BloggEd - Blog

Time is an illusion

2009-05-14T07:04:00Z

Months, weeks, years etc. doubly so.

Ok. Never, ever program time-related logic using any other model except some linear, continuous, fixed-interval unit like epoch. Why? Because handling the epoch is so easy. Number of seconds since 1970-01-01 00:00. No special cases when the year changes, or week overlaps two months, taking into account leap years, months having different number of days and so on.

Of course, you need those human-readable concepts like week and month. But they should be computed from the epoch (or similar), so that all actual processing happens with the same, simple unit.

Likely this comes naturally to most programmers, but sometimes a model like month in a given year comes so naturally, that you are lured to use month as a model, and it works, until you run into something that overlaps previous months and you hack in some incomprehensible solution involving dates, datetimes, conversions between those and myriad of obscure interval conversions like weeks in a month etc.

You’ve been warned.

Best bun I ever had

2009-04-03T11:40:00Z

This is soo off-topic, but so delicious that I wanted to share it with all my loyal readers.

It’s an Augmented Cinnamon Boston Bun (the augmentation part is associated with the amount of cinnamon). Best enjoyed with good company and a pint of skimmed, cold milk. I guarantee the result is nominal.

Ingredients (SI units only, sorry!):

Rather large baking bowl (metallic or ceramic) for the oven, cylindrical in shape (flat bottom), about 30-40 cm in diameter or two smaller bowls
A rolling pin

half a liter of milk
yeast, 50 g
sugar, 2 dl
one and a half tsp of salt
1 egg
1 tbsb of cardamom
1 kg of wheat flour
150 g of margarine (suitable for baking)

For filling:

butter, 50 g
sugar, 0.5 dl
about 16 teaspoons of cinnamon—yes, about 8 times the amount in the original recipe. This is not for wussies.

You also need one egg and small amount of margarine/butter for greasing as well as crystal sugar for the topping.

Phase one: preparing the dough

First, warm the milk so that the yeast activates (for dried yeast, you need to make it about 42 °C) and mix the yeast in. Add sugar and salt. Stir in egg, cardamom and about 1 dl or so of wheat flour. Then add margarine (warm it if necessary to get it in running form) and rest of wheat flour. Beat the dough for three minutes or so. Make sure the dough feels homogenous enough. Let it rise for 1 hour (the dough volume should increase by about a factor of two).

Phase two: filling the dough

Split the dough in two parts to make the following part easier.

Use the rolling pin to flatten the dough in rectangular shape, about [3..5]mm thick. Grease the dough evenly with butter, pour over sugar and cinnamon. The surface should now be saturated with cinnamon. Next roll the dough along the longer side of the rectangle, and cut it into 5cm pieces.

Now repeat the phase for the other part of the dough if you split it in two.

Phase three: Finalizing and putting it in the oven

First preheat the oven to 175 °C. While waiting for the oven to heat, grease the bowl and evenly position the cut rolls using a sparse algorithm (ie. for any given roll, the distance to all adjacent rolls should be a constant included in the range [12..28]mm), so that the cut surface is perpendicular to the diameter of the bowl bottom. Let rise for 20 to 30 minutes.

Last, grease the rolls with egg and scatter the rolls with crystal sugar. When the oven has reached the target temperature, put the baking bowl in the oven and bake for 40 minutes using the lowest position. When finished, cover the rolls with a suitable cloth to prevent premature dehumidisation.

Now, bask in the joy of delicious, cinnamonic bunniness.

Protecting Rails apps against nil.foo_method called bug

2009-03-04T09:48:00Z

It’s a null object pattern guard for rails. YMMV. WorksForMe™ at the moment.

Oh yeah, I’m sure better solutions exist already. But a geek has to reinvent the wheel every time, no?

Lovin' Git

2009-03-04T09:34:00Z

There are so many features in Git that ease development that I won’t even bother to mention such features as easy branching/merging, bisecting, stashing, splitting or combining previous local commits etc.

But one really, really nice thing is git add with flags --interactive -p.

The problem: you have fixed lots of things, and have tested some of them. Now you’d like to push only the small, well-tested changes to upstream. But the problem is that some files contain changes that you wish to publish, and some that you don’t (because some changes are not tested yet).

Easy. You fire git add --interactive -p, pick the changes you want to publish, and then you push the changes to upstream using git push (or git svn dcommit if your team is still using The Rather Good But Still Inferior SCM). And if you want to make sure you are about to commit exactly the right thing, you say git diff --cached.

Ajattelunaihetta

2009-02-15T22:20:00Z

Kannatan veronmaksua ja hyvinvointivaltiota, jossa kukaan ei joudu taivasalle. (Tämä on yksi syy siihen, miksi kieltäydyn olemasta minkään lajin oikeistolainen, mukaanlukien äärisellainen.) Ei ole tiukasti ottaen reilua, että kenellekään annetaan minkäänlainen asunto toisten kustannuksella, mutta kannatan sitä silti, koska vaihtoehto olisi paljon ikävämpi ja julmempi. Sosiaaliasujan, kuten muidenkin tulonsiirtojen vastaanottajan, on kuitenkin mielestäni oltava kiitollinen ja vältettävä vaatimuksia ja rutinaa. Minä esimerkiksi tunnen syvää kiitollisuutta ja nöyryyttä jokaisesta potkupuvusta, jonka perheeni on äitiyspakkausten (seksistinen nimitys) mukana maksutta saanut. Mieleenikään ei tulisi eräiden kanssakansalaisteni tavoin valittaa yleisönosastoilla, että lahjaksi saadut lastenvaatteet eivät ole kauden muotiväreissä.

Ote on suoraan Jussi Halla-Ahon tekstistä, mutta jotain minkä voisin allekirjoittaa täysin. Oli niin hyvin kuvattu, että tahdoin jakaa sen mol.. öh, kaikille lukijoilleni.

Ja nyt jotain aivan muuta

2009-02-05T11:05:00Z

Jussi Halla-Aho tekee niin teräviä havaintoja yhteiskunnasta ja ihmisten epäjohdonmukaisesta ajattelusta, että äänestäisin häntä välittömästi eduskuntaan ja/tai presidentiksi, jos hän asettusi ehdokkaaksi.

Valitettavasti tietyn normaalijakauman oikealla puoliskolla on määritelmänomaisesti vähemmän ihmisiä kuin keskellä ja vasemmalla, mikä efektiivisesti tekisi hänen valituksi tulemisen lähimain mahdottomaksi.

Github lovin'

2009-02-05T09:21:00Z

I will no longer spit out crappy pieces of code and post them to the Code section in my blog. Instead, I will post the crappy pieces to GitHub, allowing other people to gawk and fork them at will. Maybe I’ll post something actually usable there some day, who knows.

On Rails migrations

2008-12-09T16:11:00Z

You can learn lots of stuff from mistakes. Especially of your own. And, uh, you can learn even more of the big ones.

So, I learned a lot today. Hum.

To cut long story short: never use down migrates in production. That’s about it, yeah.

The long story starts at my deep inclination to automate every imaginable procedure consisting of monotonous, simple steps. Releasing new version of software is one of such tasks. With Rails, it’s basically svn up/git pull, rake db:migrate and maybe restarting the web server.

Unless you go sometimes backwards in migrations, if nothing else but to restore the database to a known, blank state. And maybe you were really asking for it and chose to modify old migrations to say, modify some column information. So you start to hack and end with something similar:

  #update_server.sh
  #!/bin/sh

  CONFLICTS=$(svn st -u|grep -c "^C")
  VER=$1
  if [[ $CONFLICTS == 0 ]] then
    backup_db_with_timestamp
    mongrel_rails cluster::stop -e production
    svn up
    if [[ $VER != "" ]] then
      rake db:migrate VERSION=VER RAILS_ENV=production
    end
    rake db:migrate after_release_stuff RAILS_ENV=production
    mongrel_rails cluster::start -e production
  else
    echo 'Resolve incoming conflicts first'
  end

Now, imagine you do something like the following:

$ ./update_server.sh 123

You’d assume that because 123 is passed to $1, the script downmigrates first to version 123 before doing the up-migrate.

Nope. It won’t. Instead, the script will run with VERSION=VER (note the missing dollar sign) and Ruby’s Object#to_i will convert any string containing no digits to zero. Yup; you will end up running

rake db:migrate VERSION=0 RAILS_ENV=production

That’s a really funny thing to do in a live, business critical production environment, destroying all user data. Fortunately you backed up the db first, didn’t you? Oh well.

There are other problems with running down migrations in production, like

Most of the time you lose the data input by users
code may become out of sync with database schema
the number of current database states increases exponentially(!) given different times and version numbers in down migrations
It’s Just The Wrong Way To Do™

Using only forward-direction migrations in production you have access to all present data, allowing you to eg. remove old schemas and store old data to new data structures. And best of all, it makes the update script/rake task (or Capistrano recipe) much more simple.

Update: my colleaque suggested to completely disallow down migrations in production mode, so I added the following extension to our project, which does just that:


# Prevent down migrations in production mode
module ActiveRecord
  class Migration
    class << self
      alias_method :orig_migrate, :migrate unless self.respond_to?(:orig_migrate)
      def migrate(direction)
        raise 'Refusing to down migrate db in production mode!' if RAILS_ENV == 'production' && direction == :down
        orig_migrate(direction)
      end 
    end
  end
end

Agile dinner in Tampere

2008-11-26T07:27:00Z

Instead of having our monthly Tampere.rb meeting on Dec 4th, most of us are attending Agile dinner in Tampere. Feel free to join us!

GMail failure

2008-09-18T18:00:00Z

I’m a happy GMail user. Have been so for almost a year now. Except for the last two days or so – it seems like it doesn’t detect any spam messages at the moment; I receive about one hundred spam messages a day, all to my inbox. Makes my email almost unusable. However, I trust the excellent folks at Google fix the problem in no time.

In the meantime, I guess I have to sort my inbox thrice a day.

Oopsie

2008-09-07T19:18:00Z

It seems like my nginx configuration pointed default virtual host to that of tampererb.info (hosted by the same server). Thanks to my most loyal reader for the tip :)

Moving to new job

2008-07-22T16:17:00Z

I’m about to start working at Adalia. I’m quite excited about my new job, not least due to the fact that I’ll be granted the opportunity to design and build very challenging, complex systems, Ruby and Mac/Linux being the most prominent technologies I will be working with. Not only that, but the folks at Adalia seem to be not only smart but quite nice too. I’m honoured to join their ranks!

However, I’m not all happy-happy-joy-joy. Why? Well, having been privileged to work at Atostek is something I’m not taking lightly. To put it straight, all key people (and not only those) in Atostek are darn-tootin, brilliantly smart people, you know, one-out-of-ten-thousand -kind of smart. I mean Done, And Gets Things Smart type (it’s not a spelling error, see the entry for explanation). Really. And what I said about smart includes the CEO too—she’s phenomenal. To put it short, I’m going to has sad mah trusty mates at Atostek. Sniff.

Ok, I wouldn’t be changing jobs for worse. It’s quite a different industry I’m working with at Adalia, and the setup seems very good. I have great trust in our CEO for where the company is heading, and I see huge potential in choice of technologies and type of people chosen for the company. Unfortunately I can’t say more at the moment, but the future seems very, very interesting for me.

And thanks for the chief for getting me a real computer to work with!

Confessions of a Mac convert

2008-07-21T11:26:00Z

First off, my apologies to both of my astute readers, who quickly realised that it’s been a long time since I blurbed anything to teh intertubes. I was having a vacation, this time almost for real, using computer only an hour or two a day. Ok, maybe more, but not much. Family and stuff, you know.

Where was I? Oh. Yup. I joined the ranks of purchasing a $3000 text editor. Ok, TextMate costs only 39 €, but it is available on Mac only, and if you’d love to have a 21st century Emacs -like überpower tool at your hands with seamless OS support, you want to get Mac—just to be able to run TextMate.

Nevertheless, I’ve been nothing but astounded by the usability and power of tools offered by OS X Leopard (not forgetting the very nice engineering of Apple hardware itself). To put it short, back in ye olde days Macs used to be scorned by the True Computer Geeks such as programmers, Unix gurus and other people familiar with deeper workings of computer hardware and operatings systems. Ok, it was generally admitted that Macs are good for novices who just want to do simple things like write memos and stuff. There were some other niche areas where Macs were often used professionally, like audio and video processing.

Now, that all has changed. To me, it seems obvious that when discarding the old OS 9 and beginning with OS X (pronounced “OS ten” to avoid embarrasing attention), which is the current Mac operating system, Apple wanted to preserve everything they were famous for and very good at, and to throw along bunch of capabilities required by the more geeky computer users and hackers. No, let me put it another way; to say throw lends for ill connotations—it sounds more like an afterthought, which couldn’t have resulted in such a seamless, consistent and fluent system as OS X Leopard is. No; they have to have designed it carefully from the very beginning, probably starting from scratch and perfecting it every now and then until the whole system, comprised of both the hardware and software, felt like a single, consistent entity.

I’ve been dissatisfied with both the Windows operating systems (XP/Vista) as well as Linux distributions for quite a long time (and I’ve tried many – I used solely RedHat professionally over two years for software development, Debian even for longer, and finally KUbuntu Linux). I mean, if you don’t want to spend hours configuring stuff and debugging problems, you have to appreciate ease of using Windows. Buy any hardware from the computer store and it just works in Windows. And if it doesn’t, you’re at least able to contact some commercial support service and have the problem fixed—after all, the product was usually designed for MS Windows, de facto standard OS, and very likely it came with some sorts of guarantee. And I won’t even mention the amount of software available for MS systems. Especially if you want to play games every now and then. But then there’s the problem of automation and customization of the system itself. If you have to do something that you don’t have special software for, or you like to do some rather complex things automatically, Windows gives very little support. Don’t tell me you use .bat or .cmd files for scripting production-quality software. Bah! Three words: date/time scripting. To accomplish such tasks, you either find a special purpose software for that, or you code one yourself. Of course, being a hacker you install Linux, used by every cool kid in the town. It sure is the king of hackable OSes. For example, if want to turn off unnecessary VGA display and keyboard support for some embedded software, you can always just recompile the kernel and take the parts off you don’t need. And when it comes to communication, Linux is famous for supporting any imaginable protocol, with the probable exception of smoke signals. However, probably the best feature of any(?) Unix system is the philosophy of pipes and filters combined with appropriate, simple but powerful tools such as grep, sed, tail and such. Those tools make it easy to do relatively complex tasks for processing text and/or system automation. For example, it takes only a simple shell script containing one to two lines to remotely back up all files more recent than two days over the network to some other machine using ssh or scp. Another example could be a poor man’s continuous integration tool, especially if combined with make (which is relatively standard unix tool). But in Unix world, there’s a price you have to pay, even though the OS itself and tools can be free. I mean, I’ve used Linux over 10 years and I have to admit that it’s not truly plug and play, even the Ubuntu versions, though sometimes you can use printer right after plugging in the usb cable, or wireless adapter. But problems in using external hardware are much more common than in MS world (understandably; it is not common that vendors give out the internal specs of their hardware, especially for free) and your mileage will likely vary. Moreover, not all software Unicen come with easy to use graphical user interfaces. In the long run, you have to learn syntax of several different configuration file formats as well as caveats and quirks. But the worst of all, which took me a long time to understand, is that most open source software suffers from certain development problem, obvious in all Linux distributions I’ve used and in several applications as well.

In my opinion, the problem is not technical but psychological. As a software programmer, I know that creating new features, starting new projects and making code work faster is much more fun than making it more robust and otherwise polishing it. Being driven by pure volunteerism alone, OSS developers attempt to make software robust only if they are enough disciplined or ambitious. I don’t mean this as an insult. Come on, it’s obvious! I know I’ve seldom finished any work I’ve written for free, and those that I have, I’ve never bothered to make them very robust, user-friendly or anything that is expected from software packages available at the store shelves. At work you’re more or less forced to, which is a good thing. Sure, Emacs is very robust and stable, capable of uptimes of months and more, but it’s been developed for decades. About time, you could say. Besides, it’s still ugly. But the reason for changing to TextMate is not ugliness but usability. Due to lack of elegant scoping system used in TextMate, Emacs keyboard shortcuts are way too long. And I don’t want to bother customizing all keyboard shortcuts to my taste in every machine I use. There’s wisdom in living with defaults, and TextMate defaults are just fine. Ok; at least I’ve switched to TextMate in Ruby (on Rails) development, because it’s the most supported editor for doing precisely that stuff. There are bundles for Ruby, Ruby on Rails, Merb, RSpec and whatnot. It might be that I still resort to Emacs when typesetting LaTeX documents, though I’ll definitely give TM’s LaTeX bundle a shot. Last, not all my computers at home are Macs. Yet. Crap.

As for the rant above about OSS, note that I’m not labeling all OSS as crap, or even blaming the open source model itself. However, I do have lost my trust in open-source operating systems deployed at end-user points. I still favor Linux in servers because setting up a DNS, mail or web server doesn’t have to be easy and it’s not something I do daily. But I do want to be able to run my routine tasks so that the tools are practically invisible and I can focus on the task at hand. And the illusion of invisible tools really does fade somewhat if the program dumps core, recovering from sleep mode leaves your screen blank forcing you to reboot, copying files from your digital camera requires editing of /etc/fstab using a syntax you always have to look up from the manual page, or anything similar. No, I only managed with Linux so far because it was the best choice I knew of, and I was mostly capable to fix the problems myself, or circumvent them if necessary. When Linux phenomenon started spread back in the ‘95 or so, it was so remarkable system back then and had so much potential that I really wanted to believe it reach superiority as a platform, no matter the task at hand. But that was mostly when I was still a single, and I didn’t realize that in reality, I spent many hours every week just trying to configure some things properly and searching for properly working versions of the software I wanted to use, alluring myself to the belief of ease of use.

Now, thanks to this 64-bit, pure goodness of an OS sporting a Mach-based kernel and supporting up to 4 TB (yes, that’s terabytes, equalling 4000 GB) of RAM I’m able to Just Get Things Done quickly and easily, be it programming, automating complex stuff or programming software with my copy of TextMate. And when I just want to watch videos, print stuff, listen to music, read e-mail or accomplish any of the more meager tasks without thinking about missing codecs, unsupported proprietary standards or incomplete implementations and ugly excuses for an interface, I just do it without hassles. Besides, the included software in OS X is far more usable than Windows counterparts. Take notepad/wordpad and paint as examples. Seriously? Even novices often abhor those tools due to lack of every single features except copy/paste and save as. Meh. With OS X you can actually get job done. TextMate is the only app I’ve purchased so far, and I’ll likely get iWork later, but it’s only $79 and offers a full office suite. Or I’ll just tug along using NeoOffice (Mac port of OpenOffice suite).

Oh, and did I mention how fast OS X is to use, and how quickly it recovers from sleep? ok, you wouldn’t believe it anyways. I won’t.

So far, after using Mac for a month my only gripe is the lack of commercial games. Sure, the situation is improving all the time and it’s way better than it was for Linux ever (even with Loki software around). Like, I can get World of Warcraft for Mac, or Lucasart’s Galactic Battlegrounds or even Empire at War, all native apps without any emulators or such; the situation is definitely better with current games, as current Macs are based on intel architecture as well (and NVidia graphics cards). But Apple store still mentions only about few hundred popular titles compared to thousands available for PC. Fortunately, I can probably play Company of Heroes using the Parallels software.

Sure, Macs come with a price tag a tad higher than PCs. But what you get is more than worth the extra cost. You just have to experience it to believe it.

Fun with marble coaster

2008-07-10T08:19:00Z

Ok, I won’t start reviewing toys. But let this be an exception. Seldom I have encountered such a great piece of design and engineering in reasonable price as with Quercetti Skyrail series. Not only for kids (Samuel plays an hour or two with it every day), it provides lots of fun for those interested in math, physics and engineering. Not surprisingly, most videos in YouTube related to the kit are made by adults fascinated by the marble coasters.

Yeah. I’m definitely going to get few box of those to my office. Hint: 28 meters of marble track for those moments when some Heisenbug fails to manifest itself during the debugging phase. Mmm.

Notes on The Functional Programming Language

2008-06-11T12:54:00Z

I dislike the idea of writing blogs with no content other than links with vague descriptions, but this time I wanted to make an exception. The reason: it seems like somebody’s train of thought runs along the same tracks as mine, except that he writes better than me and is more focused on functional programming, and it seems like I could stop writing about them and just point to his blog. I guess you could be able to deduce the particular flavor of the language by deciphering the url linked):

Now, go read http://notes-on-haskell.blogspot.com/. Good stuff for you language enthusiastics out there.