Bug: Using RCS subdirectory fails to work properly

I am using the RCS directory and I have set $useRcsDir = 1 in my TWiki.cfg. I expect I will get some speed improvements since there are fewer files for readdir to go through on accesses for topic retrievals, edits and searches.

After editing a page whose RCS file lives in RCS/, I see the metadata reporting version 1.1, There are no diffs/versions except for version 1.1. The topic's rcs file is properly updated though. Logging into the system and running rlog or rcsdiff manually on the original .txt file works properly.

I don't see any errors in the http error logs from rcs. Moving the ,v file back to the main directory makes things work properly again.

Now I do have some pages in the top level (the default ones that come with TWiki so I can stay in sync with the releases), but I think I have narrowed down the problem, but I have no clue where to go from here. I was hoping to go live with my new site Monday, but this is a showstopper. I would rather not go back to putting all the files into one directory if I can help it.

It appears that Store::RcsFile::_settings is trying to determine if we should use RCS directories by looking into the %settings has for the key "useRcsDir". However, this key doesn't seem to be getting set. Other keys such as "dataDir" and "pubDir" are being set. I haven't figured out where in the code this key should be created. If anybody can narrow down the code a bit, I would appreciate it.

Also it looks like the Store::RcsFile::_makeFileName function doesn't check to see if the file exists before it returns the ,v filename. Since RCS files can exist in two places, same directory or RCS subdirectory, rcs will search both (with the RCS directory preferred I think) and work fine. However I suspect that split installations with files being stored in both possible directories will have the issues describe above with the non RCS directory ,v files once this bug is fixed.

Maybe a warning note in the documentation that ,v files must be located in only one directory for twiki to work properly.

Test case

Enable $useRcsDir. Put your ,v file for a topic into the RCS subdirectory. Edit the topic. You will see the problem.

Environment

-- JohnRouillard - 15 Aug 2002

Follow up

The bug is in TWiki.cfg in the @storeSettings array. This patch fixes it for RCS files in the RCS subdirectory, but then break RCS files in the parent directory as I mentioned above. To work around this breakage, the following item from the ci man page comes to the rescue:

ci never changes an RCS or working file. Normally, ci unlinks the file and creates a new one; but instead of breaking a chain of one or more symbolic links to an RCS file, it unlinks the destination file instead. Therefore, ci breaks any hard or symbolic links to any working file it changes; and hard links to RCS files are ineffective, but symbolic links to RCS files are preserved.

This could be fixed by changing _makeFileName to always check for file existence, but this requires a stat for every access. This will really slow down cygwin, and the symbolic link trick works for cygwin ci as well. I just don't know how it will work for direct access from a non-cygwin server such as a native apache. My guess is that it will break, probably worse than above.

Another possible fix is to have a failure to find the ,v file force a stat of both places and possible updating of the rcs filename, but this would require internal changes to the code.

This patch and links work fine in my testing and allows me to cvs update the installed twiki to merge changes in from the twiki releases.

Index: TWiki.cfg
===================================================================
RCS file: /twiki/src/cvsroot/twiki/lib/TWiki.cfg,v
retrieving revision 1.7
diff -c -r1.7 TWiki.cfg
*** TWiki.cfg   8 Aug 2002 18:37:57 -0000   1.7
--- TWiki.cfg   15 Aug 2002 19:11:16 -0000
***************
*** 195,200 ****
--- 195,201 ----
  @storeSettings = 
    ( dataDir         => $TWiki::dataDir,
      pubDir          => $TWiki::pubDir,
+     useRcsDir       => $TWiki::useRcsDir,
      attachAsciiPath => "\.(txt|html|xml|pl)\$",
      dirPermission   => 0775,

-- JohnRouillard - 15 Aug 2002

Fix record

This is now fixed and in TWikiAlphaRelease. See also duplicate DiffsRevertsToOneError. Please reopen this bug in case there are other RCS dir related issues.

-- PeterThoeny - 02 Sep 2003