fn new_with_shard>()

in below/store/src/lib.rs [290:365]
70 lines of code
8 McCabe index (conditional complexity)

    fn new_with_shard<P: AsRef<Path>>(
        logger: slog::Logger,
        path: P,
        shard: u64,
        compression_mode: CompressionMode,
        format: Format,
    ) -> Result<Self> {
        if !path.as_ref().is_dir() {
            std::fs::create_dir(&path).with_context(|| {
                format!("Failed to create store path: {}", path.as_ref().display())
            })?;
        }

        let (data_path, index_path) = {
            let mut data_path = path.as_ref().to_path_buf();
            let mut index_path = data_path.clone();
            data_path.push(format!("data_{:011}", shard));
            index_path.push(format!("index_{:011}", shard));
            (data_path, index_path)
        };

        let index = OpenOptions::new()
            .append(true)
            .create(true)
            .open(index_path.as_path())
            .with_context(|| format!("Failed to open index file: {}", index_path.display()))?;
        nix::fcntl::flock(
            index.as_raw_fd(),
            nix::fcntl::FlockArg::LockExclusiveNonblock,
        )
        .with_context(|| {
            format!(
                "Failed to acquire file lock on index file: {}",
                index_path.display(),
            )
        })?;

        let data = OpenOptions::new()
            .append(true)
            .create(true)
            .open(data_path.as_path())
            .with_context(|| format!("Failed to open data file: {}", data_path.display()))?;
        nix::fcntl::flock(
            data.as_raw_fd(),
            nix::fcntl::FlockArg::LockExclusiveNonblock,
        )
        .with_context(|| {
            format!(
                "Failed to acquire file lock on data file: {}",
                data_path.display(),
            )
        })?;

        let data_len = data
            .metadata()
            .with_context(|| {
                format!(
                    "Failed to get metadata of data file: {}",
                    data_path.display()
                )
            })?
            .len();

        Ok(StoreWriter {
            logger,
            dir: path.as_ref().to_path_buf(),
            index,
            data,
            data_len,
            shard,
            // First compressed write initializes the compressor
            compressor: None,
            compression_mode,
            format,
        })
    }