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From: Chris Torek <chris.torek@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Karthik Nayak <karthik.188@gmail.com>, git@vger.kernel.org, ps@pks.im
Subject: Re: [PATCH 7/8] refs: add 'update-symref' command to 'update-ref'
Date: Sun, 31 Mar 2024 15:27:24 -0700	[thread overview]
Message-ID: <CAPx1GvdXdH3OdY1nC2ijVSdpWfg8jn5=j0KB+Wgv70wWeCNH5g@mail.gmail.com> (raw)
In-Reply-To: <xmqqy19yf40l.fsf@gitster.g>

On Sun, Mar 31, 2024 at 3:09 PM Junio C Hamano <gitster@pobox.com> wrote:
> ... we are giving to "update-symref" is not an object name, but a
> refname (i.e. the target of the symref at <ref> points at), so
> "newvalue" -> "new-ref" or something is needed.

I kept this line just to say, I agree on all of the above ...

> Existing "update" command can be used to create (by having "zero"
> <old-oid>) and to delete (by having "zero" <new-oid>), but we still
> have "create" and "delete" separately.  Given that we are teaching
> the command to also work with symrefs by adding command(s) for
> symrefs to an existing vocabulary, we should offer "create-symref"
> and "delete-symref" for consistency between refs and symrefs.

.. and on this, but:

> It probably is a good idea to allow "update-symref" to also create
> and delete a symref in similar ways with the existing "update"
> allows creation and deletion of a ref.  An "zero" <old-ref> may be
> an update that can happen only when the <ref> does not exist, i.e.,
> creation, and an "zero" <new-ref> may be an update that makes <ref>
> disappear.
>
> "zero" value in the context of refs is a 0{40} object name (side
> note: we have an explicit mention of 40 in the doc, which needs to
> be updated eventually, probably outside this series).  But in the
> new context of symrefs, a safe "zero" value needs to be picked
> carefully.  An empty string may not work well syntactically
> especially in the `-z` format, because you cannot tell if
>
>         update-symref NUL HEAD NUL refs/heads/main NUL NUL
>
> wants to say that <old-ref> is an empty string, or if it is missing.

For these reasons, I'd suggest that the all-zero hash be officially
deprecated in favor of create/delete and of course create-symref
and delete-symref. Of course, compatibility requires some sort
of support for the old system for some time.  As to whether that
means something like the suggestion of ".missing" etc, I have no
particular opinion -- but since the symref options are new, they
would not *need* symmetric options, if we just say that "update-symref"
cannot create or delete a symref.

Meanwhile, for testing purposes I was curious as to what happens
if you ask `git update-ref` to delete an existing symref, so after
creating a test repository:

$ git branch
* main
  symref -> main
$ git update-ref --stdin
delete refs/heads/symref
$ git branch

Whoops, this doesn't look good...

Restoring the branch name (I had saved the hash ID Just In Case):

$ echo d88ee82e6a5c29c95f712030f5efc9d43116ae79 > .git/refs/heads/main

brings things back, after which this works properly:

$ git branch -d symref
Deleted branch symref (was refs/heads/main).
$ git branch
* main

If this (deleting the target of the symref when using "delete")
is a bug, and I think it is, that's a separate topic of course...

Chris

  reply	other threads:[~2024-03-31 22:27 UTC|newest]

Thread overview: 194+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-30 22:46 [PATCH 0/8] update-ref: add support for update-symref option Karthik Nayak
2024-03-30 22:46 ` [PATCH 1/8] files-backend: extract out `create_symref_lock` Karthik Nayak
2024-04-02 12:20   ` Patrick Steinhardt
2024-04-03 14:52     ` Karthik Nayak
2024-03-30 22:46 ` [PATCH 2/8] reftable-backend: extract out `write_symref_with_log` Karthik Nayak
2024-04-02 12:20   ` Patrick Steinhardt
2024-03-30 22:46 ` [PATCH 3/8] reftable-backend: move `write_symref_with_log` up Karthik Nayak
2024-03-30 22:46 ` [PATCH 4/8] refs: accept symref in `ref_transaction_add_update` Karthik Nayak
2024-03-30 22:46 ` [PATCH 5/8] refs/files-backend: add support for symref updates Karthik Nayak
2024-04-02 12:20   ` Patrick Steinhardt
2024-03-30 22:46 ` [PATCH 6/8] refs/reftable-backend: " Karthik Nayak
2024-04-02 12:20   ` Patrick Steinhardt
2024-03-30 22:46 ` [PATCH 7/8] refs: add 'update-symref' command to 'update-ref' Karthik Nayak
2024-03-31 22:08   ` Junio C Hamano
2024-03-31 22:27     ` Chris Torek [this message]
2024-03-31 23:14       ` Junio C Hamano
2024-04-01  1:31         ` Junio C Hamano
2024-04-02 12:20           ` Patrick Steinhardt
2024-04-02 16:40             ` Junio C Hamano
2024-04-09 11:55               ` Patrick Steinhardt
2024-04-09 16:15                 ` Karthik Nayak
2024-04-10  4:20                   ` Patrick Steinhardt
2024-04-10 16:06                     ` Junio C Hamano
2024-04-10 17:31                       ` Patrick Steinhardt
2024-04-01 10:38       ` Karthik Nayak
2024-04-01 11:48     ` Karthik Nayak
2024-04-01 16:17       ` Junio C Hamano
2024-04-01 20:40         ` Junio C Hamano
2024-04-01 22:37         ` Karthik Nayak
2024-03-30 22:46 ` [PATCH 8/8] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-04-02 12:20   ` Patrick Steinhardt
2024-04-12  9:59 ` [PATCH v2 0/7] update-ref: add symref oriented commands Karthik Nayak
2024-04-12  9:59   ` [PATCH v2 1/7] refs: accept symref values in `ref_transaction[_add]_update` Karthik Nayak
2024-04-18 14:25     ` Christian Couder
2024-04-19 10:28       ` Karthik Nayak
2024-04-18 15:08     ` Phillip Wood
2024-04-19  9:40       ` Patrick Steinhardt
2024-04-19 15:47       ` Karthik Nayak
2024-05-04 15:15         ` phillip.wood123
2024-04-19  9:40     ` Patrick Steinhardt
2024-04-19 18:09       ` Karthik Nayak
2024-04-23  6:31         ` Patrick Steinhardt
2024-04-23 10:48           ` Karthik Nayak
2024-04-12  9:59   ` [PATCH v2 2/7] update-ref: add support for symref-verify Karthik Nayak
2024-04-18 14:26     ` Christian Couder
2024-04-19 21:21       ` Karthik Nayak
2024-04-19  9:40     ` Patrick Steinhardt
2024-04-19 21:53       ` Karthik Nayak
2024-04-12  9:59   ` [PATCH v2 3/7] update-ref: add support for symref-delete Karthik Nayak
2024-04-18 14:52     ` Christian Couder
2024-04-21 10:43       ` Karthik Nayak
2024-04-19  9:40     ` Patrick Steinhardt
2024-04-21 10:45       ` Karthik Nayak
2024-04-12  9:59   ` [PATCH v2 4/7] files-backend: extract out `create_symref_lock` Karthik Nayak
2024-04-12  9:59   ` [PATCH v2 5/7] update-ref: add support for symref-create Karthik Nayak
2024-04-19  9:40     ` Patrick Steinhardt
2024-04-19 15:48       ` Junio C Hamano
2024-04-21 12:50       ` Karthik Nayak
2024-04-21 15:57         ` Karthik Nayak
2024-04-23  6:39         ` Patrick Steinhardt
2024-04-23 10:52           ` Karthik Nayak
2024-04-12  9:59   ` [PATCH v2 6/7] update-ref: add support for symref-update Karthik Nayak
2024-04-19  9:40     ` Patrick Steinhardt
2024-04-21 19:00       ` Karthik Nayak
2024-04-23  6:49         ` Patrick Steinhardt
2024-04-23 11:30           ` Karthik Nayak
2024-04-12  9:59   ` [PATCH v2 7/7] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-04-12 18:01   ` [PATCH v2 0/7] update-ref: add symref oriented commands Junio C Hamano
2024-04-12 18:49     ` Karthik Nayak
2024-04-18 15:05   ` Christian Couder
2024-04-21 19:06     ` Karthik Nayak
2024-04-20  6:16   ` Patrick Steinhardt
2024-04-21 19:11     ` Karthik Nayak
2024-04-23 21:28   ` [PATCH v3 0/8] refs: add symref support to 'git-update-ref' Karthik Nayak
2024-04-23 21:28     ` [PATCH v3 1/8] refs: accept symref values in `ref_transaction[_add]_update` Karthik Nayak
2024-04-23 21:28     ` [PATCH v3 2/8] update-ref: support parsing ref targets in `parse_next_oid` Karthik Nayak
2024-04-23 21:28     ` [PATCH v3 3/8] files-backend: extract out `create_symref_lock` Karthik Nayak
2024-04-23 21:28     ` [PATCH v3 4/8] update-ref: support symrefs in the verify command Karthik Nayak
2024-04-23 21:28     ` [PATCH v3 5/8] update-ref: support symrefs in the delete command Karthik Nayak
2024-04-23 21:28     ` [PATCH v3 6/8] update-ref: support symrefs in the create command Karthik Nayak
2024-04-23 21:28     ` [PATCH v3 7/8] update-ref: support symrefs in the update command Karthik Nayak
2024-04-23 21:28     ` [PATCH v3 8/8] ref: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-04-23 22:03     ` [PATCH v3 0/8] refs: add symref support to 'git-update-ref' Jeff King
2024-04-24  1:17       ` Junio C Hamano
2024-04-24 16:25       ` Karthik Nayak
2024-04-25  6:40         ` Patrick Steinhardt
2024-04-25 21:12           ` Karthik Nayak
2024-04-25 18:01         ` Junio C Hamano
2024-04-25 21:14           ` Karthik Nayak
2024-04-25 21:55             ` Junio C Hamano
2024-04-26 12:48               ` Karthik Nayak
2024-04-26 20:41         ` Jeff King
2024-04-25 17:09     ` Junio C Hamano
2024-04-25 21:07       ` Karthik Nayak
2024-04-26 15:24     ` [PATCH v4 0/7] add symref-* commands to 'git-update-ref --stdin' Karthik Nayak
2024-04-26 15:24       ` [PATCH v4 1/7] refs: accept symref values in `ref_transaction[_add]_update` Karthik Nayak
2024-04-26 19:31         ` Junio C Hamano
2024-04-26 21:15           ` Jeff King
2024-04-29  7:02             ` Patrick Steinhardt
2024-04-29  7:55               ` Jeff King
2024-04-29  9:29                 ` phillip.wood123
2024-04-29  9:32             ` phillip.wood123
2024-04-29 16:18               ` Junio C Hamano
2024-04-30 10:33                 ` Jeff King
2024-04-30 10:30               ` Jeff King
2024-04-28 19:36           ` Karthik Nayak
2024-04-29 13:38         ` Phillip Wood
2024-04-29 14:01           ` Karthik Nayak
2024-04-26 15:24       ` [PATCH v4 2/7] files-backend: extract out `create_symref_lock` Karthik Nayak
2024-04-26 21:39         ` Junio C Hamano
2024-04-28 19:57           ` Karthik Nayak
2024-04-26 15:24       ` [PATCH v4 3/7] update-ref: add support for 'symref-verify' command Karthik Nayak
2024-04-26 22:51         ` Junio C Hamano
2024-04-28 22:28           ` Karthik Nayak
2024-04-26 15:24       ` [PATCH v4 4/7] update-ref: add support for 'symref-delete' command Karthik Nayak
2024-04-26 15:24       ` [PATCH v4 5/7] update-ref: add support for 'symref-create' command Karthik Nayak
2024-04-26 15:24       ` [PATCH v4 6/7] update-ref: add support for 'symref-update' command Karthik Nayak
2024-04-26 15:24       ` [PATCH v4 7/7] ref: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-04-30 10:14       ` [PATCH v4 0/7] add symref-* commands to 'git-update-ref --stdin' Karthik Nayak
2024-05-01 20:22       ` [PATCH v5 0/7] refs: add support for transactional symref updates Karthik Nayak
2024-05-01 20:22         ` [PATCH v5 1/7] refs: accept symref values in `ref_transaction_update()` Karthik Nayak
2024-05-01 20:22         ` [PATCH v5 2/7] files-backend: extract out `create_symref_lock()` Karthik Nayak
2024-05-01 22:06           ` Junio C Hamano
2024-05-02  7:47             ` Patrick Steinhardt
2024-05-02 11:05               ` Karthik Nayak
2024-05-02 16:49               ` Junio C Hamano
2024-05-01 20:22         ` [PATCH v5 3/7] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-05-01 23:05           ` Junio C Hamano
2024-05-02  5:32             ` Karthik Nayak
2024-05-01 20:22         ` [PATCH v5 4/7] refs: add support for transactional symref updates Karthik Nayak
2024-05-01 23:52           ` Junio C Hamano
2024-05-02  5:50             ` Karthik Nayak
2024-05-02  7:47               ` Patrick Steinhardt
2024-05-02 11:10                 ` Karthik Nayak
2024-05-02 16:51                 ` Junio C Hamano
2024-05-02 16:00               ` Junio C Hamano
2024-05-02 17:53           ` Junio C Hamano
2024-05-01 20:22         ` [PATCH v5 5/7] refs: use transaction in `refs_create_symref()` Karthik Nayak
2024-05-02  7:47           ` Patrick Steinhardt
2024-05-01 20:22         ` [PATCH v5 6/7] refs: rename `refs_create_symref()` to `refs_update_symref()` Karthik Nayak
2024-05-02  7:47           ` Patrick Steinhardt
2024-05-02 11:34             ` Karthik Nayak
2024-05-01 20:22         ` [PATCH v5 7/7] refs: remove `create_symref` and associated dead code Karthik Nayak
2024-05-02  7:47           ` Patrick Steinhardt
2024-05-02 16:53             ` Junio C Hamano
2024-05-02  0:20         ` [PATCH v5 0/7] refs: add support for transactional symref updates Junio C Hamano
2024-05-02  5:53           ` Karthik Nayak
2024-05-03 12:41         ` [PATCH v6 " Karthik Nayak
2024-05-03 12:41           ` [PATCH v6 1/7] refs: accept symref values in `ref_transaction_update()` Karthik Nayak
2024-05-04 15:18             ` Phillip Wood
2024-05-05 15:10               ` Karthik Nayak
2024-05-05 15:19                 ` phillip.wood123
2024-05-03 12:41           ` [PATCH v6 2/7] files-backend: extract out `create_symref_lock()` Karthik Nayak
2024-05-03 12:41           ` [PATCH v6 3/7] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-05-03 12:41           ` [PATCH v6 4/7] refs: add support for transactional symref updates Karthik Nayak
2024-05-05 14:09             ` Phillip Wood
2024-05-05 16:09               ` Karthik Nayak
2024-05-06  9:35                 ` Phillip Wood
2024-05-06 11:19                   ` Karthik Nayak
2024-05-06 13:19                     ` Phillip Wood
2024-05-06  9:54                 ` Phillip Wood
2024-05-06 11:22                   ` Karthik Nayak
2024-05-06 13:17                     ` Phillip Wood
2024-05-03 12:41           ` [PATCH v6 5/7] refs: use transaction in `refs_create_symref()` Karthik Nayak
2024-05-03 12:41           ` [PATCH v6 6/7] refs: rename `refs_create_symref()` to `refs_update_symref()` Karthik Nayak
2024-05-03 12:41           ` [PATCH v6 7/7] refs: remove `create_symref` and associated dead code Karthik Nayak
2024-05-03 23:09             ` Junio C Hamano
2024-05-04  9:30               ` Karthik Nayak
2024-05-03 16:45           ` [PATCH v6 0/7] refs: add support for transactional symref updates Junio C Hamano
2024-05-06  7:36           ` Patrick Steinhardt
2024-05-07  6:00           ` [PATCH v7 0/8] " Karthik Nayak
2024-05-07  6:00             ` [PATCH v7 1/8] refs: accept symref values in `ref_transaction_update()` Karthik Nayak
2024-05-07  6:00             ` [PATCH v7 2/8] files-backend: extract out `create_symref_lock()` Karthik Nayak
2024-05-07  6:00             ` [PATCH v7 3/8] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-05-07  6:00             ` [PATCH v7 4/8] refs: move `original_update_refname` to 'refs.c' Karthik Nayak
2024-05-07  6:00             ` [PATCH v7 5/8] refs: add support for transactional symref updates Karthik Nayak
2024-05-07  6:00             ` [PATCH v7 6/8] refs: use transaction in `refs_create_symref()` Karthik Nayak
2024-05-07  6:00             ` [PATCH v7 7/8] refs: rename `refs_create_symref()` to `refs_update_symref()` Karthik Nayak
2024-05-07  6:00             ` [PATCH v7 8/8] refs: remove `create_symref` and associated dead code Karthik Nayak
2024-05-07  6:25             ` [PATCH v7 0/8] refs: add support for transactional symref updates Junio C Hamano
2024-05-07  6:31               ` Junio C Hamano
2024-05-07 12:58             ` [PATCH v8 " Karthik Nayak
2024-05-07 12:58               ` [PATCH v8 1/8] refs: accept symref values in `ref_transaction_update()` Karthik Nayak
2024-05-07 12:58               ` [PATCH v8 2/8] files-backend: extract out `create_symref_lock()` Karthik Nayak
2024-05-07 12:58               ` [PATCH v8 3/8] refs: support symrefs in 'reference-transaction' hook Karthik Nayak
2024-05-07 12:58               ` [PATCH v8 4/8] refs: move `original_update_refname` to 'refs.c' Karthik Nayak
2024-05-07 12:58               ` [PATCH v8 5/8] refs: add support for transactional symref updates Karthik Nayak
2024-05-07 12:58               ` [PATCH v8 6/8] refs: use transaction in `refs_create_symref()` Karthik Nayak
2024-05-07 12:58               ` [PATCH v8 7/8] refs: rename `refs_create_symref()` to `refs_update_symref()` Karthik Nayak
2024-05-07 12:58               ` [PATCH v8 8/8] refs: remove `create_symref` and associated dead code Karthik Nayak
2024-05-07 15:50               ` [PATCH v8 0/8] refs: add support for transactional symref updates phillip.wood123
2024-05-07 16:32               ` Junio C Hamano
2024-05-12 17:17                 ` Karthik Nayak
2024-05-13 17:15                   ` Junio C Hamano

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