Merge pull request #255 from c9s/fix/binance-depth-stream

fix: binance depth stream buffering

examples/binance-book/main.go

@@ -48,16 +48,8 @@ var rootCmd = &cobra.Command{
 		stream.SetPublicOnly()
 		stream.Subscribe(types.BookChannel, symbol, types.SubscribeOptions{})
 
-		stream.OnBookSnapshot(func(book types.SliceOrderBook) {
+		streamBook := types.NewStreamBook(symbol)
-			// log.Infof("book snapshot: %+v", book)
+		streamBook.BindStream(stream)
-		})
-
-		stream.OnBookUpdate(func(book types.SliceOrderBook) {
-			// log.Infof("book update: %+v", book)
-		})
-
-		streambook := types.NewStreamBook(symbol)
-		streambook.BindStream(stream)
 
 		go func() {
 			for {
@@ -66,12 +58,12 @@ var rootCmd = &cobra.Command{
 				case <-ctx.Done():
 					return
 
-				case <-streambook.C:
+				case <-streamBook.C:
-					book := streambook.Copy()
+					book := streamBook.Copy()
 
 					if valid, err := book.IsValid(); !valid {
 						log.Errorf("order book is invalid, error: %v", err)
-						return
+						continue
 					}
 
 					bestBid, hasBid := book.BestBid()

pkg/exchange/binance/convert.go

@@ -3,6 +3,7 @@ package binance
 import (
 	"fmt"
 	"strconv"
+	"strings"
 	"time"
 
 	"github.com/adshao/go-binance/v2"
@@ -283,3 +284,19 @@ func ConvertTrades(remoteTrades []*binance.TradeV3) (trades []types.Trade, err e
 
 	return trades, err
 }
+
+func convertSubscription(s types.Subscription) string {
+	// binance uses lower case symbol name,
+	// for kline, it's "<symbol>@kline_<interval>"
+	// for depth, it's "<symbol>@depth OR <symbol>@depth@100ms"
+	switch s.Channel {
+	case types.KLineChannel:
+		return fmt.Sprintf("%s@%s_%s", strings.ToLower(s.Symbol), s.Channel, s.Options.String())
+
+	case types.BookChannel:
+		return fmt.Sprintf("%s@depth", strings.ToLower(s.Symbol))
+	}
+
+	return fmt.Sprintf("%s@%s", strings.ToLower(s.Symbol), s.Channel)
+}
+

pkg/exchange/binance/depthframe.go

@@ -2,7 +2,6 @@ package binance
 
 import (
 	"context"
-	"math/rand"
 	"sync"
 	"time"
 
@@ -11,28 +10,51 @@ import (
 
 //go:generate callbackgen -type DepthFrame
 type DepthFrame struct {
+	Symbol string
+
 	client  *binance.Client
 	context context.Context
 
-	mu            sync.Mutex
+	snapshotMutex sync.Mutex
+	snapshotDepth *DepthEvent
+
+	bufMutex  sync.Mutex
+	bufEvents []DepthEvent
+
 	once sync.Once
-	SnapshotDepth *DepthEvent
-	Symbol        string
-	BufEvents     []DepthEvent
 
 	readyCallbacks []func(snapshotDepth DepthEvent, bufEvents []DepthEvent)
 	pushCallbacks  []func(e DepthEvent)
 }
 
 func (f *DepthFrame) reset() {
-	f.mu.Lock()
+	if debugBinanceDepth {
-	f.SnapshotDepth = nil
+		log.Infof("resetting %s depth frame", f.Symbol)
-	f.BufEvents = nil
+	}
-	f.mu.Unlock()
+
+	f.bufMutex.Lock()
+	f.bufEvents = nil
+	f.bufMutex.Unlock()
+
+	f.snapshotMutex.Lock()
+	f.snapshotDepth = nil
+	f.once = sync.Once{}
+	f.snapshotMutex.Unlock()
+}
+
+func (f *DepthFrame) bufferEvent(e DepthEvent) {
+	if debugBinanceDepth {
+		log.Infof("buffering %s depth event FirstUpdateID = %d, FinalUpdateID = %d", f.Symbol, e.FirstUpdateID, e.FinalUpdateID)
+	}
+
+	f.bufMutex.Lock()
+	f.bufEvents = append(f.bufEvents, e)
+	f.bufMutex.Unlock()
 }
 
 func (f *DepthFrame) loadDepthSnapshot() {
-	f.mu.Lock()
+	log.Infof("buffering %s depth events for 3 seconds...", f.Symbol)
+	time.Sleep(3 * time.Second)
 
 	if debugBinanceDepth {
 		log.Infof("loading %s depth from the restful api", f.Symbol)
@@ -41,29 +63,52 @@ func (f *DepthFrame) loadDepthSnapshot() {
 	depth, err := f.fetch(f.context)
 	if err != nil {
 		log.WithError(err).Errorf("depth api error")
-		f.mu.Unlock()
 		return
 	}
 
 	if len(depth.Asks) == 0 {
 		log.Errorf("depth response error: empty asks")
-		f.mu.Unlock()
 		return
 	}
 
 	if len(depth.Bids) == 0 {
 		log.Errorf("depth response error: empty bids")
-		f.mu.Unlock()
 		return
 	}
 
+	if debugBinanceDepth {
+		log.Infof("loaded %s depth, last update ID = %d", f.Symbol, depth.FinalUpdateID)
+	}
+
+	f.snapshotMutex.Lock()
+	f.snapshotDepth = depth
+	f.snapshotMutex.Unlock()
+
 	// filter the events by the event IDs
+	f.bufMutex.Lock()
+	bufEvents := f.bufEvents
+	f.bufEvents = nil
+	f.bufMutex.Unlock()
+
 	var events []DepthEvent
-	for _, e := range f.BufEvents {
+	for _, e := range bufEvents {
-		if e.FirstUpdateID <= depth.FinalUpdateID || e.FinalUpdateID <= depth.FinalUpdateID {
+		if e.FinalUpdateID < depth.FinalUpdateID {
+			if debugBinanceDepth {
+				log.Infof("DROP %s depth event (final update id is %d older than the last update), updateID %d ~ %d (len %d)",
+					f.Symbol,
+					depth.FinalUpdateID-e.FinalUpdateID,
+					e.FirstUpdateID, e.FinalUpdateID, e.FinalUpdateID-e.FirstUpdateID)
+			}
+
 			continue
 		}
 
+		if debugBinanceDepth {
+			log.Infof("KEEP %s depth event, updateID %d ~ %d (len %d)",
+				f.Symbol,
+				e.FirstUpdateID, e.FinalUpdateID, e.FinalUpdateID-e.FirstUpdateID)
+		}
+
 		events = append(events, e)
 	}
 
@@ -72,85 +117,68 @@ func (f *DepthFrame) loadDepthSnapshot() {
 	// if the head event is newer than the depth we got,
 	// then there are something missed, we need to restart the process.
 	if len(events) > 0 {
+		// The first processed event should have U (final update ID) <= lastUpdateId+1 AND (first update id) >= lastUpdateId+1.
 		firstEvent := events[0]
-		if firstEvent.FirstUpdateID > depth.FinalUpdateID+1 {
+
+		// valid
+		nextID := depth.FinalUpdateID + 1
+		if firstEvent.FirstUpdateID > nextID || firstEvent.FinalUpdateID < nextID {
 			log.Warn("miss matched final update id for order book, resetting depth...")
-			f.SnapshotDepth = nil
+			f.reset()
-			f.BufEvents = nil
-			f.mu.Unlock()
 			return
 		}
+
+		if debugBinanceDepth {
+			log.Infof("VALID first %s depth event, updateID %d ~ %d (len %d)",
+				f.Symbol,
+				firstEvent.FirstUpdateID, firstEvent.FinalUpdateID, firstEvent.FinalUpdateID-firstEvent.FirstUpdateID)
+		}
 	}
 
-	f.SnapshotDepth = depth
+	if debugBinanceDepth {
-	f.BufEvents = nil
+		log.Infof("READY %s depth, %d bufferred events", f.Symbol, len(events))
-	f.mu.Unlock()
+	}
 
 	f.EmitReady(*depth, events)
 }
 
 func (f *DepthFrame) PushEvent(e DepthEvent) {
-	f.mu.Lock()
+	f.snapshotMutex.Lock()
+	snapshot := f.snapshotDepth
+	f.snapshotMutex.Unlock()
 
 	// before the snapshot is loaded, we need to buffer the events until we loaded the snapshot.
-	if f.SnapshotDepth == nil {
+	if snapshot == nil {
 		// buffer the events until we loaded the snapshot
-		f.BufEvents = append(f.BufEvents, e)
+		f.bufferEvent(e)
-		f.mu.Unlock()
 
-		f.loadDepthSnapshot()
-
-		// start a worker to update the snapshot periodically.
 		go f.once.Do(func() {
-			if debugBinanceDepth {
-				log.Infof("starting depth snapshot updater for %s market", f.Symbol)
-			}
-
-			ticker := time.NewTicker(30*time.Minute + time.Duration(rand.Intn(10))*time.Millisecond)
-			defer ticker.Stop()
-			for {
-				select {
-				case <-f.context.Done():
-					return
-
-				case <-ticker.C:
 			f.loadDepthSnapshot()
-				}
-			}
 		})
-	} else {
-		// if we have the snapshot, we could use that final update ID filter the events
-
-		// too old: drop any update ID < the final update ID
-		if e.FinalUpdateID < f.SnapshotDepth.FinalUpdateID {
-			if debugBinanceDepth {
-				log.Warnf("event final update id %d < depth final update id %d, skip", e.FinalUpdateID, f.SnapshotDepth.FinalUpdateID)
-			}
-
-			f.mu.Unlock()
 		return
 	}
 
-		// too new: if the first update ID > final update ID + 1, it means something is missing, we need to reload.
+	// drop old events
-		if e.FirstUpdateID > f.SnapshotDepth.FinalUpdateID+1 {
+	if e.FinalUpdateID <= snapshot.FinalUpdateID {
-			if debugBinanceDepth {
+		log.Infof("DROP %s depth update event, updateID %d ~ %d (len %d)",
-				log.Warnf("event first update id %d > final update id + 1 (%d), resetting snapshot", e.FirstUpdateID, f.SnapshotDepth.FirstUpdateID+1)
+			f.Symbol,
-			}
+			e.FirstUpdateID, e.FinalUpdateID, e.FinalUpdateID-e.FirstUpdateID)
-
-			f.SnapshotDepth = nil
-
-			// save the new event for later
-			f.BufEvents = append(f.BufEvents, e)
-			f.mu.Unlock()
 		return
 	}
 
-		// update the final update ID, so that we can check the next event
+	if e.FirstUpdateID > snapshot.FinalUpdateID+1 {
-		f.SnapshotDepth.FinalUpdateID = e.FinalUpdateID
+		log.Infof("MISSING %s depth update event, resetting, updateID %d ~ %d (len %d)",
-		f.mu.Unlock()
+			f.Symbol,
+			e.FirstUpdateID, e.FinalUpdateID, e.FinalUpdateID-e.FirstUpdateID)
 
+		f.reset()
+		return
+	}
+
+	f.snapshotMutex.Lock()
+	f.snapshotDepth.FinalUpdateID = e.FinalUpdateID
+	f.snapshotMutex.Unlock()
 	f.EmitPush(e)
-	}
 }
 
 // fetch fetches the depth and convert to the depth event so that we can reuse the event structure to convert it to the global orderbook type
@@ -165,6 +193,7 @@ func (f *DepthFrame) fetch(ctx context.Context) (*DepthEvent, error) {
 	}
 
 	event := DepthEvent{
+		Symbol:        f.Symbol,
 		FirstUpdateID: 0,
 		FinalUpdateID: response.LastUpdateID,
 	}

pkg/exchange/binance/parse.go

@@ -319,17 +319,40 @@ type DepthEvent struct {
 	Asks []DepthEntry
 }
 
+func (e *DepthEvent) String() (o string) {
+	o += fmt.Sprintf("Depth %s bid/ask = ", e.Symbol)
+
+	if len(e.Bids) == 0 {
+		o += "empty"
+	} else {
+		o += e.Bids[0].PriceLevel
+	}
+
+	o += "/"
+
+	if len(e.Asks) == 0 {
+		o += "empty"
+	} else {
+		o += e.Asks[0].PriceLevel
+	}
+
+	o += fmt.Sprintf(" %d ~ %d", e.FirstUpdateID, e.FinalUpdateID)
+	return o
+}
+
 func (e *DepthEvent) OrderBook() (book types.SliceOrderBook, err error) {
 	book.Symbol = e.Symbol
 
 	for _, entry := range e.Bids {
 		quantity, err := fixedpoint.NewFromString(entry.Quantity)
 		if err != nil {
+			log.WithError(err).Errorf("depth quantity parse error: %s", entry.Quantity)
 			continue
 		}
 
 		price, err := fixedpoint.NewFromString(entry.PriceLevel)
 		if err != nil {
+			log.WithError(err).Errorf("depth price parse error: %s", entry.PriceLevel)
 			continue
 		}
 
@@ -344,11 +367,13 @@ func (e *DepthEvent) OrderBook() (book types.SliceOrderBook, err error) {
 	for _, entry := range e.Asks {
 		quantity, err := fixedpoint.NewFromString(entry.Quantity)
 		if err != nil {
+			log.WithError(err).Errorf("depth quantity parse error: %s", entry.Quantity)
 			continue
 		}
 
 		price, err := fixedpoint.NewFromString(entry.PriceLevel)
 		if err != nil {
+			log.WithError(err).Errorf("depth price parse error: %s", entry.PriceLevel)
 			continue
 		}
 
@@ -360,7 +385,7 @@ func (e *DepthEvent) OrderBook() (book types.SliceOrderBook, err error) {
 		book.Asks = book.Asks.Upsert(pv, false)
 	}
 
-	return
+	return book, nil
 }
 
 func parseDepthEntry(val *fastjson.Value) (*DepthEntry, error) {

pkg/exchange/binance/stream.go

@@ -2,8 +2,8 @@ package binance
 
 import (
 	"context"
-	"fmt"
 	"math/rand"
+	"net"
 	"os"
 	"strconv"
 	"strings"
@@ -46,6 +46,10 @@ type Stream struct {
 	ListenKey  string
 	Conn       *websocket.Conn
 	connLock   sync.Mutex
+	reconnectC chan struct{}
+
+	connCtx    context.Context
+	connCancel context.CancelFunc
 
 	publicOnly bool
 
@@ -66,9 +70,14 @@ func NewStream(client *binance.Client) *Stream {
 	stream := &Stream{
 		Client:      client,
 		depthFrames: make(map[string]*DepthFrame),
+		reconnectC:  make(chan struct{}, 1),
 	}
 
 	stream.OnDepthEvent(func(e *DepthEvent) {
+		if debugBinanceDepth {
+			log.Infof("received %s depth event updateID %d ~ %d (len %d)", e.Symbol, e.FirstUpdateID, e.FinalUpdateID, e.FinalUpdateID-e.FirstUpdateID)
+		}
+
 		f, ok := stream.depthFrames[e.Symbol]
 		if !ok {
 			f = &DepthFrame{
@@ -79,27 +88,29 @@ func NewStream(client *binance.Client) *Stream {
 
 			stream.depthFrames[e.Symbol] = f
 
-			f.OnReady(func(e DepthEvent, bufEvents []DepthEvent) {
+			f.OnReady(func(snapshotDepth DepthEvent, bufEvents []DepthEvent) {
-				snapshot, err := e.OrderBook()
+				log.Infof("depth snapshot: %s", snapshotDepth.String())
+
+				snapshot, err := snapshotDepth.OrderBook()
 				if err != nil {
 					log.WithError(err).Error("book snapshot convert error")
 					return
 				}
 
 				if valid, err := snapshot.IsValid(); !valid {
-					log.Warnf("depth snapshot is invalid, event: %+v, error: %v", e, err)
+					log.Errorf("depth snapshot is invalid, event: %+v, error: %v", snapshotDepth, err)
 				}
 
 				stream.EmitBookSnapshot(snapshot)
 
 				for _, e := range bufEvents {
-					book, err := e.OrderBook()
+					bookUpdate, err := e.OrderBook()
 					if err != nil {
 						log.WithError(err).Error("book convert error")
 						return
 					}
 
-					stream.EmitBookUpdate(book)
+					stream.EmitBookUpdate(bookUpdate)
 				}
 			})
 
@@ -175,13 +186,14 @@ func NewStream(client *binance.Client) *Stream {
 		}
 	})
 
-	stream.OnConnect(func() {
+	stream.OnDisconnect(func() {
-		// reset the previous frames
+		log.Infof("resetting depth snapshots...")
 		for _, f := range stream.depthFrames {
 			f.reset()
-			f.loadDepthSnapshot()
 		}
+	})
 
+	stream.OnConnect(func() {
 		var params []string
 		for _, subscription := range stream.Subscriptions {
 			params = append(params, convertSubscription(subscription))
@@ -261,49 +273,11 @@ func (s *Stream) keepaliveListenKey(ctx context.Context, listenKey string) error
 	return s.Client.NewKeepaliveUserStreamService().ListenKey(listenKey).Do(ctx)
 }
 
-func (s *Stream) connect(ctx context.Context) error {
+func (s *Stream) emitReconnect() {
-	if s.publicOnly {
+	select {
-		log.Infof("stream is set to public only mode")
+	case s.reconnectC <- struct{}{}:
-	} else {
+	default:
-		log.Infof("request listen key for creating user data stream...")
-
-		listenKey, err := s.fetchListenKey(ctx)
-		if err != nil {
-			return err
 	}
-
-		s.ListenKey = listenKey
-		log.Infof("user data stream created. listenKey: %s", maskListenKey(s.ListenKey))
-	}
-
-	conn, err := s.dial(s.ListenKey)
-	if err != nil {
-		return err
-	}
-
-	log.Infof("websocket connected")
-
-	s.connLock.Lock()
-	s.Conn = conn
-	s.connLock.Unlock()
-
-	s.EmitConnect()
-	return nil
-}
-
-func convertSubscription(s types.Subscription) string {
-	// binance uses lower case symbol name,
-	// for kline, it's "<symbol>@kline_<interval>"
-	// for depth, it's "<symbol>@depth OR <symbol>@depth@100ms"
-	switch s.Channel {
-	case types.KLineChannel:
-		return fmt.Sprintf("%s@%s_%s", strings.ToLower(s.Symbol), s.Channel, s.Options.String())
-
-	case types.BookChannel:
-		return fmt.Sprintf("%s@depth", strings.ToLower(s.Symbol))
-	}
-
-	return fmt.Sprintf("%s@%s", strings.ToLower(s.Symbol), s.Channel)
 }
 
 func (s *Stream) Connect(ctx context.Context) error {
@@ -312,43 +286,112 @@ func (s *Stream) Connect(ctx context.Context) error {
 		return err
 	}
 
-	go s.read(ctx)
+	// start one re-connector goroutine with the base context
+	go s.reconnector(ctx)
 
 	s.EmitStart()
 	return nil
 }
 
-func (s *Stream) read(ctx context.Context) {
+func (s *Stream) reconnector(ctx context.Context) {
+	for {
+		select {
+		case <-ctx.Done():
+			return
 
-	pingTicker := time.NewTicker(10 * time.Second)
+		case <-s.reconnectC:
+			// ensure the previous context is cancelled
+			if s.connCancel != nil {
+				s.connCancel()
+			}
+
+			log.Warnf("received reconnect signal, reconnecting...")
+			time.Sleep(3 * time.Second)
+
+			if err := s.connect(ctx); err != nil {
+				log.WithError(err).Errorf("connect error, try to reconnect again...")
+				s.emitReconnect()
+			}
+		}
+	}
+}
+
+func (s *Stream) connect(ctx context.Context) error {
+	// should only start one connection one time, so we lock the mutex
+	s.connLock.Lock()
+
+	// create a new context
+	s.connCtx, s.connCancel = context.WithCancel(ctx)
+
+	if s.publicOnly {
+		log.Infof("stream is set to public only mode")
+	} else {
+		log.Infof("request listen key for creating user data stream...")
+
+		listenKey, err := s.fetchListenKey(ctx)
+		if err != nil {
+			s.connCancel()
+			s.connLock.Unlock()
+			return err
+		}
+
+		s.ListenKey = listenKey
+		log.Infof("user data stream created. listenKey: %s", maskListenKey(s.ListenKey))
+
+		go s.listenKeyKeepAlive(s.connCtx, listenKey)
+	}
+
+	// when in public mode, the listen key is an empty string
+	conn, err := s.dial(s.ListenKey)
+	if err != nil {
+		s.connCancel()
+		s.connLock.Unlock()
+		return err
+	}
+
+	log.Infof("websocket connected")
+
+	s.Conn = conn
+	s.connLock.Unlock()
+
+	s.EmitConnect()
+
+	go s.read(s.connCtx)
+	go s.ping(s.connCtx)
+	return nil
+}
+
+func (s *Stream) ping(ctx context.Context) {
+	pingTicker := time.NewTicker(15 * time.Second)
 	defer pingTicker.Stop()
 
-	keepAliveTicker := time.NewTicker(5 * time.Minute)
-	defer keepAliveTicker.Stop()
-
-	go func() {
 	for {
 		select {
 
 		case <-ctx.Done():
+			log.Info("ping worker stopped")
 			return
 
 		case <-pingTicker.C:
 			s.connLock.Lock()
 			if err := s.Conn.WriteControl(websocket.PingMessage, []byte("hb"), time.Now().Add(3*time.Second)); err != nil {
 				log.WithError(err).Error("ping error", err)
+				s.emitReconnect()
 			}
-
 			s.connLock.Unlock()
+		}
+	}
+}
 
-			case <-keepAliveTicker.C:
+func (s *Stream) listenKeyKeepAlive(ctx context.Context, listenKey string) {
-				if !s.publicOnly {
+	keepAliveTicker := time.NewTicker(5 * time.Minute)
-					if err := s.keepaliveListenKey(ctx, s.ListenKey); err != nil {
+	defer keepAliveTicker.Stop()
-						log.WithError(err).Errorf("listen key keep-alive error: %v key: %s", err, maskListenKey(s.ListenKey))
-					}
-				}
 
-			}
+	// if we exit, we should invalidate the existing listen key
+	defer func() {
+		log.Info("keepalive worker stopped")
+		if err := s.invalidateListenKey(ctx, listenKey); err != nil {
+			log.WithError(err).Error("invalidate listen key error")
 		}
 	}()
 
@@ -358,40 +401,65 @@ func (s *Stream) read(ctx context.Context) {
 		case <-ctx.Done():
 			return
 
-		default:
+		case <-keepAliveTicker.C:
-			if err := s.Conn.SetReadDeadline(time.Now().Add(3 * time.Minute)); err != nil {
+			if err := s.keepaliveListenKey(ctx, listenKey); err != nil {
-				log.WithError(err).Errorf("set read deadline error: %s", err.Error())
+				log.WithError(err).Errorf("listen key keep-alive error: %v key: %s", err, maskListenKey(listenKey))
+				s.emitReconnect()
+				return
 			}
 
-			mt, message, err := s.Conn.ReadMessage()
-			if err != nil {
-				if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway) {
-					log.WithError(err).Errorf("read error: %s", err.Error())
-				} else {
-					log.Info("websocket connection closed, going away")
 		}
+	}
+}
 
+func (s *Stream) read(ctx context.Context) {
+	defer func() {
+		if s.connCancel != nil {
+			s.connCancel()
+		}
 		s.EmitDisconnect()
+	}()
 
-				// reconnect
+	for {
-				for err != nil {
 		select {
+
 		case <-ctx.Done():
 			return
 
 		default:
-						if !s.publicOnly {
+			s.connLock.Lock()
-							if err := s.invalidateListenKey(ctx, s.ListenKey); err != nil {
+			if err := s.Conn.SetReadDeadline(time.Now().Add(5 * time.Second)); err != nil {
-								log.WithError(err).Error("invalidate listen key error")
+				log.WithError(err).Errorf("set read deadline error: %s", err.Error())
-							}
 			}
 
-						err = s.connect(ctx)
+			mt, message, err := s.Conn.ReadMessage()
-						time.Sleep(5 * time.Second)
+			s.connLock.Unlock()
-					}
+
+			if err != nil {
+				// if it's a network timeout error, we should re-connect
+				switch err := err.(type) {
+
+				// if it's a websocket related error
+				case *websocket.CloseError:
+					if err.Code == websocket.CloseNormalClosure {
+						return
 					}
 
-				continue
+					// for unexpected close error, we should re-connect
+					// emit reconnect to start a new connection
+					s.emitReconnect()
+					return
+
+				case net.Error:
+					log.WithError(err).Error("network error")
+					s.emitReconnect()
+					return
+
+				default:
+					log.WithError(err).Error("unexpected connection error")
+					s.emitReconnect()
+					return
+				}
 			}
 
 			// skip non-text messages
@@ -465,17 +533,14 @@ func (s *Stream) invalidateListenKey(ctx context.Context, listenKey string) (err
 func (s *Stream) Close() error {
 	log.Infof("closing user data stream...")
 
-	if !s.publicOnly {
+	if s.connCancel != nil {
-		if err := s.invalidateListenKey(context.Background(), s.ListenKey); err != nil {
+		s.connCancel()
-			log.WithError(err).Error("invalidate listen key error")
-		}
-		log.Infof("user data stream closed")
 	}
 
 	s.connLock.Lock()
-	defer s.connLock.Unlock()
+	err := s.Conn.Close()
-
+	s.connLock.Unlock()
-	return s.Conn.Close()
+	return err
 }
 
 func maskListenKey(listenKey string) string {

pkg/types/orderbook.go

@@ -52,6 +52,27 @@ func NewMutexOrderBook(symbol string) *MutexOrderBook {
 	}
 }
 
+func (b *MutexOrderBook) IsValid() (ok bool, err error) {
+	b.Lock()
+	ok, err = b.OrderBook.IsValid()
+	b.Unlock()
+	return ok, err
+}
+
+func (b *MutexOrderBook) BestBid() (pv PriceVolume, ok bool) {
+	b.Lock()
+	pv, ok = b.OrderBook.BestBid()
+	b.Unlock()
+	return pv, ok
+}
+
+func (b *MutexOrderBook) BestAsk() (pv PriceVolume, ok bool) {
+	b.Lock()
+	pv, ok = b.OrderBook.BestAsk()
+	b.Unlock()
+	return pv, ok
+}
+
 func (b *MutexOrderBook) Load(book SliceOrderBook) {
 	b.Lock()
 	b.OrderBook.Load(book)
@@ -66,14 +87,16 @@ func (b *MutexOrderBook) Reset() {
 
 func (b *MutexOrderBook) CopyDepth(depth int) OrderBook {
 	b.Lock()
-	defer b.Unlock()
+	book := b.OrderBook.CopyDepth(depth)
-	return b.OrderBook.CopyDepth(depth)
+	b.Unlock()
+	return book
 }
 
 func (b *MutexOrderBook) Copy() OrderBook {
 	b.Lock()
-	defer b.Unlock()
+	book := b.OrderBook.Copy()
-	return b.OrderBook.Copy()
+	b.Unlock()
+	return book
 }
 
 func (b *MutexOrderBook) Update(update SliceOrderBook) {

pkg/types/sliceorderbook.go

@@ -93,10 +93,10 @@ func (b *SliceOrderBook) PriceVolumesBySide(side SideType) PriceVolumeSlice {
 	switch side {
 
 	case SideTypeBuy:
-		return b.Bids
+		return b.Bids.Copy()
 
 	case SideTypeSell:
-		return b.Asks
+		return b.Asks.Copy()
 	}
 
 	return nil
@@ -122,11 +122,6 @@ func (b *SliceOrderBook) updateBids(pvs PriceVolumeSlice) {
 	}
 }
 
-func (b *SliceOrderBook) load(book SliceOrderBook) {
-	b.Reset()
-	b.update(book)
-}
-
 func (b *SliceOrderBook) update(book SliceOrderBook) {
 	b.updateBids(book.Bids)
 	b.updateAsks(book.Asks)
@@ -138,7 +133,8 @@ func (b *SliceOrderBook) Reset() {
 }
 
 func (b *SliceOrderBook) Load(book SliceOrderBook) {
-	b.load(book)
+	b.Reset()
+	b.update(book)
 	b.EmitLoad(b)
 }