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From: Junio C Hamano <gitster@pobox•com>
To: Patrick Steinhardt <ps@pks•im>
Cc: Karthik Nayak <karthik.188@gmail•com>,
	 git@vger•kernel.org, schwab@linux-m68k•org,
	 phillip.wood123@gmail•com
Subject: Re: [PATCH v3 3/4] refs: selectively set prefix in the seek functions
Date: Mon, 14 Jul 2025 09:09:25 -0700	[thread overview]
Message-ID: <xmqq8qkqvjnu.fsf@gitster.g> (raw)
In-Reply-To: <aG9hMP9gEFLhVgJL@pks.im> (Patrick Steinhardt's message of "Thu, 10 Jul 2025 08:44:00 +0200")

Patrick Steinhardt <ps@pks•im> writes:

>> + * When the REF_ITERATOR_SEEK_SET_PREFIX flag is set, the iterator's prefix is
>> + * updated to match the seek string, affecting all subsequent iterations. If
>> + * not, the iterator seeks to the specified reference and clears any previously
>> + * set prefix.
>>   *
>>   * Returns 0 on success, a negative error code otherwise.
>>   */
>> -int ref_iterator_seek(struct ref_iterator *ref_iterator,
>> -		      const char *prefix);
>> +int ref_iterator_seek(struct ref_iterator *ref_iterator, const char *seek,
>> +		      unsigned int flags);
>
> Another tiny nit: instead of calling the variable `seek` we can just
> call it `refname`. That might give a bit more of a hint what you're
> actually seeking for.
>
> But other than that I'm happy with the new behaviour, where we are now
> consistently either setting or resetting the prefix depending on whether
> or not the caller set the flag.

I am not sure.  The way the "prefix" is used, if I understand correctly, is

 - it is set by iterator-begin, typically to the area to iterate
   over (e.g. "refs/heads/" for iterating over branches) in the
   for_each_ref_*() family of helpers, and internally we seek to
   that area (skipping anything that come strictly before
   "refs/heads/" for example).

 - iterator-advance looks at it and decides we are done when the
   iterator points beyond that prefix

So if you are iterating inside "refs/heads/" hierarchy and seek to
"refs/heads/m", don't you still want to stop when you step outside
"refs/heads/" by keeping the original prefix, instead of unsetting
the prefix to empty?  A postimage of this patch for packed backend
(picked at random) reads like this:

        static int packed_ref_iterator_seek(struct ref_iterator *ref_iterator,
                                            const char *seek, unsigned int flags)
        {
                struct packed_ref_iterator *iter =
                        (struct packed_ref_iterator *)ref_iterator;
                const char *start;

                if (seek && *seek)
                        start = find_reference_location(iter->snapshot, seek, 0);
                else
                        start = iter->snapshot->start;

                /* Unset any previously set prefix */
                FREE_AND_NULL(iter->prefix);

                if (flags & REF_ITERATOR_SEEK_SET_PREFIX)
                        iter->prefix = xstrdup_or_null(seek);

so after (true) seeking that does not have the SET_PREFIX flag on,
wouldn't our iterator-advance run through the end since it no longer
is aware of where to stop?

Thanks.

  parent reply	other threads:[~2025-07-14 16:09 UTC|newest]

Thread overview: 102+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-07-01 15:03 [PATCH 0/4] for-each-ref: introduce seeking functionality via '--skip-until' Karthik Nayak
2025-07-01 15:03 ` [PATCH 1/4] refs: expose `ref_iterator` via 'refs.h' Karthik Nayak
2025-07-01 15:03 ` [PATCH 2/4] ref-cache: remove unused function 'find_ref_entry()' Karthik Nayak
2025-07-14 15:46   ` Junio C Hamano
2025-07-01 15:03 ` [PATCH 3/4] refs: selectively set prefix in the seek functions Karthik Nayak
2025-07-03  5:55   ` Patrick Steinhardt
2025-07-03  9:40     ` Karthik Nayak
2025-07-01 15:03 ` [PATCH 4/4] for-each-ref: introduce a '--skip-until' option Karthik Nayak
2025-07-03  5:55   ` Patrick Steinhardt
2025-07-03 10:02     ` Karthik Nayak
2025-07-03 10:59       ` Patrick Steinhardt
2025-07-01 17:08 ` [PATCH 0/4] for-each-ref: introduce seeking functionality via '--skip-until' Junio C Hamano
2025-07-02 16:45   ` Karthik Nayak
2025-07-01 21:37 ` Junio C Hamano
2025-07-02 18:19   ` Karthik Nayak
2025-07-03  8:41     ` Karthik Nayak
2025-07-02 14:14 ` Phillip Wood
2025-07-02 20:33   ` Karthik Nayak
2025-07-03  5:18     ` Patrick Steinhardt
2025-07-03  5:56       ` Junio C Hamano
2025-07-03  8:19         ` Patrick Steinhardt
2025-07-03  8:48           ` Karthik Nayak
2025-07-04 13:02 ` [PATCH v2 " Karthik Nayak
2025-07-04 13:02   ` [PATCH v2 1/4] refs: expose `ref_iterator` via 'refs.h' Karthik Nayak
2025-07-04 13:02   ` [PATCH v2 2/4] ref-cache: remove unused function 'find_ref_entry()' Karthik Nayak
2025-07-04 13:02   ` [PATCH v2 3/4] refs: selectively set prefix in the seek functions Karthik Nayak
2025-07-04 13:02   ` [PATCH v2 4/4] for-each-ref: introduce a '--skip-until' option Karthik Nayak
2025-07-07 15:30     ` Junio C Hamano
2025-07-07 18:31       ` Karthik Nayak
2025-07-04 13:41   ` [PATCH v2 0/4] for-each-ref: introduce seeking functionality via '--skip-until' Andreas Schwab
2025-07-04 14:02     ` Karthik Nayak
2025-07-04 14:52       ` Andreas Schwab
2025-07-04 14:58         ` Karthik Nayak
2025-07-04 15:55           ` Andreas Schwab
2025-07-07  8:52             ` Karthik Nayak
2025-07-04 16:39       ` Junio C Hamano
2025-07-07  8:59         ` Karthik Nayak
2025-07-07  9:45           ` Phillip Wood
2025-07-08 11:39             ` Karthik Nayak
2025-07-08 13:47 ` [PATCH v3 0/4] for-each-ref: introduce seeking functionality via '--start-after' Karthik Nayak
2025-07-08 13:47   ` [PATCH v3 1/4] refs: expose `ref_iterator` via 'refs.h' Karthik Nayak
2025-07-08 13:47   ` [PATCH v3 2/4] ref-cache: remove unused function 'find_ref_entry()' Karthik Nayak
2025-07-08 13:47   ` [PATCH v3 3/4] refs: selectively set prefix in the seek functions Karthik Nayak
2025-07-10  6:44     ` Patrick Steinhardt
2025-07-11  9:44       ` Karthik Nayak
2025-07-14 16:09       ` Junio C Hamano [this message]
2025-07-15  9:49         ` Karthik Nayak
2025-07-15 16:35           ` Junio C Hamano
2025-07-16 14:40             ` Karthik Nayak
2025-07-16 15:39               ` Junio C Hamano
2025-07-16 20:02               ` Junio C Hamano
2025-07-17  9:01                 ` Karthik Nayak
2025-07-17 17:31                   ` Junio C Hamano
2025-07-08 13:47   ` [PATCH v3 4/4] for-each-ref: introduce a '--start-after' option Karthik Nayak
2025-07-08 20:25     ` Junio C Hamano
2025-07-09  9:53       ` Karthik Nayak
2025-07-11 16:18 ` [PATCH v4 0/4] for-each-ref: introduce seeking functionality via '--start-after' Karthik Nayak
2025-07-11 16:18   ` [PATCH v4 1/4] refs: expose `ref_iterator` via 'refs.h' Karthik Nayak
2025-07-11 16:18   ` [PATCH v4 2/4] ref-cache: remove unused function 'find_ref_entry()' Karthik Nayak
2025-07-11 16:18   ` [PATCH v4 3/4] refs: selectively set prefix in the seek functions Karthik Nayak
2025-07-14 10:34     ` Christian Couder
2025-07-15  8:19       ` Karthik Nayak
2025-07-11 16:18   ` [PATCH v4 4/4] for-each-ref: introduce a '--start-after' option Karthik Nayak
2025-07-14 16:04     ` Christian Couder
2025-07-14 16:42       ` Junio C Hamano
2025-07-15  8:42       ` Karthik Nayak
2025-07-14 16:34   ` [PATCH v4 0/4] for-each-ref: introduce seeking functionality via '--start-after' Christian Couder
2025-07-14 16:49     ` Junio C Hamano
2025-07-15  9:49       ` Karthik Nayak
2025-07-15 11:28 ` [PATCH v5 0/5] " Karthik Nayak
2025-07-15 11:28   ` [PATCH v5 1/5] refs: expose `ref_iterator` via 'refs.h' Karthik Nayak
2025-07-15 11:28   ` [PATCH v5 2/5] ref-cache: remove unused function 'find_ref_entry()' Karthik Nayak
2025-07-17 14:48     ` Junio C Hamano
2025-07-17 19:31       ` Karthik Nayak
2025-07-17 20:32         ` Junio C Hamano
2025-07-15 11:28   ` [PATCH v5 3/5] refs: selectively set prefix in the seek functions Karthik Nayak
2025-07-17  2:09     ` Jeff King
2025-07-17 19:49       ` Karthik Nayak
2025-07-17 21:55         ` Jeff King
2025-07-15 11:28   ` [PATCH v5 4/5] ref-filter: remove unnecessary else clause Karthik Nayak
2025-07-15 11:28   ` [PATCH v5 5/5] for-each-ref: introduce a '--start-after' option Karthik Nayak
2025-07-17 15:31     ` Junio C Hamano
2025-07-22  8:07       ` Karthik Nayak
2025-07-15 19:00   ` [PATCH v5 0/5] for-each-ref: introduce seeking functionality via '--start-after' Junio C Hamano
2025-07-17  1:19     ` Kyle Lippincott
2025-07-17  1:54       ` Jeff King
2025-07-17 17:08         ` Kyle Lippincott
2025-07-17 19:26           ` Karthik Nayak
2025-07-17 19:35             ` Kyle Lippincott
2025-07-17 22:09               ` Jeff King
2025-07-17 22:16                 ` Jeff King
2025-07-21 14:27                 ` Karthik Nayak
2025-07-21 21:22                   ` Jeff King
2025-07-22  8:44                     ` Karthik Nayak
2025-07-17 22:21             ` Junio C Hamano
2025-07-23 21:51   ` [PATCH] ref-iterator-seek: correctly initialize the prefix_state for a new level Junio C Hamano
2025-07-23 21:57     ` Kyle Lippincott
2025-07-23 23:52     ` Jeff King
2025-07-24  8:12     ` Karthik Nayak
2025-07-24 17:01       ` Junio C Hamano
2025-07-24 22:11         ` [PATCH] ref-cache: set prefix_state when seeking Karthik Nayak
2025-07-24 22:30           ` Junio C Hamano

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