃64;return*/&＃64;Update("UPDATE goods SET stock &＃61; stock - 1, version &＃61; version &＃43; 1 WHERE id &＃61; #{id} AND stock > 0 AND version &＃61; #{version}")int decreaseStockForVersion(&＃64;Param("id") int id, &＃64;Param("version") int version);
}

&＃64;Mapper
public interface OrderDao {/*** 插入订单* 注意: order表是关键字&＃xff0c;需要&＃96;order&＃96;* &＃64;param order*/&＃64;Insert("INSERT INTO &＃96;order&＃96; (uid, gid) VALUES (#{uid}, #{gid})")&＃64;Options(useGeneratedKeys &＃61; true, keyProperty &＃61; "id")int insertOrder(Order order);
}

&＃64;Service
public class GoodsService {&＃64;Autowiredprivate GoodsDao goodsDao;&＃64;Autowiredprivate OrderDao orderDao;/*** 扣减库存* &＃64;param gid 商品id* &＃64;param uid 用户id* &＃64;return SUCCESS 1 FAILURE 0*/&＃64;Transactionalpublic int sellGoods(int gid, int uid) {// 获取库存Goods goods &＃61; goodsDao.getStock(gid);if (goods.getStock() > 0) {// 乐观锁更新库存int update &＃61; goodsDao.decreaseStockForVersion(gid, goods.getVersion());// 更新失败&＃xff0c;说明其他线程已经修改过数据&＃xff0c;本次扣减库存失败&＃xff0c;可以重试一定次数或者返回if (update &＃61;&＃61; 0) {return 0;}// 库存扣减成功&＃xff0c;生成订单Order order &＃61; new Order();order.setUid(uid);order.setGid(gid);int result &＃61; orderDao.insertOrder(order);return result;}// 失败返回return 0;}
}

&＃64;SpringBootTest
class GoodsServiceTest {&＃64;AutowiredGoodsService goodsService;&＃64;Testvoid seckill() throws InterruptedException {// 库存初始化为10&＃xff0c;这里通过CountDownLatch和线程池模拟100个并发int threadTotal &＃61; 100;ExecutorService executorService &＃61; Executors.newCachedThreadPool();final CountDownLatch countDownLatch &＃61; new CountDownLatch(threadTotal);for (int i &＃61; 0; i {try {goodsService.sellGoods(1, uid);} catch (Exception e) {e.printStackTrace();}countDownLatch.countDown();});}countDownLatch.await();executorService.shutdown();}
}