SpringBoot3+MySQL+OpenResty+Lua实现三级缓存架构

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<?xml version="1.0" encoding="UTF-8"?>
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<project>
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    <parent>
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        <groupId>org.springframework.boot</groupId>
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        <artifactId>spring-boot-starter-parent</artifactId>
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        <version>3.2.5</version>
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    </parent>
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    <dependencies>
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        <!-- Web -->
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        <dependency>
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            <groupId>org.springframework.boot</groupId>
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            <artifactId>spring-boot-starter-web</artifactId>
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        </dependency>
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        <!-- MyBatis-Plus (Spring Boot3 专用 starter) -->
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        <dependency>
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            <groupId>com.baomidou</groupId>
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            <artifactId>mybatis-plus-spring-boot3-starter</artifactId>
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            <version>3.5.7</version>
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        </dependency>
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        <!-- MySQL 驱动 -->
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        <dependency>
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            <groupId>com.mysql</groupId>
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            <artifactId>mysql-connector-j</artifactId>
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            <scope>runtime</scope>
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        </dependency>
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    </dependencies>
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</project>

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@RestController
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@RequestMapping("/api/product")
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public class ProductController {
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    private final ProductMapper productMapper;
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    private final CachePurgeService cachePurgeService;
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    public ProductController(ProductMapper productMapper, CachePurgeService cachePurgeService) {
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        this.productMapper = productMapper;
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        this.cachePurgeService = cachePurgeService;
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    }
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    /** 查询商品：L3 兜底接口，由 Lua 在 L1/L2 未命中时调用 */
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    @GetMapping("/{id}")
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    public Product getById(@PathVariable Long id) {
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        return productMapper.selectById(id);
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    }
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    /** 更新商品：更新 MySQL 后主动清掉各级缓存 */
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    @PutMapping
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    public Result update(@RequestBody Product product) {
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        productMapper.updateById(product);
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        // 清 L2(Redis) + 通知清 L1(Nginx共享内存)
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        cachePurgeService.purge(product.getId());
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        return Result.ok();
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    }
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    /** 删除商品：删除后同样清缓存 */
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    @DeleteMapping("/{id}")
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    public Result delete(@PathVariable Long id) {
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        productMapper.deleteById(id);
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        cachePurgeService.purge(id);
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        return Result.ok();
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    }
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}

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http {
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    # 开启共享内存，作为 L1 缓存（10MB，可按需调整）
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    lua_shared_dict product_cache 10m;
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    # Lua 模块搜索路径（lua-resty-redis 等）
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    lua_package_path "/usr/local/openresty/lualib/?.lua;;";
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    server {
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        listen 80;
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        # ======= 三级缓存查询入口 =======
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        location ~ ^/lua/product/(\d+)$ {
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            set $id $1;
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            content_by_lua_file /opt/lua/cache.lua;
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        }
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        # ======= 清缓存接口（后端数据变更时调用） =======
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        location ~ ^/lua/purge/(\d+)$ {
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            set $id $1;
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            content_by_lua_file /opt/lua/purge.lua;
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        }
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        # ======= 后端 SpringBoot 反向代理 =======
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        location /api/ {
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            proxy_pass http://127.0.0.1:8080;
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            proxy_set_header Host $host;
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            proxy_set_header X-Real-IP $remote_addr;
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            proxy_connect_timeout 1s;
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            proxy_read_timeout 2s;
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        }
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    }
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}

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-- =====================================================================
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-- cache.lua 三级缓存查询脚本
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--   1. 先查 OpenResty 共享内存(L1)
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--   2. 未命中查 Redis(L2)
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--   3. 未命中调后端 SpringBoot 接口查 MySQL(L3)
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--   4. 逐级回填缓存
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-- 通过响应头 X-Cache-Level 标记命中层级，方便调试和压测
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-- =====================================================================
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ngx.header.content_type = "application/json;charset=utf8"
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local id = ngx.var.id
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local cache_key = "product:" .. id
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-- ================== L1：共享内存缓存 ==================
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local shared = ngx.shared.product_cache
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local l1_data = shared:get(cache_key)
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if l1_data then
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    ngx.header["X-Cache-Level"] = "L1"
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    ngx.say(l1_data)
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    return
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end
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-- ================== L2：Redis 缓存 ==================
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local redis = require("resty.redis")
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local red = redis:new()
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red:set_timeout(1000)                 -- 1秒超时，Redis 挂了快速失败
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local ok, err = red:connect("127.0.0.1", 6379)
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if not ok then
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    ngx.log(ngx.ERR, "redis connect failed: ", err)
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end
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if ok then
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    -- 生产环境有密码：red:auth("你的密码")
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    local l2_data = red:get(cache_key)
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    if l2_data and l2_data ~= ngx.null then
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        -- 回填 L1，TTL 短一些（60秒），保证一致性
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        shared:set(cache_key, l2_data, 60)
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        ngx.header["X-Cache-Level"] = "L2"
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        ngx.say(l2_data)
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        red:set_keepalive(10000, 100)   -- 归还连接到连接池
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        return
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    end
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    red:set_keepalive(10000, 100)
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end
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-- ================== L3：MySQL（经 SpringBoot 接口） ==================
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-- 用子请求转发到后端，避免自己实现 HTTP 客户端
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local res = ngx.location.capture("/api/product/" .. id)
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if res.status == 200 and res.body and res.body ~= "null" then
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    -- 回填 L2，TTL 长一些（300秒）
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    local red2 = redis:new()
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    red2:set_timeout(1000)
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    local ok2 = red2:connect("127.0.0.1", 6379)
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    if ok2 then
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        red2:setex(cache_key, 300, res.body)
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        red2:set_keepalive(10000, 100)
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    end
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    -- 回填 L1
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    shared:set(cache_key, res.body, 60)
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    ngx.header["X-Cache-Level"] = "L3"
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    ngx.say(res.body)
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    return
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end
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-- ================== 兜底：查不到数据 ==================
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-- 缓存空值，防止恶意 id 反复穿透到后端（防缓存穿透）
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local empty_body = '{"id":' .. id .. '}'
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local red3 = redis:new()
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red3:set_timeout(1000)
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local ok3 = red3:connect("127.0.0.1", 6379)
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if ok3 then
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    red3:setex(cache_key, 60, empty_body)   -- 空值也缓存，60秒
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    red3:set_keepalive(10000, 100)
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end
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shared:set(cache_key, empty_body, 60)
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ngx.header["X-Cache-Level"] = "MISS"
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ngx.status = 404
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ngx.say('{"code":404,"msg":"商品不存在"}')

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-- =====================================================================
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-- purge.lua 清理指定商品的各级缓存
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-- 由后端在数据变更后调用：POST /lua/purge/{id}
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-- =====================================================================
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ngx.header.content_type = "application/json;charset=utf8"
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local id = ngx.var.id
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local cache_key = "product:" .. id
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-- 清 L1 共享内存
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local shared = ngx.shared.product_cache
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shared:delete(cache_key)
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-- 清 L2 Redis
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local redis = require("resty.redis")
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local red = redis:new()
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red:set_timeout(1000)
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local ok, err = red:connect("127.0.0.1", 6379)
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if not ok then
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    ngx.log(ngx.ERR, "redis connect failed: ", err)
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    ngx.say('{"code":500,"msg":"redis down"}')
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    return
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end
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red:del(cache_key)
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red:set_keepalive(10000, 100)
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ngx.say('{"code":200,"msg":"cache purged"}')