Nginx+Lua实现分布式缓存

nginx 
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local redis = require("resty.redis")
local cjson = require("cjson")
local cjson_encode = cjson.encode
local ngx_log = ngx.log
local ngx_ERR = ngx.ERR
local ngx_exit = ngx.exit
local ngx_print = ngx.print
local ngx_re_match = ngx.re.match
local ngx_var = ngx.var

local function close_redis(red)
	if not red then
		return
	end
	-- 释放连接(连接池实现)
	local pool_max_idle_time = 10000 -- 毫秒
	local pool_size = 100  -- 连接池大小
	local ok, err = red:set_keepalive(pool_max_idle_time, pool_size)
	
	if not ok then
		ngx_log(ngx_ERR, "set redis keepalive error : ", err)
	end
end

local function read_redis(id)
	local red = redis:new()
	red:set_timeout(1000)
	local ip = "127.0.0.1"
	local port = 1111
	local ok, err = red:connect(ip, port)
	if not ok then
		ngx_log(ngx_ERR, "connect to redis error : ", err)
		return close_redis(red)
	end
	
	local resp, err = red:get(id)
	if net resp then
		ngx_log(ngx_ERR, "get redis connect error : ", err)
		return close_redis(red)
	end
	-- 得到的数据为空处理
	if resp == ngx.null then
		resp = nil
	end
	close_redis(red)
	
	return resp
end

local function read_http(id)
	local resp = ngx.location.capture("/backend", {
		method = ngx.HTTP_GET,
		args = {id = id}
	})
	
	if not resp then
		ngx_log(ngx_ERR, "request error :", err)
		return
	end
	
	if resp.status ~= 200 then
		ngx_log(ngx_ERR, "request error, status :", resp.status)
		return
	end
	
	return resp.body
end

-- 获取id
local id = ngx_var.id

-- 从redis获取
local content = read_redis(id)

-- 如果redis没有，则回源到tomcat
if not content then
	ngx_log(ngx_ERR, "redis not found content, back to http, id : ", id)
	content = read_http(id)
end

-- 如果还没有，则返回404
if not content then
	ngx_log(ngx_ERR, "http not found content, id : ", id)
	return ngx_exit(404)
end

-- 输出内容
ngx.print("show_ad(")
ngx.print(cjson_encode({content = content}))
ngx.print(")")
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