Function replay_from_limit_dir

nodedb-wal/src/segmented.rs:310–332

Paginated replay from a WAL directory: reads at most `max_records` from `from_lsn`. Uses sequential I/O (not mmap) and does NOT require the WAL mutex — safe to call concurrently with writes. Sealed segments are immutable; the active segment is read via buffered I/O which sees data after the writer's fsync. Returns `(records, has_more)` where `has_more` is `true` if the limit was hit.

(
    wal_dir: &Path,
    from_lsn: u64,
    max_records: usize,
)

///
/// Returns `(records, has_more)` where `has_more` is `true` if the limit was hit.
pub fn replay_from_limit_dir(
    wal_dir: &Path,
    from_lsn: u64,
    max_records: usize,
) -> Result<(Vec<WalRecord>, bool)> {
    let segments = discover_segments(wal_dir)?;
    let mut records = Vec::with_capacity(max_records.min(4096));

    for seg in &segments {
        let reader = crate::reader::WalReader::open(&seg.path)?;
        for record_result in reader.records() {
            let record = record_result?;
            if record.header.lsn >= from_lsn {
                records.push(record);
                if records.len() >= max_records {
                    return Ok((records, true));
                }
            }
        }
    }

    Ok((records, false))
}

#[cfg(test)]
mod tests {