xfy
6543422281
- config: 反向代理、缓存、负载均衡、安全、SSL 等配置模板 - lua: API 网关、认证、动态路由、限流、WebSocket 等脚本示例 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
139 lines
3.5 KiB
Lua
139 lines
3.5 KiB
Lua
-- cache_handler.lua
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--
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-- 缓存处理逻辑：读取、写入、失效
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-- 配合 nginx.conf 中的 set 指令使用:
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-- set $cache_key "prefix:$request_uri"
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-- set $cache_ttl 60
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--
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-- 在 location 块中使用:
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-- content_by_lua_file /path/to/cache_handler.lua;
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local cjson = require "cjson.safe"
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local _M = {}
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-- 默认 TTL（秒）
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local DEFAULT_TTL = 60
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--- 获取缓存数据
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-- @param dict 共享字典对象
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-- @param key 缓存键
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-- @return data 解码后的数据, ttl 剩余秒数
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function _M.get(dict, key)
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local value = dict:get(key)
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if not value then
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return nil, 0
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end
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local ttl = dict:ttl(key) or 0
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return cjson.decode(value), ttl
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end
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--- 设置缓存数据
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-- @param dict 共享字典对象
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-- @param key 缓存键
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-- @param data 要缓存的数据（table）
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-- @param ttl 过期时间（秒），默认 60
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-- @return ok, err, forcible
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function _M.set(dict, key, data, ttl)
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ttl = ttl or DEFAULT_TTL
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local json, err = cjson.encode(data)
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if not json then
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return nil, "encode failed: " .. tostring(err)
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end
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return dict:set(key, json, ttl)
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end
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--- 手动失效单个 key
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-- @param dict 共享字典对象
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-- @param key 缓存键
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-- @return true
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function _M.invalidate(dict, key)
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dict:delete(key)
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return true
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end
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--- 批量失效（按前缀匹配）
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-- @param dict 共享字典对象
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-- @param prefix key 前缀
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-- @return count 清除数量
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function _M.invalidate_prefix(dict, prefix)
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local keys = dict:get_keys(0)
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local count = 0
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for _, key in ipairs(keys) do
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if string.sub(key, 1, #prefix) == prefix then
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dict:delete(key)
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count = count + 1
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end
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end
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return count
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end
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--- 失效全部缓存
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-- @param dict 共享字典对象
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function _M.invalidate_all(dict)
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dict:flush_all()
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dict:flush_expired(0)
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end
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--- 获取缓存统计
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-- @param dict 共享字典对象
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-- @return stats table
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function _M.stats(dict)
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local keys = dict:get_keys(0)
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return {
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capacity = dict:capacity(),
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free_space = dict:free_space(),
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key_count = #keys,
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}
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end
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--- 主入口：作为 content_by_lua_file 使用时调用
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-- 从 nginx 变量读取 key/ttl，执行 cache-then-origin 流程
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-- 外部数据通过 _M.fetch_data 回调提供
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function _M.run(fetch_data)
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local cache = ngx.shared.response_cache
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local key = ngx.var.cache_key
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if not key then
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ngx.log(ngx.ERR, "cache_key variable not set")
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ngx.status = 500
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ngx.say(cjson.encode({error = "cache key not configured"}))
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return
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end
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local ttl = tonumber(ngx.var.cache_ttl) or DEFAULT_TTL
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-- 尝试缓存命中
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local cached, remaining = _M.get(cache, key)
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if cached then
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ngx.header["X-Cache"] = "HIT"
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ngx.header["X-Cache-TTL"] = tostring(remaining)
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ngx.header["Content-Type"] = "application/json"
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ngx.say(cjson.encode(cached))
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return
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end
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-- 缓存未命中，调用外部数据源
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local data, err = fetch_data()
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if not data then
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ngx.status = 502
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ngx.say(cjson.encode({error = err or "upstream error"}))
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return
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end
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-- 写入缓存
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local ok, set_err, forcible = _M.set(cache, key, data, ttl)
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if not ok then
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ngx.log(ngx.ERR, "cache set failed: ", tostring(set_err))
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end
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if forcible then
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ngx.log(ngx.WARN, "cache LRU eviction occurred")
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end
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ngx.header["X-Cache"] = "MISS"
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ngx.header["Content-Type"] = "application/json"
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ngx.say(cjson.encode(data))
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end
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return _M
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