AddCursor.cpp

AddCursor.cpp

CUtxoCommit BuildUtxoCommit(CCoinsViewCursor* pcursor, size_t numworkers)
{
    if (numworkers == 0)
        throw std::invalid_argument("numworkers == 0");

    std::atomic<int> count(0);
    std::mutex cs;

    // spin up workers
    auto worker = [&pcursor, &cs, &count]() {
        CUtxoCommit commitment;
        bool eof = false;

        while (!eof) {
            std::vector<std::pair<COutPoint, Coin>> utxos;
            utxos.reserve(50);
            {
                std::unique_lock<std::mutex> lock(cs);
                for(int n =0; n < 50; n++) {
                    auto utxo = std::pair<COutPoint, Coin>();
                    if (!pcursor->Valid()) {
                        eof = true;
                        break;
                    }
                    if (!pcursor->GetKey(utxo.first) 
                         || !pcursor->GetValue(utxo.second)) {
                        throw std::runtime_error("failed retrieve from UTXO cursor");
                    }
                    utxos.push_back(utxo);
                    pcursor->Next();
                }
            }

            for(auto utxo : utxos) {
                commitment.Add(utxo.first, utxo.second);
                if ((count++ % 1000000) == 0) {
                    uint8_t c = *utxo.first.hash.begin();
                    LogPrintf("Generating UTXO commitment; progress %d\n",
                              uint32_t(c) * 100 / 256);
                }
            }
        }
        return commitment;
    };

    std::vector<std::future<CUtxoCommit> > workers;
    for (size_t i = 0; i < numworkers; ++i) {
        workers.push_back(std::async(std::launch::async, worker));
    }

    CUtxoCommit result;
    for (auto& w : workers) {
        w.wait();
        result.Add(w.get());
    }
    return result;
}