mrfMU      sync.Mutex
	resyncer   *replicationResyncer

	// workers:
	workers    []chan ReplicationWorkerOperation
	lrgworkers []chan ReplicationWorkerOperation

	// mrf:
	mrfWorkerKillCh chan struct{}
	mrfReplicaCh    chan ReplicationWorkerOperation
	mrfSaveCh       chan MRFReplicateEntry
	mrfStopCh       chan struct{}
	mrfWorkerSize   int
}

//
// Compaction happens when either:
//
// 1) The folder (and subfolders) contains less than dataScannerCompactLeastObject objects.
// 2) The folder itself contains more than dataScannerCompactAtFolders folders.
// 3) The folder only contains objects and no subfolders.
//
// A bucket root will never be compacted.
//
// Furthermore if a has more than dataScannerCompactAtChildren recursive children (uncompacted folders)

	if p.QueueDir != "" {
		if !filepath.IsAbs(p.QueueDir) {
			return errors.New("queueDir path should be absolute")
		}
	}

	if p.MaxOpenConnections < 0 {
		return errors.New("maxOpenConnections cannot be less than zero")
	}

	return nil
}

// PostgreSQLTarget - PostgreSQL target.
type PostgreSQLTarget struct {
	initOnce once.Init

	id         event.TargetID
	args       PostgreSQLArgs

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

	flag.StringVar(&targetPrefix, "target-prefix", "", "Select a prefix")

	flag.StringVar(&minimumObjectAge, "minimum-object-age", "0s", "Ignore objects younger than the specified age")
	flag.BoolVar(&debug, "debug", false, "Prints HTTP network calls to S3 endpoint")
	flag.BoolVar(&insecure, "insecure", false, "Disable TLS verification")
	flag.Parse()

	if sourceEndpoint == "" {

		return err
	}))
}

// WalkDirHandler - remote caller to list files and folders in a requested directory path.
func (s *storageRESTServer) WalkDirHandler(ctx context.Context, payload []byte, _ <-chan []byte, out chan<- []byte) (gerr *grid.RemoteErr) {
	var opts WalkDirOptions
	_, err := opts.UnmarshalMsg(payload)
	if err != nil {
		return grid.NewRemoteErr(err)
	}

	if !s.checkID(opts.DiskID) {

// The returned function will return the results once there is enough or input is closed,
// or the context is canceled.
func (o *listPathOptions) gatherResults(ctx context.Context, in <-chan metaCacheEntry) func() (metaCacheEntriesSorted, error) {
	resultsDone := make(chan metaCacheEntriesSorted)
	// Copy so we can mutate
	resCh := resultsDone
	var done bool
	var mu sync.Mutex
	resErr := io.EOF

	go func() {

	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)

<-chan <-chan int  // same as <-chan (<-chan int)
chan (<-chan int)
</pre>

<p>
A new, initialized channel
value can be made using the built-in function
<a href="#Making_slices_maps_and_channels"><code>make</code></a>,
which takes the channel type and an optional <i>capacity</i> as arguments:
</p>

<pre>
make(chan int, 100)
</pre>

<p>

import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * GWT emulation of {@link com.google.common.collect.ImmutableSortedSet}.
 *
 * @author Hayward Chan
 */
@ElementTypesAreNonnullByDefault
public abstract class ImmutableSortedSet<E> extends ForwardingImmutableSet<E>
    implements SortedSet<E>, SortedIterable<E> {