qlog: remove unneeded mutex from the ConnectionTracer (#4299)

Events are appended to a channel, which is able to handle concurrect writes.

qlog/qlog.go

@@ -7,7 +7,6 @@ import (
 	"log"
 	"net"
 	"runtime/debug"
-	"sync"
 	"time"
 
 	"github.com/quic-go/quic-go/internal/protocol"
@@ -49,8 +48,6 @@ func init() {
 const eventChanSize = 50
 
 type connectionTracer struct {
-	mutex sync.Mutex
-
 	w             io.WriteCloser
 	odcid         protocol.ConnectionID
 	perspective   protocol.Perspective
@@ -146,9 +143,7 @@ func NewConnectionTracer(w io.WriteCloser, p protocol.Perspective, odcid protoco
 			t.ECNStateUpdated(state, trigger)
 		},
 		ChoseALPN: func(protocol string) {
-			t.mutex.Lock()
 			t.recordEvent(time.Now(), eventALPNInformation{chosenALPN: protocol})
-			t.mutex.Unlock()
 		},
 		Debug: func(name, msg string) {
 			t.Debug(name, msg)
@@ -230,14 +225,12 @@ func (t *connectionTracer) StartedConnection(local, remote net.Addr, srcConnID,
 	if !ok {
 		return
 	}
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventConnectionStarted{
 		SrcAddr:          localAddr,
 		DestAddr:         remoteAddr,
 		SrcConnectionID:  srcConnID,
 		DestConnectionID: destConnID,
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) NegotiatedVersion(chosen logging.VersionNumber, client, server []logging.VersionNumber) {
@@ -254,19 +247,15 @@ func (t *connectionTracer) NegotiatedVersion(chosen logging.VersionNumber, clien
 			serverVersions[i] = versionNumber(v)
 		}
 	}
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventVersionNegotiated{
 		clientVersions: clientVersions,
 		serverVersions: serverVersions,
 		chosenVersion:  versionNumber(chosen),
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) ClosedConnection(e error) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventConnectionClosed{e: e})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) SentTransportParameters(tp *wire.TransportParameters) {
@@ -281,9 +270,7 @@ func (t *connectionTracer) RestoredTransportParameters(tp *wire.TransportParamet
 	ev := t.toTransportParameters(tp)
 	ev.Restore = true
 
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), ev)
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) recordTransportParameters(sentBy protocol.Perspective, tp *wire.TransportParameters) {
@@ -294,9 +281,7 @@ func (t *connectionTracer) recordTransportParameters(sentBy protocol.Perspective
 	}
 	ev.SentBy = sentBy
 
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), ev)
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) toTransportParameters(tp *wire.TransportParameters) *eventTransportParameters {
@@ -369,7 +354,6 @@ func (t *connectionTracer) sentPacket(
 	for _, f := range frames {
 		fs = append(fs, frame{Frame: f})
 	}
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventPacketSent{
 		Header:        hdr,
 		Length:        size,
@@ -377,7 +361,6 @@ func (t *connectionTracer) sentPacket(
 		ECN:           ecn,
 		Frames:        fs,
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) ReceivedLongHeaderPacket(hdr *logging.ExtendedHeader, size logging.ByteCount, ecn logging.ECN, frames []logging.Frame) {
@@ -386,7 +369,6 @@ func (t *connectionTracer) ReceivedLongHeaderPacket(hdr *logging.ExtendedHeader,
 		fs[i] = frame{Frame: f}
 	}
 	header := *transformLongHeader(hdr)
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventPacketReceived{
 		Header:        header,
 		Length:        size,
@@ -394,7 +376,6 @@ func (t *connectionTracer) ReceivedLongHeaderPacket(hdr *logging.ExtendedHeader,
 		ECN:           ecn,
 		Frames:        fs,
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) ReceivedShortHeaderPacket(hdr *logging.ShortHeader, size logging.ByteCount, ecn logging.ECN, frames []logging.Frame) {
@@ -403,7 +384,6 @@ func (t *connectionTracer) ReceivedShortHeaderPacket(hdr *logging.ShortHeader, s
 		fs[i] = frame{Frame: f}
 	}
 	header := *transformShortHeader(hdr)
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventPacketReceived{
 		Header:        header,
 		Length:        size,
@@ -411,15 +391,12 @@ func (t *connectionTracer) ReceivedShortHeaderPacket(hdr *logging.ShortHeader, s
 		ECN:           ecn,
 		Frames:        fs,
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) ReceivedRetry(hdr *wire.Header) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventRetryReceived{
 		Header: *transformHeader(hdr),
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) ReceivedVersionNegotiationPacket(dest, src logging.ArbitraryLenConnectionID, versions []logging.VersionNumber) {
@@ -427,7 +404,6 @@ func (t *connectionTracer) ReceivedVersionNegotiationPacket(dest, src logging.Ar
 	for i, v := range versions {
 		ver[i] = versionNumber(v)
 	}
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventVersionNegotiationReceived{
 		Header: packetHeaderVersionNegotiation{
 			SrcConnectionID:  src,
@@ -435,27 +411,22 @@ func (t *connectionTracer) ReceivedVersionNegotiationPacket(dest, src logging.Ar
 		},
 		SupportedVersions: ver,
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) BufferedPacket(pt logging.PacketType, size protocol.ByteCount) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventPacketBuffered{
 		PacketType: pt,
 		PacketSize: size,
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) DroppedPacket(pt logging.PacketType, pn logging.PacketNumber, size protocol.ByteCount, reason logging.PacketDropReason) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventPacketDropped{
 		PacketType:   pt,
 		PacketNumber: pn,
 		PacketSize:   size,
 		Trigger:      packetDropReason(reason),
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) UpdatedMetrics(rttStats *utils.RTTStats, cwnd, bytesInFlight protocol.ByteCount, packetsInFlight int) {
@@ -468,46 +439,36 @@ func (t *connectionTracer) UpdatedMetrics(rttStats *utils.RTTStats, cwnd, bytesI
 		BytesInFlight:    bytesInFlight,
 		PacketsInFlight:  packetsInFlight,
 	}
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventMetricsUpdated{
 		Last:    t.lastMetrics,
 		Current: m,
 	})
 	t.lastMetrics = m
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) AcknowledgedPacket(protocol.EncryptionLevel, protocol.PacketNumber) {}
 
 func (t *connectionTracer) LostPacket(encLevel protocol.EncryptionLevel, pn protocol.PacketNumber, lossReason logging.PacketLossReason) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventPacketLost{
 		PacketType:   getPacketTypeFromEncryptionLevel(encLevel),
 		PacketNumber: pn,
 		Trigger:      packetLossReason(lossReason),
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) UpdatedCongestionState(state logging.CongestionState) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventCongestionStateUpdated{state: congestionState(state)})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) UpdatedPTOCount(value uint32) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventUpdatedPTO{Value: value})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) UpdatedKeyFromTLS(encLevel protocol.EncryptionLevel, pers protocol.Perspective) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventKeyUpdated{
 		Trigger: keyUpdateTLS,
 		KeyType: encLevelToKeyType(encLevel, pers),
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) UpdatedKey(generation protocol.KeyPhase, remote bool) {
@@ -515,7 +476,6 @@ func (t *connectionTracer) UpdatedKey(generation protocol.KeyPhase, remote bool)
 	if remote {
 		trigger = keyUpdateRemote
 	}
-	t.mutex.Lock()
 	now := time.Now()
 	t.recordEvent(now, &eventKeyUpdated{
 		Trigger:    trigger,
@@ -527,11 +487,9 @@ func (t *connectionTracer) UpdatedKey(generation protocol.KeyPhase, remote bool)
 		KeyType:    keyTypeServer1RTT,
 		Generation: generation,
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) DroppedEncryptionLevel(encLevel protocol.EncryptionLevel) {
-	t.mutex.Lock()
 	now := time.Now()
 	if encLevel == protocol.Encryption0RTT {
 		t.recordEvent(now, &eventKeyDiscarded{KeyType: encLevelToKeyType(encLevel, t.perspective)})
@@ -539,11 +497,9 @@ func (t *connectionTracer) DroppedEncryptionLevel(encLevel protocol.EncryptionLe
 		t.recordEvent(now, &eventKeyDiscarded{KeyType: encLevelToKeyType(encLevel, protocol.PerspectiveServer)})
 		t.recordEvent(now, &eventKeyDiscarded{KeyType: encLevelToKeyType(encLevel, protocol.PerspectiveClient)})
 	}
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) DroppedKey(generation protocol.KeyPhase) {
-	t.mutex.Lock()
 	now := time.Now()
 	t.recordEvent(now, &eventKeyDiscarded{
 		KeyType:    encLevelToKeyType(protocol.Encryption1RTT, protocol.PerspectiveServer),
@@ -553,46 +509,35 @@ func (t *connectionTracer) DroppedKey(generation protocol.KeyPhase) {
 		KeyType:    encLevelToKeyType(protocol.Encryption1RTT, protocol.PerspectiveClient),
 		Generation: generation,
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) SetLossTimer(tt logging.TimerType, encLevel protocol.EncryptionLevel, timeout time.Time) {
-	t.mutex.Lock()
 	now := time.Now()
 	t.recordEvent(now, &eventLossTimerSet{
 		TimerType: timerType(tt),
 		EncLevel:  encLevel,
 		Delta:     timeout.Sub(now),
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) LossTimerExpired(tt logging.TimerType, encLevel protocol.EncryptionLevel) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventLossTimerExpired{
 		TimerType: timerType(tt),
 		EncLevel:  encLevel,
 	})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) LossTimerCanceled() {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventLossTimerCanceled{})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) ECNStateUpdated(state logging.ECNState, trigger logging.ECNStateTrigger) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventECNStateUpdated{state: state, trigger: trigger})
-	t.mutex.Unlock()
 }
 
 func (t *connectionTracer) Debug(name, msg string) {
-	t.mutex.Lock()
 	t.recordEvent(time.Now(), &eventGeneric{
 		name: name,
 		msg:  msg,
 	})
-	t.mutex.Unlock()
 }