The Programming Language Lua

&

OpenResty

            rmingwang@gmail.com
        

Kernel

Configuration

复杂软件系统

核心功能和内部实现，提供调用配置接口

• 编译型语言

• 静态语言
• 注重性能

调用和配置 Kernel ，丰富和定制系统

• 脚本语言

• 动态语言
• 注重业务逻辑

使用lua开发的游戏

- 魔兽争霸
- 梦幻西游
- 愤怒的小鸟（Wax）
...

API接口插件

- 魔兽世界（自定义皮肤界面）
- Dota2 （RPG地图编辑器脚本）
...

其他应用

- MySQL Proxy Scripting
- Wireshark Lua API 
- OpenWrt Lua UCI API (LuCI)
- Adobe Lightroom

WEB框架

- Sailor! A Lua MVC Framework
- Lapis (Web Framework OpenResty && Lua)
- aLiLua | A High-Performance Lua Web Framework

Isomorphic javascript

=> run on both the client and the server

• INSTALL

• Package Manager

• Basic Usage

-  Lua简明教程 

-《Programming In Lua》 

-  Lua程序设计

- The Programming Language Lua

Lua language

print "input your name:"

local name = io.read()

print("hello "..name)
--print(string.format("hello %s", name))

# CLI 

Lua language

local person = {
    first = "rming",
    last  = "wang",
}

local _dump
_dump = function(t)
    for k,v in pairs(t) do
        if k ~= '_G' and type(v) == 'table' then
            _dump(v)
        else
            print(string.format('%s=>%s', k, v))
        end
    end    
end

_dump(person)

# table dump

Lua language

window = {}
window.prototype = {
    x = 10,
    y = 11,
    width  = 100,
    height = 50,
    print  = print,
}
-- 定义 metatable 并定义 __index 方法
window.mt = {}
--window.mt.__index = window.prototype
window.mt.__index = function(table, key)
    return window.prototype[key];   
end
-- 设置 window 元表
setmetatable(window, window.mt)

-- 定义 window 构造函数
window.new = function(o)
    setmetatable(o, window.mt)
    return o
end

new_window = window.new{x = 20, y = 21}
--new_window = window.new({x = 20, y = 21})
--new_window = window.new{}

--[[
    new_window -> 有没有 x key --没有-> metatable.__index -> 返回 window.prototype[x]
--]]

new_window.print 'hello'
print(new_window.x)
print(new_window.width)

# CLASS 

Lua language

• 默认全局变量
• 匿名函数
• nil false 假
• 函数一等公民
• 元表 <=> 原型
• 标准库
• ...

- lua有趣的语法特性
- Lua vs. JavaScript
- Lua: Good, bad, and ugly parts

OpenResty github

 OpenResty = Nginx core + 3rd-party Nginx modules

• LuaJIT  ​(Just-In-Time Compiler for the Lua programming language. )
• HttpLuaModule  (ngx_lua - Embed the power of Lua into Nginx)
• LuaRestyCoreLibrary  (lua-resty-core - New FFI-based Lua API for the ngx_lua module)
• ...

Why Nginx？

• I/O multiplexing
• Connections Pool
• noBlocking!

" Don't call me, I will call you. "

• INSTALL

• 3rdPartyModules​

• Basic Usage

-  nginx 3rdPartyModules​

- OpenResty github

-  agentzh's home

-  agentzh 的 Nginx 教程

-  awesome-resty

nginx.conf scripting

- nginx + perl ?  

    ngx_http_perl_module  

- nginx + javascript ?  
    *ngx_http_js_module  

- nginx + lua ?  
    ngx_http_lua_module  

nginx.conf scripting

- Lua + Nginx API for Lua

          + ngx.shared.DICT

          + memcache / redis / mysql / postgresql 

- 应用  
         - 防止DDos,清洗流量  
         - XSS filter  
         - upstream节点健康检查  
         - 图片处理    
         - ...

nginx.conf scripting

# OpenResty Lua library 

nginx.conf scripting

# OpenResty Lua library 

-- 发起同步非阻塞请求
ngx.location.capture("/foo") 
ngx.location.capture_multi{ {"/foo"}, "/bar"}}

-- 数据字典操作，可以在nginx不同 worker 的 pool 间共享
--lua_shared_dict dogs 10m;
local dogs = ngx.shared.dogs 
dogs:add("Tom", 5) 
dogs:set("Tom", 7) 
dogs:incr("Tom", 1) 
dogs:delete("Tom", 1)

-- 延时执行
local function do_job() 
    ...
end
local ok, err = ngx.timer.at(1.5, do_job)

nginx.conf scripting

# Construct fully RESTful queries in a single location

location ~ '^/cat/(\d+)' {
    set $id $1;
    set_form_input $name; set_quote_sql_str $quoted_name $name;

    postgres_query GET "select * from cats where id=$id";
    postgres_query DELETE "delete from cats where id=$id";
    postgres_query POST "insert into cats (id, name) values($id, $quoted_name)";

    postgres_pass my_pg_backend; 
}

non-blocking MySQL

# ngx_libdrizzle

http {
    ...

    upstream cluster {
        # simple round-robin
        drizzle_server 127.0.0.1:3306 dbname=test
             password=some_pass user=monty protocol=mysql;
        drizzle_server 127.0.0.1:1234 dbname=test2
             password=pass user=bob protocol=drizzle;
    }

    upstream backend {
        drizzle_server 127.0.0.1:3306 dbname=test
             password=some_pass user=monty protocol=mysql;
    }

    server {
        location /mysql {
            drizzle_query $query_string;

            drizzle_pass backend;

            drizzle_connect_timeout    500ms; # default 60s
            drizzle_send_query_timeout 2s;    # default 60s
            drizzle_recv_cols_timeout  1s;    # default 60s
            drizzle_recv_rows_timeout  1s;    # default 60s
        }

        ...

        # for connection pool monitoring
        location /mysql-pool-status {
            allow 127.0.0.1;
            deny all;

            drizzle_status;
        }
    }
}

nginx.conf scripting

nginx lua access control

nginx.conf scripting

local function args(key, default)
    local args = ngx.req.get_uri_args()
    return args[key] or default
end


local function set_header(header)
    ngx.header.content_type = header;
end

local function pairsByKeys(t)
    local a = {}
    for n in pairs(t) do a[#a + 1] = n end
    table.sort(a)
    local i = 0
    return function ()
        i = i + 1
        return a[i], t[a[i]]
    end
end


local function is_expired(token_config)
    -- if token.date expired
    token_time = args('date', 0)
    return token_config['expires'] and os.date('%Y-%m-%d') ~= args('date') or false
end


local function is_full_params()
    -- if full params
    local tokens = {args('date'), args('version'), args('sign')}
    local count  = 0
    for k,v in pairs(tokens) do
        count =count+1
    end
    return count==3
end

local function is_verified(token_config)
    -- if token verified
    local token_str = ''
    local url = ngx.var.scheme..'://'..ngx.var.http_host..ngx.var.uri
    local tokens = {ngx.md5(url), args('date'), args('version'), token_config['secret']}
    for k,v in pairsByKeys(tokens) do
        token_str = token_str..v
    end
    return args('sign') == ngx.md5(token_str)
end

--[[
    set config['expires'] = false disable token expires
]]--
local config = {
    secret  = 'your_secret_here',
    expires = true,
}

if not is_full_params() or is_expired(config) or not is_verified(config)  then
    ngx.exit(ngx.HTTP_FORBIDDEN)
end

nginx lua random avatar

nginx.conf scripting

local function args(key, default)
    local args = ngx.req.get_uri_args()
    return args[key] or default
end


local function set_header(header)
    ngx.header.content_type = header;
end

local function pairsByKeys(t)
    local a = {}
    for n in pairs(t) do a[#a + 1] = n end
    table.sort(a)
    local i = 0
    return function ()
        i = i + 1
        return a[i], t[a[i]]
    end
end

function split(inputstr, sep)
    if sep == nil then
        sep = "%s"
    end
    local t={} ; i=1
    for str in string.gmatch(inputstr, "([^"..sep.."]+)") do
        t[i] = str
        i = i + 1
    end
    return t
end


local function is_full_params()
    -- if full params
    local params = {
        appid = args('appid'),
        pid   = args('pid'),
        uid   = args('uid'),
        v     = args('v')
    }
    local count  = 0
    for k,v in pairs(params) do
        count = count + 1
    end
    return count==4 and params or false
end

local function range(min, max)
    local rangex = {}
    for i = min, max do
        table.insert(rangex, i)
    end
    return rangex
end

function file_exists(name)
   local f=io.open(name,"r")
   if f~=nil then io.close(f) return true else return false end
end

local function redis_connect(address, port)
    local redis = require "resty.redis"
    local red = redis:new()
    red:set_timeout(1000)

    local ok, err = red:connect(address, port)
    if not ok then
        ngx.log(ngx.ERR, "failed to connect: ", err)
        return false
    else
        return red
    end
end


local function generateCMD(gmbin, color, origin, dst, dst_width, dst_height)
    local dst_width  = dst_width or 120
    local dst_height = dst_height or 120
    local cmd = '%s convert -background "%s" -gravity center -extent %dx%d %s %s'
    return string.format(cmd, gmbin, color, dst_width, dst_height, origin, dst)
end

--局部函数，防止lua调用全局函数报错
local random_avatar,find_avatar,random
random = require "resty.random"

--从查询头像池中取得一个头像
random_avatar = function (red, post_hash_k, user_filed, root_filed, avatars_pool, colors)
    --spop query [avatar set remained]
    local res, err = red:spop(avatars_pool)
    local error_message = function(format)
        return string.format(format, avatars_pool)
    end
    if not res then
        --redis query error
        ngx.log(ngx.ERR, error_message("failed spop %s: "), err)
    elseif res == ngx.null then
        --avatar pool is empty
        ngx.log(ngx.INFO, error_message("%s pool is empty "), err)
        --查询楼主头像，产生头像池
        local resx = find_avatar(red, post_hash_k, root_filed, root_filed, avatars_pool, colors)
        if not resx then return false end
        for i,v in pairs(range(1, 12)) do
            if v~=resx then
                red:sadd(avatars_pool, v)
            end
        end

        --递归调用继续查询随机头像
        res = random_avatar(red, post_hash_k, user_filed, root_filed, avatars_pool, colors)
    else
        --random avatar found
        ngx.log(ngx.INFO, error_message("spop %s: "), res)
        --随机生成后，记录到redis
        res = string.format('%s|%s', res, colors[random.number(1,12)])
        red:hset(post_hash_k, user_filed, res)
    end
    return res
end


--是否存在头像记录
find_avatar = function (red, post_hash_k, user_filed, root_filed, avatars_pool, colors)
    --hget query [hash user_filed]
    local res, err = red:hget(post_hash_k, user_filed)
    --error_message closure
    local error_message = function(format)
        return string.format(format, post_hash_k, user_filed)
    end
    if not res then
        --redis query error
        ngx.log(ngx.ERR, error_message("failed hmget %s %s: "), err)
    elseif res == ngx.null then
        --hash filed not found
        ngx.log(ngx.INFO, error_message("%s %s not found "), err)
        if user_filed==root_filed then
            --如果找不到楼主什么头像，则生成一个头像
            res = random.number(1,12)
            res = string.format('%s|%s', res, colors[random.number(1,12)])
            red:hset(post_hash_k, root_filed, res)
        else
            --找不到头像时，头像池中取一个头像
            res = random_avatar(red, post_hash_k, user_filed, root_filed, avatars_pool, colors)
        end
    else
        --hash filed found
        ngx.log(ngx.INFO, error_message("hget %s %s: "), res)
    end
    return res
end

--http://file.avatar.com/avatar?appid=sapp&pid=11&uid=1&v=2
set_header('text/plain')

--检查参数是否完整
local params = is_full_params()
if not params then
    ngx.exit(ngx.HTTP_NOT_FOUND)
end

--定义 redis key 的规则
local post_hash_k  = string.format('avatar.%s.%s.%s', params['appid'], params['pid'], params['v'])
local avatars_pool = string.format('%s.pool', post_hash_k)
local user_filed   = string.format('u.%s', params['uid'])
local root_filed   = string.format('u.%s', 0)
--local avatar_file = string.format('avatar.file.%s.%s', avatar_id, color_id)

local config
if  file_exists(ngx.var.document_root..'/online') then
    config = {
        --网站目录相关配置
        webroot = ngx.var.document_root,
        origin  = '/static/avatars/%d.png',
        dst     = '/upload/avatars/thumbnails/%s.png',
        --GraphicsMagick 路径
        gmbin   = '/usr/bin/gm',
        --redis 配置
        redis = {
            host = '10.172.169.246',
            port = 6379,
        }
    }
elseif file_exists(ngx.var.document_root..'/test') then
    config = {
        --网站目录相关配置
        webroot = ngx.var.document_root,
        origin  = '/static/avatars/%d.png',
        dst     = '/upload/avatars/thumbnails/%s.png',
        --GraphicsMagick 路径
        gmbin   = '/usr/bin/gm',
        --redis 配置
        redis = {
            host = '10.171.80.244',
            port = 6379,
        }
    }
else
    config = {
        --网站目录相关配置
        webroot = ngx.var.document_root,
        origin  = '/static/avatars/%d.png',
        dst     = '/upload/avatars/thumbnails/%s.png',
        --GraphicsMagick 路径
        gmbin   = '/usr/local/bin/gm',
        --redis 配置
        redis = {
            host = '127.0.0.1',
            port = 6379,
        }
    }
end

local colors  = {'#fd788e', '#ffcd43', '#77b7fc', '#9f90db', '#60d5b5', '#ff8784', '#e5619d', '#00c2de', '#d19dc6', '#4ee3f0', '#00a4df', '#80dd80'}
local avatars = range(1,12)

--redis connection
local red = redis_connect(config.redis.host, config.redis.port)
if not red then return end

local avatar_data = find_avatar(red, post_hash_k, user_filed, root_filed, avatars_pool, colors)
if not avatar_data then return end

local avatar_data = split(avatar_data, '|')
local color       = table.remove(avatar_data) or colors[random.number(1,12)]
local avatar_id   = table.remove(avatar_data) or random.number(1,12)

local dst_uri = string.format(config.dst, avatar_id..color)
local origin  = config.webroot..string.format(config.origin, avatar_id)
local dst     = config.webroot..dst_uri

local cmd = generateCMD(config.gmbin, color, origin, dst)

if file_exists(dst) then
    ngx.exec(dst_uri)
else
    _,_,dst_dir,dst_filename = string.find(dst,'(.-)([^/]*)$')
    os.execute('mkdir -p '..dst_dir)
    os.execute(cmd)
    if file_exists(dst) then
        ngx.exec(dst_uri)
    else
        ngx.exit(ngx.ERR)
    end
end

Any questions?

Thank you!

* 图片、代码来源于网络，感谢作者分享