高并发场景防止库存数量超卖少卖

package com.yiridancan.reduceInventory.service.impl; import com.yiridancan.reduceInventory.entity.Goods; import com.yiridancan.reduceInventory.mapper.GoodsMapper; import com.yiridancan.reduceInventory.service.IGoodsService; import lombok.extern.slf4j.Slf4j; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.redis.core.StringRedisTemplate; import org.springframework.data.redis.core.script.DefaultRedisScript; import org.springframework.stereotype.Service; import java.util.Collections; import java.util.List; import java.util.Map; import java.util.Objects; /** * 商品实现类 * @author yiridancan * @date 2024/3/23 18:35 */ @Slf4j @Service public class GoodsServiceImpl implements IGoodsService { @Autowired private GoodsMapper goodsMapper; @Autowired private StringRedisTemplate stringRedisTemplate; /** * 扣减库存 * @param goodsId 商品id * @author yiridancan * @date 2024/3/23 18:33 */ @Override public void reduceInventory(int goodsId) { //1.根据商品id获取商品库存数量 Goods goods = goodsMapper.findGoodsInventory(goodsId); if(Objects.isNull(goods)){ log.error("未获取到商品信息"); return; } //2.如果库存数量大于0则扣减库存，如果等于0代表没有货物打印错误信息 if(goods.getInventoryCount() > 0 ){ //默认扣减库存1 goods.setInventoryCount(goods.getInventoryCount()-1); goodsMapper.updateGoodsInventory(goods); log.info("{}扣减库存成功，扣减后库存为：{}",goods.getName(),goods.getInventoryCount()); }else { log.error("{}库存为0",goods.getName()); } } /** * 通过乐观锁实现扣减库存 * @param goodsId 商品id * @author yiridancan * @date 2024/3/25 22:33 */ @Override public void casReduceInventory(int goodsId) { int retryCount = 0; //重试次数设置为3，避免无休止的重试占用紫鸢 while (retryCount <=3){ //1.根据商品id获取商品信息 Goods goods = goodsMapper.findGoodsInventory(goodsId); if(Objects.isNull(goods) || goods.getInventoryCount() == 0){ log.error("未获取到商品信息或库存数量不足"); return; } //默认扣减库存1 goods.setInventoryCount(goods.getInventoryCount()-1); int updateRow = goodsMapper.updateGoodsInventoryByCAS(goods); //如果修改条数大于0代表扣减库存成功 if(updateRow > 0 ){ log.info("{}扣减库存成功，扣减后库存为：{}",goods.getName(),goods.getInventoryCount()); return; } retryCount++; log.error("{}商品被修改过，进行重试！！版本号：{}",goods.getName(),goods.getDataVersion()); } } /** * 通过Redis扣减库存 * * @param goodsId 商品id * @author yiridancan * @date 2024/3/27 15:48 */ @Override public void redisReduceInventory(int goodsId) { String prefix = "goodsInventory:"; //将商品数据缓存到Redis中，key是商品id，value是商品库存数量 goodsMapper.findGoodsAll().forEach(goods -> { stringRedisTemplate.opsForValue().set(prefix+goods.getId(),String.valueOf(goods.getInventoryCount())); }); //lua脚本，一般放在文件中 String script = "local key = KEYS[1] -- 商品的键名\n" + "local amount = tonumber(ARGV[1]) -- 扣减的数量\n" + "\n" + "-- 获取商品当前的库存量\n" + "local stock = tonumber(redis.call('get', key))\n" + "\n" + "-- 如果库存足够，则减少库存并返回新的库存量\n" + "if stock >= amount then\n" + " redis.call('decrby', key, amount)\n" + " return redis.call('get', key)\n" + "else\n" + " return \"INSUFFICIENT STOCK\"\n" + "end\n"; DefaultRedisScript<String> redisScript = new DefaultRedisScript<>(script, String.class); // 创建一个包含库存key的列表 List<String> keys = Collections.singletonList(prefix + goodsId); // 创建一个包含扣减数量的参数列表 List<String> args = Collections.singletonList(Integer.toString(1)); // 执行Lua脚本，传入键列表和参数列表 String result = stringRedisTemplate.execute(redisScript, keys, args.toArray(new String[0])); //如果不是库存不足代表扣减成功 if(!result.equals("INSUFFICIENT STOCK")){ log.info("扣减库存成功，库存数量：{}",result); }else { log.error("库存数量不足"); } } }