From: Derrick Stolee <stolee@gmail.com>
Date: Fri, 13 Oct 2017 13:55:15 GMT
Subject: Re: git-clone causes out of memory
Message-ID: <53f98311-3c5f-9863-5f6c-bc4f25fad317@gmail.com>
In-Reply-To: <20171013135058.q7vhufdtin42ddic@sigill.intra.peff.net>

On 10/13/2017 9:50 AM, Jeff King wrote:
> On Fri, Oct 13, 2017 at 09:39:14AM -0400, Derrick Stolee wrote:
>
>> Since I don't understand enough about the consumers to diff_tree_oid() (and
>> the fact that the recursive behavior may be wanted in some cases), I think
>> we can fix this in builtin/rev-list.c with this simple diff:
>>
>> ---
>>
>> diff --git a/builtin/rev-list.c b/builtin/rev-list.c
>> index ded1577424..b2e8e02cc8 100644
>> --- a/builtin/rev-list.c
>> +++ b/builtin/rev-list.c
>> @@ -285,6 +285,9 @@ int cmd_rev_list(int argc, const char **argv, const char
>> *prefix)
>>
>>          git_config(git_default_config, NULL);
>>          init_revisions(&revs, prefix);
>> +
>> +       revs.pruning.flags = revs.pruning.flags & ~DIFF_OPT_RECURSIVE;
>> +

(Note: I'm running tests now and see that this breaks behavior. 
Definitely not the solution we want.)

> Hmm, this feels wrong, because we _do_ want to recurse down and follow
> the pathspec to see if there are real changes.
>
> We should be comparing an empty tree and d0/d0/d0/d0 (or however deep
> your pathspec goes). We should be able to see immediately that the entry
> is not present between the two and not bother descending. After all,
> we've set the QUICK flag in init_revisions(). So the real question is
> why QUICK is not kicking in.
>
> -Peff

I'm struggling to understand your meaning. We want to walk from root to 
d0/d0/d0/d0, but there is no reason to walk beyond that tree. But maybe 
that's what the QUICK flag is supposed to do.

Thanks,
-Stolee