Method next_header

nodedb-wal/src/lazy_reader.rs:68–96

Read the next record header (30 bytes) without reading the payload. Returns `None` at EOF or first corruption. After this call, use either `read_payload()` to get the payload or `skip_payload()` to seek past it.

(&mut self)

    /// either `read_payload()` to get the payload or `skip_payload()` to
    /// seek past it.
    pub fn next_header(&mut self) -> Result<Option<RecordHeader>> {
        let mut header_buf = [0u8; HEADER_SIZE];
        match self.read_exact(&mut header_buf) {
            Ok(()) => {}
            Err(WalError::Io(e)) if e.kind() == std::io::ErrorKind::UnexpectedEof => {
                return Ok(None);
            }
            Err(e) => return Err(e),
        }

        let header = RecordHeader::from_bytes(&header_buf);

        if header.validate(self.offset - HEADER_SIZE as u64).is_err() {
            return Ok(None);
        }

        // Check for unknown required record types.
        let logical_type = header.logical_record_type();
        if crate::record::RecordType::from_raw(logical_type).is_none()
            && crate::record::RecordType::is_required(logical_type)
        {
            return Err(WalError::UnknownRequiredRecordType {
                record_type: header.record_type,
                lsn: header.lsn,
            });
        }

        Ok(Some(header))
    }

    /// Read the payload for a header that was just returned by `next_header()`.
    ///