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Fix issues with unaligned atomic operations.

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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.
This commit is contained in:
Juliusz Chroboczek 2020-12-27 01:24:52 +01:00
parent e88942c9a9
commit 9e4aede72a
4 changed files with 78 additions and 49 deletions
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109
rtpconn/rtpconn.go
View file

@ -66,19 +66,23 @@ type iceConnection interface {
flushICECandidates() error
}
type downTrackAtomics struct {
rtt uint64
sr uint64
srNTP uint64
remoteNTP uint64
remoteRTP uint32
}
type rtpDownTrack struct {
track *webrtc.TrackLocalStaticRTP
remote conn.UpTrack
ssrc webrtc.SSRC
maxBitrate *bitrate
rate *estimator.Estimator
stats *receiverStats
srTime uint64
srNTPTime uint64
remoteNTPTime uint64
remoteRTPTime uint32
cname atomic.Value
rtt uint64
track *webrtc.TrackLocalStaticRTP
remote conn.UpTrack
ssrc webrtc.SSRC
maxBitrate *bitrate
rate *estimator.Estimator
stats *receiverStats
atomics *downTrackAtomics
cname atomic.Value
}
func (down *rtpDownTrack) WriteRTP(packet *rtp.Packet) error {
@ -90,8 +94,33 @@ func (down *rtpDownTrack) Accumulate(bytes uint32) {
}
func (down *rtpDownTrack) SetTimeOffset(ntp uint64, rtp uint32) {
atomic.StoreUint64(&down.remoteNTPTime, ntp)
atomic.StoreUint32(&down.remoteRTPTime, rtp)
atomic.StoreUint64(&down.atomics.remoteNTP, ntp)
atomic.StoreUint32(&down.atomics.remoteRTP, rtp)
}
func (down *rtpDownTrack) getTimeOffset() (uint64, uint32) {
ntp := atomic.LoadUint64(&down.atomics.remoteNTP)
rtp := atomic.LoadUint32(&down.atomics.remoteRTP)
return ntp, rtp
}
func (down *rtpDownTrack) getRTT() uint64 {
return atomic.LoadUint64(&down.atomics.rtt)
}
func (down *rtpDownTrack) setRTT(rtt uint64) {
atomic.StoreUint64(&down.atomics.rtt, rtt)
}
func (down *rtpDownTrack) getSRTime() (uint64, uint64) {
tm := atomic.LoadUint64(&down.atomics.sr)
ntp := atomic.LoadUint64(&down.atomics.srNTP)
return tm, ntp
}
func (down *rtpDownTrack) setSRTime(tm uint64, ntp uint64) {
atomic.StoreUint64(&down.atomics.sr, tm)
atomic.StoreUint64(&down.atomics.srNTP, ntp)
}
func (down *rtpDownTrack) SetCname(cname string) {
@ -177,21 +206,25 @@ func (down *rtpDownConnection) flushICECandidates() error {
return err
}
type rtpUpTrack struct {
track *webrtc.TrackRemote
label string
rate *estimator.Estimator
cache *packetcache.Cache
jitter *jitter.Estimator
type upTrackAtomics struct {
lastPLI uint64
lastFIR uint64
firSeqno uint32
}
type rtpUpTrack struct {
track *webrtc.TrackRemote
label string
rate *estimator.Estimator
cache *packetcache.Cache
jitter *jitter.Estimator
atomics *upTrackAtomics
cname atomic.Value
localCh chan localTrackAction
readerDone chan struct{}
mu sync.Mutex
cname string
srTime uint64
srNTPTime uint64
srRTPTime uint32
@ -477,6 +510,7 @@ func newUpConn(c group.Client, id string, labels map[string]string) (*rtpUpConne
cache: packetcache.New(minPacketCache(remote)),
rate: estimator.New(time.Second),
jitter: jitter.New(remote.Codec().ClockRate),
atomics: &upTrackAtomics{},
localCh: make(chan localTrackAction, 2),
readerDone: make(chan struct{}),
}
@ -505,12 +539,12 @@ func (up *rtpUpConnection) sendPLI(track *rtpUpTrack) error {
if !track.hasRtcpFb("nack", "pli") {
return ErrUnsupportedFeedback
}
last := atomic.LoadUint64(&track.lastPLI)
last := atomic.LoadUint64(&track.atomics.lastPLI)
now := rtptime.Jiffies()
if now >= last && now-last < rtptime.JiffiesPerSec/2 {
return ErrRateLimited
}
atomic.StoreUint64(&track.lastPLI, now)
atomic.StoreUint64(&track.atomics.lastPLI, now)
return sendPLI(up.pc, track.track.SSRC())
}
@ -525,20 +559,20 @@ func (up *rtpUpConnection) sendFIR(track *rtpUpTrack, increment bool) error {
// to drop the packet due to rate limiting.
var seqno uint8
if increment {
seqno = uint8(atomic.AddUint32(&track.firSeqno, 1) & 0xFF)
seqno = uint8(atomic.AddUint32(&track.atomics.firSeqno, 1) & 0xFF)
} else {
seqno = uint8(atomic.LoadUint32(&track.firSeqno) & 0xFF)
seqno = uint8(atomic.LoadUint32(&track.atomics.firSeqno) & 0xFF)
}
if !track.hasRtcpFb("ccm", "fir") {
return ErrUnsupportedFeedback
}
last := atomic.LoadUint64(&track.lastFIR)
last := atomic.LoadUint64(&track.atomics.lastFIR)
now := rtptime.Jiffies()
if now >= last && now-last < rtptime.JiffiesPerSec/2 {
return ErrRateLimited
}
atomic.StoreUint64(&track.lastFIR, now)
atomic.StoreUint64(&track.atomics.lastFIR, now)
return sendFIR(up.pc, track.track.SSRC(), seqno)
}
@ -709,9 +743,7 @@ func rtcpUpListener(conn *rtpUpConnection, track *rtpUpTrack, r *webrtc.RTPRecei
if i.Type != rtcp.SDESCNAME {
continue
}
track.mu.Lock()
track.cname = i.Text
track.mu.Unlock()
track.cname.Store(i.Text)
for _, l := range local {
l.SetCname(i.Text)
}
@ -847,8 +879,7 @@ func sendSR(conn *rtpDownConnection) error {
var nowRTP uint32
remoteNTP := atomic.LoadUint64(&t.remoteNTPTime)
remoteRTP := atomic.LoadUint32(&t.remoteRTPTime)
remoteNTP, remoteRTP := t.getTimeOffset()
if remoteNTP != 0 {
srTime := rtptime.NTPToTime(remoteNTP)
d := now.Sub(srTime)
@ -868,12 +899,11 @@ func sendSR(conn *rtpDownConnection) error {
PacketCount: p,
OctetCount: b,
})
atomic.StoreUint64(&t.srTime, jiffies)
atomic.StoreUint64(&t.srNTPTime, nowNTP)
t.setSRTime(jiffies, nowNTP)
}
cname, ok := t.cname.Load().(string)
if ok {
if ok && cname != "" {
item := rtcp.SourceDescriptionItem{
Type: rtcp.SDESCNAME,
Text: cname,
@ -1054,11 +1084,10 @@ func handleReport(track *rtpDownTrack, report rtcp.ReceptionReport, jiffies uint
if report.LastSenderReport != 0 {
jiffies := rtptime.Jiffies()
srTime := atomic.LoadUint64(&track.srTime)
srTime, srNTPTime := track.getSRTime()
if jiffies < srTime || jiffies-srTime > 8*rtptime.JiffiesPerSec {
return
}
srNTPTime := atomic.LoadUint64(&track.srNTPTime)
if report.LastSenderReport == uint32(srNTPTime>>16) {
delay := uint64(report.Delay) *
(rtptime.JiffiesPerSec / 0x10000)
@ -1066,12 +1095,12 @@ func handleReport(track *rtpDownTrack, report rtcp.ReceptionReport, jiffies uint
return
}
rtt := (jiffies - srTime) - delay
oldrtt := atomic.LoadUint64(&track.rtt)
oldrtt := track.getRTT()
newrtt := rtt
if oldrtt > 0 {
newrtt = (3*oldrtt + rtt) / 4
}
atomic.StoreUint64(&track.rtt, newrtt)
track.setRTT(newrtt)
}
}
}
@ -1095,7 +1124,7 @@ func updateUpTrack(track *rtpUpTrack) {
_, j := ll.stats.Get(now)
jitter := uint64(j) *
(rtptime.JiffiesPerSec / uint64(clockrate))
rtt := atomic.LoadUint64(&ll.rtt)
rtt := ll.getRTT()
rto := rtt + 4*jitter
if rto > maxrto {
maxrto = rto

3
rtpconn/rtpstats.go
View file

@ -2,7 +2,6 @@ package rtpconn
import (
"sort"
"sync/atomic"
"time"
"github.com/jech/galene/rtptime"
@ -51,7 +50,7 @@ func (c *webClient) GetStats() *stats.Client {
}
for _, t := range down.tracks {
rate, _ := t.rate.Estimate()
rtt := rtptime.ToDuration(atomic.LoadUint64(&t.rtt),
rtt := rtptime.ToDuration(t.getRTT(),
rtptime.JiffiesPerSec)
loss, jitter := t.stats.Get(jiffies)
j := time.Duration(jitter) * time.Second /

4
rtpconn/rtpwriter.go
View file

@ -266,12 +266,12 @@ func rtpWriterLoop(writer *rtpWriter, up *rtpUpConnection, track *rtpUpTrack) {
track.mu.Lock()
ntp := track.srNTPTime
rtp := track.srRTPTime
cname := track.cname
track.mu.Unlock()
if ntp != 0 {
action.track.SetTimeOffset(ntp, rtp)
}
if cname != "" {
cname, ok := track.cname.Load().(string)
if ok && cname != "" {
action.track.SetCname(cname)
}

11
rtpconn/webclient.go
View file

@ -411,6 +411,7 @@ func addDownTrack(c *webClient, conn *rtpDownConnection, remoteTrack conn.UpTrac
maxBitrate: new(bitrate),
stats: new(receiverStats),
rate: estimator.New(time.Second),
atomics: &downTrackAtomics{},
}
conn.tracks = append(conn.tracks, track)
@ -1159,7 +1160,7 @@ func handleClientMessage(c *webClient, m clientMessage) error {
c.write(clientMessage{
Type: "close",
Id: m.Id,
});
})
case "ice":
if m.Candidate == nil {
return group.ProtocolError("null candidate")
@ -1415,11 +1416,11 @@ func (c *webClient) Warn(oponly bool, message string) error {
}
return c.write(clientMessage{
Type: "usermessage",
Kind: "warning",
Dest: c.id,
Type: "usermessage",
Kind: "warning",
Dest: c.id,
Privileged: true,
Value: &message,
Value: &message,
})
}