Method open_with_start_lsn

nodedb-wal/src/writer.rs:225–254

Open a new WAL segment file with a specific starting LSN. Used by `SegmentedWal` when rolling to a new segment. The file must not already exist (or be empty). The writer will assign LSNs starting from `start_lsn`.

(
        path: &Path,
        config: WalWriterConfig,
        start_lsn: u64,
    )

    /// not already exist (or be empty). The writer will assign LSNs starting
    /// from `start_lsn`.
    pub fn open_with_start_lsn(
        path: &Path,
        config: WalWriterConfig,
        start_lsn: u64,
    ) -> Result<Self> {
        let mut opts = OpenOptions::new();
        opts.create(true).write(true).append(false);

        #[cfg(not(target_arch = "wasm32"))]
        if config.use_direct_io {
            opts.custom_flags(libc::O_DIRECT);
        }

        let file = opts.open(path)?;
        let buffer = AlignedBuf::new(config.write_buffer_size, config.alignment)?;

        let double_write = open_dwb_for(&config, path);

        Ok(Self {
            file,
            buffer,
            file_offset: 0,
            next_lsn: AtomicU64::new(start_lsn),
            sealed: false,
            config,
            encryption_ring: None,
            segment_preamble: None,
            double_write,
        })
    }

    /// Open a WAL writer with O_DIRECT disabled (for testing on tmpfs, etc.).
    pub fn open_without_direct_io(path: &Path) -> Result<Self> {