https://travis-ci.org/github/bitcoin/bitcoin/jobs/679885530#L8791
{
        if (!m_node.mempool) return true;
        LockPoints lp;
        CTxMemPoolEntry entry(tx, 0, 0, 0, false, 0, lp);
        CTxMemPool::setEntries ancestors;
        auto limit_ancestor_count = gArgs.GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT);
        auto limit_ancestor_size = gArgs.GetArg("-limitancestorsize", DEFAULT_ANCESTOR_SIZE_LIMIT) * 1000;
        auto limit_descendant_count = gArgs.GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT);
        auto limit_descendant_size = gArgs.GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT) * 1000;
        std::string unused_error_string;
        LOCK(m_node.mempool->cs);
        return m_node.mempool->CalculateMemPoolAncestors(
            entry, ancestors, limit_ancestor_count, limit_ancestor_size,
            limit_descendant_count, limit_descendant_size, unused_error_string);
    }
    CFeeRate estimateSmartFee(int num_blocks, bool conservative, FeeCalculation* calc) override
    {
        if (!m_node.fee_estimator) return {};
        return m_node.fee_estimator->estimateSmartFee(num_blocks, calc, conservative);
    }
    unsigned int estimateMaxBlocks() override
    {
        if (!m_node.fee_estimator) return 0;
        return m_node.fee_estimator->HighestTargetTracked(FeeEstimateHorizon::LONG_HALFLIFE);
    }
    CFeeRate mempoolMinFee() override