threshold_util.cpp

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#include "consensus/babe/impl/threshold_util.hpp"

#include <boost/range/adaptors.hpp>
#include <boost/range/numeric.hpp>

namespace kagome::consensus {

  Threshold calculateThreshold(const std::pair<uint64_t, uint64_t> &ratio,
                               const primitives::AuthorityList &authorities,
                               primitives::AuthorityIndex authority_index) {
    double float_point_ratio = double(ratio.first) / ratio.second;

    using boost::adaptors::transformed;
    double theta = double(authorities[authority_index].weight)
                   / boost::accumulate(
                       authorities | transformed([](const auto &authority) {
                         return authority.weight;
                       }),
                       0.);

    using namespace boost::multiprecision;  // NOLINT
    cpp_rational p_rat(1. - pow(1. - float_point_ratio, theta));
    static const auto a = (uint256_t{1} << 128);
    return Threshold{a * numerator(p_rat) / denominator(p_rat)};
  }

}  // namespace kagome::consensus