Function updateChain

tools/parser/main.cpp:87–211

template <typename ParserTag>
std::vector<blocksci::RawBlock> updateChain(const ParserConfiguration<ParserTag> &config, blocksci::BlockHeight maxBlockNum, HashIndexCreator &hashDb) {
    using namespace std::chrono_literals;

    /* Load and update the persisted (serialized) ChainIndex object that contains information about all blocks (without transaction data)
     * Generate the ChainIndex if no data is available on disk.
     *
     * This step represents the "xx.x% done fetching block headers" step of the parser output messages.
     */
    auto chainBlocks = [&]() {
        ChainIndex<ParserTag> index;
        std::ifstream inFile(config.blockListPath().str(), std::ios::binary);
        if (inFile.good()) {
            try {
                cereal::BinaryInputArchive ia(inFile);
                ia(index);
            } catch (const std::exception &) {
                std::cout << "Error loading chain index. Reparsing from scratch\n";
                index = ChainIndex<ParserTag>{};
            }
        }
        
        index.update(config, maxBlockNum);
        auto blocks = index.generateChain(maxBlockNum);
        std::ofstream of(config.blockListPath().str(), std::ios::binary);
        cereal::BinaryOutputArchive oa(of);
        oa(index);
        return blocks;
    }();

    /* Determine whether blocks have to be removed from the old chain (due to a fork, eg. caused by miners)
     *
     * This step represents the "Starting with chain of X blocks" and "Adding X blocks" step of the parser output messages.
     */
    blocksci::BlockHeight splitPoint = [&]() {
        blocksci::ChainAccess oldChain{config.dataConfig.chainDirectory(), config.dataConfig.blocksIgnored, config.dataConfig.errorOnReorg};
        blocksci::BlockHeight maxSize = std::min(oldChain.blockCount(), static_cast<blocksci::BlockHeight>(chainBlocks.size()));
        auto splitPoint = maxSize;
        for (blocksci::BlockHeight i{0}; i < maxSize; i++) {
            blocksci::uint256 oldHash = oldChain.getBlock(maxSize - 1 - i)->hash;
            blocksci::uint256 newHash = chainBlocks[static_cast<size_t>(static_cast<int>(maxSize - 1 - i))].hash;
            if (!(oldHash == newHash)) {
                splitPoint = maxSize - 1 - i;
                break;
            }
        }

        if(static_cast<blocksci::BlockHeight>(oldChain.blockCount()) != splitPoint) {
            std::cout << "Previously parsed chain is on a different fork than the longest chain. You may need to reparse. Aborting." << std::endl;
            exit(1);
        }
        
        std::cout << "Starting with chain of " << oldChain.blockCount() << " blocks" << std::endl;
        std::cout << "Adding " << static_cast<blocksci::BlockHeight>(chainBlocks.size()) - splitPoint << " blocks" << std::endl;
        
        return splitPoint;
    }();

    std::vector<BlockInfo<ParserTag>> blocksToAdd{chainBlocks.begin() + static_cast<int>(splitPoint), chainBlocks.end()};