storage/remote/wal_watcher.go
func (w *WALWatcher) findSegmentForIndex(index int) (int, error) {
	refs, err := w.segments(w.walDir)
	if err != nil {
		return -1, nil
	}

	for _, r := range refs {
		if r >= index {
			return r, nil
		}
	}

	return -1, errors.New("failed to find segment for index")
}
func (w *WALWatcher) findSegmentForIndex(index int) (int, error) {
	refs, err := w.segments(w.walDir)
	if err != nil {
		return -1, nil
	}

	for _, r := range refs {
		if r >= index {
			return r, nil
		}
	}

	return -1, errors.New("failed to find segment for index")
}
// findSegmentForIndex finds the first segment greater than or equal to index.