Re: [PATCH v2] name-hash: don't add sparse directories in threaded lazy init

From: Junio C Hamano <gitster@pobox.com>
Date: May 21, 2025, 20:32 UTC
Message-ID: <xmqqecwhaemu.fsf@gitster.g>
In-Reply-To: <pull.1970.v2.git.git.1747858585623.gitgitgadget@gmail.com>

"Alex Mironov via GitGitGadget" <gitgitgadget@gmail.com> writes:

Show 9 quoted lines

> From: Alex Mironov <alexandrfox@gmail.com>
>
> Ensure that logic added in 5f11669586 (name-hash: don't add directories
> to name_hash, 2021-04-12) also applies in multithreaded hashtable init
> path.
>
> Sparse directory entries represent a directory that is outside the
> sparse-checkout definition. These are not paths to blobs, so should not
> be added to the name_hash table as they must never be queried.

The second paragraph sounds as if this is a correctness fix, i.e. "should not be added" hints that we would see a wrong result returned from the hashmap if you added these entries to the name_hash. If this is a performance-only fix, that should be more clearly stated. Also, can we have performance numbers in the proposed log message as well, or is the improvement too small to measure?

Thanks.