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Re: Adding LAN support to Subversion - Clarification

From: Barry Scott <barry_at_barrys-emacs.org>
Date: 2003-10-27 20:59:54 CET

At 27-10-2003 18:30, Kopp David K wrote:

>Thanks to everyone for the discussion.
>I had posted this in a message a few days ago. This may clear some things up.
>--- snip ----
>We have VSS set up so that the repository is on a shared network drive.
>Somehow VSS has a locking mechanism that keeps the different clients from
>hosing the repository. Would it be possible to add something similar to
>Subversion? I would guess it might work something like this:

I wish this was true. A Client can hose VSS trivially,
pull out the LAN cable while you are working on VSS.
I expect BDB will die from a similar action.

You will need repair utilities and procedures in place
to try and keep the repo going. You probable need to
do this already with VSS.

>1) User A does an initial checkout by typing
>svn checkout lan:///k:/logpars/subverion/powerLOGJ/trunk
>2) svn notices that the URL protocol is lan, (or nfs or whatever bogus
>protocol you like). It determines that K:\logpars\subversion\powerLOGJ is
>the directory holding the Subversion repository, so it checks to see if a
>file (let's call it lan.lock) exists in that directory. If it does, it
>aborts and tells the user that someone else is currently using the
>repository and they should try again in a couple of minutes. If not, it
>creates lan.lock itself.
>3) Assuming we were able to lock the repository, we do the checkout
>4) We delete lan.lock
>5) All done
>I guess the big question is, is there a way to check for the existence of
>a lock file, and then create it, without introducing a bunch of nasty race

Yes using Win32 file API calls; look at CreateFile. I expect
you will not find APR functions to help with this.

I recommend that you work on your admin folks to allow you to run an SVN
The alternative's are all ways to madness.

Received on Mon Oct 27 21:01:14 2003

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