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From now on I will be posting on

Most of my postings have code snippets in them and I've been using markdown, checking into a GitHub repo, then copying and pasting the contents. Using a static site generated with Jekyll just seems easier. Thanks, Blogger - I have moved on...
Recent posts

Waiting for an answer

I want to describe my first iteration of exsim, the core server for the large scale simulation I described in my last blog post. A Listener module opens a socket for listening to incoming connections. Once a connection is made, a process is spawned for handling the login and the listener continues listening for new connections. Once logged in, a Player is created, and a Solarsystem is started (if it hasn't already). The solar system also starts a PhysicsProxy, and the player starts a Ship. These are all GenServer processes. The source for this is up on GitHub: Player The player takes ownership of the TCP connection and handles communication with the game client (or bot). Incoming messages are parsed in handle_info/2 and handled by the player or routed to the ship, as appropriate. The player creates the ship in its init/1 function. The state for the player holds the ship and the name of the player. Ship The ship holds the state of the ship - …

Large scale ambitions

Learning new things is important for every developer. I've mentioned this before, and in the spirit of doing just that, I've started a somewhat ambitious project.

I want to do a large-scale simulation, using Elixir and Go, coupled with a physics simulation in C++. I've never done anything in Elixir before, and only played a little bit with Go, but I figure, how hard can it be?

Exsim I've dubbed this project exsim - it's a simulation done in Elixir. Someday I'll think about a more catchy name - for now I'm just focusing on the technical bits. Here's an overview of the system as I see it today:

exsim sits at the heart of it - this is the main server, implemented in Elixir. exsim-physics is the physics simulation. It is implemented in C++, using the Bullet physics library. exsim-physics-viewer is a simple viewer for the state of the physics simulation, written in Go. exsim-bot is a bot for testing exsim, written in Go. exsim-client is the game client, for inter…


My employer laid a bunch off people yesterday. While I still have a job, this makes me really sad. I feel bad for those people that didn't have a job to go to this morning - some of them have worked here a long time, some of them are good friends, some acquaintances, some I can't really say I know.

I'm sure they will find good jobs elsewhere - unemployment here in Iceland is very low these days, but then again, there aren't that many game developers. For some, this will mean not only changing jobs, but moving to a different country, on a very short notice. While that can be exciting, it can also be very upsetting.

I mostly feel disappointed. I really believed this company had evolved past this sort of behavior. We've seen layoffs here before - it was painful, and we've really made an effort of avoiding getting ourselves into this situation. Or so I thought.

Shifting focus is sometimes - often, maybe - necessary. I just wish companies could do that without letti…

Mnesia queries

I've added search and trim to my expiring records module in Erlang. This started out as an in-memory key/value store, that I then migrated over to using Mnesia and eventually to a replicated Mnesia table. The fetch/1 function is already doing a simple query, with match_object. Result=mnesia:match_object(expiring_records, #record{key=Key, value='_', expires_at='_'}, read) The three parameters there are the name of the table - expiring_records, the matching pattern and the lock type (read lock). The fetch/1 function looks up the key as it was added to the table with store/3. If the key is a tuple, we can also do a partial match: Result=mnesia:match_object(expiring_records, #record{key= {'_', "bongo"}, value='_', expires_at='_'}, read) I've added a search/1 function the module that takes in a matching pattern and returns a list of items where the key matches the pattern. Here's the test for the search/1 function: search_partial_…

Go, bots, go!

Earlier this year I started experimenting with the Xmppprotocol, and implemented bots in Python to communicate with an Xmpp server. I've now revisited those bots and reimplemented them in Go. I've been meaning to learn Go for quite a while, and this seemed like a reasonable first project to tackle. The source code lives on GitHub: If you are an experienced Go developer, I would appreciate any feedback and suggestions on how to improve the code - if you are just starting out with Go like myself, I hope this blog and the code is useful to you. As before, I'm using Prosody to communicate with. Just like I did in Python, my first experiment is to simply open up a socket and poke the server to see where that takes us: funcmain() { conn, err:= net.Dial("tcp", "localhost:5222") if err != nil { fmt.Errorf("Couldn't connect") } message:="<?xml version='1.0'?>…