From: Derrick Stolee <stolee@gmail.com>
Date: Tue, 06 Nov 2018 20:16:35 GMT
Subject: Re: [PATCH 0/1] send-pack: set core.warnAmbiguousRefs=false
Message-ID: <f2ff23be-9f26-6296-f7a4-b95f9f2ec1f6@gmail.com>
In-Reply-To: <20181106195131.GA5289@sigill.intra.peff.net>

On 11/6/2018 2:51 PM, Jeff King wrote:
> On Tue, Nov 06, 2018 at 02:44:42PM -0500, Jeff King wrote:
>
>>> The fix for this is simple: set core.warnAmbiguousRefs to false for this
>>> specific call of git pack-objects coming from git send-pack. We don't want
>>> to default it to false for all calls to git pack-objects, as it is valid to
>>> pass ref names instead of object ids. This helps regain these seconds during
>>> a push.
>> I don't think you actually care about the ambiguity check between refs
>> here; you just care about avoiding the ref check when we've seen (and
>> are mostly expecting) a 40-hex sha1. We have a more specific flag for
>> that: warn_on_object_refname_ambiguity.
>>
>> And I think it would be OK to enable that all the time for pack-objects,
>> which is plumbing that does typically expect object names. See prior art
>> in 25fba78d36 (cat-file: disable object/refname ambiguity check for
>> batch mode, 2013-07-12) and 4c30d50402 (rev-list: disable object/refname
>> ambiguity check with --stdin, 2014-03-12).
> I'd probably do it here:
>
> diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
> index e50c6cd1ff..d370638a5d 100644
> --- a/builtin/pack-objects.c
> +++ b/builtin/pack-objects.c
> @@ -3104,6 +3104,7 @@ static void get_object_list(int ac, const char **av)

Scoping the change into get_object_list does make sense. I was doing it 
a level higher, which is not worth it. I'll reproduce your change here.

>   	struct rev_info revs;
>   	char line[1000];
>   	int flags = 0;
> +	int save_warning;
>   
>   	repo_init_revisions(the_repository, &revs, NULL);
>   	save_commit_buffer = 0;
> @@ -3112,6 +3113,9 @@ static void get_object_list(int ac, const char **av)
>   	/* make sure shallows are read */
>   	is_repository_shallow(the_repository);
>   
> +	save_warning = warn_on_object_refname_ambiguity;
> +	warn_on_object_refname_ambiguity = 0;
> +
>   	while (fgets(line, sizeof(line), stdin) != NULL) {
>   		int len = strlen(line);
>   		if (len && line[len - 1] == '\n')
> @@ -3138,6 +3142,8 @@ static void get_object_list(int ac, const char **av)
>   			die(_("bad revision '%s'"), line);
>   	}
>   
> +	warn_on_object_refname_ambiguity = save_warning;
> +
>   	if (use_bitmap_index && !get_object_list_from_bitmap(&revs))
>   		return;
>   
>
> But I'll leave it to you to wrap that up in a patch, since you probably
> should re-check your timings (which it would be interesting to include
> in the commit message, if you have reproducible timings).

The timings change a lot depending on the disk cache and the remote 
refs, which is unfortunate, but I have measured a three-second improvement.

Thanks,
-Stolee