ret := &ObjectSet{}
	for _, obj := range o.objMap {
		hasAll := true
		for _, l := range labels {
			lkv := strings.Split(l, "=")
			if len(lkv) != 2 {
				panic("label must have format key=value")
			}
			if !hasLabel(obj, lkv[0], lkv[1]) {
				hasAll = false
				break
			}
		}
		if hasAll {
			ret.append(obj)
		}
	}
	return ret
}

	doneCh := make(chan struct{})
	defer close(doneCh)
	if err := ps.Subscribe(MaskAll, ch1, doneCh, nil); err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if err := ps.Subscribe(MaskAll, ch2, doneCh, nil); err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	ps.Lock()
	defer ps.Unlock()

	if len(ps.subs) != 2 || ps.NumSubscribers(MaskAll) != 2 || ps.Subscribers() != 2 {
		t.Fatalf("expected 2 subscribers")
	}
}

// If data is not xlv2, it is returned in full.
func readXLMetaNoData(r io.Reader, size int64) ([]byte, error) {
	initial := size
	hasFull := true
	if initial > metaDataReadDefault {
		initial = metaDataReadDefault
		hasFull = false
	}

	buf := metaDataPoolGet()[:initial]
	_, err := io.ReadFull(r, buf)
	if err != nil {
		return nil, fmt.Errorf("readXLMetaNoData(io.ReadFull): %w", err)