Method _copy_from

libCacheSim/dataStructure/sparsepp/spp.h:2752–2786

Used to actually do the rehashing when we grow/shrink a hashtable -----------------------------------------------------------------

    // Used to actually do the rehashing when we grow/shrink a hashtable
    // -----------------------------------------------------------------
    void _copy_from(const sparse_hashtable &ht, size_type min_buckets_wanted)
    {
        clear();            // clear table, set num_deleted to 0

        // If we need to change the size of our table, do it now
        const size_type resize_to = settings.min_buckets(ht.size(), min_buckets_wanted);

        if (resize_to > bucket_count())
        {
            // we don't have enough buckets
            table.resize(resize_to);               // sets the number of buckets
            settings.reset_thresholds(bucket_count());
        }

        // We use a normal iterator to get bcks from ht
        // We could use insert() here, but since we know there are
        // no duplicates, we can be more efficient
        assert((bucket_count() & (bucket_count()-1)) == 0);      // a power of two
        for (const_iterator it = ht.begin(); it != ht.end(); ++it)
        {
            size_type num_probes = 0;              // how many times we've probed
            size_type bucknum;
            const size_type bucket_count_minus_one = bucket_count() - 1;
            for (bucknum = hash(get_key(*it)) & bucket_count_minus_one;
                 table.test(bucknum);                                   // table.test() OK since no erase()
                 bucknum = (bucknum + JUMP_(key, num_probes)) & bucket_count_minus_one)
            {
                ++num_probes;
                assert(num_probes < bucket_count()
                       && "Hashtable is full: an error in key_equal<> or hash<>");
            }
            table.set(bucknum, *it);               // copies the value to here
        }
        settings.inc_num_ht_copies();
    }

    // Implementation is like _copy_from, but it destroys the table of the
    // "from" guy by freeing sparsetable memory as we iterate.  This is