simplify the Tracer interface by combining the TracerFor... methods

client.go

@@ -176,7 +176,7 @@ func dialContext(
 	c.packetHandlers = packetHandlers
 
 	if c.config.Tracer != nil {
-		c.tracer = c.config.Tracer.TracerForClient(c.destConnID)
+		c.tracer = c.config.Tracer.TracerForConnection(protocol.PerspectiveClient, c.destConnID)
 	}
 	if err := c.dial(ctx); err != nil {
 		return nil, err

client_test.go

@@ -68,7 +68,7 @@ var _ = Describe("Client", func() {
 		originalClientSessConstructor = newClientSession
 		tracer = mocks.NewMockConnectionTracer(mockCtrl)
 		tr := mocks.NewMockTracer(mockCtrl)
-		tr.EXPECT().TracerForClient(gomock.Any()).Return(tracer).MaxTimes(1)
+		tr.EXPECT().TracerForConnection(protocol.PerspectiveClient, gomock.Any()).Return(tracer).MaxTimes(1)
 		config = &Config{Tracer: tr}
 		Eventually(areSessionsRunning).Should(BeFalse())
 		// sess = NewMockQuicSession(mockCtrl)

logging/interface.go

@@ -79,12 +79,11 @@ const (
 
 // A Tracer traces events.
 type Tracer interface {
-	// TracerForServer requests a new tracer for a connection that was accepted by the server.
+	// ConnectionTracer requests a new tracer for a connection.
+	// The ODCID is the original destination connection ID:
+	// The destination connection ID that the client used on the first Initial packet it sent on this connection.
 	// If nil is returned, tracing will be disabled for this connection.
-	TracerForServer(odcid ConnectionID) ConnectionTracer
-	// TracerForServer requests a new tracer for a connection that was dialed by the client.
-	// If nil is returned, tracing will be disabled for this connection.
-	TracerForClient(odcid ConnectionID) ConnectionTracer
+	TracerForConnection(p Perspective, odcid ConnectionID) ConnectionTracer
 }
 
 // A ConnectionTracer records events.

logging/multiplex.go

@@ -22,20 +22,10 @@ func NewMultiplexedTracer(tracers ...Tracer) Tracer {
 	return &tracerMultiplexer{tracers}
 }
 
-func (m *tracerMultiplexer) TracerForServer(odcid ConnectionID) ConnectionTracer {
+func (m *tracerMultiplexer) TracerForConnection(p Perspective, odcid ConnectionID) ConnectionTracer {
 	var connTracers []ConnectionTracer
 	for _, t := range m.tracers {
-		if ct := t.TracerForServer(odcid); ct != nil {
-			connTracers = append(connTracers, ct)
-		}
-	}
-	return newConnectionMultiplexer(connTracers...)
-}
-
-func (m *tracerMultiplexer) TracerForClient(odcid ConnectionID) ConnectionTracer {
-	var connTracers []ConnectionTracer
-	for _, t := range m.tracers {
-		if ct := t.TracerForClient(odcid); ct != nil {
+		if ct := t.TracerForConnection(p, odcid); ct != nil {
 			connTracers = append(connTracers, ct)
 		}
 	}

logging/multiplex_test.go

@@ -23,42 +23,36 @@ var _ = Describe("Tracing", func() {
 			tracer = NewMultiplexedTracer(tr1, tr2)
 		})
 
-		It("multiplexes the TracerForServer call", func() {
-			tr1.EXPECT().TracerForServer(ConnectionID{1, 2, 3})
-			tr2.EXPECT().TracerForServer(ConnectionID{1, 2, 3})
-			tracer.TracerForServer(ConnectionID{1, 2, 3})
-		})
-
-		It("multiplexes the TracerForClient call", func() {
-			tr1.EXPECT().TracerForClient(ConnectionID{1, 2, 3})
-			tr2.EXPECT().TracerForClient(ConnectionID{1, 2, 3})
-			tracer.TracerForClient(ConnectionID{1, 2, 3})
+		It("multiplexes the TracerForConnection call", func() {
+			tr1.EXPECT().TracerForConnection(PerspectiveClient, ConnectionID{1, 2, 3})
+			tr2.EXPECT().TracerForConnection(PerspectiveClient, ConnectionID{1, 2, 3})
+			tracer.TracerForConnection(PerspectiveClient, ConnectionID{1, 2, 3})
 		})
 
 		It("uses multiple connection tracers", func() {
 			ctr1 := NewMockConnectionTracer(mockCtrl)
 			ctr2 := NewMockConnectionTracer(mockCtrl)
-			tr1.EXPECT().TracerForClient(ConnectionID{1, 2, 3}).Return(ctr1)
-			tr2.EXPECT().TracerForClient(ConnectionID{1, 2, 3}).Return(ctr2)
-			tr := tracer.TracerForClient(ConnectionID{1, 2, 3})
+			tr1.EXPECT().TracerForConnection(PerspectiveServer, ConnectionID{1, 2, 3}).Return(ctr1)
+			tr2.EXPECT().TracerForConnection(PerspectiveServer, ConnectionID{1, 2, 3}).Return(ctr2)
+			tr := tracer.TracerForConnection(PerspectiveServer, ConnectionID{1, 2, 3})
 			ctr1.EXPECT().LossTimerCanceled()
 			ctr2.EXPECT().LossTimerCanceled()
 			tr.LossTimerCanceled()
 		})
 
 		It("handles tracers that return a nil ConnectionTracer", func() {
 			ctr1 := NewMockConnectionTracer(mockCtrl)
-			tr1.EXPECT().TracerForClient(ConnectionID{1, 2, 3}).Return(ctr1)
-			tr2.EXPECT().TracerForClient(ConnectionID{1, 2, 3})
-			tr := tracer.TracerForClient(ConnectionID{1, 2, 3})
+			tr1.EXPECT().TracerForConnection(PerspectiveServer, ConnectionID{1, 2, 3}).Return(ctr1)
+			tr2.EXPECT().TracerForConnection(PerspectiveServer, ConnectionID{1, 2, 3})
+			tr := tracer.TracerForConnection(PerspectiveServer, ConnectionID{1, 2, 3})
 			ctr1.EXPECT().LossTimerCanceled()
 			tr.LossTimerCanceled()
 		})
 
 		It("returns nil when all tracers return a nil ConnectionTracer", func() {
-			tr1.EXPECT().TracerForClient(ConnectionID{1, 2, 3})
-			tr2.EXPECT().TracerForClient(ConnectionID{1, 2, 3})
-			Expect(tracer.TracerForClient(ConnectionID{1, 2, 3})).To(BeNil())
+			tr1.EXPECT().TracerForConnection(PerspectiveClient, ConnectionID{1, 2, 3})
+			tr2.EXPECT().TracerForConnection(PerspectiveClient, ConnectionID{1, 2, 3})
+			Expect(tracer.TracerForConnection(PerspectiveClient, ConnectionID{1, 2, 3})).To(BeNil())
 		})
 	})
 

metrics/metrics.go

@@ -44,12 +44,8 @@ var _ logging.Tracer = &tracer{}
 // NewTracer creates a new metrics tracer.
 func NewTracer() logging.Tracer { return &tracer{} }
 
-func (t *tracer) TracerForServer(logging.ConnectionID) logging.ConnectionTracer {
-	return newConnTracer(t, logging.PerspectiveServer)
-}
-
-func (t *tracer) TracerForClient(logging.ConnectionID) logging.ConnectionTracer {
-	return newConnTracer(t, logging.PerspectiveClient)
+func (t *tracer) TracerForConnection(p logging.Perspective, _ logging.ConnectionID) logging.ConnectionTracer {
+	return newConnTracer(t, p)
 }
 
 type connTracer struct {

qlog/qlog.go

@@ -30,16 +30,9 @@ func NewTracer(getLogWriter func(connectionID []byte) io.WriteCloser) logging.Tr
 	return &tracer{getLogWriter: getLogWriter}
 }
 
-func (t *tracer) TracerForServer(odcid protocol.ConnectionID) logging.ConnectionTracer {
+func (t *tracer) TracerForConnection(p logging.Perspective, odcid protocol.ConnectionID) logging.ConnectionTracer {
 	if w := t.getLogWriter(odcid.Bytes()); w != nil {
-		return newConnectionTracer(w, protocol.PerspectiveServer, odcid)
-	}
-	return nil
-}
-
-func (t *tracer) TracerForClient(odcid protocol.ConnectionID) logging.ConnectionTracer {
-	if w := t.getLogWriter(odcid.Bytes()); w != nil {
-		return newConnectionTracer(w, protocol.PerspectiveClient, odcid)
+		return newConnectionTracer(w, p, odcid)
 	}
 	return nil
 }

qlog/qlog_test.go

@@ -52,8 +52,7 @@ var _ = Describe("Tracing", func() {
 	Context("tracer", func() {
 		It("returns nil when there's no io.WriteCloser", func() {
 			t := NewTracer(func([]byte) io.WriteCloser { return nil })
-			Expect(t.TracerForClient(logging.ConnectionID{1, 2, 3, 4})).To(BeNil())
-			Expect(t.TracerForServer(logging.ConnectionID{1, 2, 3, 4})).To(BeNil())
+			Expect(t.TracerForConnection(logging.PerspectiveClient, logging.ConnectionID{1, 2, 3, 4})).To(BeNil())
 		})
 	})
 
@@ -66,7 +65,7 @@ var _ = Describe("Tracing", func() {
 		BeforeEach(func() {
 			buf = &bytes.Buffer{}
 			t := NewTracer(func([]byte) io.WriteCloser { return nopWriteCloser(buf) })
-			tracer = t.TracerForServer(logging.ConnectionID{0xde, 0xad, 0xbe, 0xef})
+			tracer = t.TracerForConnection(logging.PerspectiveServer, logging.ConnectionID{0xde, 0xad, 0xbe, 0xef})
 		})
 
 		It("exports a trace that has the right metadata", func() {

server.go

@@ -453,7 +453,7 @@ func (s *baseServer) createNewSession(
 			if origDestConnID.Len() > 0 {
 				connID = origDestConnID
 			}
-			tracer = s.config.Tracer.TracerForServer(connID)
+			tracer = s.config.Tracer.TracerForConnection(protocol.PerspectiveServer, connID)
 		}
 		sess = s.newSession(
 			&conn{pconn: s.conn, currentAddr: remoteAddr},