Function _dictExpandIfNeeded

src/dict.cpp:1348–1374

Expand the hash table if needed */

/* Expand the hash table if needed */
static int _dictExpandIfNeeded(dict *d)
{
    static const size_t SHRINK_FACTOR = 4;
    /* Incremental rehashing already in progress. Return. */
    if (dictIsRehashing(d)) return DICT_OK;

    /* If the hash table is empty expand it to the initial size. */
    if (d->ht[0].size == 0) return _dictExpand(d, DICT_HT_INITIAL_SIZE, false /*fShrink*/, nullptr);

    /* If we reached the 1:1 ratio, and we are allowed to resize the hash
     * table (global setting) or we should avoid it but the ratio between
     * elements/buckets is over the "safe" threshold, we resize doubling
     * the number of buckets. */
    if (d->ht[0].used >= d->ht[0].size &&
        (dict_can_resize ||
         d->ht[0].used/d->ht[0].size > dict_force_resize_ratio) &&
        dictTypeExpandAllowed(d))
    {
        return _dictExpand(d, d->ht[0].used + 1, false /*fShrink*/, nullptr);
    }
    else if (d->ht[0].used > 0 && d->ht[0].size >= (1024*SHRINK_FACTOR) && (d->ht[0].used * 16) < d->ht[0].size && dict_can_resize && !d->noshrink)
    {
        // If the dictionary has shurnk a lot we'll need to shrink the hash table instead
        return _dictExpand(d, d->ht[0].size/SHRINK_FACTOR, true /*fShrink*/, nullptr);
    }
    return DICT_OK;
}

/* Our hash table capability is a power of two */
static unsigned long _dictNextPower(unsigned long size)