Method open

nodedb-wal/src/writer.rs:139–174

Open or create a WAL file at the given path.

(path: &Path, config: WalWriterConfig)

impl WalWriter {
    /// Open or create a WAL file at the given path.
    pub fn open(path: &Path, config: WalWriterConfig) -> Result<Self> {
        let mut opts = OpenOptions::new();
        opts.create(true).write(true).append(false);

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

        let file = opts.open(path)?;

        let buffer = AlignedBuf::new(config.write_buffer_size, config.alignment)?;

        // Scan existing WAL for recovery if the file has data.
        let (file_offset, next_lsn) = if path.exists() && std::fs::metadata(path)?.len() > 0 {
            let info = crate::recovery::recover(path)?;
            (info.end_offset, info.next_lsn())
        } else {
            (0, 1)
        };

        let double_write = open_dwb_for(&config, path);

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

    /// Set the encryption key. When set, all subsequent records will have
    /// their payloads encrypted with AES-256-GCM.