1
Fork 0
mirror of https://github.com/jech/galene.git synced 2024-12-23 07:45:46 +01:00
galene/rtpconn/rtpwriter.go
Juliusz Chroboczek 9e4aede72a Fix issues with unaligned atomic operations.
This could be solved by simply reordering the fields, but it
is more robust to move the atomics into their own structure,
and the extra indirection should not cost much.
2020-12-27 01:31:31 +01:00

434 lines
8.4 KiB
Go

package rtpconn
import (
"errors"
"log"
"sort"
"strings"
"time"
"github.com/pion/rtp"
"github.com/jech/galene/conn"
"github.com/jech/galene/packetcache"
"github.com/jech/galene/rtptime"
)
// packetIndex is a request to send a packet from the cache.
type packetIndex struct {
// the packet's seqno
seqno uint16
// the index in the cache
index uint16
}
// An rtpWriterPool is a set of rtpWriters
type rtpWriterPool struct {
conn *rtpUpConnection
track *rtpUpTrack
writers []*rtpWriter
count int
}
// sqrt computes the integer square root
func sqrt(n int) int {
if n < 2 {
return n
}
s := sqrt(n/2) * 2
l := s + 1
if l*l > n {
return s
} else {
return l
}
}
// add adds or removes a track from a writer pool
func (wp *rtpWriterPool) add(track conn.DownTrack, add bool) error {
n := 4
if wp.count > 16 {
n = sqrt(wp.count)
}
i := 0
for i < len(wp.writers) {
w := wp.writers[i]
err := w.add(track, add, n)
if err == nil {
if add {
wp.count++
} else {
if wp.count > 0 {
wp.count--
} else {
log.Printf("Negative writer count!")
}
}
return nil
} else if err == ErrWriterDead {
wp.del(wp.writers[i])
} else {
i++
}
}
if add {
writer := newRtpWriter(wp.conn, wp.track)
wp.writers = append(wp.writers, writer)
err := writer.add(track, true, n)
if err == nil {
wp.count++
}
return err
} else {
return errors.New("deleting unknown track")
}
}
// del deletes a writer.
func (wp *rtpWriterPool) del(w *rtpWriter) bool {
for i, ww := range wp.writers {
if ww == w {
close(w.ch)
wp.writers = append(wp.writers[:i], wp.writers[i+1:]...)
return true
}
}
return false
}
// close deletes all writers.
func (wp *rtpWriterPool) close() {
for _, w := range wp.writers {
close(w.ch)
}
wp.writers = nil
wp.count = 0
}
// write writes a packet stored in the packet cache to all local tracks
func (wp *rtpWriterPool) write(seqno uint16, index uint16, delay uint32, isvideo bool, marker bool) {
pi := packetIndex{seqno, index}
var dead []*rtpWriter
for _, w := range wp.writers {
if w.drop > 0 {
// currently dropping
if marker {
// last packet in frame
w.drop = 0
} else {
w.drop--
}
continue
}
select {
case w.ch <- pi:
// all is well
case <-w.done:
// the writer is dead.
dead = append(dead, w)
default:
// the writer is congested
if isvideo {
// drop until the end of the frame
if !marker {
w.drop = 7
}
continue
}
// audio, try again with a delay
d := delay / uint32(2*len(wp.writers))
timer := time.NewTimer(rtptime.ToDuration(
uint64(d), rtptime.JiffiesPerSec,
))
select {
case w.ch <- pi:
timer.Stop()
case <-w.done:
dead = append(dead, w)
case <-timer.C:
}
}
}
if dead != nil {
for _, d := range dead {
wp.del(d)
}
dead = nil
}
}
var ErrWriterDead = errors.New("writer is dead")
var ErrWriterBusy = errors.New("writer is busy")
var ErrUnknownTrack = errors.New("unknown track")
type writerAction struct {
add bool
track conn.DownTrack
maxTracks int
ch chan error
}
// an rtpWriter is a thread writing to a set of tracks.
type rtpWriter struct {
ch chan packetIndex
done chan struct{}
action chan writerAction
// this is not touched by the writer loop, used by the caller
drop int
}
func newRtpWriter(conn *rtpUpConnection, track *rtpUpTrack) *rtpWriter {
writer := &rtpWriter{
ch: make(chan packetIndex, 32),
done: make(chan struct{}),
action: make(chan writerAction, 1),
}
go rtpWriterLoop(writer, conn, track)
return writer
}
// add adds or removes a track from a writer.
func (writer *rtpWriter) add(track conn.DownTrack, add bool, max int) error {
ch := make(chan error, 1)
select {
case writer.action <- writerAction{add, track, max, ch}:
select {
case err := <-ch:
return err
case <-writer.done:
return ErrWriterDead
}
case <-writer.done:
return ErrWriterDead
}
}
func sendKeyframe(kf []uint16, track conn.DownTrack, cache *packetcache.Cache) {
buf := make([]byte, packetcache.BufSize)
var packet rtp.Packet
for _, seqno := range kf {
bytes := cache.Get(seqno, buf)
if bytes == 0 {
return
}
err := packet.Unmarshal(buf[:bytes])
if err != nil {
return
}
err = track.WriteRTP(&packet)
if err != nil && err != conn.ErrKeyframeNeeded {
return
}
track.Accumulate(uint32(bytes))
}
}
const (
kfUnneeded = iota
kfNeededPLI
kfNeededFIR
kfNeededNewFIR
)
// rtpWriterLoop is the main loop of an rtpWriter.
func rtpWriterLoop(writer *rtpWriter, up *rtpUpConnection, track *rtpUpTrack) {
defer close(writer.done)
codec := track.track.Codec()
buf := make([]byte, packetcache.BufSize)
var packet rtp.Packet
local := make([]conn.DownTrack, 0)
kfNeeded := kfUnneeded
for {
select {
case action := <-writer.action:
if action.add {
if len(local) >= action.maxTracks {
action.ch <- ErrWriterBusy
close(action.ch)
continue
}
local = append(local, action.track)
action.ch <- nil
close(action.ch)
track.mu.Lock()
ntp := track.srNTPTime
rtp := track.srRTPTime
track.mu.Unlock()
if ntp != 0 {
action.track.SetTimeOffset(ntp, rtp)
}
cname, ok := track.cname.Load().(string)
if ok && cname != "" {
action.track.SetCname(cname)
}
found, _, lts := track.cache.Last()
kts, _, kf := track.cache.Keyframe()
if strings.ToLower(codec.MimeType) == "video/vp8" &&
found && len(kf) > 0 {
if ((lts-kts)&0x80000000) != 0 ||
lts-kts < 2*90000 {
// we got a recent keyframe
go sendKeyframe(
kf,
action.track,
track.cache,
)
} else {
// Request a new keyframe
kfNeeded = kfNeededNewFIR
}
} else {
// no keyframe yet, one should
// arrive soon. Do nothing.
}
} else {
found := false
for i, t := range local {
if t == action.track {
local = append(local[:i],
local[i+1:]...)
found = true
break
}
}
if !found {
action.ch <- ErrUnknownTrack
} else {
action.ch <- nil
}
close(action.ch)
if len(local) == 0 {
return
}
}
case pi, ok := <-writer.ch:
if !ok {
return
}
bytes := track.cache.GetAt(pi.seqno, pi.index, buf)
if bytes == 0 {
continue
}
err := packet.Unmarshal(buf[:bytes])
if err != nil {
continue
}
for _, l := range local {
err := l.WriteRTP(&packet)
if err != nil {
if err == conn.ErrKeyframeNeeded {
kfNeeded = kfNeededPLI
} else {
continue
}
}
l.Accumulate(uint32(bytes))
}
if kfNeeded > kfUnneeded {
kf, kfKnown :=
isKeyframe(codec.MimeType, &packet)
if kf {
kfNeeded = kfUnneeded
}
if kfNeeded >= kfNeededFIR {
err := up.sendFIR(
track,
kfNeeded >= kfNeededNewFIR,
)
if err == ErrUnsupportedFeedback {
kfNeeded = kfNeededPLI
} else {
kfNeeded = kfNeededFIR
}
}
if kfNeeded == kfNeededPLI {
up.sendPLI(track)
}
if !kfKnown {
// we cannot detect keyframes for
// this codec, reset our state
kfNeeded = kfUnneeded
}
}
}
}
}
// nackWriter is called when bufferedNACKs becomes non-empty. It decides
// which nacks to ship out.
func nackWriter(conn *rtpUpConnection, track *rtpUpTrack) {
// a client might send us a NACK for a packet that has already
// been nacked by the reader loop. Give recovery a chance.
time.Sleep(50 * time.Millisecond)
track.mu.Lock()
nacks := track.bufferedNACKs
track.bufferedNACKs = nil
track.mu.Unlock()
if len(nacks) == 0 || !track.hasRtcpFb("nack", "") {
return
}
time.Sleep(50 * time.Millisecond)
// drop any nacks before the last keyframe
var cutoff uint16
found, seqno, _ := track.cache.KeyframeSeqno()
if found {
cutoff = seqno
} else {
last, lastSeqno, _ := track.cache.Last()
if !last {
// NACK on a fresh track? Give up.
return
}
// no keyframe, use an arbitrary cutoff
cutoff = lastSeqno - 256
}
i := 0
for i < len(nacks) {
if ((nacks[i] - cutoff) & 0x8000) != 0 {
// earlier than the cutoff, drop
nacks = append(nacks[:i], nacks[i+1:]...)
continue
}
l := track.cache.Get(nacks[i], nil)
if l > 0 {
// the packet arrived in the meantime
nacks = append(nacks[:i], nacks[i+1:]...)
continue
}
i++
}
sort.Slice(nacks, func(i, j int) bool {
return nacks[i]-cutoff < nacks[j]-cutoff
})
if len(nacks) > 0 {
conn.sendNACKs(track, nacks)
}
}