Function MapGenericRemoteCalcScore

catboost/private/libs/distributed/master.cpp:326–375

template <typename TBinCalcMapper, typename TScoreCalcMapper>
void MapGenericRemoteCalcScore(
    double scoreStDev,
    TVector<TCandidatesContext>* candidatesContexts,
    TLearnContext* ctx) {

    Y_ASSERT(ctx->Params.SystemOptions->IsMaster());

    auto scoreDistribution = GetScoreDistribution(ctx->Params.ObliviousTreeOptions->RandomScoreType);

    // Flatten candidateLists from all contexts to ensure even parallelization
    TCandidateList allCandidatesList;
    for (auto& candidatesContext : *candidatesContexts) {
        allCandidatesList.insert(
            allCandidatesList.end(),
            candidatesContext.CandidateList.begin(),
            candidatesContext.CandidateList.end());
    }

    NPar::TJobDescription job;
    NPar::Map(&job, new TBinCalcMapper(), &allCandidatesList);
    NPar::RemoteMap(&job, new TScoreCalcMapper);
    NPar::TJobExecutor exec(&job, TMasterEnvironment::GetRef().SharedTrainData);
    TVector<typename TScoreCalcMapper::TOutput> allScores;
    exec.GetRemoteMapResults(&allScores);
    // set best split for each candidate
    Y_ASSERT(allCandidatesList.size() == allScores.size());
    const ui64 randSeed = ctx->LearnProgress->Rand.GenRand();

    size_t allScoresOffset = 0;
    for (auto& candidatesContext : *candidatesContexts) {
        auto& candidateList = candidatesContext.CandidateList;
        ctx->LocalExecutor->ExecRange(
            [&] (int candidateIdx) {
                auto& candidates = candidateList[candidateIdx].Candidates;
                CB_ENSURE(candidates.size() > 0, "Some score calcer did not produce ay scores");

                SetBestScore(
                    randSeed + candidateIdx,
                    allScores[allScoresOffset + candidateIdx],
                    scoreDistribution,
                    scoreStDev,
                    candidatesContext,
                    &candidates);
            },
            0,
            candidateList.ysize(),
            NPar::TLocalExecutor::WAIT_COMPLETE);
        allScoresOffset += candidateList.size();
    }
}

void MapRemotePairwiseCalcScore(
    double scoreStDev,