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From: Han-Wen Nienhuys <hanwen@google.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Han-Wen Nienhuys via GitGitGadget <gitgitgadget@gmail.com>,
	git <git@vger.kernel.org>, Han-Wen Nienhuys <hanwenn@gmail.com>
Subject: Re: [PATCH v3 0/3] Remove special casing for PSEUDOREF updates
Date: Mon, 3 Aug 2020 21:07:18 +0200	[thread overview]
Message-ID: <CAFQ2z_O1sRm-_SNP=-GvgNLqB+qgf6k9YVfbF1XCAmFWdeX6Ew@mail.gmail.com> (raw)
In-Reply-To: <xmqqpn8hgca7.fsf@gitster.c.googlers.com>

On Mon, Jul 27, 2020 at 6:20 PM Junio C Hamano <gitster@pobox.com> wrote:
> > On Fri, Jul 17, 2020 at 12:10 AM Junio C Hamano <gitster@pobox.com> wrote:
> >> I reviewed some codepaths that deal with FETCH_HEAD recently.
> >>
> >> As the file is quite different from all the other pseudo references
> >> in that it needs to store more than one object name and in that each
> >> ref in it needs more than just the object name, I doubt that it
> >> makes much sense to enhance the refs API so that its requirements
> >> can be covered.
> >
> > I agree. Do we ever pretend that FETCH_HEAD is a ref today?
>
> "git rev-parse FETCH_HEAD", "git show FETCH_HEAD" etc. all should keep
> working, so in that sense, it is treated as a ref.

I added this to the last version of the full reftable patch series
that I posted,  as patches
"Split off reading loose ref data in separate function" and "Read
FETCH_HEAD as loose ref".

Which other refs that aren't really refs should also be supported? The
JGit source code suggests that MERGE_HEAD should also be special
cased?

It's not pretty, though. The entry point is read_raw_ref(), which gets
a ref_store as argument. ref_store doesn't have generic API to get at
the repository directory, so the implementation of reading the
FETCH_HEAD file has to be pushed down to the ref backend (which does
know the directory).

> It does not
> protect the history leading to the objects listed in it from being
> collected, though.

Is there documented agreement of how pseudo refs and GC should interact?

> "git merge FETCH_HEAD" is an interesting case---I haven't thought it
> through.
>
> What should happen after "git pull origin foo bar" attempts to grab
> two branches and make an octopus merge into the branch currently
> checked out, and then "git reset --hard && git merge FETCH_HEAD" is
> given?

I don't understand this question.

-- 
Han-Wen Nienhuys - Google Munich
I work 80%. Don't expect answers from me on Fridays.
--
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  reply	other threads:[~2020-08-03 19:07 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-06 17:29 [PATCH 0/2] " Han-Wen Nienhuys via GitGitGadget
2020-07-06 17:29 ` [PATCH 1/2] Modify pseudo refs through ref backend storage Han-Wen Nienhuys via GitGitGadget
2020-07-06 20:26   ` Junio C Hamano
2020-07-07 13:56     ` Han-Wen Nienhuys
2020-07-07 15:20       ` Junio C Hamano
2020-07-07 17:15         ` Han-Wen Nienhuys
2020-07-07 18:14           ` Junio C Hamano
2020-07-06 17:29 ` [PATCH 2/2] Make HEAD a PSEUDOREF rather than PER_WORKTREE Han-Wen Nienhuys via GitGitGadget
2020-07-06 20:30   ` Junio C Hamano
2020-07-07  9:24     ` Han-Wen Nienhuys
2020-07-09 21:11 ` [PATCH v2 0/3] Remove special casing for PSEUDOREF updates Han-Wen Nienhuys via GitGitGadget
2020-07-09 21:11   ` [PATCH v2 1/3] t1400: use git rev-parse for testing PSEUDOREF existence Han-Wen Nienhuys via GitGitGadget
2020-07-09 21:11   ` [PATCH v2 2/3] Modify pseudo refs through ref backend storage Han-Wen Nienhuys via GitGitGadget
2020-07-09 21:11   ` [PATCH v2 3/3] Make HEAD a PSEUDOREF rather than PER_WORKTREE Han-Wen Nienhuys via GitGitGadget
2020-07-10 19:25   ` [PATCH v2 0/3] Remove special casing for PSEUDOREF updates Junio C Hamano
2020-07-16 18:45   ` [PATCH v3 " Han-Wen Nienhuys via GitGitGadget
2020-07-16 18:45     ` [PATCH v3 1/3] t1400: use git rev-parse for testing PSEUDOREF existence Han-Wen Nienhuys via GitGitGadget
2020-07-16 18:45     ` [PATCH v3 2/3] Modify pseudo refs through ref backend storage Han-Wen Nienhuys via GitGitGadget
2020-07-17  8:52       ` Johannes Schindelin
2020-07-27 15:41         ` Han-Wen Nienhuys
2020-07-16 18:45     ` [PATCH v3 3/3] Make HEAD a PSEUDOREF rather than PER_WORKTREE Han-Wen Nienhuys via GitGitGadget
2020-07-16 22:09     ` [PATCH v3 0/3] Remove special casing for PSEUDOREF updates Junio C Hamano
2020-07-27  8:50       ` Han-Wen Nienhuys
2020-07-27 16:20         ` Junio C Hamano
2020-08-03 19:07           ` Han-Wen Nienhuys [this message]
2020-08-03 20:07             ` Junio C Hamano
2020-08-05  1:45               ` Junio C Hamano
2020-08-05 10:48                 ` Han-Wen Nienhuys
2020-08-05 15:54                   ` Junio C Hamano
2020-08-10 14:27                     ` Han-Wen Nienhuys
2020-08-10 16:04                       ` Junio C Hamano
2020-08-11 10:49                         ` Han-Wen Nienhuys
2020-08-11 18:38                           ` Junio C Hamano
2020-08-19 13:19                     ` Han-Wen Nienhuys
2020-08-19 15:52                       ` Junio C Hamano
2020-07-27 16:25     ` [PATCH v4 " Han-Wen Nienhuys via GitGitGadget
2020-07-27 16:25       ` [PATCH v4 1/3] t1400: use git rev-parse for testing PSEUDOREF existence Han-Wen Nienhuys via GitGitGadget
2020-07-27 16:25       ` [PATCH v4 2/3] Modify pseudo refs through ref backend storage Han-Wen Nienhuys via GitGitGadget
2020-07-27 16:25       ` [PATCH v4 3/3] Make HEAD a PSEUDOREF rather than PER_WORKTREE Han-Wen Nienhuys via GitGitGadget

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