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From: Jeff King <peff@peff.net>
To: Taylor Blau <me@ttaylorr.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH v2 07/15] rev-list: allow bitmaps when counting objects
Date: Sat, 15 Feb 2020 01:55:00 -0500
Message-ID: <20200215065500.GC1633703@coredump.intra.peff.net> (raw)
In-Reply-To: <20200215004555.GB15192@syl.local>

On Fri, Feb 14, 2020 at 04:45:55PM -0800, Taylor Blau wrote:

> >  static int try_bitmap_count(struct rev_info *revs)
> >  {
> > -	uint32_t commit_count;
> > +	uint32_t commit_count = 0,
> > +		 tag_count = 0,
> > +		 tree_count = 0,
> > +		 blob_count = 0;
> 
> Hmm, I don't usually see the comma-separated declaration/initialization
> in git.git. Is there a reason you did it here? Not that I really mind
> one way or the other, just interested.

The variables are all related, and all should have the same type. I'd
complain about a patch that did:

  int ret, count;

because there's no logical reason those two variables have the same
type. They just happen to. And putting them both on the same line is
even worse, because it makes a diff changing one of them noisy.

But in the code quoted above, if one of them changes, they would all
(presumably) change. So I think it communicates something to group them
like this. That said, if we had a style guideline that strictly forbade
this (because it's often applied in _bad_ spots), I wouldn't be that
sad to convert it.

> > +	if (revs->max_count >= 0 &&
> > +	    (revs->tag_objects || revs->tree_objects || revs->blob_objects))
> 
> An aside unrelated to the patch at hand: the expression
> 
>   (revs->tag_objects || revs->tree_objects || revs->blob_objects)
> 
> does occur in an awful lot of places throughout this file. Do you
> imagine it'd be useful to pull this check out into its own function,
> perhaps as a preparatory patch in a later version of this series?
> 
> I'm also not fussed if you don't think that such a change would be
> useful, it's just an observation I had after seeing this expression a
> few times.

The most amusing part about it is that there's actually no way to
specify one type without the other. Most of the revision code tries to
be respectful of the fact that we might one day change that (though
there are some subtleties; e.g., asking for blobs but not trees would
still need to traverse the trees, but just not show them).

So this really could have been revs->objects. :) But I think given the
effort to treat them individually so far, it would be a step backwards
to switch now.

As far as whether there should be something like:

  int revs_show_objects(struct rev_info *revs)
  {
	return revs->tag_objects || revs->tree_objects || revs->blob_objects;
  }

I don't feel strongly either way. I find doing it inline perfectly
readable, but it's entirely possible my brain has been rotted by years
of looking at the revision code.

-Peff

  reply index

Thread overview: 73+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-13  2:15 [PATCH 0/13] combining object filters and bitmaps Jeff King
2020-02-13  2:16 ` [PATCH 01/13] pack-bitmap: factor out type iterator initialization Jeff King
2020-02-13 17:45   ` Junio C Hamano
2020-02-13  2:16 ` [PATCH 02/13] pack-bitmap: fix leak of haves/wants object lists Jeff King
2020-02-13 18:12   ` Junio C Hamano
2020-02-13  2:17 ` [PATCH 03/13] rev-list: fallback to non-bitmap traversal when filtering Jeff King
2020-02-13 18:19   ` Junio C Hamano
2020-02-13 18:40     ` Jeff King
2020-02-13  2:17 ` [PATCH 04/13] rev-list: consolidate bitmap-disabling options Jeff King
2020-02-13  2:18 ` [PATCH 05/13] rev-list: factor out bitmap-optimized routines Jeff King
2020-02-13 18:34   ` Junio C Hamano
2020-02-13  2:19 ` [PATCH 06/13] rev-list: make --count work with --objects Jeff King
2020-02-13 19:14   ` Junio C Hamano
2020-02-13 20:27     ` Jeff King
2020-02-13  2:20 ` [PATCH 07/13] rev-list: allow bitmaps when counting objects Jeff King
2020-02-13 21:47   ` Junio C Hamano
2020-02-13 22:27     ` Jeff King
2020-02-13  2:20 ` [PATCH 08/13] pack-bitmap: basic noop bitmap filter infrastructure Jeff King
2020-02-13  2:21 ` [PATCH 09/13] rev-list: use bitmap filters for traversal Jeff King
2020-02-13 22:22   ` Junio C Hamano
2020-02-13 22:34     ` Jeff King
2020-02-13  2:21 ` [PATCH 10/13] bitmap: add bitmap_unset() function Jeff King
2020-02-13  2:23 ` [PATCH 11/13] pack-bitmap: implement BLOB_NONE filtering Jeff King
2020-02-13  2:25 ` [PATCH 12/13] pack-bitmap: implement BLOB_LIMIT filtering Jeff King
2020-02-13 23:17   ` Junio C Hamano
2020-02-13  2:25 ` [PATCH 13/13] pack-objects: support filters with bitmaps Jeff King
2020-02-14 18:21 ` [PATCH v2 0/15] combining object filters and bitmaps Jeff King
2020-02-14 18:22   ` [PATCH v2 01/15] pack-bitmap: factor out type iterator initialization Jeff King
2020-02-15  0:10     ` Taylor Blau
2020-02-14 18:22   ` [PATCH v2 02/15] pack-bitmap: fix leak of haves/wants object lists Jeff King
2020-02-15  0:15     ` Taylor Blau
2020-02-15  6:46       ` Jeff King
2020-02-18 17:58     ` Derrick Stolee
2020-02-18 20:02       ` Jeff King
2020-02-14 18:22   ` [PATCH v2 03/15] rev-list: fallback to non-bitmap traversal when filtering Jeff King
2020-02-15  0:22     ` Taylor Blau
2020-02-14 18:22   ` [PATCH v2 04/15] pack-bitmap: refuse to do a bitmap traversal with pathspecs Jeff King
2020-02-14 19:03     ` Junio C Hamano
2020-02-14 20:51       ` Jeff King
2020-02-14 18:22   ` [PATCH v2 05/15] rev-list: factor out bitmap-optimized routines Jeff King
2020-02-15  0:35     ` Taylor Blau
2020-02-14 18:22   ` [PATCH v2 06/15] rev-list: make --count work with --objects Jeff King
2020-02-15  0:42     ` Taylor Blau
2020-02-15  6:48       ` Jeff King
2020-02-16 23:34         ` Junio C Hamano
2020-02-18  5:24           ` Jeff King
2020-02-18 17:28             ` Junio C Hamano
2020-02-18 19:55               ` Jeff King
2020-02-18 21:19                 ` Junio C Hamano
2020-02-18 21:23                   ` Jeff King
2020-02-18 18:05     ` Derrick Stolee
2020-02-18 19:59       ` Jeff King
2020-02-14 18:22   ` [PATCH v2 07/15] rev-list: allow bitmaps when counting objects Jeff King
2020-02-15  0:45     ` Taylor Blau
2020-02-15  6:55       ` Jeff King [this message]
2020-02-16 23:36         ` Junio C Hamano
2020-02-14 18:22   ` [PATCH v2 08/15] t5310: factor out bitmap traversal comparison Jeff King
2020-02-15  2:14     ` Taylor Blau
2020-02-15  7:00       ` Jeff King
2020-02-14 18:22   ` [PATCH v2 09/15] rev-list: allow commit-only bitmap traversals Jeff King
2020-02-18 18:18     ` Derrick Stolee
2020-02-18 20:05       ` Jeff King
2020-02-18 20:11         ` Derrick Stolee
2020-02-14 18:22   ` [PATCH v2 10/15] pack-bitmap: basic noop bitmap filter infrastructure Jeff King
2020-02-14 18:22   ` [PATCH v2 11/15] rev-list: use bitmap filters for traversal Jeff King
2020-02-14 18:22   ` [PATCH v2 12/15] bitmap: add bitmap_unset() function Jeff King
2020-02-14 18:22   ` [PATCH v2 13/15] pack-bitmap: implement BLOB_NONE filtering Jeff King
2020-02-18 19:26     ` Derrick Stolee
2020-02-18 19:36       ` Derrick Stolee
2020-02-18 20:30         ` Jeff King
2020-02-18 20:24       ` Jeff King
2020-02-14 18:22   ` [PATCH v2 14/15] pack-bitmap: implement BLOB_LIMIT filtering Jeff King
2020-02-14 18:22   ` [PATCH v2 15/15] pack-objects: support filters with bitmaps Jeff King

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