sequenceDiagram participant client as 用户 participant shop as 云商城 participant cache as 缓存 participant db as 数据库 client->>shop: 传递 passport_id, product_id, 添加记录 shop->>cache: 根据 passport_id 获取总条数 cache->>shop: 总条数 count alt count > 100 shop->>cache:查询 the_oldst_id shop->>cache:通过 the_oldst_id 删除对应的记录 cache->>db:通过 the_oldst_id 删除对应的记录 end shop->>shop:通过 product_id 获取对应的 product_info shop->>cache:添加记录, passport_id, product_info, lastAccessTime cache->>db:添加记录