congestion

Documentation

Index

• func NewCubicSender(clock Clock, rttStats *utils.RTTStats, ...) *cubicSender
• type Bandwidth
  • func BandwidthFromDelta(bytes protocol.ByteCount, delta time.Duration) Bandwidth
• type Clock
• type Cubic
  • func NewCubic(clock Clock) *Cubic
  • func (c *Cubic) CongestionWindowAfterAck(ackedBytes protocol.ByteCount, currentCongestionWindow protocol.ByteCount, ...) protocol.ByteCount
  • func (c *Cubic) CongestionWindowAfterPacketLoss(currentCongestionWindow protocol.ByteCount) protocol.ByteCount
  • func (c *Cubic) OnApplicationLimited()
  • func (c *Cubic) Reset()
  • func (c *Cubic) SetNumConnections(n int)
• type DefaultClock
  • func (DefaultClock) Now() time.Time
• type HybridSlowStart
  • func (s *HybridSlowStart) IsEndOfRound(ack protocol.PacketNumber) bool
  • func (s *HybridSlowStart) OnPacketAcked(ackedPacketNumber protocol.PacketNumber)
  • func (s *HybridSlowStart) OnPacketSent(packetNumber protocol.PacketNumber)
  • func (s *HybridSlowStart) Restart()
  • func (s *HybridSlowStart) ShouldExitSlowStart(latestRTT time.Duration, minRTT time.Duration, ...) bool
  • func (s *HybridSlowStart) StartReceiveRound(lastSent protocol.PacketNumber)
  • func (s *HybridSlowStart) Started() bool
• type SendAlgorithm
• type SendAlgorithmWithDebugInfos

Functions

func NewCubicSender

func NewCubicSender(
	clock Clock,
	rttStats *utils.RTTStats,
	initialMaxDatagramSize protocol.ByteCount,
	reno bool,
	tracer *logging.ConnectionTracer,
) *cubicSender

NewCubicSender makes a new cubic sender

Types

type Bandwidth

type Bandwidth uint64

Bandwidth of a connection

const (
	// BitsPerSecond is 1 bit per second
	BitsPerSecond Bandwidth = 1
	// BytesPerSecond is 1 byte per second
	BytesPerSecond = 8 * BitsPerSecond
)

func BandwidthFromDelta

func BandwidthFromDelta(bytes protocol.ByteCount, delta time.Duration) Bandwidth

BandwidthFromDelta calculates the bandwidth from a number of bytes and a time delta

type Clock

type Clock interface {
	Now() time.Time
}

A Clock returns the current time

type Cubic

type Cubic struct {
	// contains filtered or unexported fields
}

Cubic implements the cubic algorithm from TCP

func NewCubic

func NewCubic(clock Clock) *Cubic

NewCubic returns a new Cubic instance

func (*Cubic) CongestionWindowAfterAck

func (c *Cubic) CongestionWindowAfterAck(
	ackedBytes protocol.ByteCount,
	currentCongestionWindow protocol.ByteCount,
	delayMin time.Duration,
	eventTime time.Time,
) protocol.ByteCount

CongestionWindowAfterAck computes a new congestion window to use after a received ACK. Returns the new congestion window in packets. The new congestion window follows a cubic function that depends on the time passed since last packet loss.

func (*Cubic) CongestionWindowAfterPacketLoss

func (c *Cubic) CongestionWindowAfterPacketLoss(currentCongestionWindow protocol.ByteCount) protocol.ByteCount

CongestionWindowAfterPacketLoss computes a new congestion window to use after a loss event. Returns the new congestion window in packets. The new congestion window is a multiplicative decrease of our current window.

func (*Cubic) OnApplicationLimited

func (c *Cubic) OnApplicationLimited()

OnApplicationLimited is called on ack arrival when sender is unable to use the available congestion window. Resets Cubic state during quiescence.

func (*Cubic) Reset

func (c *Cubic) Reset()

Reset is called after a timeout to reset the cubic state

func (*Cubic) SetNumConnections

func (c *Cubic) SetNumConnections(n int)

SetNumConnections sets the number of emulated connections

type DefaultClock

type DefaultClock struct{}

DefaultClock implements the Clock interface using the Go stdlib clock.

func (DefaultClock) Now

func (DefaultClock) Now() time.Time

Now gets the current time

type HybridSlowStart

type HybridSlowStart struct {
	// contains filtered or unexported fields
}

HybridSlowStart implements the TCP hybrid slow start algorithm

func (*HybridSlowStart) IsEndOfRound

func (s *HybridSlowStart) IsEndOfRound(ack protocol.PacketNumber) bool

IsEndOfRound returns true if this ack is the last packet number of our current slow start round.

func (*HybridSlowStart) OnPacketAcked

func (s *HybridSlowStart) OnPacketAcked(ackedPacketNumber protocol.PacketNumber)

OnPacketAcked gets invoked after ShouldExitSlowStart, so it's best to end the round when the final packet of the burst is received and start it on the next incoming ack.

func (*HybridSlowStart) OnPacketSent

func (s *HybridSlowStart) OnPacketSent(packetNumber protocol.PacketNumber)

OnPacketSent is called when a packet was sent

func (*HybridSlowStart) Restart

func (s *HybridSlowStart) Restart()

Restart the slow start phase

func (*HybridSlowStart) ShouldExitSlowStart

func (s *HybridSlowStart) ShouldExitSlowStart(latestRTT time.Duration, minRTT time.Duration, congestionWindow protocol.ByteCount) bool

ShouldExitSlowStart should be called on every new ack frame, since a new RTT measurement can be made then. rtt: the RTT for this ack packet. minRTT: is the lowest delay (RTT) we have seen during the session. congestionWindow: the congestion window in packets.

func (*HybridSlowStart) StartReceiveRound

func (s *HybridSlowStart) StartReceiveRound(lastSent protocol.PacketNumber)

StartReceiveRound is called for the start of each receive round (burst) in the slow start phase.

func (*HybridSlowStart) Started

func (s *HybridSlowStart) Started() bool

Started returns true if started

type SendAlgorithm

type SendAlgorithm interface {
	TimeUntilSend(bytesInFlight protocol.ByteCount) time.Time
	HasPacingBudget(now time.Time) bool
	OnPacketSent(sentTime time.Time, bytesInFlight protocol.ByteCount, packetNumber protocol.PacketNumber, bytes protocol.ByteCount, isRetransmittable bool)
	CanSend(bytesInFlight protocol.ByteCount) bool
	MaybeExitSlowStart()
	OnPacketAcked(number protocol.PacketNumber, ackedBytes protocol.ByteCount, priorInFlight protocol.ByteCount, eventTime time.Time)
	OnCongestionEvent(number protocol.PacketNumber, lostBytes protocol.ByteCount, priorInFlight protocol.ByteCount)
	OnRetransmissionTimeout(packetsRetransmitted bool)
	SetMaxDatagramSize(protocol.ByteCount)
}

A SendAlgorithm performs congestion control

type SendAlgorithmWithDebugInfos

type SendAlgorithmWithDebugInfos interface {
	SendAlgorithm
	InSlowStart() bool
	InRecovery() bool
	GetCongestionWindow() protocol.ByteCount
	BandwidthEstimate() Bandwidth
}

A SendAlgorithmWithDebugInfos is a SendAlgorithm that exposes some debug infos