在nginx中使用lua直接访问mysql和memcaced达到数据接口的统一

安装nginx参见《nginx+lua+redis构建高并发应用》

让nginx 中的nginx_lua_module支持mysql 和memcache
下载
https://github.com/agentzh/lua-resty-memcached
https://github.com/agentzh/lua-resty-mysql

对于访问接口的统一有很多的处理方式，这里介绍使用nginx lua 访问mysql并用memcache缓存起来。

配置如下：

...
location /getinfo {
default_type 'text/plain';
content_by_lua '

local args = ngx.req.get_uri_args()

if args["appleid"] == nil then
ngx.say("param appleid is nil")
return
end

local memcached = require "memcached"
local memc, err = memcached:new()
if not memc then
ngx.say("failed to instantiate memc: ", err)
return
end

memc:set_timeout(1000) -- 1 sec

local ok, err = memc:connect("172.16.18.114", 11211)
if not ok then
ngx.say("failed to connect: ", err)
return
end

local res, flags, err = memc:get(args["appleid"])
if err then
ngx.say("failed to get memc: ", err)
return
end

if not res then

local mysql = require "mysql"
local db, err = mysql:new()
if not db then
ngx.say("failed to instantiate mysql: ", err)
return
end

db:set_timeout(1000) -- 1 sec

local ok, err, errno, sqlstate = db:connect{
host = "172.16.18.162",
port = 3306,
database = "test",
user = "root",
password = "cpyf",
max_packet_size = 1024 * 1024
}

if not ok then
ngx.say("failed to connect: ", err, ": ", errno, " ", sqlstate)
return
end

-- ngx.say("connected to mysql.")

sql = "select * from tagval where tag = \'" .. args["appleid"] .. "\'"

res, err, errno, sqlstate = db:query(sql)
if not res then
ngx.say("bad result: ", err, ": ", errno, ": ", sqlstate, ".")
return
end

local json = require "json"
ngx.say("mysql found")
ngx.say(json.encode(res))

local ok, err = memc:set(args["appleid"], json.encode(res))
if not ok then
ngx.say("failed to set memc: ", err)
return
end

local ok, err = db:set_keepalive(0, 100)
if not ok then
ngx.say("failed to set keepalive: ", err)
return
end

return

end

ngx.say("memc found")
ngx.say(res)

memc:set_keepalive(0, 100)

';
}
...

第二次运行：

curl --get http://app.ca-sim.com/getinfo?appleid=jfy

mysql found
[{"val":"123","tag":"jfy"}]

第二次后运行：

curl --get http://app.ca-sim.com/getinfo?appleid=jfy

memc found
[{"val":"123","tag":"jfy"}]

结果已被缓存