Re: [PATCH v4 4/4] sha1_name: minimize OID comparisons during disambiguation

[Derrick Stolee <stolee@gmail.com>]

On 10/10/2017 9:30 AM, Jeff King wrote:
> On Tue, Oct 10, 2017 at 09:11:15AM -0400, Derrick Stolee wrote:
>
>> 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.
> Ah, that answers my earlier question. Junio mean unique_in_pack(). And
> yeah, I think it suffers from the same problem.
>
>> Should open_pack_index() return a non-zero status if the packfile is empty?
>> Or, is there a meaningful reason to have empty packfiles?
> I can't think of a compelling reason to have an empty packfile. But nor
> do I think we should consider them an error when we can handle them
> quietly (and returning non-zero status would cause Git to complain on
> many operations in a repository that has such a file).
>
> -Peff

Thanks for the comments. I found some typos in my commit messages, too.

I plan to send a (hopefully) final version tomorrow (Thursday). It will 
include:

* Make 'pos' unsigned in get_hex_char_from_oid()

* Check response from open_pack_index()

* Small typos in commit messages

If there are other issues, then please let me know.

Thanks,
-Stolee