// A non-nil error value will be returned as RemoteErr(msg) to client.
	StatelessHandlerFn func(ctx context.Context, payload []byte, resp chan<- []byte) *RemoteErr

	// StatelessHandler is handlers for one to many requests,
	// where responses may be dropped.
	// Stateless requests provide no incoming stream and there is no flow control
	// on outgoing messages.
	StatelessHandler struct {
		Handle StatelessHandlerFn

)

const letterBytes = "abcdefghijklmnopqrstuvwxyz01234569"
const (
	letterIdxBits = 6                    // 6 bits to represent a letter index
	letterIdxMask = 1<<letterIdxBits - 1 // All 1-bits, as many as letterIdxBits
	letterIdxMax  = 63 / letterIdxBits   // # of letter indices fitting in 63 bits
)

// Random number state.
// We generate random temporary file names so that there's a good

	register := func(manager *Manager) {
		errFatal(manager.RegisterStreamingHandler(handlerTest, StreamHandler{
			Handle: func(ctx context.Context, payload []byte, request <-chan []byte, resp chan<- []byte) *RemoteErr {
				// Send many responses.
				// Test that this doesn't block.
				for i := byte(0); i < 100; i++ {
					select {
					case resp <- []byte{i}:
					// ok
					case <-ctx.Done():
						return NewRemoteErr(ctx.Err())
					}

	disks, _ := set.getOnlineDisksWithHealing(false)
	if len(disks) == 0 {
		return fmt.Errorf("no online drives found for set with endpoints %s", set.getEndpoints())
	}

	// However many we ask, versions must exist on ~50%
	listingQuorum := (set.setDriveCount + 1) / 2

	// How to resolve partial results.
	resolver := metadataResolutionParams{

	MaxSize      int64    // Return error if size is exceed.
	MetadataOnly bool     // Read as XL meta and truncate data.
	AbortOn404   bool     // Stop reading after first file not found.
	MaxResults   int      // Stop after this many successful results. <= 0 means all.
}

// ReadMultipleResp contains a single response from a ReadMultipleReq.
type ReadMultipleResp struct {
	Bucket  string    // Bucket as given by request.

	disks, _ := set.getOnlineDisksWithHealing(false)
	if len(disks) == 0 {
		return fmt.Errorf("no online drives found for set with endpoints %s", set.getEndpoints())
	}

	// However many we ask, versions must exist on ~50%
	listingQuorum := (set.setDriveCount + 1) / 2

	// How to resolve partial results.
	resolver := metadataResolutionParams{

}

// StorageFull storage ran out of space.
type StorageFull struct{}

func (e StorageFull) Error() string {
	return "Storage reached its minimum free drive threshold."
}

// SlowDown  too many file descriptors open or backend busy .
type SlowDown struct{}

func (e SlowDown) Error() string {
	return "Please reduce your request rate"
}

// RQErrType reason for read quorum error.
type RQErrType int

	serverPools.FilterMaxUsed(100 - (100 * diskReserveFraction))
	total := serverPools.TotalAvailable()
	if total == 0 {
		return -1
	}
	// choose when we reach this many
	choose := rand.Uint64() % total
	atTotal := uint64(0)
	for _, pool := range serverPools {
		atTotal += pool.Available
		if atTotal > choose && pool.Available > 0 {
			return pool.Index
		}
	}

	dataScannerCompactAtChildren     = 10000                            // Compact when there are this many children in a branch.
	dataScannerCompactAtFolders      = dataScannerCompactAtChildren / 4 // Compact when this many subfolders in a single folder.
	dataScannerForceCompactAtFolders = 1_000_000                        // Compact when this many subfolders in a single folder (even top level).

	ObjectAttributes    map[string]struct{} // Attribute tags defined by the users for the GetObjectAttributes request
	MaxParts            int                 // used in GetObjectAttributes. Signals how many parts we should return
	PartNumberMarker    int                 // used in GetObjectAttributes. Signals the part number after which results should be returned