Subject: Re: [PATCH v3] name-hash: don't add sparse directories in threaded lazy init

From: Junio C Hamano <[email-masked]>
Date: Wed, 21 May 2025 14:47:35 -0700

"Alex Mironov via GitGitGadget" <[email-masked]> writes:

> From: Alex Mironov <[email-masked]>
>
> 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.
>
> As per the original single-threaded change above: 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. Instead, they should be added to the directory hashtable when
> 'ignore_case' is true.
>
> Add a condition to avoid placing sparse directories into the name_hash
> hashtable. This avoids filling the table with extra entries that will
> never be queried.
>
> Signed-off-by: Alex Mironov <[email-masked]>
> ---

Sounds quite sensible and the above reads better.

> diff --git a/name-hash.c b/name-hash.c
> index d66de1cdfd5..b91e2762678 100644
> --- a/name-hash.c
> +++ b/name-hash.c
> @@ -492,8 +492,10 @@ static void *lazy_name_thread_proc(void *_data)
>  	for (k = 0; k < d->istate->cache_nr; k++) {
>  		struct cache_entry *ce_k = d->istate->cache[k];
>  		ce_k->ce_flags |= CE_HASHED;
> -		hashmap_entry_init(&ce_k->ent, d->lazy_entries[k].hash_name);
> -		hashmap_add(&d->istate->name_hash, &ce_k->ent);
> +		if (!S_ISSPARSEDIR(ce_k->ce_mode)) {
> +			hashmap_entry_init(&ce_k->ent, d->lazy_entries[k].hash_name);
> +			hashmap_add(&d->istate->name_hash, &ce_k->ent);
> +		}
>  	}

This unfortunately gives us deeper nesting than your previous round,
but the conditional matches the original commit and easier to see
what is going on by comparing the uni- and multi-threaded variants.

Nicely done.  Will queue.

Thanks.