use go 1.12

Signed-off-by: hongming <talonwan@yunify.com>
2019-03-12 15:47:56 +08:00
parent b59c244ca2
commit 4144404b0b
1110 changed files with 161100 additions and 14519 deletions
--- a/vendor/github.com/lucas-clemente/quic-go/internal/congestion/cubic_sender.go
+++ b/vendor/github.com/lucas-clemente/quic-go/internal/congestion/cubic_sender.go
@@ -0,0 +1,318 @@
+package congestion
+
+import (
+	"time"
+
+	"github.com/lucas-clemente/quic-go/internal/protocol"
+	"github.com/lucas-clemente/quic-go/internal/utils"
+)
+
+const (
+	maxBurstBytes                                     = 3 * protocol.DefaultTCPMSS
+	renoBeta                       float32            = 0.7 // Reno backoff factor.
+	defaultMinimumCongestionWindow protocol.ByteCount = 2 * protocol.DefaultTCPMSS
+)
+
+type cubicSender struct {
+	hybridSlowStart HybridSlowStart
+	prr             PrrSender
+	rttStats        *RTTStats
+	stats           connectionStats
+	cubic           *Cubic
+
+	reno bool
+
+	// Track the largest packet that has been sent.
+	largestSentPacketNumber protocol.PacketNumber
+
+	// Track the largest packet that has been acked.
+	largestAckedPacketNumber protocol.PacketNumber
+
+	// Track the largest packet number outstanding when a CWND cutback occurs.
+	largestSentAtLastCutback protocol.PacketNumber
+
+	// Whether the last loss event caused us to exit slowstart.
+	// Used for stats collection of slowstartPacketsLost
+	lastCutbackExitedSlowstart bool
+
+	// When true, exit slow start with large cutback of congestion window.
+	slowStartLargeReduction bool
+
+	// Congestion window in packets.
+	congestionWindow protocol.ByteCount
+
+	// Minimum congestion window in packets.
+	minCongestionWindow protocol.ByteCount
+
+	// Maximum congestion window.
+	maxCongestionWindow protocol.ByteCount
+
+	// Slow start congestion window in bytes, aka ssthresh.
+	slowstartThreshold protocol.ByteCount
+
+	// Number of connections to simulate.
+	numConnections int
+
+	// ACK counter for the Reno implementation.
+	numAckedPackets uint64
+
+	initialCongestionWindow    protocol.ByteCount
+	initialMaxCongestionWindow protocol.ByteCount
+
+	minSlowStartExitWindow protocol.ByteCount
+}
+
+var _ SendAlgorithm = &cubicSender{}
+var _ SendAlgorithmWithDebugInfo = &cubicSender{}
+
+// NewCubicSender makes a new cubic sender
+func NewCubicSender(clock Clock, rttStats *RTTStats, reno bool, initialCongestionWindow, initialMaxCongestionWindow protocol.ByteCount) SendAlgorithmWithDebugInfo {
+	return &cubicSender{
+		rttStats:                   rttStats,
+		initialCongestionWindow:    initialCongestionWindow,
+		initialMaxCongestionWindow: initialMaxCongestionWindow,
+		congestionWindow:           initialCongestionWindow,
+		minCongestionWindow:        defaultMinimumCongestionWindow,
+		slowstartThreshold:         initialMaxCongestionWindow,
+		maxCongestionWindow:        initialMaxCongestionWindow,
+		numConnections:             defaultNumConnections,
+		cubic:                      NewCubic(clock),
+		reno:                       reno,
+	}
+}
+
+// TimeUntilSend returns when the next packet should be sent.
+func (c *cubicSender) TimeUntilSend(bytesInFlight protocol.ByteCount) time.Duration {
+	if c.InRecovery() {
+		// PRR is used when in recovery.
+		if c.prr.CanSend(c.GetCongestionWindow(), bytesInFlight, c.GetSlowStartThreshold()) {
+			return 0
+		}
+	}
+	delay := c.rttStats.SmoothedRTT() / time.Duration(2*c.GetCongestionWindow())
+	if !c.InSlowStart() { // adjust delay, such that it's 1.25*cwd/rtt
+		delay = delay * 8 / 5
+	}
+	return delay
+}
+
+func (c *cubicSender) OnPacketSent(
+	sentTime time.Time,
+	bytesInFlight protocol.ByteCount,
+	packetNumber protocol.PacketNumber,
+	bytes protocol.ByteCount,
+	isRetransmittable bool,
+) {
+	if !isRetransmittable {
+		return
+	}
+	if c.InRecovery() {
+		// PRR is used when in recovery.
+		c.prr.OnPacketSent(bytes)
+	}
+	c.largestSentPacketNumber = packetNumber
+	c.hybridSlowStart.OnPacketSent(packetNumber)
+}
+
+func (c *cubicSender) InRecovery() bool {
+	return c.largestAckedPacketNumber <= c.largestSentAtLastCutback && c.largestAckedPacketNumber != 0
+}
+
+func (c *cubicSender) InSlowStart() bool {
+	return c.GetCongestionWindow() < c.GetSlowStartThreshold()
+}
+
+func (c *cubicSender) GetCongestionWindow() protocol.ByteCount {
+	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() {
+	if c.InSlowStart() && c.hybridSlowStart.ShouldExitSlowStart(c.rttStats.LatestRTT(), c.rttStats.MinRTT(), c.GetCongestionWindow()/protocol.DefaultTCPMSS) {
+		c.ExitSlowstart()
+	}
+}
+
+func (c *cubicSender) OnPacketAcked(
+	ackedPacketNumber protocol.PacketNumber,
+	ackedBytes protocol.ByteCount,
+	priorInFlight protocol.ByteCount,
+	eventTime time.Time,
+) {
+	c.largestAckedPacketNumber = utils.MaxPacketNumber(ackedPacketNumber, c.largestAckedPacketNumber)
+	if c.InRecovery() {
+		// PRR is used when in recovery.
+		c.prr.OnPacketAcked(ackedBytes)
+		return
+	}
+	c.maybeIncreaseCwnd(ackedPacketNumber, ackedBytes, priorInFlight, eventTime)
+	if c.InSlowStart() {
+		c.hybridSlowStart.OnPacketAcked(ackedPacketNumber)
+	}
+}
+
+func (c *cubicSender) OnPacketLost(
+	packetNumber protocol.PacketNumber,
+	lostBytes protocol.ByteCount,
+	priorInFlight protocol.ByteCount,
+) {
+	// TCP NewReno (RFC6582) says that once a loss occurs, any losses in packets
+	// already sent should be treated as a single loss event, since it's expected.
+	if packetNumber <= c.largestSentAtLastCutback {
+		if c.lastCutbackExitedSlowstart {
+			c.stats.slowstartPacketsLost++
+			c.stats.slowstartBytesLost += lostBytes
+			if c.slowStartLargeReduction {
+				// Reduce congestion window by lost_bytes for every loss.
+				c.congestionWindow = utils.MaxByteCount(c.congestionWindow-lostBytes, c.minSlowStartExitWindow)
+				c.slowstartThreshold = c.congestionWindow
+			}
+		}
+		return
+	}
+	c.lastCutbackExitedSlowstart = c.InSlowStart()
+	if c.InSlowStart() {
+		c.stats.slowstartPacketsLost++
+	}
+
+	c.prr.OnPacketLost(priorInFlight)
+
+	// TODO(chromium): Separate out all of slow start into a separate class.
+	if c.slowStartLargeReduction && c.InSlowStart() {
+		if c.congestionWindow >= 2*c.initialCongestionWindow {
+			c.minSlowStartExitWindow = c.congestionWindow / 2
+		}
+		c.congestionWindow -= protocol.DefaultTCPMSS
+	} else if c.reno {
+		c.congestionWindow = protocol.ByteCount(float32(c.congestionWindow) * c.RenoBeta())
+	} else {
+		c.congestionWindow = c.cubic.CongestionWindowAfterPacketLoss(c.congestionWindow)
+	}
+	if c.congestionWindow < c.minCongestionWindow {
+		c.congestionWindow = c.minCongestionWindow
+	}
+	c.slowstartThreshold = c.congestionWindow
+	c.largestSentAtLastCutback = c.largestSentPacketNumber
+	// reset packet count from congestion avoidance mode. We start
+	// counting again when we're out of recovery.
+	c.numAckedPackets = 0
+}
+
+func (c *cubicSender) RenoBeta() float32 {
+	// kNConnectionBeta is the backoff factor after loss for our N-connection
+	// emulation, which emulates the effective backoff of an ensemble of N
+	// TCP-Reno connections on a single loss event. The effective multiplier is
+	// computed as:
+	return (float32(c.numConnections) - 1. + renoBeta) / float32(c.numConnections)
+}
+
+// Called when we receive an ack. Normal TCP tracks how many packets one ack
+// represents, but quic has a separate ack for each packet.
+func (c *cubicSender) maybeIncreaseCwnd(
+	ackedPacketNumber protocol.PacketNumber,
+	ackedBytes protocol.ByteCount,
+	priorInFlight protocol.ByteCount,
+	eventTime time.Time,
+) {
+	// Do not increase the congestion window unless the sender is close to using
+	// the current window.
+	if !c.isCwndLimited(priorInFlight) {
+		c.cubic.OnApplicationLimited()
+		return
+	}
+	if c.congestionWindow >= c.maxCongestionWindow {
+		return
+	}
+	if c.InSlowStart() {
+		// TCP slow start, exponential growth, increase by one for each ACK.
+		c.congestionWindow += protocol.DefaultTCPMSS
+		return
+	}
+	// Congestion avoidance
+	if c.reno {
+		// Classic Reno congestion avoidance.
+		c.numAckedPackets++
+		// Divide by num_connections to smoothly increase the CWND at a faster
+		// rate than conventional Reno.
+		if c.numAckedPackets*uint64(c.numConnections) >= uint64(c.congestionWindow)/uint64(protocol.DefaultTCPMSS) {
+			c.congestionWindow += protocol.DefaultTCPMSS
+			c.numAckedPackets = 0
+		}
+	} else {
+		c.congestionWindow = utils.MinByteCount(c.maxCongestionWindow, c.cubic.CongestionWindowAfterAck(ackedBytes, c.congestionWindow, c.rttStats.MinRTT(), eventTime))
+	}
+}
+
+func (c *cubicSender) isCwndLimited(bytesInFlight protocol.ByteCount) bool {
+	congestionWindow := c.GetCongestionWindow()
+	if bytesInFlight >= congestionWindow {
+		return true
+	}
+	availableBytes := congestionWindow - bytesInFlight
+	slowStartLimited := c.InSlowStart() && bytesInFlight > congestionWindow/2
+	return slowStartLimited || availableBytes <= maxBurstBytes
+}
+
+// BandwidthEstimate returns the current bandwidth estimate
+func (c *cubicSender) BandwidthEstimate() Bandwidth {
+	srtt := c.rttStats.SmoothedRTT()
+	if srtt == 0 {
+		// If we haven't measured an rtt, the bandwidth estimate is unknown.
+		return 0
+	}
+	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
+func (c *cubicSender) SetNumEmulatedConnections(n int) {
+	c.numConnections = utils.Max(n, 1)
+	c.cubic.SetNumConnections(c.numConnections)
+}
+
+// OnRetransmissionTimeout is called on an retransmission timeout
+func (c *cubicSender) OnRetransmissionTimeout(packetsRetransmitted bool) {
+	c.largestSentAtLastCutback = 0
+	if !packetsRetransmitted {
+		return
+	}
+	c.hybridSlowStart.Restart()
+	c.cubic.Reset()
+	c.slowstartThreshold = c.congestionWindow / 2
+	c.congestionWindow = c.minCongestionWindow
+}
+
+// OnConnectionMigration is called when the connection is migrated (?)
+func (c *cubicSender) OnConnectionMigration() {
+	c.hybridSlowStart.Restart()
+	c.prr = PrrSender{}
+	c.largestSentPacketNumber = 0
+	c.largestAckedPacketNumber = 0
+	c.largestSentAtLastCutback = 0
+	c.lastCutbackExitedSlowstart = false
+	c.cubic.Reset()
+	c.numAckedPackets = 0
+	c.congestionWindow = c.initialCongestionWindow
+	c.slowstartThreshold = c.initialMaxCongestionWindow
+	c.maxCongestionWindow = c.initialMaxCongestionWindow
+}
+
+// SetSlowStartLargeReduction allows enabling the SSLR experiment
+func (c *cubicSender) SetSlowStartLargeReduction(enabled bool) {
+	c.slowStartLargeReduction = enabled
+}