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

[Derrick Stolee <stolee@gmail.com>]

On 5/21/2025 5:47 PM, Junio C Hamano wrote:
> "Alex Mironov via GitGitGadget" <gitgitgadget@gmail.com> writes:
> 
>> 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.
>>
>> 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 <alexandrfox@gmail.com>
>> ---
> 
> 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.
I agree that this version is ready to go. Thanks for shepherding
the v2 discussion.

-Stolee