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From: Junio C Hamano <gitster@pobox.com>
To: "Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, Han-Wen Nienhuys <hanwenn@gmail.com>,
	Han-Wen Nienhuys <hanwen@google.com>
Subject: Re: [PATCH 4/4] RFC: refs: reflog entries aren't written based on reflog existence.
Date: Mon, 30 Aug 2021 14:14:50 -0700	[thread overview]
Message-ID: <xmqqbl5e3a9h.fsf@gitster.g> (raw)
In-Reply-To: <2f11fd7718005d1e94b3139f086134896da202f1.1630334929.git.gitgitgadget@gmail.com> (Han-Wen Nienhuys via GitGitGadget's message of "Mon, 30 Aug 2021 14:48:48 +0000")

"Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Han-Wen Nienhuys <hanwen@google.com>
>
> Before, if we aren't supposed to update reflogs (eg.
> core.logallrefupdates=NONE), we would still write reflog entries if the
> reflog file (.git/logs/REFNAME) existed.
>
> The reftable storage backend cannot distinguish between a non-existing
> reflog, and an empty one. Therefore it cannot mimick this functionality.
>
> In CAFQ2z_Ps3YxycA+NJ9VKt_PEXb+m83JdNB7ujzWw1fTPKyZ=fg@mail.gmail.com,
> we came to the conclusion that this feature is probably a remnant from
> the time that reflogs weren't enabled by default, and it does not need
> to be kept.
>
> Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
> ---
>  refs/files-backend.c  | 20 +-------------------
>  t/t1400-update-ref.sh |  7 +++----
>  2 files changed, 4 insertions(+), 23 deletions(-)

While I like the loss of lines and reduced complexity...

One potential harm this change will bring to us is what happens to
people who disable core.logAllRefUpdates manually after using the
repository for a while.  Their @{4} will point at the same commit no
matter how many operations are done on the current branch after they
do so.  I wouldn't mind if "git reflog disable" command is given to
the users prominently and core.logAllRefUpdates becomes a mere
implementation detail nobody has to care about---in such a world, we
could set the configuration and drop the existing reflog records at
the same time and nobody will be hurt.

If we keep the current behaviour, what are we harming instead?
Growth of diskspace usage is an obvious one, but disks are cheaper
compared to human brainwave cycles cost.

> diff --git a/t/t1400-update-ref.sh b/t/t1400-update-ref.sh
> index de0cf678f8e..52433f6d0d2 100755
> --- a/t/t1400-update-ref.sh
> +++ b/t/t1400-update-ref.sh
> @@ -269,7 +269,7 @@ test_expect_success "(not) changed .git/$m" '
>  '
>  
>  rm -f .git/logs/refs/heads/main
> -test_expect_success "create $m (logged by touch)" '
> +test_expect_success "create $m" '
>  	test_config core.logAllRefUpdates false &&
>  	GIT_COMMITTER_DATE="2005-05-26 23:30" \
>  	git update-ref --create-reflog HEAD $A -m "Initial Creation" &&
> @@ -315,12 +315,10 @@ test_expect_success 'symref empty directory removal' '
>  	test_path_is_file .git/logs/HEAD
>  '
>  
> -TAB='	'
>  cat >expect <<EOF
>  $Z $A $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117150200 +0000	Initial Creation
> -$A $B $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117150260 +0000	Switch
> -$B $A $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117150860 +0000$TAB
>  EOF
> +
>  test_expect_success "verifying $m's log (logged by touch)" '
>  	test_when_finished "git update-ref -d $m && rm -rf .git/logs actual expect" &&
>  	test-tool ref-store main for-each-reflog-ent $m > actual &&
> @@ -346,6 +344,7 @@ test_expect_success "set $m (logged by config)" '
>  	test $A = $(git show-ref -s --verify $m)
>  '
>  
> +TAB='	'
>  cat >expect <<EOF
>  $Z $A $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117150320 +0000	Initial Creation
>  $A $B $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117150380 +0000	Switch

Moving the definition of TAB= around in the test is not all that
welcome.  If anything, I'd suggest doing so nearer to the beginning
of the test sequence, before the first test that uses the ref-store
test-tool, because it is just like $GIT_COMMITTER_EMAIL and $RUN
that define constants used throughout the remainder of the test
script.

THanks.

  parent reply	other threads:[~2021-08-30 21:15 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-30 14:48 [PATCH 0/4] Gets rid of "if reflog exists, append to it regardless of config settings" Han-Wen Nienhuys via GitGitGadget
2021-08-30 14:48 ` [PATCH 1/4] test-ref-store: tweaks to for-each-reflog-ent format Han-Wen Nienhuys via GitGitGadget
2021-08-30 19:57   ` Taylor Blau
2021-08-30 20:23   ` Taylor Blau
2021-08-30 20:51   ` Junio C Hamano
2021-08-30 20:58     ` Taylor Blau
2021-08-30 21:59       ` Junio C Hamano
2021-08-30 14:48 ` [PATCH 2/4] t1400: use test-helper ref-store to inspect reflog contents Han-Wen Nienhuys via GitGitGadget
2021-08-30 20:55   ` Junio C Hamano
2021-08-30 14:48 ` [PATCH 3/4] refs: drop force_create argument of create_reflog API Han-Wen Nienhuys via GitGitGadget
2021-08-30 21:03   ` Junio C Hamano
2021-08-30 14:48 ` [PATCH 4/4] RFC: refs: reflog entries aren't written based on reflog existence Han-Wen Nienhuys via GitGitGadget
2021-08-30 21:10   ` Taylor Blau
2021-08-30 21:14   ` Junio C Hamano [this message]
2021-09-06 16:52 ` [PATCH v2 0/5] Gets rid of "if reflog exists, append to it regardless of config settings" Han-Wen Nienhuys via GitGitGadget
2021-09-06 16:52   ` [PATCH v2 1/5] refs: trim newline from reflog message Han-Wen Nienhuys via GitGitGadget
2021-09-06 22:38     ` Ævar Arnfjörð Bjarmason
2021-09-06 16:52   ` [PATCH v2 2/5] test-ref-store: tweaks to for-each-reflog-ent format Han-Wen Nienhuys via GitGitGadget
2021-09-06 22:34     ` Ævar Arnfjörð Bjarmason
2021-09-07 13:33       ` Han-Wen Nienhuys
2021-09-07 15:53         ` Ævar Arnfjörð Bjarmason
2021-09-06 16:52   ` [PATCH v2 3/5] t1400: use test-helper ref-store to inspect reflog contents Han-Wen Nienhuys via GitGitGadget
2021-09-06 16:52   ` [PATCH v2 4/5] refs: drop force_create argument of create_reflog API Han-Wen Nienhuys via GitGitGadget
2021-09-06 22:42     ` Ævar Arnfjörð Bjarmason
2021-09-06 16:52   ` [PATCH v2 5/5] RFC: refs: reflog entries aren't written based on reflog existence Han-Wen Nienhuys via GitGitGadget
2021-09-06 22:50     ` Ævar Arnfjörð Bjarmason
2021-09-07 13:36   ` [PATCH v3 0/7] Gets rid of "if reflog exists, append to it regardless of config settings" Han-Wen Nienhuys via GitGitGadget
2021-09-07 13:36     ` [PATCH v3 1/7] show-branch: show reflog message Han-Wen Nienhuys via GitGitGadget
2021-09-07 13:36     ` [PATCH v3 2/7] refs: trim newline from " Han-Wen Nienhuys via GitGitGadget
2021-09-07 13:36     ` [PATCH v3 3/7] test-ref-store: tweaks to for-each-reflog-ent format Han-Wen Nienhuys via GitGitGadget
2021-09-07 13:36     ` [PATCH v3 4/7] t1400: use test-helper ref-store to inspect reflog contents Han-Wen Nienhuys via GitGitGadget
2021-09-07 13:36     ` [PATCH v3 5/7] refs: drop force_create argument of create_reflog API Han-Wen Nienhuys via GitGitGadget
2021-09-07 13:36     ` [PATCH v3 6/7] RFC: refs: reflog entries aren't written based on reflog existence Han-Wen Nienhuys via GitGitGadget
2021-09-07 13:36     ` [PATCH v3 7/7] refs: change log_ref_setup calling convention Han-Wen Nienhuys via GitGitGadget
2021-10-05 15:54     ` [PATCH v3 0/7] Gets rid of "if reflog exists, append to it regardless of config settings" Han-Wen Nienhuys
2021-10-06 18:20       ` Junio C Hamano
2021-10-06 18:27         ` Junio C Hamano
2021-10-07 17:38           ` Junio C Hamano
2021-11-11 11:46             ` Han-Wen Nienhuys
2021-11-11 14:38               ` Ævar Arnfjörð Bjarmason

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