Guest Post: Crash – Exam – Relaunch

This is a guest post from my Google Summer of Code Student Arthur Arlt.

Isn’t it a funny title for a blog post? But there is a reason for that because it happend a lot in the last weeks…


Having done my first review requests for my GSoC project, my new (six week old!!!) solid state drive stopped working from one moment to the other. I tried to get it running in other systems, but it was no longer detected by any BIOS. Taking a look at the homepage of Kingston I had to discover, that they found a technical issue of exactly that brand of SSD I had installed to my system. They are strongly recommending to do a firmware upgrade because this failure could lead to a total crash of the drive…
Thanks for the information 🙁 Luckily I made my review requests before, so at least the work done for GSoC so far was saved. But everything I did in these six weeks on my laptop is gone…
I got the SSD replaced, but this took almost two month, since the producer had to check by itself that the SSD is broken… So I bought a new one, because it was no fun working with my slow, old HDD.


I did not have too much time to be angry about the loss of data. I had to study for an exam in “Principles of Dependable Distributed Systems” which took place at Friday before Whitsun. After that, I have spent a lot of time to (re-)set up the build environment during the holidays.


I am now working into Martins hands supporting him to port KWin to Wayland. Especially the class Scene and its subclasses were provided with some signal and slot functionality.
A very important step to Wayland is to remove all X11 specific stuff from class Toplevel and to insert it into a new class XWindow which will then provide the functionality for X11 based windows. This refactoring emerged to be too difficult at that moment and Martin and me decided to do some other refactoring first. The parts I am currently working on is on the one hand to move all Workspace functions implemented in the file composite.cpp to an own class Compositor. On the other hand I am introducing a new class
DecorationPaintRedirector, which handles the composited decorations.

Work done so far

Some functionality of KWin was moved to own classes or even deleted. For example the broken functionality of TopMenu was removed. The functionalities of screen edge handling and Tabbox were moved to its own classes. The same happend to the tiling functionality. I also added some build option to chose whether KWin should be build with or without supporting a specific functionality. These build options are provided for Tabbox, Tiling, DesktopChangeOSD and ScreenEdges. They are automatically deactivated if building KWin for mobile devices is enabled.


Thanks to the refactoring work done so far some parts of KWin are better structured and readable as before. One thing which confused me when I was starting coding for KWin was that in one file there could be several classed implemented. That issue was changed for some classes like Tabbox and Tiling by introducing new files or classes and by moving the related functions to the appropriate classes. These changes do not only make the code better readable but also better maintainable.

Desktop Summit

Two weeks ago I attended the Desktop Summit 2011 in Berlin. I was helping as a volunteer for video operation. Since I did not know anyone there, doing the volunteer work was a great decision. I never expected that I will get to know so many nice people. I was talking to other GSoC students and we were telling each other about our projects and the current state. Meeting some developers of KWin and Plasma was a great occasion. It’s kind of funny meeting them in real life if you had only virtual contact before 🙂 Last but not least the daily social events were the best opportunity to meet new friends. And one can say: Partying with open source people kicks ass!
The days in Berlin were very exhausting, but I had a wonderful time and I don’t want to have missed it.


The GSoC project “Modularization of KWin” did not have a specific goal to reach, since we did not know how much work it will be to refactor all this stuff. One can say that there are still lots of things to do, but I am satisfied with my work done so far. The main point for me was to get into the community and I can say that doing a Google Summer of Code is a great opportunity to achieve this. I am really looking forward to go on with my contribution on KWin because it is really fun working with such a great team.


3 Replies to “Guest Post: Crash – Exam – Relaunch”

  1. I read the first 2 segments as. “I did not learn my lesson when it comes to regular incremental backups, or how to use distributed systems to avoid data loss” . Seriously… buy another hdd, or use the extra you have and start doing daily, or at least weekly rsnapshot backups. Kwin is on git now right? Why on earth do you not have a cloned repo on a public repo host like github somewhere? that you push to regularly. As a Perl developer I would literally lose nothing on a single drive failure because my drives in my home dev system are mdadm raid10 (2 drives) and a backup drive that I run rsnapshot weekly, and keep monthly backups and yearly backups of as well. All of my code is pushed to github so I can’t lose it. I’m even thinking about paying for github for private repo’s.

  2. Great work, and really good to see the results of your GSoC project already being merged into master. I think that makes it very worthwhile for us all. 🙂

  3. This sounds great. Congratulations to making it through the entire GSOC time. I am very happy to hear that you will continue working with Martin and the other KWin developers. Cheers to you!

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