[BUG] Missing preprocess_query for Distance in InMemDataStore

[wdongyu]

Expected Behavior

For cosine metric, InMemDataStore use AVXNormalizedCosineDistanceFloat to compute distances and preprocess_query should be called when query. But it seems missing after #384.

1. Before Adding a new PQ Distance Metric and PQ Data Store #384, in diskann::Index::search and some other snippets, preprocess_query is called through the dist_fn()

_data_store->get_dist_fn()->preprocess_query(query, _data_store->get_dims(), scratch->aligned_query());

2. After Adding a new PQ Distance Metric and PQ Data Store #384, it change to call _data_store->preprocess_query. But when we navigate to the implementation of InMemDataStore, it only complete the memcpy but missing preprocess_query

template <typename data_t>
void InMemDataStore<data_t>::preprocess_query(const data_t *query, AbstractScratch<data_t> *query_scratch) const
{
    if (query_scratch != nullptr)
    {
        memcpy(query_scratch->aligned_query_T(), query, sizeof(data_t) * this->get_dims());

        // We should add implementation for preprocess_query here?
    }
    else
    {
        ...
    }
}

Actual Behavior

Describe above.

Example Code

Describe above.

Dataset Description

Error

Your Environment

• Operating system：Debian GNU/Linux 8
• DiskANN version: from main branch

Additional Details