Method tryInitPath

programs/local/LocalServer.cpp:474–559

If path is specified and not empty, will try to setup server environment and load existing metadata

/// If path is specified and not empty, will try to setup server environment and load existing metadata
void LocalServer::tryInitPath()
{
    std::string path;

    if (getClientConfiguration().has("path"))
    {
        /// User-supplied path.
        path = getClientConfiguration().getString("path");
        Poco::trimInPlace(path);

        if (path.empty())
        {
            throw Exception(ErrorCodes::BAD_ARGUMENTS,
                "Cannot work with empty storage path that is explicitly specified"
                " by the --path option. Please check the program options and"
                " correct the --path.");
        }
    }
    else
    {
        /// The user requested to use a temporary path - use a unique path in the system temporary directory
        /// (or in the current dir if a temporary doesn't exist)
        LoggerRawPtr log = &logger();
        std::filesystem::path parent_folder;
        std::filesystem::path default_path;

        try
        {
            /// Try to guess a tmp folder name, and check if it's a directory (throw an exception otherwise).
            parent_folder = std::filesystem::temp_directory_path();

        }
        catch (const fs::filesystem_error & e)
        {
            // The tmp folder doesn't exist? Is it a misconfiguration? Or chroot?
            LOG_DEBUG(log, "Can not get temporary folder: {}", e.what());
            parent_folder = std::filesystem::current_path();

            (void)std::filesystem::is_directory(parent_folder); // checks the path is accessible (may throw on I/O error)
            LOG_DEBUG(log, "Will create working directory inside current directory: {}", parent_folder.string());
        }

        /// we can have another clickhouse-local running simultaneously, even with the same PID (for ex. - several dockers mounting the same folder)
        /// or it can be some leftovers from other clickhouse-local runs
        /// as we can't accurately distinguish those situations we don't touch any existent folders
        /// we just try to pick some free name for our working folder

        default_path = parent_folder / fmt::format("clickhouse-local-{}", UUIDHelpers::generateV4());

        if (fs::exists(default_path))
            throw Exception(ErrorCodes::FILE_ALREADY_EXISTS, "Unsuccessful attempt to set up the working directory: {} already exists.", default_path.string());

        /// The directory can be created lazily during the runtime.
        temporary_directory_to_delete = default_path;

        path = default_path.string();
        LOG_DEBUG(log, "Working directory will be created as needed: {}", path);
    }