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Use the next power of 2 for default_bucket_count #199

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Use the next power of 2 for default_bucket_count #199

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6 changes: 3 additions & 3 deletions include/fixed_containers/fixed_robinhood_hashtable.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -393,10 +393,10 @@ class FixedRobinhoodHashtable

constexpr std::size_t default_bucket_count(std::size_t value_count)
{
// oversize the bucket array by 30%
// Oversize the bucket array by 30% to reduce collisions as the container becomes full.
// TODO: think about the oversize percentage
// TODO: round to a nearby power of 2 to improve modulus performance
return (value_count * 130) / 100;
// Additionally, use the next power of 2 to improve modulo runtime efficiency.
return std::bit_ceil((value_count * 130) / 100);
}

} // namespace fixed_containers::fixed_robinhood_hashtable_detail
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