Elixir & PhoenixFunctional |> Concurrent |> Pragmatic |> Fun

Who am I?

• Jared Smith

• Software Engineer at One Month

• @sublimecoder

• www.sublimecoding.com

Lets get started

First lets talk about Erlang

• Elixir runs on the Erlang VM

• Many of the standard lib function calls in Elixir call Erlang functions directly.

• Elixir piggy backs on the Erlang ecosystem

Why Erlang VM?

• 30 year old battle tested VM

• Highly available, fault tolerant, and distributed

History of Erlang

• Developed by Ericsson

• Used and developed for Telecommunications

• In fact its standard library is the OTP (Open Telecom Platform)

Telecommunications

• High availability is king

• Remote Telecom switches need to run for years sometimes with out being disturbed

Built with Erlang

• 50 person engineering team

• managing 900 million users.

• Up to 2 million active users per server.

https://blog.whatsapp.com/196/1-million-is-so-2011

2 Million Active Users?

• Intel Xeon CPU x5675 @ 3.07GHz 24 Cores - 96GB Ram

• Using only 40% of the CPU/Memory

https://blog.whatsapp.com/196/1-million-is-so-2011

So Erlang is pretty awesome

• Wouldn’t it be nice if we could harness this power?

• Why isn’t everyone using Erlang?

Elixir

• Elixir utilizes much of the power of Erlang

• While giving us a much nicer syntax and api to work with.

History of Elixir

• Created by Josè Valím - (Joe-zay Val-eem)

• First released in 2012

Elixir’s Strengths

• Concurrency

• Meta-programming Capability

• Transformation of data as a core ideal

Plus it has Ruby like syntax

Pipe Operator• The following code is valid elixir.

• With the pipe operator we can write our code this way instead. Keeping us out of nested function hell.

Pattern Matching

• Pattern matching is a core part of Erlang and Elixir

What is Pattern Matching?

• Make left side look like the right side

• a = 99

• [a,b,c] = [1,2,3]

• [head | tail] = [1,2,3]

Immutability

• Once you set a value it can never change.

Immutability

You’re already familiar with immutability you just don’t know it.

• a = 99

• We all know 99 is always 99.

• integers are immutable values, even in Ruby.

• You’d be upset if someone monkey patched 99 to be 3 right?

Why is Immutability a good thing?

• Immutability provides a contract that each piece of information has one source of truth.

• Concurrency is a natural side effect of immutability.

Does this mean I can never change a variable once I set it?

• The short answer is no, you can reassign variables as much as you like.

• Erlang would not be so kind, but Elixir we have this luxury.

So how is it immutable if I can change things?

• You can change things, elixir will just copy the values you don’t change, but the original reference stays intact.

• The original reference can then be used in part or in whole later in the application.

Isn’t this inefficient?

• At first glance it would seem that way, but the opposite is true.

• Won’t all the old reference values balloon elixirs memory?

• Yes this means you could have thousands of unused variables floating in memory

Concurrency

Concurrency fixes everything

• Because the data is immutable we can rely on it always being a certain value

• which means we can make our programs concurrent and not worry.

• Elixir uses its concurrency to help with garbage collections. Each process gets it own heap allocated and that heap is garbage collected or reclaimed as needed for that individual process.

Concurrency

• Elixir will eat as many cores/computers as you can throw at it.

• It treats each core as though it were a computer on the network with near zero latency.

Phoenix Framework Productive |> Reliable |> Fast

Phoenix Framework

• Created by Chris McCord

• Release 1.0 August 28th 2015

Phoenix Framework

• It’s not rails for Elixir

• It has been influence heavily by rails as well as many other frameworks.

• Focus on API and web sockets

Speed• Web request response time is often measured in

micro seconds and not milliseconds.

Benchmarks

• Recently benchmarked 2 million+ web socket connections

• With 2 - 3 second broadcast times to all 2 million connections

Benchmarks

https://github.com/mroth/phoenix-showdown

iMac Intel Core i7 (4.0 GHz 4 Cores) 32 GB RAM

https://github.com/mroth/phoenix-showdown

2.8 Ghz, 10 core Intel® Xeon 128 GB RAM

Easy Startup

• mix phoenix.new ./app/path/my_app

• mix ecto.create && mix ecto.migrate

• mix phoenix.server

Directory Structure

Web Dir Structure

Mix

• Mix is essentially bundler and rake combined

• Additionally mix is your test runner.

• It’s included with Elixir

Rails like Generators

• mix phoenix.gen.html Post posts title body:text

• mix phoenix.gen.json User users name:string

• mix phoenix.gen.model User users name:string

Concurrency

• Async processing with out the need for DelayedJob or Resque/sidekiq

• We can write code that looks like this.

Isolated & Concurrent

• Crashes are isolated

• Data is isolated (GC is per process, no global pauses)

• Load Balances on IO and CPU - Efficient on a multicore

Garbage Collection

• No triggering massive garbage collection

• GC per process / end of process life cycle

• Ensuring top 10 percent of requests are not vastly slower than any other request

Request Pipeline

• Just a series of function calls that transform data.

• connection |> endpoint|> router|> pipelines|> controller

Request Pipeline• Phoenix makes it easy to add middleware or

plugs to this pipeline. We could easily add authentication to this.

• connection |> endpoint|> router|> pipelines|> authenticate_user|> controller

Explicitness Over Magic

• Phoenix Removes a lot of the confusion and “magic” found in rails and replaces it with explicit calls.

• Models, Controllers and Views are singular named by convention.

Phoenix Router

Phoenix Router

Phoenix Router

Phoenix Controllers

Phoenix Model

Phoenix View

Phoenix Template

Learn More• Elixir-Lang on Slack

https://elixir-slackin.herokuapp.com/

• #elixir-lang on Freenode IRC

• http://www.phoenixframework.org

• http://elixir-lang.org/

• https://github.com/h4cc/awesome-elixir