Dangling locks in the Subversion tree

September 26, 2008 by · 2 Comments
Filed under: Configuration Management 

I recently ran into another rather peculiar and interesting case with subversion. As I’ve already explained, I don’t have actual physical access to the subversion servers we are perusing for our project. We use TortoiseSVN for access to the repository on our local systems.

My boss was working with some excel and word files checked into the repository. He had template.xls locked as he was working in it, he decided to rename it to a template, so template.xlt it is (and checked in). After doing some more work, he decided this was a bad idea, so he changes it back to template.xls, and tries to check it back in again… no luck, it wont work.

15-20 minutes worth of investigation later, we found the problem. TortoiseSVN had been configured to always check “Keep Locks” on commit, hence the client kept the lock when he commited the template.xls deletion. To fix this problem, run svnadmin lslock and then svnadmin rmlock the file in question. Please note that this requires actual access to the physical subversion repository. Http or svnserve will not do in other words.

A step by step on how to cause the Dangling lock problem — All of the actions are done via TortoiseSVN interface:

  1. Create a repository.
  2. Check out the repository.
  3. Add a file to the repository, set the svn:needs-lock property.
  4. Commit the file.
  5. Lock the file.
  6. Change name of the file, and check the “Keep locks” checkbutton.
  7. Commit the changes.
  8. Change the filename back to the original filename.
  9. Commit the change. This step will fail.

This is a rather funny problem imho :-). We finally managed to get it fixed after contacting the IT department and sending them the command. 10 minutes to cause the problem, 20 minutes to analyze it, 20 hours to wait for the fix. Sometimes there should be less depth in organizations.

Svnsync automatisation via Windows Scheduler

September 20, 2008 by · 1 Comment
Filed under: Configuration Management, Development, Windows 

Recently I’ve been setting up for a project, as you might have noticed, and one of the problems we ran into was the fact that we have a centralized subversion repository. We don’t have access to control or install anything on the actual server unfortunately, so hence we can’t install trac on that system, as previously explained. The solution is to sync the main subversion databases to the trac server as previously explained.

A secondary problem arising from this, is that we can’t actually change the hook files of the master repository. The solution to this, is to add a synchronizing scheduler. As I was stressed, and had no time to deal with this properly, I had to run with the Windows Scheduler of all horrible solutions. The following explains how to set it up.

Windows Scheduled synchronize Task

Warning! The windows scheduler does not start automatically when you reboot etc. If you do this, the task restarts at it’s start time, so if it’s set to run at 00.00 every day, and then every 5 minutes, it will restart and start running at 00.00, not as soon as the machine is started up again. This is pure evil.

A scheduled task is set up as follows, create a bat file (ie, c:projectssvnprojectsvnsync-project.bat):

svnsync synchronize http://localhost/svn/project –sync-username slaveuser –sync-password tjohej –source-password password
c:Python25Scriptstrac-admin.exe c:projectstracproject resync

The Second line unfortunately has to be done to resync the new changes with the trac database. After this, create a scheduled task in windows as follows:

  1. Go to start -> control panel -> scheduled tasks
  2. Click Add scheduled task
  3. Click Next
  4. Click Browse…
  5. Browse to your svnsync-project.bat file, as described above. Double click it.
  6. Set name (default is ok). Perform this task: Daily
  7. Click Next
  8. Start time: 00:00, Every day, Start date: today
  9. Fill in username/password to run it as.
  10. Select open advanced properties for this task. Click Finish.
  11. Go to tab Schedule. Choose Advanced.
  12. Click Repeat task, fill in Every 10 minutes, and click Time and fill in 23:59
  13. Click OK.
  14. Click OK
  15. Done.

This could most likely be done from cruisecontrol, but as stated, i’m stressed. I hate windows by now (at/cron is just sooo much nicer to handle).

Trac on separate server from subversion

September 11, 2008 by · Leave a Comment
Filed under: Configuration Management, Windows 

It is possible to have Trac on a different server than the subversion server, albeit a bit convoluted. This is slightly stolen note from http://blogs.open.collab.net/svn/2007/08/mirroring-repos.html

Set up the master subversion server as you would normally. We will get back to this one.

On the trac server, install subversion etc as well. This server will rely on svnsync to become a secondary/mirror subversion server. It must not be used for checking in or working against, it is purely a repository for reading.

Set up trac and all other tools required on the mirror server.

Now, you need to set up user accounts on the mirror server. To start with, create the mirror subversion repository, it will be empty to begin with:

svnadmin create MIRROR_REPOS_PATH

After that, create authz authentication files for the repositories to stop anyone from writing/working against the mirror repository, such as the following:

* = r
svnsync = rw

You could extend this by writing hook scripts blocking anything but the svnsync user.

If the master subversion repository is live while adding the trac database, all of the following must be done during server maintenance window (ie, close it down from any kind of access, except the mirror machine).

Once all that is done, its time to initialize the the mirror server with the master subversion repository (ie, move over the data).

svnsync initialize URL_TO_MIRROR_REPO URL_TO_MASTER_REPO –username=svnsync –password=svnsyncpassword

And once that has successfully been done, do as follows:

svnsync synchronize URL_TO_MIRROR_REPO –username=svnsync –password=svnsyncpassword

The final step is to either add a scheduler (cron.d) script, or a post-commit hook script running the following:

# Example for synchronizing one repository from the post-commit hook
$SVNSYNC synchronize URL_TO_MIRROR_REPO –username=svnsync –password=svnsyncpassword &
exit 0

Preferably run it from post-commit as it gives better refresh rate.

You can now run the trac against the mirrored subversion server.

Trac on windows

September 10, 2008 by · 1 Comment
Filed under: Configuration Management, Windows 

Trac is a rightfull bitch to install on win32 as it requires very specific version matching of packages. This is a long winded installation note with the more or less latest versions available as of this writing.

I’m hoping to get working on TortoiseSVN and Trac integration once this is done (ie, make tortoise automatically set variables etc sent in change notes, which can hence update the issue tracking systems in trac and so forth. The way of working is really really sweet imho, and I think it could be a really nice way of working. I’m just sad that I have to set all this serverstuff up on windows though.

Let’s begin with a list of all the installation files used:




These packages should be fairly simple to get started with. Install them straight on, in the order mentioned.

Install the above packages in that order. Some errors i ran into:

Unsupported version control system “svn”

I accidentally used svn-python-1.5.0.win32-py2.5.exe. It also complained about not finding SSLEAY32.DLL which threw me off course, looking for the wrong solution.
Secondary applications
On top of this, the following applications where installed (not yet configured/set up).

The Apache2.2.9 must be installed before svn-win32-1.5.2.zip files are, and the .so files must be put in 2.2.9 as that package will not run on Apache2.2.8. Apache 2.2.8 with svn-win32-1.5.2.zip will die silently without hint as to why it died.
Once all of the above is installed, create a svn repository in c:\projects\svn\test (create directories, and then right click test and choose TortoiseSVN -> Create repository here.
Now create a trac database in c:\projects\trac\test\ by running
c:\python2.5\trac-admin.exe c:\projects\trac\test\ initenv

Answer the questions asked by trac-admin.exe. To test the trac at this point, run tracd.exe per ordinations from trac-admin.exe.
Contains required files to make dav_svn work in apache2.2, edited extract on how to install:
For an Apache server here’s the essentials:
1. Copy bin/mod_dav_svn.so and bin/mod_authz_svn.so to the Apache modules directory.
2. Add the Subversion/bin directory to the SYSTEM PATH.
3. Edit the Apache configuration file (httpd.conf) and make the following changes:
3a. Uncomment the following two lines:

#LoadModule dav_fs_module modules/mod_dav_fs.so
#LoadModule dav_module modules/mod_dav.so
3b. Add the following two lines to the end of the LoadModule section:
LoadModule dav_svn_module modules/mod_dav_svn.so
LoadModule authz_svn_module modules/mod_authz_svn.so
3c. Add the following to end of the file.
<location /svn>
DAV svn
SVNPath c:\projects\svn\test
AuthType Basic
AuthName “My Subversion repository”
AuthUserFile “c:\projects\svn\test\conf\passwd” Require valid-user
Add users to passwd file above:
C:\wampbin\apache\apache2.2.9\bin\htpasswd.exe -b \projects\svn\test\conf\passwd myuser hejhej

Finally installing Trac in apache2.2

To run trac via apache, you need the above module for apache as well. Once this is done, add the following to modules section of apache:
LoadModule python_module modules/mod_python.so

To test the python installation add the following to the end of your httpd.conf:

<location /mpinfo>

SetHandler mod_python
PythonInterpreter main_interpreter
PythonHandler mod_python.testhandler

And if that works, test the following:

<Location /trac>

SetHandler mod_python
PythonInterpreter main_interpreter
PythonHandler trac.web.modpython_frontend
PythonOption TracEnv “c:/projects/trac/test/”
PythonOption TracUriRoot /trac

Further reading

Continuous integration and buildserver

So, I finally got around to trying out continuous integration and got a buildserver at home. Ok, not much use on any 1-man projects, but should be good enough for some testing at least. I’m currently using cruisecontrol for it, and so far so good. I’ve got a few points I sincerely react against, but I’ll get back to that a bit later.

For those not knowing what continuous integration is, I suggest reading the above link. Basically, when you run a project, you always run into some “final” integration problems. People have coded each on their own side, and you wind up having to “integrating” the code so that it all works as supposed. In the one extreme, you have everyone coding on their own tree from start to end, and then you finally have an integration session. In this shitty situation, you have no clue how long it will take. On the other extreme, you have “perfect” continuous integration, where every single line of code is tested and checked that it doesnt screw things up.

A buildserver such as cruisecontrol is an excellent tool for doing “good” continuous integration. What it does is as follows, it connects to your central code repository, checks for any changes. If there was changes, it downloads them, and then rebuilds the project(s). If you have done it properly, you also have a ton of tests that you can run on the project. This is then reported or output in several different ways. Did it fail, did it succeed, and so forth.

I might be able to convince my new project manager to use a cruisecontrol server for the project I am working on at the moment, and he sounds like he likes the idea. We just need to consider everything for this project, and I need to figure out just how it works and how to configure it etc etc etc =) . Either way, I think it will be interesting to find out more about this type of development, and to see if it actually changes the development in any large way.

Oh, yes, I currently got two things I need to figure out with cruisecontrol. If I got it right, it doesn’t support GNU Make. Not supporting make seems… well, to be honest, totally stupid. It’s been one of the biggest make systems for 20 years or more, so there’s bound to be like 500000+ projects out there already running Make. I know it’s an old system, but it works, and it’s there already.

The second thing, I’m not totally certain of this, but subversion support seems to be abysmal. I need to look more at it however to find out the lay of the land or something.

Slow grasswidow evening

What do you do when you are home alone a saturday evening? Personally, I web2.0’d my life (i got facebook, a blog, remember the milk, dipity, evernote, and decided to rewrite/update my webpage). Also, I really got started building the Fokker DR.1.

To update frozentux.net, I screwed around a bit with eclipse pdt. I want to do this since I think the whole site looks pretty awful. I was ok with it “back then”, but not any more. I’ve been using eclipse for a few months to code c, c++, qt and I’ve grown rather fond of it. My first time with eclipse left me… well, let’s just say i went back for a few years to vim and loved it. Still wish there was a decent vim/eclipse plugin as i love vims command/edit mode.

I digress. Basically, what I did was Install subversion, make a copy of frozentux.net in subersion and a few other projects in there. I setup subversion with apache2. I know I suck that haven’t done this before. After that, I installed pdt, subclipse and a few other modules in eclipse and got it all working together. I think I might like the subclipse module, but still got a few things I need to find out.

I’m gonna get started on rewriting frozentux today I hope. Now, going for a walk first.

« Previous Page