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privatize some methods in the congestion controller package

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This commit is contained in:
Marten Seemann 2020-07-22 13:42:18 +07:00
parent c8255cbaf5
commit e79e45e3a2
2 changed files with 22 additions and 38 deletions
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38
internal/congestion/cubic_sender.go
View file

@ -54,7 +54,7 @@ type cubicSender struct {
maxCongestionWindow protocol.ByteCount maxCongestionWindow protocol.ByteCount
// Slow start congestion window in bytes, aka ssthresh. // Slow start congestion window in bytes, aka ssthresh.
slowstartThreshold protocol.ByteCount slowStartThreshold protocol.ByteCount
// Number of connections to simulate. // Number of connections to simulate.
numConnections int numConnections int
@ -86,7 +86,7 @@ func newCubicSender(clock Clock, rttStats *RTTStats, reno bool, initialCongestio
initialMaxCongestionWindow: initialMaxCongestionWindow, initialMaxCongestionWindow: initialMaxCongestionWindow,
congestionWindow: initialCongestionWindow, congestionWindow: initialCongestionWindow,
minCongestionWindow: minCongestionWindow, minCongestionWindow: minCongestionWindow,
slowstartThreshold: initialMaxCongestionWindow, slowStartThreshold: initialMaxCongestionWindow,
maxCongestionWindow: initialMaxCongestionWindow, maxCongestionWindow: initialMaxCongestionWindow,
numConnections: defaultNumConnections, numConnections: defaultNumConnections,
cubic: NewCubic(clock), cubic: NewCubic(clock),
@ -130,28 +130,17 @@ func (c *cubicSender) InRecovery() bool {
} }
func (c *cubicSender) InSlowStart() bool { func (c *cubicSender) InSlowStart() bool {
return c.GetCongestionWindow() < c.GetSlowStartThreshold() return c.GetCongestionWindow() < c.slowStartThreshold
} }
func (c *cubicSender) GetCongestionWindow() protocol.ByteCount { func (c *cubicSender) GetCongestionWindow() protocol.ByteCount {
return c.congestionWindow return c.congestionWindow
} }
func (c *cubicSender) GetSlowStartThreshold() protocol.ByteCount {
return c.slowstartThreshold
}
func (c *cubicSender) ExitSlowstart() {
c.slowstartThreshold = c.congestionWindow
}
func (c *cubicSender) SlowstartThreshold() protocol.ByteCount {
return c.slowstartThreshold
}
func (c *cubicSender) MaybeExitSlowStart() { func (c *cubicSender) MaybeExitSlowStart() {
if c.InSlowStart() && c.hybridSlowStart.ShouldExitSlowStart(c.rttStats.LatestRTT(), c.rttStats.MinRTT(), c.GetCongestionWindow()/maxDatagramSize) { if c.InSlowStart() && c.hybridSlowStart.ShouldExitSlowStart(c.rttStats.LatestRTT(), c.rttStats.MinRTT(), c.GetCongestionWindow()/maxDatagramSize) {
c.ExitSlowstart() // exit slow start
c.slowStartThreshold = c.congestionWindow
} }
} }
@ -185,7 +174,7 @@ func (c *cubicSender) OnPacketLost(
if c.slowStartLargeReduction { if c.slowStartLargeReduction {
// Reduce congestion window by lost_bytes for every loss. // Reduce congestion window by lost_bytes for every loss.
c.congestionWindow = utils.MaxByteCount(c.congestionWindow-lostBytes, c.minSlowStartExitWindow) c.congestionWindow = utils.MaxByteCount(c.congestionWindow-lostBytes, c.minSlowStartExitWindow)
c.slowstartThreshold = c.congestionWindow c.slowStartThreshold = c.congestionWindow
} }
} }
return return
@ -202,21 +191,21 @@ func (c *cubicSender) OnPacketLost(
} }
c.congestionWindow -= maxDatagramSize c.congestionWindow -= maxDatagramSize
} else if c.reno { } else if c.reno {
c.congestionWindow = protocol.ByteCount(float32(c.congestionWindow) * c.RenoBeta()) c.congestionWindow = protocol.ByteCount(float32(c.congestionWindow) * c.renoBeta())
} else { } else {
c.congestionWindow = c.cubic.CongestionWindowAfterPacketLoss(c.congestionWindow) c.congestionWindow = c.cubic.CongestionWindowAfterPacketLoss(c.congestionWindow)
} }
if c.congestionWindow < c.minCongestionWindow { if c.congestionWindow < c.minCongestionWindow {
c.congestionWindow = c.minCongestionWindow c.congestionWindow = c.minCongestionWindow
} }
c.slowstartThreshold = c.congestionWindow c.slowStartThreshold = c.congestionWindow
c.largestSentAtLastCutback = c.largestSentPacketNumber c.largestSentAtLastCutback = c.largestSentPacketNumber
// reset packet count from congestion avoidance mode. We start // reset packet count from congestion avoidance mode. We start
// counting again when we're out of recovery. // counting again when we're out of recovery.
c.numAckedPackets = 0 c.numAckedPackets = 0
} }
func (c *cubicSender) RenoBeta() float32 { func (c *cubicSender) renoBeta() float32 {
// kNConnectionBeta is the backoff factor after loss for our N-connection // kNConnectionBeta is the backoff factor after loss for our N-connection
// emulation, which emulates the effective backoff of an ensemble of N // emulation, which emulates the effective backoff of an ensemble of N
// TCP-Reno connections on a single loss event. The effective multiplier is // TCP-Reno connections on a single loss event. The effective multiplier is
@ -281,11 +270,6 @@ func (c *cubicSender) BandwidthEstimate() Bandwidth {
return BandwidthFromDelta(c.GetCongestionWindow(), srtt) return BandwidthFromDelta(c.GetCongestionWindow(), srtt)
} }
// HybridSlowStart returns the hybrid slow start instance for testing
func (c *cubicSender) HybridSlowStart() *HybridSlowStart {
return &c.hybridSlowStart
}
// SetNumEmulatedConnections sets the number of emulated connections // SetNumEmulatedConnections sets the number of emulated connections
func (c *cubicSender) SetNumEmulatedConnections(n int) { func (c *cubicSender) SetNumEmulatedConnections(n int) {
c.numConnections = utils.Max(n, 1) c.numConnections = utils.Max(n, 1)
@ -300,7 +284,7 @@ func (c *cubicSender) OnRetransmissionTimeout(packetsRetransmitted bool) {
} }
c.hybridSlowStart.Restart() c.hybridSlowStart.Restart()
c.cubic.Reset() c.cubic.Reset()
c.slowstartThreshold = c.congestionWindow / 2 c.slowStartThreshold = c.congestionWindow / 2
c.congestionWindow = c.minCongestionWindow c.congestionWindow = c.minCongestionWindow
} }
@ -314,7 +298,7 @@ func (c *cubicSender) OnConnectionMigration() {
c.cubic.Reset() c.cubic.Reset()
c.numAckedPackets = 0 c.numAckedPackets = 0
c.congestionWindow = c.initialCongestionWindow c.congestionWindow = c.initialCongestionWindow
c.slowstartThreshold = c.initialMaxCongestionWindow c.slowStartThreshold = c.initialMaxCongestionWindow
c.maxCongestionWindow = c.initialMaxCongestionWindow c.maxCongestionWindow = c.initialMaxCongestionWindow
} }

22
internal/congestion/cubic_sender_test.go
View file

@ -182,9 +182,9 @@ var _ = Describe("Cubic Sender", func() {
Expect(sender.GetCongestionWindow()).To(Equal(expectedSendWindow)) Expect(sender.GetCongestionWindow()).To(Equal(expectedSendWindow))
// Now RTO and ensure slow start gets reset. // Now RTO and ensure slow start gets reset.
Expect(sender.HybridSlowStart().Started()).To(BeTrue()) Expect(sender.hybridSlowStart.Started()).To(BeTrue())
sender.OnRetransmissionTimeout(true) sender.OnRetransmissionTimeout(true)
Expect(sender.HybridSlowStart().Started()).To(BeFalse()) Expect(sender.hybridSlowStart.Started()).To(BeFalse())
}) })
It("slow start packet loss with large reduction", func() { It("slow start packet loss with large reduction", func() {
@ -233,9 +233,9 @@ var _ = Describe("Cubic Sender", func() {
Expect(sender.GetCongestionWindow()).To(Equal(expectedSendWindow)) Expect(sender.GetCongestionWindow()).To(Equal(expectedSendWindow))
// Now RTO and ensure slow start gets reset. // Now RTO and ensure slow start gets reset.
Expect(sender.HybridSlowStart().Started()).To(BeTrue()) Expect(sender.hybridSlowStart.Started()).To(BeTrue())
sender.OnRetransmissionTimeout(true) sender.OnRetransmissionTimeout(true)
Expect(sender.HybridSlowStart().Started()).To(BeFalse()) Expect(sender.hybridSlowStart.Started()).To(BeFalse())
}) })
It("slow start half packet loss with large reduction", func() { It("slow start half packet loss with large reduction", func() {
@ -368,13 +368,13 @@ var _ = Describe("Cubic Sender", func() {
It("RTO congestion window", func() { It("RTO congestion window", func() {
Expect(sender.GetCongestionWindow()).To(Equal(defaultWindowTCP)) Expect(sender.GetCongestionWindow()).To(Equal(defaultWindowTCP))
Expect(sender.SlowstartThreshold()).To(Equal(MaxCongestionWindow)) Expect(sender.slowStartThreshold).To(Equal(MaxCongestionWindow))
// Expect the window to decrease to the minimum once the RTO fires // Expect the window to decrease to the minimum once the RTO fires
// and slow start threshold to be set to 1/2 of the CWND. // and slow start threshold to be set to 1/2 of the CWND.
sender.OnRetransmissionTimeout(true) sender.OnRetransmissionTimeout(true)
Expect(sender.GetCongestionWindow()).To(Equal(2 * maxDatagramSize)) Expect(sender.GetCongestionWindow()).To(Equal(2 * maxDatagramSize))
Expect(sender.SlowstartThreshold()).To(Equal(5 * maxDatagramSize)) Expect(sender.slowStartThreshold).To(Equal(5 * maxDatagramSize))
}) })
It("RTO congestion window no retransmission", func() { It("RTO congestion window no retransmission", func() {
@ -458,7 +458,7 @@ var _ = Describe("Cubic Sender", func() {
LoseNPackets(1) LoseNPackets(1)
// We should now have fallen out of slow start with a reduced window. // We should now have fallen out of slow start with a reduced window.
expectedSendWindow = protocol.ByteCount(float32(expectedSendWindow) * sender.RenoBeta()) expectedSendWindow = protocol.ByteCount(float32(expectedSendWindow) * sender.renoBeta())
Expect(sender.GetCongestionWindow()).To(Equal(expectedSendWindow)) Expect(sender.GetCongestionWindow()).To(Equal(expectedSendWindow))
// No congestion window growth should occur in recovery phase, i.e., until the // No congestion window growth should occur in recovery phase, i.e., until the
@ -557,7 +557,7 @@ var _ = Describe("Cubic Sender", func() {
It("reset after connection migration", func() { It("reset after connection migration", func() {
Expect(sender.GetCongestionWindow()).To(Equal(defaultWindowTCP)) Expect(sender.GetCongestionWindow()).To(Equal(defaultWindowTCP))
Expect(sender.SlowstartThreshold()).To(Equal(MaxCongestionWindow)) Expect(sender.slowStartThreshold).To(Equal(MaxCongestionWindow))
// Starts with slow start. // Starts with slow start.
sender.SetNumEmulatedConnections(1) sender.SetNumEmulatedConnections(1)
@ -578,13 +578,13 @@ var _ = Describe("Cubic Sender", func() {
// start threshold is also updated. // start threshold is also updated.
expectedSendWindow = protocol.ByteCount(float32(expectedSendWindow) * renoBeta) expectedSendWindow = protocol.ByteCount(float32(expectedSendWindow) * renoBeta)
Expect(sender.GetCongestionWindow()).To(Equal(expectedSendWindow)) Expect(sender.GetCongestionWindow()).To(Equal(expectedSendWindow))
Expect(sender.SlowstartThreshold()).To(Equal(expectedSendWindow)) Expect(sender.slowStartThreshold).To(Equal(expectedSendWindow))
// Resets cwnd and slow start threshold on connection migrations. // Resets cwnd and slow start threshold on connection migrations.
sender.OnConnectionMigration() sender.OnConnectionMigration()
Expect(sender.GetCongestionWindow()).To(Equal(defaultWindowTCP)) Expect(sender.GetCongestionWindow()).To(Equal(defaultWindowTCP))
Expect(sender.SlowstartThreshold()).To(Equal(MaxCongestionWindow)) Expect(sender.slowStartThreshold).To(Equal(MaxCongestionWindow))
Expect(sender.HybridSlowStart().Started()).To(BeFalse()) Expect(sender.hybridSlowStart.Started()).To(BeFalse())
}) })
It("default max cwnd", func() { It("default max cwnd", func() {