Function validate_commit_header

crates/commitlog/src/segment.rs:516–530

Try to extract the commit header from the asked position without advancing seek. `IndexFileMut` fsync asynchoronously, which makes it important for reader to verify its entry

(
    mut reader: &mut Reader,
    byte_offset: u64,
)

/// Try to extract the commit header from the asked position without advancing seek.
/// `IndexFileMut` fsync asynchoronously, which makes it important for reader to verify its entry
pub fn validate_commit_header<Reader: io::Read + io::Seek>(
    mut reader: &mut Reader,
    byte_offset: u64,
) -> io::Result<commit::Header> {
    let pos = reader.stream_position()?;
    reader.seek(SeekFrom::Start(byte_offset))?;

    let hdr = commit::Header::decode(&mut reader)
        .and_then(|hdr| hdr.ok_or_else(|| io::Error::new(ErrorKind::UnexpectedEof, "unexpected EOF")));

    // Restore the original position
    reader.seek(SeekFrom::Start(pos))?;

    hdr
}

/// Pair of transaction offset and payload.
///