type mrfState struct {
	opCh chan partialOperation
}

// Add a partial S3 operation (put/delete) when one or more disks are offline.
func (m *mrfState) addPartialOp(op partialOperation) {
	if m == nil {
		return
	}

	select {
	case m.opCh <- op:
	default:
	}
}

var healSleeper = newDynamicSleeper(5, time.Second, false)

// healRoutine listens to new disks reconnection events and

// Msgsize returns 0.
func (p NoPayload) Msgsize() int {
	return 0
}

// UnmarshalMsg satisfies the interface, but is a no-op.
func (NoPayload) UnmarshalMsg(bytes []byte) ([]byte, error) {
	return bytes, nil
}

// MarshalMsg satisfies the interface, but is a no-op.
func (NoPayload) MarshalMsg(bytes []byte) ([]byte, error) {
	return bytes, nil
}

// NewNoPayload returns an empty NoPayload struct.

	b, op, err := wsutil.ReadData(conn, c.side)
	if err != nil {
		return err
	}
	if op != ws.OpBinary {
		return fmt.Errorf("unexpected connect response type %v", op)
	}
	if c.incomingBytes != nil {
		c.incomingBytes(int64(len(b)))
	}

	var m message
	_, _, err = m.parse(b)
	if err != nil {
		return err
	}
	if m.Op != r.Op() {

	tierPut
	tierDelete
)

func (op tierOp) String() string {
	switch op {
	case tierGet:
		return "GET"
	case tierPut:
		return "PUT"
	case tierDelete:
		return "DELETE"
	}
	return "UNKNOWN"
}

type tierPermErr struct {
	Op  tierOp
	Err error
}

func (te tierPermErr) Error() string {
	return fmt.Sprintf("failed to perform %s: %v", te.Op, te.Err)
}

func (m *muxClient) roundtrip(h HandlerID, req []byte) ([]byte, error) {
	if m.init {
		return nil, errors.New("mux client already used")
	}
	m.init = true
	m.singleResp = true
	msg := message{
		Op:         OpRequest,
		MuxID:      m.MuxID,
		Handler:    h,
		Flags:      m.BaseFlags | FlagEOF,
		Payload:    req,
		DeadlineMS: uint32(m.deadline.Milliseconds()),
	}
	if m.subroute != nil {

		var message message
		_, _, err = message.parse(msg)
		if err != nil {
			writeErr(fmt.Errorf("error parsing grid connect: %w", err))
			return
		}
		if message.Op != OpConnect {
			writeErr(fmt.Errorf("unexpected connect op: %v", message.Op))
			return
		}
		var cReq connectReq
		_, err = cReq.UnmarshalMsg(message.Payload)
		if err != nil {
			writeErr(fmt.Errorf("error parsing connectReq: %w", err))

	}
)

// logSuccess will update the last successful operation time.
func (h *healthDiskCtxValue) logSuccess() {
	atomic.StoreInt64(h.lastSuccess, time.Now().UnixNano())
}

// noopDoneFunc is a no-op done func.
// Can be reused.
var noopDoneFunc = func(_ *error) {}

// TrackDiskHealth for this request.
// When a non-nil error is returned 'done' MUST be called

		srcInfo.UserDefined[xhttp.AmzBucketReplicationStatus] = rs
	}

	op := replication.ObjectReplicationType
	if srcInfo.metadataOnly {
		op = replication.MetadataReplicationType
	}
	if dsc := mustReplicate(ctx, dstBucket, dstObject, srcInfo.getMustReplicateOptions(op, dstOpts)); dsc.ReplicateAny() {
		srcInfo.UserDefined[ReservedMetadataPrefixLower+ReplicationStatus] = dsc.PendingStatus()

		if len(logger.AuditTargets()) == 0 {
			return
		}

		op := auditTierOp{
			Tier:        tier,
			OutputBytes: bytes,
		}

		if err == nil {
			since := time.Since(startTime)
			op.TimeToResponseNS = since.Nanoseconds()
			globalTierMetrics.Observe(tier, since)
			globalTierMetrics.logSuccess(tier)
		} else {
			op.Error = err.Error()
			globalTierMetrics.logFailure(tier)
		}

		if strings.EqualFold(az.StorageClass, string(t)) {
			return t
		}
	}
	return azblob.AccessTierType("")
}

// FIXME: add support for remote version ID in Azure remote tier and remove
// this. Currently it's a no-op.

func (az *warmBackendAzure) Put(ctx context.Context, object string, r io.Reader, length int64) (remoteVersionID, error) {
	blobURL := az.serviceURL.NewContainerURL(az.Bucket).NewBlockBlobURL(az.getDest(object))