From: Jeff King <peff@peff.net>
Date: Wed, 10 Apr 2024 18:10:20 GMT
Subject: Re: [PATCH 05/24] pack-bitmap: move some initialization to `bitmap_writer_init()`
Message-ID: <20240410181020.GD2260545@coredump.intra.peff.net>
In-Reply-To: <a65316567391160dddae70fb036f03858772014f.1710972293.git.me@ttaylorr.com>

On Wed, Mar 20, 2024 at 06:05:13PM -0400, Taylor Blau wrote:

> The pack-bitmap-writer machinery uses a oidmap (backed by khash.h) to
> map from commits selected for bitmaps (by OID) to a bitmapped_commit
> structure (containing the bitmap itself, among other things like its XOR
> offset, etc.)
> 
> This map was initialized at the end of `bitmap_writer_build()`. New
> entries are added in `pack-bitmap-write.c::store_selected()`, which is
> called by the bitmap_builder machinery (which is responsible for
> traversing history and generating the actual bitmaps).
> 
> Reorganize when this field is initialized and when entries are added to
> it so that we can quickly determine whether a commit is a candidate for
> pseudo-merge selection, or not (since it was already selected to receive
> a bitmap, and thus is ineligible for pseudo-merge inclusion).

OK, makes sense. I don't think this should violate any assumptions in
the current bitmap code (and the sanity checks for duplicate/missing
entries in the hash seem right to me).

-Peff