Method GetStateFor

src/versionbits.cpp:18–110

}

ThresholdState AbstractThresholdConditionChecker::GetStateFor(const CBlockIndex* pindexPrev, const Consensus::Params& params, ThresholdConditionCache& cache) const
{
    int nPeriod = Period(params);
    int nThreshold = Threshold(params);
    int min_activation_height = MinActivationHeight(params);
    // ELEMENTS: We interpret this as block height, not block time!
    int64_t nTimeStart = BeginTime(params);
    int64_t nTimeTimeout = EndTime(params);

    // Check if this deployment is always active.
    if (nTimeStart == Consensus::BIP9Deployment::ALWAYS_ACTIVE) {
        return ThresholdState::ACTIVE;
    }

    // Check if this deployment is never active.
    if (nTimeStart == Consensus::BIP9Deployment::NEVER_ACTIVE) {
        return ThresholdState::FAILED;
    }

    // A block's state is always the same as that of the first of its period, so it is computed based on a pindexPrev whose height equals a multiple of nPeriod - 1.
    if (pindexPrev != nullptr) {
        pindexPrev = pindexPrev->GetAncestor(pindexPrev->nHeight - ((pindexPrev->nHeight + 1) % nPeriod));
    }

    // Walk backwards in steps of nPeriod to find a pindexPrev whose information is known
    std::vector<const CBlockIndex*> vToCompute;
    while (cache.count(pindexPrev) == 0) {
        if (pindexPrev == nullptr) {
            // The genesis block is by definition defined.
            cache[pindexPrev] = ThresholdState::DEFINED;
            break;
        }
        if (GetBIP9Time(pindexPrev, params) < nTimeStart) {
            // Optimization: don't recompute down further, as we know every earlier block will be before the start time
            cache[pindexPrev] = ThresholdState::DEFINED;
            break;
        }
        vToCompute.push_back(pindexPrev);
        pindexPrev = pindexPrev->GetAncestor(pindexPrev->nHeight - nPeriod);
    }

    // At this point, cache[pindexPrev] is known
    assert(cache.count(pindexPrev));
    ThresholdState state = cache[pindexPrev];

    // Now walk forward and compute the state of descendants of pindexPrev
    while (!vToCompute.empty()) {
        ThresholdState stateNext = state;
        pindexPrev = vToCompute.back();
        vToCompute.pop_back();

        switch (state) {
            case ThresholdState::DEFINED: {
                if (GetBIP9Time(pindexPrev, params) >= nTimeStart) {
                    stateNext = ThresholdState::STARTED;
                }
                break;
            }