mirror of
https://github.com/livekit/livekit.git
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f8b994d491
* Forwarding latency measurement tweaks. - prom transmission type public - do not measure short term values as it is not used and saves some lock contention time in packet path potentially. Adding a separate method for that. - Change latency/jitter summary reporting to `ns` also to match the histogram. * add GetShortStats
115 lines
2.8 KiB
Go
115 lines
2.8 KiB
Go
package sfu
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import (
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"sync"
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"time"
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"github.com/livekit/livekit-server/pkg/telemetry/prometheus"
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"github.com/livekit/protocol/logger"
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"github.com/livekit/protocol/utils"
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"github.com/livekit/protocol/utils/mono"
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)
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const (
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cHighForwardingLatency = 20 * time.Millisecond
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cSkewFactor = 10
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)
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type ForwardStats struct {
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lock sync.Mutex
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latency *utils.LatencyAggregate
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lowest int64
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highest int64
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lastUpdateAt int64
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closeCh chan struct{}
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}
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func NewForwardStats(latencyUpdateInterval, reportInterval, latencyWindowLength time.Duration) *ForwardStats {
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s := &ForwardStats{
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latency: utils.NewLatencyAggregate(latencyUpdateInterval, latencyWindowLength),
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lowest: time.Second.Nanoseconds(),
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closeCh: make(chan struct{}),
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}
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go s.report(reportInterval)
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return s
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}
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func (s *ForwardStats) Update(arrival, left int64) (int64, bool) {
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transit := left - arrival
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isHighForwardingLatency := false
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if time.Duration(transit) > cHighForwardingLatency {
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isHighForwardingLatency = true
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}
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s.lock.Lock()
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s.latency.Update(time.Duration(arrival), float64(transit))
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s.lowest = min(transit, s.lowest)
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s.highest = max(transit, s.highest)
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s.lastUpdateAt = arrival
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s.lock.Unlock()
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prometheus.RecordForwardLatencySample(transit)
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return transit, isHighForwardingLatency
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}
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func (s *ForwardStats) GetStats(shortDuration time.Duration) (time.Duration, time.Duration) {
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s.lock.Lock()
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// a dummy sample to flush the pipe to current time
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now := mono.UnixNano()
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if (now - s.lastUpdateAt) > shortDuration.Nanoseconds() {
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s.latency.Update(time.Duration(now), 0)
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}
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wLong := s.latency.Summarize()
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lowest := s.lowest
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s.lowest = time.Second.Nanoseconds()
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highest := s.highest
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s.highest = 0
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s.lock.Unlock()
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latencyLong, jitterLong := time.Duration(wLong.Mean()), time.Duration(wLong.StdDev())
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if jitterLong > latencyLong*cSkewFactor {
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logger.Infow(
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"high jitter in forwarding path",
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"lowest", time.Duration(lowest),
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"highest", time.Duration(highest),
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"countLong", wLong.Count(),
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"latencyLong", latencyLong,
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"jitterLong", jitterLong,
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)
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}
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return latencyLong, jitterLong
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}
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func (s *ForwardStats) GetShortStats(shortDuration time.Duration) (time.Duration, time.Duration) {
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s.lock.Lock()
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wShort := s.latency.SummarizeLast(shortDuration)
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s.lock.Unlock()
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return time.Duration(wShort.Mean()), time.Duration(wShort.StdDev())
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}
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func (s *ForwardStats) Stop() {
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close(s.closeCh)
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}
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func (s *ForwardStats) report(reportInterval time.Duration) {
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ticker := time.NewTicker(reportInterval)
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defer ticker.Stop()
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for {
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select {
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case <-s.closeCh:
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return
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case <-ticker.C:
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latencyLong, jitterLong := s.GetStats(reportInterval)
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prometheus.RecordForwardJitter(uint32(jitterLong.Nanoseconds()))
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prometheus.RecordForwardLatency(uint32(latencyLong.Nanoseconds()))
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}
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}
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}
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