snapshot of https://github.com/livekit/livekit.git @ 08c5433449c106943231037d0b892895f6e92d3b (2026-09-15)

pkg/rtc/datadowntrack.go

@@ -0,0 +1,137 @@
+// Copyright 2023 LiveKit, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package rtc
+
+import (
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/livekit/livekit-server/pkg/rtc/types"
+	"github.com/livekit/protocol/datatrack"
+	"github.com/livekit/protocol/livekit"
+	"github.com/livekit/protocol/logger"
+)
+
+var _ types.DataDownTrack = (*DataDownTrack)(nil)
+var _ types.DataTrackSender = (*DataDownTrack)(nil)
+
+type DataDownTrackParams struct {
+	Logger           logger.Logger
+	SubscriberID     livekit.ParticipantID
+	PublishDataTrack types.DataTrack
+	Handle           uint16
+	Transport        types.DataTrackTransport
+	BytesTrackStats  *BytesTrackStats
+}
+
+type DataDownTrack struct {
+	params    DataDownTrackParams
+	logger    logger.Logger
+	createdAt int64
+
+	lock    sync.Mutex
+	closed  bool
+	onClose func()
+}
+
+func NewDataDownTrack(params DataDownTrackParams) (*DataDownTrack, error) {
+	d := &DataDownTrack{
+		params:    params,
+		createdAt: time.Now().UnixNano(),
+	}
+	d.logger = params.Logger.WithValues("name", d.Name(), "handle", d.Handle())
+
+	if err := d.params.PublishDataTrack.AddDataDownTrack(d); err != nil {
+		d.logger.Warnw("could not add data down track", err)
+		return nil, err
+	}
+
+	d.logger.Infow("created data down track")
+	return d, nil
+}
+
+func (d *DataDownTrack) Close() {
+	d.lock.Lock()
+	onClose := d.onClose
+	if d.closed {
+		d.lock.Unlock()
+		return
+	}
+	d.closed = true
+	d.lock.Unlock()
+
+	d.logger.Infow("closing data down track")
+	if d.params.BytesTrackStats != nil {
+		d.params.BytesTrackStats.Stop()
+	}
+	d.params.PublishDataTrack.DeleteDataDownTrack(d.SubscriberID())
+
+	if onClose != nil {
+		onClose()
+	}
+}
+
+func (d *DataDownTrack) OnClose(fn func()) {
+	d.lock.Lock()
+	d.onClose = fn
+	closed := d.closed
+	d.lock.Unlock()
+	if closed && fn != nil {
+		fn()
+	}
+}
+
+func (d *DataDownTrack) Handle() uint16 {
+	return d.params.Handle
+}
+
+func (d *DataDownTrack) PublishDataTrack() types.DataTrack {
+	return d.params.PublishDataTrack
+}
+
+func (d *DataDownTrack) ID() livekit.TrackID {
+	return d.params.PublishDataTrack.ID()
+}
+
+func (d *DataDownTrack) Name() string {
+	return d.params.PublishDataTrack.Name()
+}
+
+func (d *DataDownTrack) SubscriberID() livekit.ParticipantID {
+	// add `createdAt` to ensure repeated subscriptions from same subscriber to same publisher does not collide
+	return livekit.ParticipantID(fmt.Sprintf("%s:%d", d.params.SubscriberID, d.createdAt))
+}
+
+func (d *DataDownTrack) WritePacket(data []byte, packet *datatrack.Packet, _arrivalTime int64) {
+	forwardedPacket := *packet
+	forwardedPacket.Handle = d.params.Handle
+	buf, err := forwardedPacket.Marshal()
+	if err != nil {
+		d.logger.Warnw("could not marshal data track message", err)
+		return
+	}
+	if err := d.params.Transport.SendDataTrackMessage(buf); err != nil {
+		d.logger.Warnw("could not send data track message", err)
+		return
+	}
+	if d.params.BytesTrackStats != nil {
+		d.params.BytesTrackStats.AddBytes(uint64(len(buf)), true)
+	}
+}
+
+func (d *DataDownTrack) UpdateSubscriptionOptions(subscriptionOptions *livekit.DataTrackSubscriptionOptions) {
+	// DT-TODO
+}