Re: [PATCH 6/9] pack-bitmap: expose function to iterate over bitmapped objects

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 27, 2025, 23:32 UTC
Message-ID: <xmqqo6yn55gv.fsf@gitster.g>
In-Reply-To: <Z8Dz6EkIpr/g3vuY@nand.local>

Taylor Blau <me@ttaylorr.com> writes:

Show 7 quoted lines

> It looks like the aim here is to introduce a function which executes a
> callback for each object of some type in a bitmap. That's a thin wrapper
> over the ewah_iterator, but it's not clear why we need a wrapper around
> that function since it is internal to pack-bitmap.c. Likewise, this is a
> performance critical area, so I am not sure I'm in favor of adding a
> function pointer to a hot path which executes once per object for some
> object type.

It internally introduced ewah_for_type(), giving the "struct bitmap_index" object an abstraction that callers can ask for the bitmap for any type the caller wants. Before the <type>_all bitmaps were introduced, there were one ewah-bitmap per type, so it made sense for a caller to ask "Now, for this bitmap_index, give me the ewah-bitmap for commits", but with "commits_all" added to the bitmap_index object, it is no longer clear to me what the answer to that question should be.