ifup.org by Brandon Philips contains excerpts from my code, work and play.

I love writing systems software and my current passion and work is CoreOS.

luvit: node's ziggy stardust

I recently gave a talk at Open Source Bridge about luvit, this great platform we are building that is like node.js only using lua as the implementation language.

Anyways, my slides are available but I wanted to create a slide by slide blog post with my notes too. So here goes!

Also, if you are in Portland for OSCON I will be giving a talk (update: slides posted) about how we are building an on server monitoring agent for Rackspace Cloud Monitoring on top of luvit. I will cover why we were interested in using luvit, how luvit works and how we are embedding it in our monitoring agent.

Untechnical Overview

Luvit is a platform for building your app in an event driven manner.

  • Scrawny
  • Awkward
  • Space Themed (lua)
  • <3 community
  • Familiar node APIs

Notes: luvit is scrawny like Mr. Stardust and uses very little memory. luvit is a young project and still growing, expect awkwardness. lua is Portuguese for moon so it is space themed just like Ziggy. There is a great community with a good sense of humor (luv_handles are a great data structure name)

HTTP Server Example

local http = require("http")

http.createServer(function (req, res)
  local body = "Hello world\n"
  res:writeHead(200, {
    ["Content-Type"] = "text/plain",
    ["Content-Length"] = #body

print("Server listening at http://localhost:8080/")

Notes: This code works today. It serves up an HTTP 1.1. server on 8080 that tells you Hello!

History of the project

  • Started by Tim Caswell
  • Strong community of contributors
    • Vladimir Dronnikov
    • Ryan Phillips
    • Paul Querna
    • Brandon Philips (me)
  • People taking the project in a variety of directions
    • HTTP Application Servers
    • SDL demos on Linux
    • iPhone app development
    • Cloud monitoring agent

Notes: There is a great community of people working on this project. The best part is how many people are interested in different uses- not just web stuff. In particular Rackspace is interested in a really small memory footprint monitoring agent.


Lua - Javascript’s Long Lost Brazilian Cousin

  • Dynamic language
  • Floating point numbers only
  • First class functions
  • Lexical closures
  • Metatables
  • Embeddable

Notes: Lua shares a lot of features with javascript like using floating point numbers only, being dynamic and having first class functions. It is like node’s long lost Brazilian cousin

luajit Features

  • x86, ARM, PPC, MIPS
  • API compatible with Lua 5.1
  • 125K for VM, 85K for JIT compiler
  • JIT inlines FFI

Notes: luajit is an alternative tracing VM for lua that has a great FFI layer. It is small and fast.

Basic idea

  • Two types of events in the loop:
    • I/O on file descriptors
    • Timers for future events
  • Callbacks are attached to these events
  • epoll()/completion ports/kqueue() wait
  • callback is called on the correct event

Notes: Essentially libuv is just a big loop (see the next section) that runs poll on a bunch of file descriptors with the timeout of the poll set to the next timer that needs to run. When the poll complete a callback is made so the user can handle the event. I have talk on libuv that covers all the details too

Other platforms built on libuv

Notes: A number of new platforms are using libuv. Rust is a new language from mozilla. candor is a limited subset of javascript. luvmonkey is mozilla’s spidermonkey with libuv. http://julialang.org/ is also using libuv.

Follow along at home

git clone git://github.com/luvit/luvit.git
cd luvit

gyp (all platforms)

make -C out
tools/build.py test
Welcome to the Luvit repl

make (linux, embedded)

make test
Welcome to the Luvit repl

Object system

local Object = require('core').Object
local Rectangle = Object:extend()
function Rectangle:initialize(w, h)
  self.w = w
  self.h = h
function Rectangle:getArea()
  return self.w * self.h

local rect = Rectangle:new(3, 4)

Notes: Lua doesn’t have an object system so we impelemted our own in order to do our inheritance of stream, event emitter, etc

JSON Example

local JSON = require('json')
local value = JSON.parse([[
  "author": "Brandon Philips <brandon@ifup.org>",
  "name": "luvit - node's Ziggy Stardust",
  "description": "a talk about luvit"

local json = JSON.stringify(value, {beautify=true,indent_string="  "});

Notes: Luvit has a JSON parser using yajl. It has some nice features like allowing comments


Notes: There are a number of users of luvit today. Lets see some of them

Real world applications

  • luvit.io is hosted using luvit
  • Rackspace agent (see me at OSCON)
  • Demos of using SDL/GL and Joystick interaction

Thanks to the luvit community for all of their hard work. Also thanks to Rackspace for letting me do work in the open.

Tue Jul 3, 2012


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