After some months, I just updated my local ikiwiki sources, and rebuilt the Hurd web pages, http://git.savannah.gnu.org/cgit/hurd/web.git/.

I was confused, having switched to the new automatic (thanks!) --gettime mechanism, why on some pages the timestamps had changed compared to my previous use of --getctime and setting files' mtimes (using a script) according to the last Git commit. For example:

community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.html

old:

Last edited <span class="date">2008-09-11 18:11:53 UTC</span>
<!-- Created <span class="date">2008-09-11 17:47:08 UTC</span> -->

new:

Last edited <span class="date">2008-09-11 18:12:22 UTC</span>
<!-- Created <span class="date">2008-09-11 17:47:50 UTC</span> -->

I had a look at what git.pm is doing, and began to manually replay / investigate:

$ git log --pretty=fuller --name-only --relative -- community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn
commit 8f1b97bfe45b2f173e3a7d55dee226a9e289a695
Author:     arnebab <arne_bab@web.de>
AuthorDate: Thu Sep 11 20:11:53 2008 +0200
Commit:     arnebab <arne_bab@web.de>
CommitDate: Thu Sep 11 20:11:53 2008 +0200

    Added a link to the X.org guide in this wiki.

community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn

commit 3ef8b7d80d80572c436c4c60c71879bc74409816
Author:     arnebab <arne_bab@web.de>
AuthorDate: Thu Sep 11 19:47:08 2008 +0200
Commit:     arnebab <arne_bab@web.de>
CommitDate: Thu Sep 11 19:47:08 2008 +0200

    Minor update on the enty trying to get X working -> 'watch this place for updates'

community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn

OK, these are my old dates.

$ git log --pretty=format:%ci --name-only --relative -- community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn 
2008-09-11 20:11:53 +0200
community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn

2008-09-11 19:47:08 +0200
community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn

$ git log --pretty=format:%ct --name-only --relative -- community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn 
1221156713
community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn

1221155228
community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn

$ date -d @1221156713
Thu Sep 11 18:11:53 UTC 2008
$ date -d @1221155228
Thu Sep 11 17:47:08 UTC 2008

That's all consistent.

But:

$ perl -le 'use Storable; my $index=Storable::retrieve("indexdb"); use Data::Dumper; print Dumper $index'
[...]
                      'community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn' => {
                                                                                    'ctime' => '1221155270',
                                                                                    'dest' => [
                                                                                                'community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.html'
                                                                                              ],
                                                                                    'typedlinks' => {
                                                                                                      'tag' => {}
                                                                                                    },
                                                                                    'mtime' => 1221156742,
                                                                                    'depends_simple' => {
                                                                                                          'sidebar' => 1
                                                                                                        },
                                                                                    'links' => [
                                                                                                 'community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x/discussion',
                                                                                                 'Hurd/DebianXorg'
                                                                                               ],
                                                                                    'state' => {
[...]

$ date -d @1221156742
Thu Sep 11 18:12:22 UTC 2008
$ date -d @1221155270
Thu Sep 11 17:47:50 UTC 2008

That's different, and it matches what the new ikiwiki writes into the HTML file.

Back to Git again, this time without specifying the file:

$ git log --pretty=format:%ct --name-only --relative
[...]
1221255713
1221255655
unsorted/PortingIssues.mdwn

1221156742 [Thu Sep 11 18:12:22 UTC 2008]
1221156713 [Thu Sep 11 18:11:53 UTC 2008]
community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn

1221156267
1221156235
index.mdwn

1221156122
1221156091
index.mdwn

1221155942
1221155910
index.mdwn

1221155270 [Thu Sep 11 17:47:50 UTC 2008]
1221155228 [Thu Sep 11 17:47:08 UTC 2008]
community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn

1221154986
community/gsoc.mdwn
community/gsoc/project_ideas.mdwn

1221147244
whatsnew.html
[...]

Aha!

... and some more detail:

$ git log --pretty=fuller --name-only --relative
[...]
commit e4e89e1683012c879012522105a3471a00714613
Author:     Samuel Thibault <samuel.thibault@ens-lyon.org>
AuthorDate: Fri Sep 12 23:40:55 2008 +0200
Commit:     Samuel Thibault <samuel.thibault@ens-lyon.org>
CommitDate: Fri Sep 12 23:40:55 2008 +0200

    MSG_NOSIGNAL and IPV6_PKTINFO got fixed

unsorted/PortingIssues.mdwn

commit c389fae98dff86527be62f895ff7272e4ab1932c
Merge: 0339e3e 8f1b97b
Author:     GNU Hurd wiki engine <web-hurd@gnu.org>
AuthorDate: Thu Sep 11 18:12:22 2008 +0000
Commit:     GNU Hurd wiki engine <web-hurd@gnu.org>
CommitDate: Thu Sep 11 18:12:22 2008 +0000

    Merge branch 'master' of wiki@192.168.10.50:wiki

commit 8f1b97bfe45b2f173e3a7d55dee226a9e289a695
Author:     arnebab <arne_bab@web.de>
AuthorDate: Thu Sep 11 20:11:53 2008 +0200
Commit:     arnebab <arne_bab@web.de>
CommitDate: Thu Sep 11 20:11:53 2008 +0200

    Added a link to the X.org guide in this wiki.

community/weblogs/ArneBab/2008-08-02-gnu_hurd_and_x.mdwn
[...]

So, merges are involved there.

What (the new) ikiwiki code does, is use the timestamp when the merge was done instead of the timestamp when the commit was done. Is this intentional? Otherwise I could supply a patch.

--tschwinge

In order to be nice and fast, the git backend runs git log once and records data for all files. Rather than looking at the log for a given file. So amoung other things, it does not follow renames.

AFAICS, git log only shows merges modifying files if it was a conflicted merge. As the file is then actually modified to resolve the merge I think it makes sense to count the merge as the last modification in that case. --Joey

That'd be reasonable, but git log will also show merges that are not conflicting (as in my case).

Actually when displaying a merge, git log --stat only lists files that were actually modified in a new way as part of the merge resolution. Ie, if the merge resolution only joins together some of the parent hunks, the file is not listed as having been modified.

So, no, ikiwiki's use of git log will not show files modified in non-conflicting merges. --Joey

Yet, I'm not totally disagreeing with your choice. With this git log invocation, you're not able to tell from its output whether a conflict was resolved or not.

Also, it's a bit like the should we use the author timestamp or commit timestamp discussion. Your code will always use the latest timestamp.

I guess I'll get my head wrapped around that, and it's fine, so this is done.

--tschwinge