Agis Anastasopoulos

Speeding Up Our Build Pipelines

Fri, 23 Aug 2019 11:39:01 +0000

A cross-post from the Skroutz Engineering blog, showing how we optimized our build pipelines and introducing mistry, a general-purpose build server.

Read the article here.

Slides from "Go at Skroutz" talk

Wed, 13 Mar 2019 00:00:00 +0000

Following are the slides of a talk I gave at the 4th Athens Gopher Meetup.

At a glance we present:

why we introduced a new language in the organization and why that was Go
how we approached the transition
some of the projects we built in Go
the challenges we faced and the lessons we learned in the process

You can also download the slides.

Introducing Kafka to a monolithic Rails application

Mon, 16 Apr 2018 00:00:00 +0000

A cross-post from the Skroutz Engineering blog, showing how we introduced Kafka to our large, monolithic Rails codebase.

Read the article here.

Rewriting an analytics tracking service in Go

Sun, 02 Jul 2017 00:00:00 +0000

A cross-post from the Skroutz Engineering blog, showing how we spawned a Go microservice from a big Rails monolith and the challenges we faced along the way.

Read the article here.

Contiguous stacks in Go

Sun, 23 Mar 2014 00:00:00 +0000

Lately I’ve been messing with Go and I really like it. The 1.3 release is due in June 2014 and among other performance improvements, the runtime will implement contiguous stacks. Let’s see what this is about.

Segmented stacks

The 1.2 runtime uses segmented stacks, also known as split stacks.

In this approach, stacks are discontiguous and grow incrementally.

Each stack starts with a single segment. When the stack needs to grow, another segment is allocated and linked to the previous one, and so forth. Each stack is effectively a doubly linked list of one or more segments.

Dabbling in Erlang, part 2: A minimal introduction

Sat, 12 Oct 2013 00:00:00 +0000

It’s been a while since the last post which was a short introduction into functional programming in general and now it’s time to dive into some of the basic concepts of the language.

Single assignment & pattern matching

In Erlang we should think variables in a mathematical sense of the term, which means that once you’ve bound a variable, you cannot change its value . If you state that X is 5, then it will always be 5 (a variable is called bound if already contains a value, unbound otherwise):

Dabbling in Erlang, part 1: Hello function

Sun, 19 May 2013 00:00:00 +0000

Recently I’ve been dabbling in Erlang and I’m enjoying it a lot. I decided to start a series of posts in which I’ll address things that I believe are worth mentioning.

Meet Erlang

Erlang is a functional, concurrent, dynamically-typed language initially developed at Ericsson around 1986 in order to power its telecom infrastructure.

It is a great fit when scalability, availability and distribution are crucial (exactly what telecom applications need). This greatness stems from Erlang’s concurrency model, its error-handling capabilities and the OTP framework.

Rails tips, part 2

Mon, 17 Dec 2012 00:00:00 +0000

I have finally found some time for another post. Here are some more Rails tips I wish I’d known earlier.

(In case you missed it, here is the first part of this post.)

Tip #4: Silence Postgres Warnings

Are you annoyed by messages like these in your terminal when you run migrations?

NOTICE:  CREATE TABLE will create implicit sequence "notification_settings_id_seq" for serial column "notification_settings.id"
NOTICE:  CREATE TABLE / PRIMARY KEY will create implicit index "notification_settings_pkey" for table "notification_settings"

Well these are notifications, not warnings, that inform us about the awesome stuff Postgres is doing for us. But what do they actually tell us?

Validating Paperclip image dimensions in Rails

Fri, 14 Sep 2012 00:00:00 +0000

I love using Paperclip for handling image uploads in my Rails apps. It’s super easy to use and plays nice with Amazon S3. It even has validators for attachment’s content-type, filesize & presence.

What it lacks is a built-in validator for image dimensions, but I’ve found out that it’s not so hard to build one yourself. In my last project, BathLiving, I needed the user to upload images of specific dimensions. These images where going to be used in image sliders, thumbnails etc. I didn’t want to use ImageMagick’s resizing/scaling options since I wanted the quality of the image to remain intact. So I had to force the admins to create images with the proper width & height in the first place.

Hands-on Rack

Thu, 31 May 2012 00:00:00 +0000

Rack provides a minimal interface between webservers supporting Ruby and Ruby frameworks.

Our first project in the Code Reading group was Rack. At first I thought it was going to be a complex project to go through but Rack’s logic is really simple. This is an overview of how it actually works.

Indeed, the Rack API is as simple as it gets:

A Rack application is any Ruby object that responds to call. It takes exactly one argument, the environment hash, and returns an Array of exactly three values: The status, the headers, and the body.

Rails tips, part 1

Thu, 24 May 2012 00:00:00 +0000

Mostly like a note to myself, here are some tips that were proved useful to me over time.

Tip #1: Skipping Test::Unit

If you’re like me, you prefer RSpec over Test::Unit for its expressiveness and the awesome DSL it provides. Everytime you create a new app, you can use the -T option to skip all the folders and files related to Test::Unit.

$ rails new app -T

Note that this will not only skip the test directory, but also won’t create any new test files when you use the built-in controller & model generators.