Re: [PATCH v3 0/2] Implement filtering repacks

From: Christian Couder <christian.couder@gmail.com>
Date: Dec 21, 2022, 03:53 UTC
Message-ID: <CAP8UFD2_ZbrOh4Tto2V80wn4ki+3j6Giegx+QyrLqd7uH6U4GQ@mail.gmail.com>
In-Reply-To: <xmqqa64ipl4r.fsf@gitster.g>

On Wed, Nov 23, 2022 at 1:31 AM Junio C Hamano <gitster@pobox.com> wrote:

Show 12 quoted lines

>
> Christian Couder <christian.couder@gmail.com> writes:
>
> > In the discussions with Junio and Taylor following the first and
> > second versions, Junio suggested adding `--filter=<filter-spec>` to
> > `git gc` and I am still Ok with doing it, either later in a followup
> > patch or in a v4. I haven't done it yet, as it's not clear how to
> > implement it efficiently only in `git gc`.
>
> Did I make such a suggestion?  I only said --filter=<filter-spec>
> does not seem like a good option to surface and stress at the
> end-user level for "git pack-objects".

In https://lore.kernel.org/git/xmqqilkm9wv6.fsf@gitster.g/ you wrote:

-> Unlike prune-packed, pruning objects that could be refetched has -> negative performance impact. So adding an option to enable/disable -> such pruning is needed. If the frontmost UI entry point were "gc", -> it needs an opt-in option to invoke the "filtering repack", in other -> words. "pack-objects" should not need any more work than what you -> have here (with the "terminal" and "force" discarded), as "--filter" -> is such an opt-in option already.

I understood the above to mean that you would be Ok with adding a "--filter" flag to `git gc`.

Show 9 quoted lines

> The similarity of "git prune-packed" with this new operation was
> brought up to illustrate the point that users of "git gc" do not
> want to even know about having to remove redundantly available
> objects via "prune-packed" by giving an extra option to "git gc"
> (hence --prune is the default), and honoring the filter spec when
> objects are known to be available via the configured promisor remote
> is likely what users at the "git gc" level would want to see happen
> automatically.  IOW, adding more options to "gc" would be the last
> thing I would want to see.

I still think that users should be able to control if `git gc` performs such a filtering when repacking, and I don't see how it could be done without any new option at all. I think that for example only checking the 'remote.<name>.partialclonefilter' config variable to decide if it should be done or not is just too dangerous for people already using this variable.

In the v4 I will send really soon now, I tentatively implemented a 'gc.repackFilter' config option for the purpose of telling `git gc` that it should perform filtering repacks with the specified filter. I hope that this will help move the discussion forward.

BTW in the latest "What's cooking in git.git" emails there is the following about this patch series:

-> Seems to break CI. -> cf. https://github.com/git/git/actions/runs/3560918726

I took a look at the failures in the different failing tests and they don't seem related to this patch series and seem quite random:

=== Failed test: t3106-ls-tree-pattern ===
The full logs are in the 'print test failures' step below.
See also the 'failed-tests-*' artifacts attached to this run.
Error: failed: t3106.3 combine with "--object-only"
failure: t3106.3 combine with "--object-only"
Error: failed: t3106.5 combine with "--long"
failure: t3106.5 combine with "--long"

=== Failed test: t5601-clone ===
The full logs are in the 'print test failures' step below.
See also the 'failed-tests-*' artifacts attached to this run.
skip: t5601.60 clone c:temp is dos drive
skip: t5601.101 colliding file detection
Error: failed: t5601.110 auto-discover bundle URI from HTTP clone
failure: t5601.110 auto-discover bundle URI from HTTP clone
Error: failed: t5601.111 auto-discover multiple bundles from HTTP clone
failure: t5601.111 auto-discover multiple bundles from HTTP clone

=== Failed test: t5556-http-auth ===
The full logs are in the 'print test failures' step below.
See also the 'failed-tests-*' artifacts attached to this run.
Error: failed: t5556.2 http auth anonymous no challenge
failure: t5556.2 http auth anonymous no challenge
Error: failed: t5556.3 http auth www-auth headers to credential helper
bearer valid
failure: t5556.3 http auth www-auth headers to credential helper bearer valid

=== Failed test: t4203-mailmap ===
The full logs are in the 'print test failures' step below.
See also the 'failed-tests-*' artifacts attached to this run.
Error: failed: t4203.66 git cat-file -s returns correct size with --use-mailmap
failure: t4203.66 git cat-file -s returns correct size with --use-mailmap
Error: failed: t4203.67 git cat-file -s returns correct size with
--use-mailmap for tag objects
failure: t4203.67 git cat-file -s returns correct size with
--use-mailmap for tag objects

etc

I tried different build flags but can't reproduce locally.