The handler function has this signature.

Sample handler:
```go
    handler :=  func(ctx context.Context, payload []byte, in <-chan []byte, out chan<- []byte) *RemoteErr {
        fmt.Println("Got request with initial payload", p, "from", GetCaller(ctx context.Context))
        fmt.Println("Subroute:", GetSubroute(ctx))
        for {
            select {

	if !s.checkID(params.DiskID) {
		return grid.NewRemoteErr(errDiskNotFound)
	}
	if params.Cache == nil {
		return grid.NewRemoteErrString("NSScannerHandler: provided cache is nil")
	}

	// Collect updates, stream them before the full cache is sent.
	updates := make(chan dataUsageEntry, 1)
	var wg sync.WaitGroup
	wg.Add(1)

type WaitGroup struct {
	count int32
	done  chan struct{}
}

func NewWaitGroup() *WaitGroup {
	return &WaitGroup{
		done: make(chan struct{}),
	}
}

func NewWaitForNCalls(t *testing.T, n int32) (*WaitGroup, func()) {
	wg := &WaitGroup{
		done: make(chan struct{}),
	}

	wg.Add(n)
	return wg, func() {
		select {
		case <-wg.C():

	// Buffers below this is not reused.
	minBufferSize = 1 << 10

	// defaultBufferSize is the default buffer allocation size.
	defaultBufferSize = 4 << 10

	// maxBufferSize is the maximum buffer size.
	// Buffers larger than this is not reused.
	maxBufferSize = 96 << 10

	// This is the assumed size of bigger buffers and allocation size.
	biggerBufMin = 32 << 10

	// This is the maximum size of bigger buffers.
	biggerBufMax = maxBufferSize

	name := newTgt.Name()

	currentBuff, ok := logChBuffers[name]
	if !ok {
		logChBuffers[name] = make(chan interface{}, requiredCap)
		currentCap = requiredCap
	} else {
		currentCap = cap(currentBuff)
		requiredCap += len(currentBuff)
	}

	if requiredCap > currentCap {
		logChBuffers[name] = make(chan interface{}, requiredCap)

		if len(currentBuff) > 0 {
		drain:
			for {
				select {

package com.google.common.collect;

import com.google.common.annotations.GwtCompatible;

/**
 * Dummy class that makes the GWT serialization policy happy. It isn't used on the server-side.
 *
 * @author Hayward Chan
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
class ForwardingImmutableCollection {
  private ForwardingImmutableCollection() {}

func (w *metacacheWriter) stream() (chan<- metaCacheEntry, error) {
	if w.creator != nil {
		err := w.creator()
		w.creator = nil
		if err != nil {
			return nil, fmt.Errorf("metacacheWriter: unable to create writer: %w", err)
		}
		if w.mw == nil {
			return nil, errors.New("metacacheWriter: writer not initialized")
		}
	}
	objs := make(chan metaCacheEntry, 100)
	w.streamErr = nil

 * limitations under the License.
 */

package com.google.common.collect;

import java.util.Collections;
import java.util.Set;

/**
 * GWT emulation of {@link RegularImmutableSet}.
 *
 * @author Hayward Chan
 */
@ElementTypesAreNonnullByDefault
final class RegularImmutableSet<E> extends ForwardingImmutableSet<E> {
  static final RegularImmutableSet<Object> EMPTY =
      new RegularImmutableSet<Object>(Collections.emptySet());

	xioutil "github.com/minio/minio/internal/ioutil"
	"github.com/minio/minio/internal/logger"
	"github.com/minio/minio/internal/mcontext"
)

type apiConfig struct {
	mu sync.RWMutex

	requestsPool           chan struct{}
	clusterDeadline        time.Duration
	listQuorum             string
	corsAllowOrigins       []string
	replicationPriority    string
	replicationMaxWorkers  int
	replicationMaxLWorkers int

// globalGridStart is a channel that will block startup of grid connections until closed.
var globalGridStart = make(chan struct{})

// globalLockGridStart is a channel that will block startup of lock grid connections until closed.
var globalLockGridStart = make(chan struct{})

func initGlobalGrid(ctx context.Context, eps EndpointServerPools) error {
	hosts, local := eps.GridHosts()