https://travis-ci.org/github/bitcoin/bitcoin/jobs/679885530#L8791
size_t getMempoolDynamicUsage() override { return m_context->mempool ? m_context->mempool->DynamicMemoryUsage() : 0; }
    bool getHeaderTip(int& height, int64_t& block_time) override
    {
        LOCK(::cs_main);
        if (::pindexBestHeader) {
            height = ::pindexBestHeader->nHeight;
            block_time = ::pindexBestHeader->GetBlockTime();
            return true;
        }
        return false;
    }
    int getNumBlocks() override
    {
        LOCK(::cs_main);
        return ::ChainActive().Height();
    }
    uint256 getBestBlockHash() override
    {
        const CBlockIndex* tip = WITH_LOCK(::cs_main, return ::ChainActive().Tip());
        return tip ? tip->GetBlockHash() : Params().GenesisBlock().GetHash();
    }
    int64_t getLastBlockTime() override
    {
        LOCK(::cs_main);
        if (::ChainActive().Tip()) {
            return ::ChainActive().Tip()->GetBlockTime();
        }
        return Params().GenesisBlock().GetBlockTime(); 
    }
    double getVerificationProgress() override