Squashed 'livekit-server/' content from commit 154b4d26

git-subtree-dir: livekit-server
git-subtree-split: 154b4d26b769c68a03c096124094b97bf61a996f

pkg/sfu/downtrackspreader.go

@@ -0,0 +1,118 @@
+// 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 sfu
+
+import (
+	"sync"
+
+	"github.com/livekit/protocol/livekit"
+	"github.com/livekit/protocol/logger"
+	"github.com/livekit/protocol/utils"
+)
+
+type DownTrackSpreaderParams struct {
+	Threshold int
+	Logger    logger.Logger
+}
+
+type DownTrackSpreader struct {
+	params DownTrackSpreaderParams
+
+	downTrackMu      sync.RWMutex
+	downTracks       map[livekit.ParticipantID]TrackSender
+	downTracksShadow []TrackSender
+}
+
+func NewDownTrackSpreader(params DownTrackSpreaderParams) *DownTrackSpreader {
+	d := &DownTrackSpreader{
+		params:     params,
+		downTracks: make(map[livekit.ParticipantID]TrackSender),
+	}
+
+	return d
+}
+
+func (d *DownTrackSpreader) GetDownTracks() []TrackSender {
+	d.downTrackMu.RLock()
+	defer d.downTrackMu.RUnlock()
+	return d.downTracksShadow
+}
+
+func (d *DownTrackSpreader) ResetAndGetDownTracks() []TrackSender {
+	d.downTrackMu.Lock()
+	defer d.downTrackMu.Unlock()
+
+	downTracks := d.downTracksShadow
+
+	d.downTracks = make(map[livekit.ParticipantID]TrackSender)
+	d.downTracksShadow = nil
+
+	return downTracks
+}
+
+func (d *DownTrackSpreader) Store(ts TrackSender) {
+	d.downTrackMu.Lock()
+	defer d.downTrackMu.Unlock()
+
+	d.downTracks[ts.SubscriberID()] = ts
+	d.shadowDownTracks()
+}
+
+func (d *DownTrackSpreader) Free(subscriberID livekit.ParticipantID) {
+	d.downTrackMu.Lock()
+	defer d.downTrackMu.Unlock()
+
+	delete(d.downTracks, subscriberID)
+	d.shadowDownTracks()
+}
+
+func (d *DownTrackSpreader) HasDownTrack(subscriberID livekit.ParticipantID) bool {
+	d.downTrackMu.RLock()
+	defer d.downTrackMu.RUnlock()
+
+	_, ok := d.downTracks[subscriberID]
+	return ok
+}
+
+func (d *DownTrackSpreader) Broadcast(writer func(TrackSender)) int {
+	downTracks := d.GetDownTracks()
+	if len(downTracks) == 0 {
+		return 0
+	}
+
+	threshold := uint64(d.params.Threshold)
+	if threshold == 0 {
+		threshold = 1000000
+	}
+
+	// 100µs is enough to amortize the overhead and provide sufficient load balancing.
+	// WriteRTP takes about 50µs on average, so we write to 2 down tracks per loop.
+	step := uint64(2)
+	utils.ParallelExec(downTracks, threshold, step, writer)
+	return len(downTracks)
+}
+
+func (d *DownTrackSpreader) DownTrackCount() int {
+	d.downTrackMu.RLock()
+	defer d.downTrackMu.RUnlock()
+	return len(d.downTracksShadow)
+}
+
+func (d *DownTrackSpreader) shadowDownTracks() {
+	d.downTracksShadow = make([]TrackSender, 0, len(d.downTracks))
+	for _, dt := range d.downTracks {
+		d.downTracksShadow = append(d.downTracksShadow, dt)
+	}
+}