Andrii Nakryiko's blog

FreeBSD hi-res console

Sat, 29 Dec 2012 12:13:59 +0200

Starting from FreeBSD 9.1 GENERIC kernel is built with everything we need, so it’s really easy. Everything should be done under root.

To see all available video modes:

vidcontrol -i mode

Suppose we are interested in mode 325 (1280x1024x32). To check if it is OK to set it:

vidcontrol MODE_325

If console switched to desired mode without any problems, then edit /boot/device.hint to do the following diff:

 hint.psm.0.irq="12"
-hint.sc.0.flags="0x100"
+hint.sc.0.flags="0x180"
+hint.sc.0.vesa_mode="325"
 hint.uart.0.at="isa"

That’s all, after reboot as soon as kernel will be loaded, the console will switch to selected video mode, so boot log will be printed in hi-res mode, without waiting for rc.conf loading.

Automatic assembly versioning solution - MSBuild Versioning

Wed, 20 Jul 2011 14:45:00 +0300

Automatic assembly versioning solution - MSBuild Versioning:

Nice small project for automatic build versioning. It was always a problem for me, but now the problem is solved once and for all! It supports nicely both Mercurial and SVN repositories to retrieve revision number and/or ID. Check Tokens page for more custom tags.

MVC Mini Profiler with Entity Framework and SQL Server CE 4.0

Mon, 18 Jul 2011 11:50:00 +0300

Recently I was trying to use MVC Mini Profiler released by Stack Overflow folks with my site on ASP.NET MVC 3 framework and had some problems to use its all features, because I had a little specific setup (more on that a bit later).

It was a piece of cake to use it for profiling usual code with:

using (MiniProfiler.Current.Step("Some profiling step description"))

Everything worked like a charm with just following a step-by-step guide on project’s site (http://code.google.com/p/mvc-mini-profiler/).

Problems started when I got to DB profiling support. I should point out that the specific situation I was in includes using SQL Server CE 4.0 with Entity Framework 4 with DB first approach.

As you can read from their instructions, you have to substitute their profiled connection for the real connection you usually use. But as it turned out not everything is so simple and after some experimenting and searching through Stack Overflow and generally Internet I arrived at the following solution to get Entity Framework’s ObjectContext for you DB Model.

public static T GetDb<T>(string connectionStringName) where T: ObjectContext
{
    var connectionString = ConfigurationManager.ConnectionStrings[connectionStringName].ConnectionString;
    var entityConnStr = new EntityConnectionStringBuilder(connectionString);
    var realConnection = new SqlCeConnection(entityConnStr.ProviderConnectionString);
    var profiledConnection = ProfiledDbConnection.Get(realConnection, MiniProfiler.Current);
    return profiledConnection.CreateObjectContext<T>();
}

Here connectionStringName is the name of connection string in your web.config (or app.config) file, T specifies the type of your ObjectContext.

So what do we do here is the following:

We get connection string for web.config (or app.config). If you are using Entity Framework, this connection string will contain not only connection string per se, but also some metadata, which in my case was causing throwing exception by SqlCeConnection constructor.
So we need to get rid of this metadata. We create EntityConnectionStringBuilder which parses nicely our long connection string and provides us with separate parts of it.
For the bare connection to SQL Server CE 4.0 we need just a provider connection string part, which we extract with ProviderConnectionString property.
After that we use ProfiledDbConnection.Get helper method provided by MVC Mini Profiler to create a profiled version of that connection, which we should use instead of standard one.
We use another helper method (which is extension method and is contained within a static class ObjectContextUtils which is also provided by MVC Mini Profiler) to create our DB model object context.

And that’s all. Works very well for me. If you are using not CE edition of SQL Server, you have to change the SqlCeConnection class to SqlConnection.

I suppose you’ll create one more method for your specific application to not provide connection string name throughout all your application:

public static MyObjectContext GetDb() 
{
    return GetDb<MyObjectContext>("MyObjectContextConnStr");
}

Hope it helps not only for me next time you’ll try to use MVC Mini Profiler which is a really awesome project. Thanks to Stack Overflow guys for this thing! :)

Update (2011-08-02):

The original post was written while using MvcMiniProfiler 1.4. After updating today to version 1.7, DB profiling stopped working giving the following error message: “Unable to find the requested .Net Framework Data Provider. It may not be installed.” After quick googling, it appears that the following addition to web.config is enough to overcome this problem:

<system.data>
    <DbProviderFactories>
        <remove invariant="MvcMiniProfiler.Data.ProfiledDbProvider" />
        <add description="MvcMiniProfiler.Data.ProfiledDbProvider" invariant="MvcMiniProfiler.Data.ProfiledDbProvider" type="MvcMiniProfiler.Data.ProfiledDbProviderFactory, MvcMiniProfiler" name="MvcMiniProfiler.Data.ProfiledDbProvider" />
    </DbProviderFactories>
</system.data>

We just register DB provider for MvcMiniProfiler and everything keeps working. :)

List of the canonical introductory textbooks covering the major branches of computer science

Mon, 18 Apr 2011 12:33:40 +0300

List of the canonical introductory textbooks covering the major branches of computer science

Could not load file or assembly '' or one of its dependencies. An attempt was made to load a program with an incorrect format.

Thu, 17 Feb 2011 17:31:00 +0200

Today I stuck with the following problem: when I run my web project through local dev server or IIS Express — everything is fine, but when I host it through IIS, I get “Could not load file or assembly ‘<some assembly name>’ or one of its dependencies. An attempt was made to load a program with an incorrect format.”

One crucial detail: my server is 64-bit.

The solution is in application pool settings: in advanced settings of AppPool, set Enable 32-bit applications to true.

Silverlight memory leaks finding

Thu, 17 Feb 2011 17:06:00 +0200

Quick post to not forget :)

Article (mentions x86 WinDbg installation under x64 OS): http://dotnetspeak.com/index.php/2010/09/using-windbg-to-find-memory-leaks-in-silverlight-applications/

Also quick cheatsheet:

.load C:\Program Files (x86)\Microsoft Silverlight\4.0.60129.0\sos.dll
!dumpheap -stat
!dumpheap -MT <mt>
!gcroot <addr>

Slow Visual Studio 2010 tab closing

Thu, 21 Oct 2010 11:09:00 +0300

If you experience this issue try to add your project’s folder to your antivirus location exception. I have Microsoft Security Essentials and this slowness irritated me for quite some time until I accidentally found on some forum this advice. And it really helped me (after reboot, actually, but I think it depends on antivirus).

Hope it helps you as well.

Update: just found interesting discussion on VS performanve optimizations on StackOverflow.com: Visual Studio Optimizations.

mercurial with ssh setup on windows

Thu, 30 Sep 2010 14:36:00 +0300

mercurial with ssh setup on windows:

Mercurial setting up for serious work under Windows :)

Kubuntu stuff

Mon, 16 Aug 2010 19:30:00 +0300

I recently decided to completely switch to Kubuntu as my main OS and while it is really user-friendly comparing to the dark times when I first tried *nixes, still it lacks tiny bits and some tuning, so I’ll gather different useful links to posts, tutorials and how-to’s that helped me to make work and “living” in Kubuntu more pleasant.

My Perfect Kubuntu 10.04 Desktop
How to: Consolas font in Linux
Установка Sun Java на Ubuntu 10.04 Lucid Lynx (in russian)
How to use Dropbox outside GNOME
Don’t forget to install Yakuake, a very convenient Quake-style console, that once launched can be called by pressing F12
I really miss something equal to Total Commander from Windows world, but at least we have something like Norton Commander (interestingly, how many people who read this post have ever used that program-legend? :) So here is how you can install it: Install Midnight Commander (MC) 4.7.3 In Ubuntu
For those using VirtualBox to run other OS. Sometimes you need to resize virtual HDD of you virtual machine, but there is no option to do so in VirtualBox GUI. Here is an article that describes how to do this in a REALLY EASY way: http://www.banadiga.com/blog/administrator/158-resize-hard-disk-in-vbox. It is in Ukrainian, but it is really in those two commands in console the whole magic is hidden. :)

Update from 16 Aug 2010:

Recently I updated to KDE SC 4.5. I won’t describe changes as they are described in a lot places, but I had some regular crashes from Nepomuk service, so I have disabled it… It’s not hard :)

Also there were troubles with KPackageKit: it saw all the new KDE SC 4.5 version packages, but categorized them as Blocked updates. I wonder what it is. Still, I wanted to update my system quite badly, so Google to the rescue! :) Here is a comfortable two-command line to install all available updates:

sudo apt-get update && sudo apt-get dist-upgrade

Silverlight and tcp.net bindings for WCF

Tue, 29 Jun 2010 18:34:00 +0300

I’m working with Silverlight 4 on my work for quite some time (from early betas).

And I was wondering about new cool feature of the Silverlight 4 - tcp.net binding. But it seems using it is quite more involved than BasicHttpBinding, but still - I want to understand it and use on my Silverlight project. Here I’ll post some useful links I’ve found - they are for me, just to not google for them one more time. I plan to come back here after IIS Express is out for beta testing (because one can’t use tcp.net with integrated in VisualStudio ASP.NET web-server, but I don’t want to install heavy-weight IIS7 on my working machine).

So, here are those links:

http://www.42spikes.com/post/Using-Silverlight-4-and-NetTCP-Duplex-Callbacks.aspx (I guess the most useful article on how to setup everything)
http://tomasz.janczuk.org/2009/11/wcf-nettcp-protocol-in-silverlight-4.html (I was very surprised with those benchmarking numbers, very impressive difference!)
http://tomasz.janczuk.org/2009/08/improving-performance-of-concurrent-wcf.html (I didn’t think about benefits of using Worker threads until this article)
http://tomasz.janczuk.org/2009/11/pubsub-sample-with-wcf-nettcp-protocol.html (quite informative as well, it is worth studying)
http://www.silverlightshow.net/items/WCF-NET.TCP-Protocol-in-Silverlight-4.aspx (I didn’t look at it, but it was recommended in the first article)

I’ve finally made it! Now I can read distance to the...

Sun, 31 Jan 2010 03:12:00 +0200

I’ve finally made it! Now I can read distance to the closest object with the help of ultrasonic range finder Devantech SRF10. It took two days to make it work and communicate (actually it is due to my own stupidity…) and a lot of help from my father! Thanks, dad!

On this video you can see how things look like now. You can see that I reworked LEDs so they look much more solid :) and representable. Also I put all DB-9 contacts into cases, so it is much easier to unplug them, and quite a lot safer to use them because you don’t need to worry about accidental short circuit.

I tried to demonstrate the work of sonar. You can see that LEDs can work in to modes, which I can switch with that tiny black button (so called “soft button”) on Command module. In the first of them LED-console shows a demonstrably a distance to the object: the furthest the object - the more LEDs are on. Seems very natural to me and what about you? As you can somehow see I move my hand closer of farther to/from range finder and LEDs dynamically (they refresh about three times per second right now, but no problem to make them refresh 15 times and even more often) change their “level of signal”.
The second mode represents the measured distance in binary format on LED-console with the least significant bit represented by the closest to us LED. The value of distance is in centimeters. This mode is handy to check a robustness and accuracy of sonar. As you can see it is actually not to consistent, it returns for almost the same situation quite different values. But I think the situation can be improved by playing with internal settings of range finder. I didn’t get into that yet, though, but it will be my next logical step and I’ll report of the results. Ok, thats all for today, enjoy this video and don’t forget that it is very pleasant to get some feedback from you, people!

Ultrasonic range finder connected and mounted somehow…...

Fri, 29 Jan 2010 00:25:00 +0200

Ultrasonic range finder connected and mounted somehow… Time to power on! Stay tuned! (;

Right now there is no video available, sorry! I’ll upload...

Thu, 28 Jan 2010 22:39:00 +0200

Right now there is no video available, sorry! I’ll upload it today-tomorrow when I’ll get access to my camera. (8

Yesterday I spent few hours late at night to make this thing. (8 I prefer to think about it as a “debug console” to output some numbers rather than just some funny set of useless LEDs… Right now it is 6-bit capable, but tomorrow I’ll buy one more DB-9 connector and will attach last 2 LEDs. So it will actually will be capable to output any 8-bit numbers (0..255) I plan to use it just for debugging. Unfortunately this 8 LEDs are taking almost all available I/O lines in Command module, so I’ll have to remove some of them when I’ll have to attach some additional hardware, but still - it’s fun and it’s easy to use! (8 What you think?

Here is a low quality photo of what it looks like now.

P.S. Sorry for so bad quality of video, my camera is at my “second home”, so I have no other option than shot video on my mobile phone…

P.P.S. I almost forgot in all that excitement what I made this LEDs for… (: I want to attach ultrasonic range finder to Create and I needed some way to check what distance is it giving.. Now I have one! Now - for sonars!!! :)

Technonecrophilia and nostalgy in IT sphere - synonyms?

Tue, 26 Jan 2010 00:36:11 +0200

Technonecrophilia and nostalgy in IT sphere - synonyms?:

Michael Vincent created Windows 3.1 with pure Javascript… Isn’t it to the same degree cool, nostalgic and useless?..

Interesting, who worked in Windows 3.1 or 3.11? Leave comments, please, ancient IT-guys! (;

Other robotics hardware we have here in LNU

Tue, 26 Jan 2010 00:30:04 +0200

Other robotics hardware we have here in LNU

And this is the reason I bought soldering iron and supporting...

Tue, 26 Jan 2010 00:27:00 +0200

And this is the reason I bought soldering iron and supporting things. iRobot Create! Some nice piece of robotics hardware with Command Module plugged in (green thing in the middle of white robot). Oh! And there are the red LED and switch button in the cargo bay (button is not working, don’t know why, need more attention and time from we, I guess (; ). Red LED is blinking! Believe me! :)

Nostalgy… Being child I tried to do a lot of things:...

Tue, 26 Jan 2010 00:10:20 +0200

Nostalgy…

Being child I tried to do a lot of things: soldering was one of them… It’s so good to recall those merry days! :)

P.S. You can see a small device near the pincers, it’s one of the two sonars we’ve got for experimenting with robotics. Still need to connect it to our iRobot Create to make some useful thing out it. :) Right now it is just a small piece of expensive hardware…

Amazing "home" physics

Sat, 23 Jan 2010 17:43:05 +0200

Amazing "home" physics:

Steve Sprangler demonstrates some very cool and interesting experiments, most of which you could do on your own!!!

One more useful look from the hights of experience

Wed, 13 Jan 2010 15:29:00 +0200

I haven’t been posting since my first blog post for quite a while, so I decided to post at least something more or less useful and/or interesting to somebody else to not forget about my intention to become at least lazy blogger. :)

I just read an interesting article, written by Jonathan Danylko, entitled “20/20: Top 20 Programming Lessons I’ve Learned in 20 Years”.

I recommend to read it and think about lessons author kindly share with us, young and too arrogant programmers. Remember, dumb people don’t learn anything from own mistakes, smart ones learn from own mistakes and only wise people learn from others mistakes. So give it a try, take something from other experience to make less mistakes on your own!

My bit to populating distributed version control systems

Sun, 22 Nov 2009 16:42:00 +0200

I guess everyone, who knows what is programming not only from school or university classes, have heard about version control systems (VCS). At the time, I guess I won’t make mistake if I say that the most popular one is Subversion. It was developed as the evolved replacement for CVS, older VCS. But both CVS and Subversion are quite old and even if subversion is good enough for many projects, it is not the best one.

I’ve heard of distributed VCS (DVCS) few months ago and get curious about them. Although I haven’t used it yet, I’m planning to do that for my university master’s project. So I decided to refresh my knowledge about principles of DVCS, namely Git, which is one of the three most popular free DVCS: Git, Mercury, Bazaar.

DVCS have a number of advantages before classical VCS and they are more modern, which is for my quite a strong motivation to start using it.

Anyway, I’m not going to describe those advantages, because I’m quite lazy and not in the mood to formulate too much of my thought in written form, but believe me: you won’t lose anything, but instead will get to know something new that is rapidly becoming very popular (in fact, it is very popular even now, a lot of open-source projects use DVCS for their work, i.e.: part of FreeBSD, KDE applications, Qt cross-platform UI framework, Ubuntu community have developed their own DVCS — Bazaar, etc). So, why am I posting it here? Actually, just to begin some blogging as I’m quite jealous for those people, who blog a lot and have fun with their readers. It will be my first step, hope not to bad ;). And secondly, just to let somebody know about existing of such a thing - Git.

So, if I managed to get you interested, please consider reading a Git parable, very good and simple introduction to Git, which will give you insight of how it is working. But don’t expect you’ll know how use Git after reading Parable, no! To learn actually how to use it, please consider link at the end of the article. Also I’ve been told by some blogger that a book ‘Pro Git’ is very good for beginners. They have on-line version of the book on their official site.

So, have fun with Git!

P.S. At last! My first blog post! :) I thought it will never happen…

P.P.S. If you want some place to host your own open-source project using git as VCS, take a look at Gitorious and GitHub.