Function open_segment_reader

crates/commitlog/src/repo/mod.rs:425–437

Open the existing segment at `offset` for reading. Unlike [`resume_segment_writer`], this does not traverse the segment. It does, however, attempt to read the segment header and checks that the log format version and checksum algorithm are compatible.

(
    repo: &R,
    max_log_format_version: u8,
    offset: u64,
)

/// does, however, attempt to read the segment header and checks that the log
/// format version and checksum algorithm are compatible.
pub fn open_segment_reader<R: Repo>(
    repo: &R,
    max_log_format_version: u8,
    offset: u64,
) -> io::Result<Reader<R::SegmentReader>> {
    let segment = segment_label(repo, offset);
    debug!("open segment reader for {segment}");
    let storage = repo
        .open_segment_reader(offset)
        .map_err(|source| with_segment_context("opening segment for read", repo, offset, source))?;
    Reader::new(max_log_format_version, offset, storage)
        .map_err(|source| with_segment_context("reading segment header", repo, offset, source))
}

/// Obtain the canonical [CompressOnce] compressor for segments.
///