Function LastChunkSnapshot

tsdb/head_wal.go:1558–1600

LastChunkSnapshot returns the directory name and index of the most recent chunk snapshot. If dir does not contain any chunk snapshots, ErrNotFound is returned.

(dir string)

// LastChunkSnapshot returns the directory name and index of the most recent chunk snapshot.
// If dir does not contain any chunk snapshots, ErrNotFound is returned.
func LastChunkSnapshot(dir string) (string, int, int, error) {
	files, err := os.ReadDir(dir)
	if err != nil {
		return "", 0, 0, err
	}
	maxIdx, maxOffset := -1, -1
	maxFileName := ""
	for i := range files {
		fi := files[i]

		if !strings.HasPrefix(fi.Name(), chunkSnapshotPrefix) {
			continue
		}
		if !fi.IsDir() {
			return "", 0, 0, fmt.Errorf("chunk snapshot %s is not a directory", fi.Name())
		}

		splits := strings.Split(fi.Name()[len(chunkSnapshotPrefix):], ".")
		if len(splits) != 2 {
			// Chunk snapshots is not in the right format, we do not care about it.
			continue
		}

		idx, err := strconv.Atoi(splits[0])
		if err != nil {
			continue
		}

		offset, err := strconv.Atoi(splits[1])
		if err != nil {
			continue
		}

		if idx > maxIdx || (idx == maxIdx && offset > maxOffset) {
			maxIdx, maxOffset = idx, offset
			maxFileName = filepath.Join(dir, fi.Name())
		}
	}
	if maxFileName == "" {
		return "", 0, 0, record.ErrNotFound
	}
	return maxFileName, maxIdx, maxOffset, nil
}

// DeleteChunkSnapshots deletes all chunk snapshots in a directory below a given index.
func DeleteChunkSnapshots(dir string, maxIndex, maxOffset int) error {