From: Derrick Stolee <stolee@gmail.com>
To: Junio C Hamano <gitster@pobox.com>,
Derrick Stolee <dstolee@microsoft.com>
Cc: git@vger.kernel.org, git@jeffhostetler.com, sbeller@google.com,
Jeff King <peff@peff.net>
Subject: Re: [PATCH v3 3/5] sha1_name: Unroll len loop in find_unique_abbrev_r
Date: Wed, 4 Oct 2017 09:19:59 -0400 [thread overview]
Message-ID: <a6653525-94f2-fd7d-8c27-9334d473a556@gmail.com> (raw)
In-Reply-To: <xmqqtvzfcuoy.fsf@gitster.mtv.corp.google.com>
On 10/4/2017 2:07 AM, Junio C Hamano wrote:
> Derrick Stolee <dstolee@microsoft.com> writes:
>
>> - exists = has_sha1_file(sha1);
>> - while (len < GIT_SHA1_HEXSZ) {
>> - struct object_id oid_ret;
>> - status = get_short_oid(hex, len, &oid_ret, GET_OID_QUIETLY);
>> - if (exists
>> - ? !status
>> - : status == SHORT_NAME_NOT_FOUND) {
>> - hex[len] = 0;
>> - return len;
>> - }
>> - len++;
>> - }
>> - return len;
> The "always_call_fn" thing is a big sledgehammer that overrides
> everything else in update_candidates(). It bypasses the careful
> machinery set up to avoid having to open ambiguous object to learn
> their types as much as possible. One narrow exception when it is OK
> to use is if we never limit our candidates with type.
I do not modify get_short_oid, which uses these advanced options,
depending on the flags given. find_unique_abbrev_r() does not use these
advanced options.
> And it might appear that the conversion is safe (if only because we
> do not see any type limitation in the get_short_oid() call above),
> but I think there is one case where this patch changes the
> behaviour: what happens if core.disambiguate was set to anything
> other than "none"? The new code does not know anything about type
> based filtering, so it can end up reporting longer abbreviation than
> it was asked to produce. It may not be a problem in practice, though.
>
> I am not sure if setting core.disambiguate is generally a good idea
> in the first place, and if it is OK to break find_unique_abbrev()
> with respect to the configuration variable like this patch does.
I do not think that type-aware disambiguation goes through this code
path, since it requires giving different parameters to get_short_oid().
Test t1512-rev-parse-disambituagion.sh has a test 'core.disambiguate
config can prefer types' that verifies this behavior.
> I'd feel safe if we get extra input from Peff, who introduced the
> feature in 5b33cb1f ("get_short_sha1: make default disambiguation
> configurable", 2016-09-27).
I look forward to more feedback. Thanks for taking the time to look at
my patch series.
Thanks,
-Stolee
next prev parent reply other threads:[~2017-10-04 13:20 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-25 9:54 [PATCH v2 0/5] Improve abbreviation disambiguation Derrick Stolee
2017-09-25 9:54 ` [PATCH v2 1/5] test-list-objects: List a subset of object ids Derrick Stolee
2017-09-26 9:24 ` Junio C Hamano
2017-10-05 8:42 ` Jeff King
2017-10-05 9:48 ` Junio C Hamano
2017-10-05 10:00 ` Jeff King
2017-10-05 10:16 ` Junio C Hamano
2017-10-05 12:39 ` Derrick Stolee
2017-10-06 14:11 ` Jeff King
2017-10-07 19:12 ` Derrick Stolee
2017-10-07 19:33 ` Jeff King
2017-10-08 1:46 ` Junio C Hamano
2017-09-25 9:54 ` [PATCH v2 2/5] p0008-abbrev.sh: Test find_unique_abbrev() perf Derrick Stolee
2017-09-26 9:27 ` Junio C Hamano
2017-10-05 8:55 ` Jeff King
2017-10-05 8:57 ` Jeff King
2017-09-25 9:54 ` [PATCH v2 3/5] sha1_name: Unroll len loop in find_unique_abbrev_r Derrick Stolee
2017-09-25 9:54 ` [PATCH v2 4/5] sha1_name: Parse less while finding common prefix Derrick Stolee
2017-09-25 23:42 ` Stefan Beller
2017-10-02 14:52 ` Derrick Stolee
2017-09-25 9:54 ` [PATCH v2 5/5] sha1_name: Minimize OID comparisons during disambiguation Derrick Stolee
2017-10-02 14:56 ` [PATCH v3 0/5] Improve abbreviation disambituation Derrick Stolee
2017-10-05 9:49 ` Jeff King
2017-10-02 14:56 ` [PATCH v3 1/5] test-list-objects: List a subset of object ids Derrick Stolee
2017-10-03 4:16 ` Junio C Hamano
2017-10-02 14:56 ` [PATCH v3 2/5] p0008-abbrev.sh: Test find_unique_abbrev() perf Derrick Stolee
2017-10-02 14:56 ` [PATCH v3 3/5] sha1_name: Unroll len loop in find_unique_abbrev_r Derrick Stolee
2017-10-03 10:49 ` Junio C Hamano
2017-10-03 11:26 ` Derrick Stolee
2017-10-04 6:10 ` Junio C Hamano
2017-10-04 13:06 ` Derrick Stolee
2017-10-04 6:07 ` Junio C Hamano
2017-10-04 13:19 ` Derrick Stolee [this message]
2017-10-05 1:26 ` Junio C Hamano
2017-10-05 9:13 ` Jeff King
2017-10-05 9:50 ` Junio C Hamano
2017-10-02 14:56 ` [PATCH v3 4/5] sha1_name: Parse less while finding common prefix Derrick Stolee
2017-10-04 6:14 ` Junio C Hamano
2017-10-02 14:56 ` [PATCH v3 5/5] sha1_name: Minimize OID comparisons during disambiguation Derrick Stolee
2017-10-03 15:55 ` Stefan Beller
2017-10-03 17:05 ` Derrick Stolee
2017-10-05 9:44 ` Jeff King
2017-10-06 13:52 ` [PATCH] cleanup: fix possible overflow errors in binary search Derrick Stolee
2017-10-06 14:18 ` Jeff King
2017-10-06 14:41 ` Derrick Stolee
2017-10-08 18:29 ` [PATCH v2] " Derrick Stolee
2017-10-09 13:33 ` Jeff King
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