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From: Derrick Stolee <stolee@gmail.com>
To: Junio C Hamano <gitster@pobox.com>, Jeff King <peff@peff.net>
Cc: Derrick Stolee <dstolee@microsoft.com>, git@vger.kernel.org, ramsay@ramsayjones.plus.com, sbeller@google.com
Subject: Re: [PATCH v4 4/4] sha1_name: minimize OID comparisons during disambiguation
Date: Tue, 10 Oct 2017 09:11:15 -0400
Message-ID: <f9add2c3-5499-085e-e433-799427dda6d8@gmail.com> (raw)
In-Reply-To: <xmqqbmlfp3eh.fsf@gitster.mtv.corp.google.com>

On 10/10/2017 8:56 AM, Junio C Hamano wrote:
> Jeff King <peff@peff.net> writes:
>
>> OK, I think that makes more sense. But note the p->num_objects thing I
>> mentioned. If I do:
>>
>>    git pack-objects .git/objects/pack/pack </dev/null
>>
>> then I have a pack with zero objects, which I think we'd similarly want
>> to return early from. I.e., I think we need:
>>
>>    if (p->num_objects)
>> 	return;
>>
>> Technically that also covers open_pack_index() failure, too, but that's
>> a subtlety I don't think we should rely on.
> True.  I notice that the early part of the two functions look almost
> identical.  Do we need error condition handling for the other one,
> too?

I prefer to fix the problem in all code clones when they cause review 
friction, so I'll send a fifth commit showing just the diff for these 
packfile issues in sha1_name.c. See patch below.

Should open_pack_index() return a non-zero status if the packfile is 
empty? Or, is there a meaningful reason to have empty packfiles?

Thanks,
-Stolee


diff --git a/sha1_name.c b/sha1_name.c
index 49ba67955..9f8a33e82 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -153,7 +153,9 @@ static void unique_in_pack(struct packed_git *p,
         uint32_t num, last, i, first = 0;
         const struct object_id *current = NULL;

-       open_pack_index(p);
+       if (open_pack_index(p) || !p->num_objects)
+               return;
+
         num = p->num_objects;
         last = num;
         while (first < last) {
@@ -513,7 +515,9 @@ static void find_abbrev_len_for_pack(struct 
packed_git *p,
         uint32_t num, last, first = 0;
         struct object_id oid;

-       open_pack_index(p);
+       if (open_pack_index(p) || !p->num_objects)
+               return;
+
         num = p->num_objects;
         last = num;
         while (first < last) {


  parent reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-08 18:49 [PATCH v4 0/4] Improve abbreviation disambiguation Derrick Stolee
2017-10-08 18:49 ` [PATCH v4 3/4] sha1_name: parse less while finding common prefix Derrick Stolee
2017-10-09 13:42   ` Jeff King
2017-10-08 18:49 ` [PATCH v4 4/4] sha1_name: minimize OID comparisons during disambiguation Derrick Stolee
2017-10-09 13:49   ` Jeff King
2017-10-10 12:16     ` Derrick Stolee
2017-10-10 12:36       ` Jeff King
2017-10-10 12:56         ` Junio C Hamano
2017-10-10 13:09           ` Jeff King
2017-10-10 13:11           ` Derrick Stolee [this message]
2017-10-10 13:30             ` Jeff King
2017-10-11 13:58               ` Derrick Stolee
2017-10-12 12:02                 ` [PATCH v5 0/4] Improve abbreviation disambiguation Derrick Stolee
2017-10-12 12:04                   ` Derrick Stolee
2017-10-12 12:21                     ` Junio C Hamano
2017-10-12 14:22                       ` Jeff King
2017-10-12 12:02                 ` [PATCH v5 1/4] p4211-line-log.sh: add log --online --raw --parents perf test Derrick Stolee
2017-10-12 12:02                 ` [PATCH v5 2/4] sha1_name: unroll len loop in find_unique_abbrev_r Derrick Stolee
2017-10-12 12:02                 ` [PATCH v5 3/4] sha1_name: parse less while finding common prefix Derrick Stolee
2017-10-12 12:02                 ` [PATCH v5 4/4] sha1_name: minimize OID comparisons during disambiguation Derrick Stolee

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