pruning of empty directories

[Ian Clatworthy]

Tom Widmer posted to the bazaar mailing list on 21/Jul/2009 ....

Bazaar tracks directories, unlike most other DVCSes. However, the fastimport format (as far as I know) has no way of specifying directory creation or deletion, or, if it does, hg and git exporters don't to my knowledge make use of it (since they don't think that such operations exist!).

Is there any way to get bzr fast-import to prune empty directories (e.g. when the last file in a directory is removed, automatically remove the directory in the same revision)? That would resolve the problems I am having trying to convert an hg repository to bzr.

[Ian Clatworthy (ian-clatworthy)]

Fix committed in rev 195.

[Tom Widmer (tom-widmer)]

Thanks for that. I've just tested the fix, and discovered that it doesn't remove parents-of-parents(-of-parents, etc.). If you have:
adir
|_
   bdir
   |_
      cfile

and you delete cfile, both adir and bdir should be pruned. Current fix only removes bdir, not adir.

[Ian Clatworthy (ian-clatworthy)]

I believe rev 214 fixes the upwards recursion issue.

[Tom Widmer (tom-widmer)]

I have a working fix locally that I can push to launchpad. I have a feeling (untested) that your fix still has problems. Use of osutils.minimum_path_selection is wrong I think - that will mean you will miss deleting subfolders. e.g.

a\b\cfile
a\bfile

A single commit deletes cfile and bfile, so a and a\b are candidates for deleting. osutils.minimum_path_selection will choose only a to check, but a is not empty (it contains b), so no folders will be removed.

My fix is attached. If you're happy with it, you could roll your fix back (except for the test case!).

[Ian Clatworthy (ian-clatworthy)]

Thanks - it's late here so I'll take a look in the morning. If you're keen, it would be cool to add a test for the case above as well!

[Tom Widmer (tom-widmer)]

If you're happy to wait until next week (obviously it's not holding me up now, and no one else has complained), I'll see what I can do about adding a few tests and a final polished fix (including rolling back your changes if necessary). But note I've never done any Python coding before. I'll push my branch to lp and request a merge when it's ready.

[Tom Widmer (tom-widmer)]

I've proposed a branch for merging to fix this issue. I added some new tests that failed before my change. The change fixes these tests and causes no regressions.