From: Jeff King <peff@peff.net>
Date: Sat, 11 Feb 2023 02:15:40 GMT
Subject: Re: [PATCH] cache-tree: fix strbuf growth in prime_cache_tree_rec()
Message-ID: <Y+b6TAmxel48QHJa@coredump.intra.peff.net>
In-Reply-To: <xmqqwn4pgt1f.fsf@gitster.g>

On Fri, Feb 10, 2023 at 12:33:00PM -0800, Junio C Hamano wrote:

> > strbuf_setlen() truncates the string to the directory name.  strbuf_grow() then
> > makes enough room to add that directory name again (that's what I mean with
> > "double") plus the entry path.  We don't add the directory name a second time,
> > so we don't need to make room for it.
> 
> Yeah, I think I made the same mistake number of years ago, thinking
> that strbuf_grow() was to grow the buffer to the given size, but in
> reality it is to grow the buffer by the given size, which felt a bit
> unnatural, at least to me.  I do not feel it too strongly but we
> might want to rename _grow() to _grow_by() and make _grow() call it
> while giving deprecation warning X-<.

Having been confused by that myself, I would be happy to see such a
name change.

> There are ~45 calls to strbuf_grow() in C files other than strbuf.c;
> I suspect probably a half or more of them can and should be removed
> to reduce the resulting code size without hurting anything.

My gut feeling is that your suspicion is giving strbuf_grow() users too
much credit. ;) And having looked at the first 7 grep hits, every single
one of them seemed pointless to me.

I wonder if these would make a good #leftoverbits / micro-project
candidate.

-Peff