From: Junio C Hamano <gitster@pobox.com>
To: "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>
Cc: git@vger.kernel.org, me@ttaylorr.com, peff@peff.net,
Derrick Stolee <dstolee@microsoft.com>
Subject: Re: [PATCH v2 1/2] t5319: replace 'touch -m' with 'test-tool chmtime'
Date: Wed, 01 Apr 2020 14:35:25 -0700 [thread overview]
Message-ID: <xmqq369m6g9u.fsf@gitster.c.googlers.com> (raw)
In-Reply-To: <24e26ecda632421e4c1a61ebabf6ea78301685b1.1585774844.git.gitgitgadget@gmail.com> (Derrick Stolee via GitGitGadget's message of "Wed, 01 Apr 2020 21:00:43 +0000")
"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:
> From: Derrick Stolee <dstolee@microsoft.com>
>
> The use of 'touch -m' to modify a file's mtime is slightly less
> portable than using our own 'test-tool chmtime'.
Portability aside, the relative form would also be resistant against
skews between filesystem time and wallclock time and is preferrable
when we can use it.
> The important
> thing is that these pack-files are ordered in a special way to
> ensure the multi-pack-index selects some as the "newer" pack-files
> when resolving duplicate objects.
This note is very much appreciated.
> rm -rf .git/objects/pack &&
> mv .git/objects/pack-backup .git/objects/pack &&
> - touch -m -t 201901010000 .git/objects/pack/pack-D* &&
> - touch -m -t 201901010001 .git/objects/pack/pack-C* &&
> - touch -m -t 201901010002 .git/objects/pack/pack-B* &&
> - touch -m -t 201901010003 .git/objects/pack/pack-A* &&
> + test-tool chmtime =-5 .git/objects/pack/pack-D* &&
> + test-tool chmtime =-4 .git/objects/pack/pack-C* &&
> + test-tool chmtime =-3 .git/objects/pack/pack-B* &&
> + test-tool chmtime =-2 .git/objects/pack/pack-A* &&
The original wants D to be the oldest and A to be the newest, and
the updated would want the same ordering.
When created, we know A gets created before B which gets created
before C and so on, in the "setup expire tests" part. If each step
takes too much time (e.g. the VM is heavily loaded), wouldn't the
adjustment above become insufficient?
In other words, would we want to flip the order these packs get
created in the "setup" part, in addition to the use of chmtime
(which reads the existing file timestamp using stat(2) and then
updates the file timestamp relative to the original timestamp)
we see here?
Also, in the best case (i.e. original timestamp of A/B/C/D are the
same), the above seems to assume that the filesystem has at least 1
second file timestamp granularity. Do we want to make them at least
2 seconds apart, or am I worried too much about ancient filesystems
that no longer metter?
Thanks.
> ls .git/objects/pack >expect &&
> MINSIZE=$(test-tool path-utils file-size .git/objects/pack/*pack | sort -n | head -n 1) &&
> git multi-pack-index repack --batch-size=$MINSIZE &&
next prev parent reply other threads:[~2020-04-01 21:35 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-01 18:11 [PATCH] commit-graph: fix buggy --expire-time option Derrick Stolee via GitGitGadget
2020-04-01 18:17 ` Derrick Stolee
2020-04-01 18:56 ` Taylor Blau
2020-04-01 19:27 ` Taylor Blau
2020-04-01 19:36 ` Eric Sunshine
2020-04-01 19:47 ` SZEDER Gábor
2020-04-01 19:49 ` Junio C Hamano
2020-04-01 19:57 ` Jeff King
2020-04-01 20:33 ` Junio C Hamano
2020-04-01 20:51 ` Derrick Stolee
2020-04-01 20:14 ` Derrick Stolee
2020-04-01 21:00 ` [PATCH v2 0/2] " Derrick Stolee via GitGitGadget
2020-04-01 21:00 ` [PATCH v2 1/2] t5319: replace 'touch -m' with 'test-tool chmtime' Derrick Stolee via GitGitGadget
2020-04-01 21:35 ` Junio C Hamano [this message]
2020-04-02 0:06 ` Derrick Stolee
2020-04-02 12:51 ` Jeff King
2020-04-02 16:36 ` Junio C Hamano
2020-04-01 21:00 ` [PATCH v2 2/2] commit-graph: fix buggy --expire-time option Derrick Stolee via GitGitGadget
2020-04-01 21:05 ` [PATCH v2 0/2] " Junio C Hamano
2020-04-01 23:33 ` Derrick Stolee
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