145 lines
3.7 KiB
Go
145 lines
3.7 KiB
Go
package congestion
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import (
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"github.com/metacubex/quic-go/congestion"
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"time"
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)
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const (
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initMaxDatagramSize = 1252
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pktInfoSlotCount = 4
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minSampleCount = 50
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minAckRate = 0.8
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)
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type BrutalSender struct {
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rttStats congestion.RTTStatsProvider
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bps congestion.ByteCount
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maxDatagramSize congestion.ByteCount
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pacer *pacer
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pktInfoSlots [pktInfoSlotCount]pktInfo
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ackRate float64
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}
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type pktInfo struct {
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Timestamp int64
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AckCount uint64
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LossCount uint64
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}
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func NewBrutalSender(bps congestion.ByteCount) *BrutalSender {
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bs := &BrutalSender{
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bps: bps,
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maxDatagramSize: initMaxDatagramSize,
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ackRate: 1,
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}
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bs.pacer = newPacer(func() congestion.ByteCount {
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return congestion.ByteCount(float64(bs.bps) / bs.ackRate)
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})
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return bs
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}
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func (b *BrutalSender) SetRTTStatsProvider(rttStats congestion.RTTStatsProvider) {
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b.rttStats = rttStats
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}
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func (b *BrutalSender) TimeUntilSend(bytesInFlight congestion.ByteCount) time.Time {
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return b.pacer.TimeUntilSend()
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}
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func (b *BrutalSender) HasPacingBudget(now time.Time) bool {
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return b.pacer.Budget(now) >= b.maxDatagramSize
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}
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func (b *BrutalSender) CanSend(bytesInFlight congestion.ByteCount) bool {
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return bytesInFlight < b.GetCongestionWindow()
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}
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func (b *BrutalSender) GetCongestionWindow() congestion.ByteCount {
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rtt := maxDuration(b.rttStats.LatestRTT(), b.rttStats.SmoothedRTT())
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if rtt <= 0 {
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return 10240
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}
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return congestion.ByteCount(float64(b.bps) * rtt.Seconds() * 1.5 / b.ackRate)
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}
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func (b *BrutalSender) OnPacketSent(sentTime time.Time, bytesInFlight congestion.ByteCount,
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packetNumber congestion.PacketNumber, bytes congestion.ByteCount, isRetransmittable bool) {
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b.pacer.SentPacket(sentTime, bytes)
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}
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func (b *BrutalSender) OnPacketAcked(number congestion.PacketNumber, ackedBytes congestion.ByteCount,
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priorInFlight congestion.ByteCount, eventTime time.Time) {
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currentTimestamp := eventTime.Unix()
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slot := currentTimestamp % pktInfoSlotCount
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if b.pktInfoSlots[slot].Timestamp == currentTimestamp {
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b.pktInfoSlots[slot].AckCount++
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} else {
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// uninitialized slot or too old, reset
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b.pktInfoSlots[slot].Timestamp = currentTimestamp
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b.pktInfoSlots[slot].AckCount = 1
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b.pktInfoSlots[slot].LossCount = 0
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}
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b.updateAckRate(currentTimestamp)
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}
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func (b *BrutalSender) OnPacketLost(number congestion.PacketNumber, lostBytes congestion.ByteCount,
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priorInFlight congestion.ByteCount) {
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currentTimestamp := time.Now().Unix()
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slot := currentTimestamp % pktInfoSlotCount
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if b.pktInfoSlots[slot].Timestamp == currentTimestamp {
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b.pktInfoSlots[slot].LossCount++
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} else {
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// uninitialized slot or too old, reset
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b.pktInfoSlots[slot].Timestamp = currentTimestamp
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b.pktInfoSlots[slot].AckCount = 0
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b.pktInfoSlots[slot].LossCount = 1
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}
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b.updateAckRate(currentTimestamp)
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}
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func (b *BrutalSender) SetMaxDatagramSize(size congestion.ByteCount) {
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b.maxDatagramSize = size
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b.pacer.SetMaxDatagramSize(size)
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}
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func (b *BrutalSender) updateAckRate(currentTimestamp int64) {
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minTimestamp := currentTimestamp - pktInfoSlotCount
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var ackCount, lossCount uint64
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for _, info := range b.pktInfoSlots {
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if info.Timestamp < minTimestamp {
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continue
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}
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ackCount += info.AckCount
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lossCount += info.LossCount
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}
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if ackCount+lossCount < minSampleCount {
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b.ackRate = 1
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}
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rate := float64(ackCount) / float64(ackCount+lossCount)
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if rate < minAckRate {
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b.ackRate = minAckRate
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}
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b.ackRate = rate
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}
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func (b *BrutalSender) InSlowStart() bool {
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return false
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}
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func (b *BrutalSender) InRecovery() bool {
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return false
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}
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func (b *BrutalSender) MaybeExitSlowStart() {}
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func (b *BrutalSender) OnRetransmissionTimeout(packetsRetransmitted bool) {}
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func maxDuration(a, b time.Duration) time.Duration {
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if a > b {
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return a
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}
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return b
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}
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