trace congestion state changes

logging/interface.go

@@ -106,6 +106,7 @@ type ConnectionTracer interface {
 	DroppedPacket(PacketType, ByteCount, PacketDropReason)
 	UpdatedMetrics(rttStats *RTTStats, cwnd, bytesInFlight ByteCount, packetsInFlight int)
 	LostPacket(EncryptionLevel, PacketNumber, PacketLossReason)
+	UpdatedCongestionState(CongestionState)
 	UpdatedPTOCount(value uint32)
 	UpdatedKeyFromTLS(EncryptionLevel, Perspective)
 	UpdatedKey(generation KeyPhase, remote bool)

logging/mock_connection_tracer_test.go

@@ -5,14 +5,13 @@
 package logging
 
 import (
-	"net"
-	"reflect"
-	"time"
-
-	"github.com/golang/mock/gomock"
-	"github.com/lucas-clemente/quic-go/internal/protocol"
-	"github.com/lucas-clemente/quic-go/internal/utils"
-	"github.com/lucas-clemente/quic-go/internal/wire"
+	gomock "github.com/golang/mock/gomock"
+	protocol "github.com/lucas-clemente/quic-go/internal/protocol"
+	utils "github.com/lucas-clemente/quic-go/internal/utils"
+	wire "github.com/lucas-clemente/quic-go/internal/wire"
+	net "net"
+	reflect "reflect"
+	time "time"
 )
 
 // MockConnectionTracer is a mock of ConnectionTracer interface
@@ -230,6 +229,18 @@ func (mr *MockConnectionTracerMockRecorder) StartedConnection(arg0, arg1, arg2,
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "StartedConnection", reflect.TypeOf((*MockConnectionTracer)(nil).StartedConnection), arg0, arg1, arg2, arg3, arg4)
 }
 
+// UpdatedCongestionState mocks base method
+func (m *MockConnectionTracer) UpdatedCongestionState(arg0 CongestionState) {
+	m.ctrl.T.Helper()
+	m.ctrl.Call(m, "UpdatedCongestionState", arg0)
+}
+
+// UpdatedCongestionState indicates an expected call of UpdatedCongestionState
+func (mr *MockConnectionTracerMockRecorder) UpdatedCongestionState(arg0 interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "UpdatedCongestionState", reflect.TypeOf((*MockConnectionTracer)(nil).UpdatedCongestionState), arg0)
+}
+
 // UpdatedKey mocks base method
 func (m *MockConnectionTracer) UpdatedKey(arg0 protocol.KeyPhase, arg1 bool) {
 	m.ctrl.T.Helper()

logging/multiplex.go

@@ -120,6 +120,12 @@ func (m *connTracerMultiplexer) DroppedPacket(typ PacketType, size ByteCount, re
 	}
 }
 
+func (m *connTracerMultiplexer) UpdatedCongestionState(state CongestionState) {
+	for _, t := range m.tracers {
+		t.UpdatedCongestionState(state)
+	}
+}
+
 func (m *connTracerMultiplexer) UpdatedMetrics(rttStats *RTTStats, cwnd, bytesInFLight ByteCount, packetsInFlight int) {
 	for _, t := range m.tracers {
 		t.UpdatedMetrics(rttStats, cwnd, bytesInFLight, packetsInFlight)

logging/multiplex_test.go

@@ -169,6 +169,12 @@ var _ = Describe("Tracing", func() {
 			tracer.DroppedPacket(PacketTypeInitial, 1337, PacketDropHeaderParseError)
 		})
 
+		It("traces the UpdatedCongestionState event", func() {
+			tr1.EXPECT().UpdatedCongestionState(CongestionStateRecovery)
+			tr2.EXPECT().UpdatedCongestionState(CongestionStateRecovery)
+			tracer.UpdatedCongestionState(CongestionStateRecovery)
+		})
+
 		It("traces the UpdatedMetrics event", func() {
 			rttStats := &RTTStats{}
 			rttStats.UpdateRTT(time.Second, 0, time.Now())

logging/types.go

@@ -81,3 +81,16 @@ const (
 	// This reason is not defined in the qlog draft, but very useful for debugging.
 	TimeoutReasonIdle
 )
+
+type CongestionState uint8
+
+const (
+	// CongestionStateSlowStart is the slow start phase of Reno / Cubic
+	CongestionStateSlowStart CongestionState = iota
+	// CongestionStateCongestionAvoidance is the slow start phase of Reno / Cubic
+	CongestionStateCongestionAvoidance
+	// CongestionStateCongestionAvoidance is the recovery phase of Reno / Cubic
+	CongestionStateRecovery
+	// CongestionStateApplicationLimited means that the congestion controller is application limited
+	CongestionStateApplicationLimited
+)