if handler == nil {
		return nil, ErrUnknownHandler
	}

	var requests chan []byte
	var responses chan Response
	if handler.InCapacity > 0 {
		requests = make(chan []byte, handler.InCapacity)
	}
	if handler.OutCapacity > 0 {
		responses = make(chan Response, handler.OutCapacity)
	} else {
		responses = make(chan Response, 1)
	}

	cl, err := c.newMuxClient(ctx)
	if err != nil {

		confirms := ch.NotifyPublish(make(chan amqp091.Confirmation, 1))
		if err := ch.Confirm(false); err != nil {
			ch.Close()
			return nil, nil, err
		}
		return ch, confirms, nil
	}

	return ch, nil, nil
}

// send - sends an event to the AMQP091.
func (target *AMQPTarget) send(eventData event.Event, ch *amqp091.Channel, confirms chan amqp091.Confirmation) error {

	getProgressFunc func() (int64, int64)
	bytesReturned   int64

	payloadBuffer      []byte
	payloadBufferIndex int
	payloadCh          chan *bytes.Buffer

	finBytesScanned, finBytesProcessed int64

	errCh  chan []byte
	doneCh chan struct{}
}

func (writer *messageWriter) write(data []byte) bool {
	if _, err := writer.writer.Write(data); err != nil {
		return false
	}

		// not be required but makes reproduction much easier.
		nsLk.lockMapMutex.Lock()

		// lk3 blocks.
		lk3ch := make(chan bool)
		go func() {
			lk3ch <- nsLk.lock(ctx, "volume", "path", "source", "opsID", false, 0)
		}()

		// lk4, blocks.
		lk4ch := make(chan bool)
		go func() {
			lk4ch <- nsLk.lock(ctx, "volume", "path", "source", "opsID", false, 0)
		}()
		runtime.Gosched()

	saver := z.serverPools[o.pool].sets[o.set]

	// Disconnect from call above, but cancel on exit.
	listCtx, cancel := context.WithCancel(GlobalContext)
	saveCh := make(chan metaCacheEntry, metacacheBlockSize)
	inCh := make(chan metaCacheEntry, metacacheBlockSize)
	outCh := make(chan metaCacheEntry, o.Limit)

	filteredResults := o.gatherResults(ctx, outCh)

	mc := o.newMetacache()

}

// Borrowed from mutex_test.go
func HammerMutex(m *DRWMutex, loops int, cdone chan bool) {
	for range loops {
		m.Lock(id, source)
		m.Unlock(context.Background())
	}
	cdone <- true
}

// Borrowed from mutex_test.go
func TestMutex(t *testing.T) {
	loops := 200
	if testing.Short() {
		loops = 5
	}
	c := make(chan bool)
	m := NewDRWMutex(ds, "test")
	for range 10 {
		go HammerMutex(m, loops, c)

// Singleton contains a pointer to T that must be set once.
// Until the value is set all Get() calls will block.
type Singleton[T any] struct {
	v   *T
	set chan struct{}
}

// NewSingleton creates a new unset singleton.
func NewSingleton[T any]() *Singleton[T] {
	return &Singleton[T]{set: make(chan struct{}), v: nil}
}

// Get will return the singleton value.
func (s *Singleton[T]) Get() *T {
	<-s.set
	return s.v
}

type httpListener struct {
	opts        TCPOptions
	listeners   []net.Listener    // underlying TCP listeners.
	acceptCh    chan acceptResult // channel where all TCP listeners write accepted connection.
	ctxDoneCh   <-chan struct{}
	ctxCanceler context.CancelFunc
}

// start - starts separate goroutine for each TCP listener.  A valid new connection is passed to httpListener.acceptCh.

		// Register a single handler which echos the payload.
		errFatal(remote.RegisterStreamingHandler(handlerTest, StreamHandler{
			// Send 10x response.
			Handle: func(ctx context.Context, payload []byte, _ <-chan []byte, out chan<- []byte) *RemoteErr {
				for i := range responses {
					toSend := GetByteBuffer()[:0]
					toSend = append(toSend, byte(i))
					toSend = append(toSend, payload...)
					select {
					case <-ctx.Done():

}

// mrfState sncapsulates all the information
// related to the global background MRF.
type mrfState struct {
	opCh chan PartialOperation

	closed  int32
	closing int32
	wg      sync.WaitGroup
}

func newMRFState() mrfState {
	return mrfState{
		opCh: make(chan PartialOperation, mrfOpsQueueSize),
	}
}

// Add a partial S3 operation (put/delete) when one or more disks are offline.