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From: 欣韩 <hanxin.hx@bytedance.com>
To: Patrick Steinhardt <ps@pks.im>
Cc: chiyutianyi@gmail.com, derrickstolee@github.com,
	git@vger.kernel.org, haiyangtand@gmail.com,
	jonathantanmy@google.com, me@ttaylorr.com
Subject: Re: [External] Re: [PATCH v1] commit-graph.c: no lazy fetch in lookup_commit_in_graph()
Date: Mon, 20 Jun 2022 16:53:47 +0800	[thread overview]
Message-ID: <CAKgqsWVfjOw-b4hbz1WDH5sevUab_bQVLb703apew3fX7B60rQ@mail.gmail.com> (raw)
In-Reply-To: <YrAcrNApaZDngLL+@ncase>

On Mon, Jun 20, 2022 at 3:34 PM Patrick Steinhardt <ps@pks.im> wrote:
>
> On Sat, Jun 18, 2022 at 11:01:30AM +0800, Han Xin wrote:
> > If a commit is in the commit graph, we would expect the commit to also
> > be present. So we should use has_object() instead of
> > repo_has_object_file(), which will help us avoid getting into an endless
> > loop of lazy fetch.
> >
> > We can see the endless loop issue via this[1].
> >
> > 1. https://lore.kernel.org/git/20220612161707.21807-1-chiyutianyi@gmail.com/
> >
> > Signed-off-by: Han Xin <hanxin.hx@bytedance.com>
>
> Thanks a lot for working on this issue!
>
> > ---
> >  commit-graph.c                             |  2 +-
> >  t/t5329-no-lazy-fetch-with-commit-graph.sh | 50 ++++++++++++++++++++++
> >  2 files changed, 51 insertions(+), 1 deletion(-)
> >  create mode 100755 t/t5329-no-lazy-fetch-with-commit-graph.sh
> >
> > diff --git a/commit-graph.c b/commit-graph.c
> > index 2b52818731..2dd9bcc7ea 100644
> > --- a/commit-graph.c
> > +++ b/commit-graph.c
> > @@ -907,7 +907,7 @@ struct commit *lookup_commit_in_graph(struct repository *repo, const struct obje
> >               return NULL;
> >       if (!search_commit_pos_in_graph(id, repo->objects->commit_graph, &pos))
> >               return NULL;
> > -     if (!repo_has_object_file(repo, id))
> > +     if (!has_object(repo, id, 0))
> >               return NULL;
>
> Agreed, this change makes sense to me.
>
> >       commit = lookup_commit(repo, id);
> > diff --git a/t/t5329-no-lazy-fetch-with-commit-graph.sh b/t/t5329-no-lazy-fetch-with-commit-graph.sh
> > new file mode 100755
> > index 0000000000..ea5940b9f1
> > --- /dev/null
> > +++ b/t/t5329-no-lazy-fetch-with-commit-graph.sh
> > @@ -0,0 +1,50 @@
> > +#!/bin/sh
> > +
> > +test_description='test for no lazy fetch with the commit-graph'
> > +
> > +. ./test-lib.sh
> > +
> > +test_expect_success 'setup' '
>
> Nit: I find it a bit confusing that you only call the first test case
> `setup`, while all the other tests except for the last one are also only
> setting up the necessary state.

Nod.
There is indeed some misleading information here.
I will adjust it in the next patch.

>
> > +     git init --bare dest.git &&
> > +     test_commit one &&
> > +     git checkout -b tmp &&
> > +     test_commit two &&
> > +     git push dest.git --all
> > +'
> > +
> > +test_expect_success 'prepare a alternates repository without commit two' '
> >
> > +     git clone --bare dest.git alternates &&
> >
> > +     oid=$(git -C alternates rev-parse refs/heads/tmp) &&
> > +     git -C alternates update-ref -d refs/heads/tmp &&
> > +     git -C alternates gc --prune=now &&
> > +     pack=$(echo alternates/objects/pack/*.pack) &&
> > +     git verify-pack -v "$pack" >have &&
> > +     ! grep "$oid" have
> > +'
>
> Instead of going into the low-level details you could just verify that
> `git cat-file -e $oid` returns `1`.
>

Nod.

> > +
> > +test_expect_success 'prepare a repository with a commit-graph contains commit two' '
> > +     git init source &&
> > +     echo "$(pwd)/dest.git/objects" >source/.git/objects/info/alternates &&
> > +     git -C source remote add origin "$(pwd)/dest.git" &&
> > +     git -C source config remote.origin.promisor true &&
> > +     git -C source config remote.origin.partialclonefilter blob:none &&
> > +     # the source repository has the whole refs contains refs/heads/tmp
> > +     git -C source fetch origin &&
> > +     (
> > +             cd source &&
> > +             test_commit three &&
> > +             git -c gc.writeCommitGraph=true gc
> > +     )
> > +'
> > +
> > +test_expect_success 'change the alternates of source to that without commit two' '
> > +     # now we have a commit-graph in the source repository but without the commit two
> > +     echo "$(pwd)/alternates/objects" >source/.git/objects/info/alternates
> > +'
> > +
> > +test_expect_success 'fetch the missing commit' '
> > +     git -C source fetch origin $oid 2>fetch.out &&
> > +     grep "$oid" fetch.out
> > +'
>
> This test passes even without your fix, albeit a lot slower compared
> to with it. Can we somehow cause it to fail reliably so that the test
> becomes effective in catching a regression here?
>

Could you help me find the reason why this testcase passes even
without the fix.

From the execution of Github Action, it seems that the problem always exist:
https://github.com/chiyutianyi/git/actions/runs/2527421443.

Thanks.
-Han Xin

> > +test_done
> > --
> > 2.36.1
> >
>
> Patrick

  reply	other threads:[~2022-06-20  8:57 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-14  7:25 An endless loop fetching issue with partial clone, alternates and commit graph Haiyng Tan
2022-06-15  2:18 ` Taylor Blau
2022-06-16  3:38   ` [RFC PATCH 0/2] " Han Xin
2022-06-16  3:38     ` [RFC PATCH 1/2] commit-graph.c: add "flags" to lookup_commit_in_graph() Han Xin
2022-06-16  3:38     ` [RFC PATCH 2/2] fetch-pack.c: pass "oi_flags" " Han Xin
2022-06-17 21:47     ` [RFC PATCH 0/2] Re: An endless loop fetching issue with partial clone, alternates and commit graph Jonathan Tan
2022-06-18  3:01     ` [PATCH v1] commit-graph.c: no lazy fetch in lookup_commit_in_graph() Han Xin
2022-06-20  7:07       ` Patrick Steinhardt
2022-06-20  8:53         ` 欣韩 [this message]
2022-06-20  9:05           ` [External] " Patrick Steinhardt
2022-06-21 18:23       ` Jonathan Tan
2022-06-22  3:17         ` Han Xin
2022-06-24  5:27       ` [PATCH v2 0/2] " Han Xin
2022-06-24  5:27         ` [PATCH v2 1/2] test-lib.sh: add limited processes to test-lib Han Xin
2022-06-24 16:03           ` Junio C Hamano
2022-06-25  1:35             ` Han Xin
2022-06-27 12:22               ` Junio C Hamano
2022-06-24  5:27         ` [PATCH v2 2/2] commit-graph.c: no lazy fetch in lookup_commit_in_graph() Han Xin
2022-06-24 16:56           ` Junio C Hamano
2022-06-25  2:25             ` Han Xin
2022-06-25  2:31               ` Han Xin
2022-06-28  2:02         ` [PATCH v3 0/2] " Han Xin
2022-06-28  2:02           ` [PATCH v3 1/2] test-lib.sh: add limited processes to test-lib Han Xin
2022-06-28  2:02           ` [PATCH v3 2/2] commit-graph.c: no lazy fetch in lookup_commit_in_graph() Han Xin
2022-06-28  7:49             ` Ævar Arnfjörð Bjarmason
2022-06-28 17:36               ` Junio C Hamano
2022-06-30 12:21                 ` Johannes Schindelin
2022-06-30 13:43                   ` Ævar Arnfjörð Bjarmason
2022-06-30 15:40                     ` Junio C Hamano
2022-06-30 18:47                       ` Ævar Arnfjörð Bjarmason
2022-07-01 19:31                       ` Johannes Schindelin
2022-07-01 20:47                         ` Junio C Hamano
2022-06-29  2:08               ` Han Xin
2022-06-30 17:37           ` test name conflict + js/ci-github-workflow-markup regression (was: [PATCH v3 0/2] no lazy fetch in lookup_commit_in_graph()) Ævar Arnfjörð Bjarmason
2022-07-01  1:34           ` [PATCH v4 0/1] no lazy fetch in lookup_commit_in_graph() Han Xin
2022-07-01  1:34             ` [PATCH v4 1/1] commit-graph.c: " Han Xin
2022-07-09 12:23               ` Michael J Gruber
2022-07-11 15:09                 ` Jeff King
2022-07-11 20:17                   ` Junio C Hamano
2022-07-12  1:52                     ` [External] " Han Xin
2022-07-12  5:23                       ` Junio C Hamano
2022-07-12  5:32                         ` Han Xin
2022-07-12  6:37                         ` [External] " Jeff King
2022-07-12 14:19                           ` Junio C Hamano
2022-07-12  6:50             ` [PATCH v5 0/1] " Han Xin
2022-07-12  6:50               ` [PATCH v5 1/1] commit-graph.c: " Han Xin
2022-07-12  9:50                 ` Ævar Arnfjörð Bjarmason
2022-07-13  1:26                   ` Han Xin
2022-07-12  6:58               ` [PATCH v5 0/1] " Jeff King
2022-07-12  8:01             ` [PATCH v1] t5330: remove run_with_limited_processses() Han Xin

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