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switch to a byte-based congestion controller

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Chrome removed the packet-based congestion controller and switched to
byte-based as well.
This commit is contained in:
Marten Seemann
2018-04-06 14:54:20 +07:00
parent 2127e2f1de
commit 2b97fb41c9
13 changed files with 442 additions and 459 deletions
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23
internal/congestion/prr_sender.go
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@@ -1,10 +1,7 @@
package congestion
import (
"time"
"github.com/lucas-clemente/quic-go/internal/protocol"
"github.com/lucas-clemente/quic-go/internal/utils"
)
// PrrSender implements the Proportional Rate Reduction (PRR) per RFC 6937
@@ -23,9 +20,9 @@ func (p *PrrSender) OnPacketSent(sentBytes protocol.ByteCount) {
// OnPacketLost should be called on the first loss that triggers a recovery
// period and all other methods in this class should only be called when in
// recovery.
func (p *PrrSender) OnPacketLost(bytesInFlight protocol.ByteCount) {
func (p *PrrSender) OnPacketLost(priorInFlight protocol.ByteCount) {
p.bytesSentSinceLoss = 0
p.bytesInFlightBeforeLoss = bytesInFlight
p.bytesInFlightBeforeLoss = priorInFlight
p.bytesDeliveredSinceLoss = 0
p.ackCountSinceLoss = 0
}
@@ -36,28 +33,22 @@ func (p *PrrSender) OnPacketAcked(ackedBytes protocol.ByteCount) {
p.ackCountSinceLoss++
}
// TimeUntilSend calculates the time until a packet can be sent
func (p *PrrSender) TimeUntilSend(congestionWindow, bytesInFlight, slowstartThreshold protocol.ByteCount) time.Duration {
// CanSend returns if packets can be sent
func (p *PrrSender) CanSend(congestionWindow, bytesInFlight, slowstartThreshold protocol.ByteCount) bool {
// Return QuicTime::Zero In order to ensure limited transmit always works.
if p.bytesSentSinceLoss == 0 || bytesInFlight < protocol.DefaultTCPMSS {
return 0
return true
}
if congestionWindow > bytesInFlight {
// During PRR-SSRB, limit outgoing packets to 1 extra MSS per ack, instead
// of sending the entire available window. This prevents burst retransmits
// when more packets are lost than the CWND reduction.
// limit = MAX(prr_delivered - prr_out, DeliveredData) + MSS
if p.bytesDeliveredSinceLoss+p.ackCountSinceLoss*protocol.DefaultTCPMSS <= p.bytesSentSinceLoss {
return utils.InfDuration
}
return 0
return p.bytesDeliveredSinceLoss+p.ackCountSinceLoss*protocol.DefaultTCPMSS > p.bytesSentSinceLoss
}
// Implement Proportional Rate Reduction (RFC6937).
// Checks a simplified version of the PRR formula that doesn't use division:
// AvailableSendWindow =
// CEIL(prr_delivered * ssthresh / BytesInFlightAtLoss) - prr_sent
if p.bytesDeliveredSinceLoss*slowstartThreshold > p.bytesSentSinceLoss*p.bytesInFlightBeforeLoss {
return 0
}
return utils.InfDuration
return p.bytesDeliveredSinceLoss*slowstartThreshold > p.bytesSentSinceLoss*p.bytesInFlightBeforeLoss
}