var GetByteBuffer = func() []byte {
	return make([]byte, 0, 4096)
}

// Sub - subscriber entity.
type Sub[T Maskable] struct {
	ch     chan T
	types  Mask
	filter func(entry T) bool
}

// PubSub holds publishers and subscribers
type PubSub[T Maskable, M Maskable] struct {
	// atomics, keep at top:
	types          uint64
	numSubscribers int32
	maxSubscribers int32

	// not atomics:

func TestMultiPubSub(t *testing.T) {
	ps := New[Maskable, Maskable](2)
	ch1 := make(chan Maskable, 1)
	ch2 := make(chan Maskable, 1)
	doneCh := make(chan struct{})
	defer close(doneCh)
	if err := ps.Subscribe(MaskAll, ch1, doneCh, func(entry Maskable) bool { return true }); err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if err := ps.Subscribe(MaskAll, ch2, doneCh, func(entry Maskable) bool { return true }); err != nil {

func (t *Mask) MergeMaskable(other Maskable) {
	*t |= Mask(other.Mask())
}

// SetIf will add other if b is true.
func (t *Mask) SetIf(b bool, other Mask) {
	if b {
		*t |= other
	}
}

// Mask returns the mask as a uint64.
func (t Mask) Mask() uint64 {
	return uint64(t)
}

// Maskable implementations must return their mask as a 64 bit uint.
type Maskable interface {
	Mask() uint64