From 74509731c92f1003b9efa54ceab172bf23baaadc Mon Sep 17 00:00:00 2001
From: Sam Xie <sam@samxie.me>
Date: Sat, 1 May 2021 21:19:03 +0800
Subject: [PATCH 1/8] Add tracing interceptor

---
 interceptors/tracing/interceptors.go      |  59 ++++
 interceptors/tracing/interceptors_test.go | 317 ++++++++++++++++++++++
 interceptors/tracing/kv/value.go          | 171 ++++++++++++
 interceptors/tracing/kv/value_test.go     |  56 ++++
 interceptors/tracing/reporter.go          |  65 +++++
 interceptors/tracing/tracing.go           |  57 ++++
 6 files changed, 725 insertions(+)
 create mode 100644 interceptors/tracing/interceptors.go
 create mode 100644 interceptors/tracing/interceptors_test.go
 create mode 100644 interceptors/tracing/kv/value.go
 create mode 100644 interceptors/tracing/kv/value_test.go
 create mode 100644 interceptors/tracing/reporter.go
 create mode 100644 interceptors/tracing/tracing.go

diff --git a/interceptors/tracing/interceptors.go b/interceptors/tracing/interceptors.go
new file mode 100644
index 000000000..681d581ae
--- /dev/null
+++ b/interceptors/tracing/interceptors.go
@@ -0,0 +1,59 @@
+package tracing
+
+import (
+	"context"
+
+	"google.golang.org/grpc"
+
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors"
+)
+
+type SpanKind string
+
+const (
+	SpanKindServer SpanKind = "server"
+	SpanKindClient SpanKind = "client"
+)
+
+type reportable struct {
+	tracer Tracer
+}
+
+func (r *reportable) ServerReporter(ctx context.Context, _ interface{}, typ interceptors.GRPCType, service string, method string) (interceptors.Reporter, context.Context) {
+	return r.reporter(ctx, service, method, SpanKindServer)
+}
+
+func (r *reportable) ClientReporter(ctx context.Context, _ interface{}, typ interceptors.GRPCType, service string, method string) (interceptors.Reporter, context.Context) {
+	return r.reporter(ctx, service, method, SpanKindClient)
+}
+
+func (r *reportable) reporter(ctx context.Context, service string, method string, kind SpanKind) (interceptors.Reporter, context.Context) {
+	newCtx, span := r.tracer.Start(ctx, interceptors.FullMethod(service, method), kind)
+	reporter := reporter{ctx: newCtx, span: span}
+
+	return &reporter, newCtx
+}
+
+// UnaryClientInterceptor returns a new unary client interceptor that optionally traces the execution of external gRPC calls.
+// Tracer will use tags (from tags package) available in current context as fields.
+func UnaryClientInterceptor(tracer Tracer) grpc.UnaryClientInterceptor {
+	return interceptors.UnaryClientInterceptor(&reportable{tracer: tracer})
+}
+
+// StreamClientInterceptor returns a new streaming client interceptor that optionally traces the execution of external gRPC calls.
+// Tracer will use tags (from tags package) available in current context as fields.
+func StreamClientInterceptor(tracer Tracer) grpc.StreamClientInterceptor {
+	return interceptors.StreamClientInterceptor(&reportable{tracer: tracer})
+}
+
+// UnaryServerInterceptor returns a new unary server interceptors that optionally traces endpoint handling.
+// Tracer will use tags (from tags package) available in current context as fields.
+func UnaryServerInterceptor(tracer Tracer) grpc.UnaryServerInterceptor {
+	return interceptors.UnaryServerInterceptor(&reportable{tracer: tracer})
+}
+
+// StreamServerInterceptor returns a new stream server interceptors that optionally traces endpoint handling.
+// Tracer will use tags (from tags package) available in current context as fields.
+func StreamServerInterceptor(tracer Tracer) grpc.StreamServerInterceptor {
+	return interceptors.StreamServerInterceptor(&reportable{tracer: tracer})
+}
diff --git a/interceptors/tracing/interceptors_test.go b/interceptors/tracing/interceptors_test.go
new file mode 100644
index 000000000..99d592964
--- /dev/null
+++ b/interceptors/tracing/interceptors_test.go
@@ -0,0 +1,317 @@
+package tracing_test
+
+import (
+	"context"
+	"io"
+	"strconv"
+	"sync/atomic"
+	"testing"
+	
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/suite"
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/metadata"
+	
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tags"
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing"
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing/kv"
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/testing/testpb"
+)
+
+var (
+	id               int64 = 0
+	traceIDHeaderKey       = "traceid"
+	spanIDHeaderKey        = "spanid"
+)
+
+func extractFromContext(ctx context.Context, kind tracing.SpanKind) *mockSpan {
+	var m metadata.MD
+	if kind == tracing.SpanKindClient {
+		m, _ = metadata.FromOutgoingContext(ctx)
+	} else {
+		m, _ = metadata.FromIncomingContext(ctx)
+	}
+	
+	traceIDValues := m.Get(traceIDHeaderKey)
+	if len(traceIDValues) == 0 {
+		return nil
+	}
+	spanIDValues := m.Get(spanIDHeaderKey)
+	if len(spanIDValues) == 0 {
+		return nil
+	}
+	
+	return &mockSpan{
+		traceID: traceIDValues[0],
+		spanID:  spanIDValues[0],
+	}
+}
+
+func injectWithContext(ctx context.Context, span *mockSpan, kind tracing.SpanKind) context.Context {
+	var m metadata.MD
+	if kind == tracing.SpanKindClient {
+		m, _ = metadata.FromOutgoingContext(ctx)
+	} else {
+		m, _ = metadata.FromIncomingContext(ctx)
+	}
+	m = m.Copy()
+	
+	m.Set(traceIDHeaderKey, span.traceID)
+	m.Set(spanIDHeaderKey, span.spanID)
+	
+	ctx = metadata.NewOutgoingContext(ctx, m)
+	return ctx
+}
+
+func genID() string {
+	return strconv.FormatInt(atomic.AddInt64(&id, 1), 10)
+}
+
+// Implements Tracker
+type mockTracer struct {
+	spanStore map[string]*mockSpan
+}
+
+func (t *mockTracer) ListSpan(kind tracing.SpanKind) []*mockSpan {
+	var spans []*mockSpan
+	for _, v := range t.spanStore {
+		if v.kind == kind {
+			spans = append(spans, v)
+		}
+	}
+	return spans
+}
+
+func (t *mockTracer) Reset() {
+	t.spanStore = make(map[string]*mockSpan)
+}
+
+func newMockTracer() *mockTracer {
+	return &mockTracer{
+		spanStore: make(map[string]*mockSpan),
+	}
+}
+
+func (t *mockTracer) Start(ctx context.Context, spanName string, kind tracing.SpanKind) (context.Context, tracing.Span) {
+	span := mockSpan{
+		spanID:     genID(),
+		name:       spanName,
+		kind:       kind,
+		statusCode: codes.OK,
+	}
+	
+	// parentSpan := spanFromContext(ctx)
+	parentSpan := extractFromContext(ctx, kind)
+	if parentSpan != nil {
+		// Fetch span from context as parent span
+		span.traceID = parentSpan.traceID
+		span.parentSpanID = parentSpan.spanID
+	} else {
+		span.traceID = genID()
+	}
+	
+	t.spanStore[span.spanID] = &span
+	
+	// ctx = contextWithSpan(ctx, &span)
+	if kind == tracing.SpanKindClient {
+		ctx = injectWithContext(ctx, &span, kind)
+	}
+	return ctx, &span
+}
+
+// Implements Span
+type mockSpan struct {
+	traceID      string
+	spanID       string
+	parentSpanID string
+	
+	name string
+	kind tracing.SpanKind
+	end  bool
+	
+	statusCode    codes.Code
+	statusMessage string
+	
+	msgSendCounter     int
+	msgReceivedCounter int
+	eventNameList      []string
+	attributesList     [][]kv.KeyValue
+}
+
+func (s *mockSpan) SetAttributes(attrs ...kv.KeyValue) {
+	s.attributesList = append(s.attributesList, attrs)
+}
+
+func (s *mockSpan) End() {
+	s.end = true
+}
+
+func (s *mockSpan) SetStatus(code codes.Code, message string) {
+	s.statusCode = code
+	s.statusMessage = message
+}
+
+func (s *mockSpan) AddEvent(name string, attrs ...kv.KeyValue) {
+	s.eventNameList = append(s.eventNameList, name)
+	
+	for _, v := range attrs {
+		switch v {
+		case tracing.RPCMessageTypeSent:
+			s.msgSendCounter++
+		case tracing.RPCMessageTypeReceived:
+			s.msgReceivedCounter++
+		}
+	}
+}
+
+type tracingSuite struct {
+	*testpb.InterceptorTestSuite
+	tracer *mockTracer
+}
+
+func (s *tracingSuite) BeforeTest(suiteName, testName string) {
+	s.tracer.Reset()
+}
+
+func (s *tracingSuite) TestPing() {
+	method := "/testing.testpb.v1.TestService/Ping"
+	errorMethod := "/testing.testpb.v1.TestService/PingError"
+	t := s.T()
+	
+	testCases := []struct {
+		name         string
+		error        bool
+		errorMessage string
+	}{
+		{
+			name:  "OK",
+			error: false,
+		},
+		{
+			name:         "invalid argument error",
+			error:        true,
+			errorMessage: "Userspace error.",
+		},
+	}
+	
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			s.tracer.Reset()
+			
+			var err error
+			if tc.error {
+				req := &testpb.PingErrorRequest{ErrorCodeReturned: uint32(codes.InvalidArgument)}
+				_, err = s.Client.PingError(s.SimpleCtx(), req)
+			} else {
+				req := &testpb.PingRequest{Value: "something"}
+				_, err = s.Client.Ping(s.SimpleCtx(), req)
+			}
+			if tc.error {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+			}
+			
+			clientSpans := s.tracer.ListSpan(tracing.SpanKindClient)
+			serverSpans := s.tracer.ListSpan(tracing.SpanKindServer)
+			require.Len(t, clientSpans, 1)
+			require.Len(t, serverSpans, 1)
+			
+			clientSpan := clientSpans[0]
+			assert.True(t, clientSpan.end)
+			assert.Equal(t, 1, clientSpan.msgSendCounter)
+			assert.Equal(t, 1, clientSpan.msgReceivedCounter)
+			assert.Equal(t, []string{"message", "message"}, clientSpan.eventNameList)
+			
+			serverSpan := serverSpans[0]
+			assert.True(t, serverSpan.end)
+			assert.Equal(t, 1, serverSpan.msgSendCounter)
+			assert.Equal(t, 1, serverSpan.msgReceivedCounter)
+			assert.Equal(t, []string{"message", "message"}, serverSpan.eventNameList)
+			
+			assert.Equal(t, clientSpan.traceID, serverSpan.traceID)
+			assert.Equal(t, clientSpan.spanID, serverSpan.parentSpanID)
+			
+			if tc.error {
+				assert.Equal(t, codes.InvalidArgument, clientSpan.statusCode)
+				assert.Equal(t, tc.errorMessage, clientSpan.statusMessage)
+				assert.Equal(t, errorMethod, clientSpan.name)
+				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(3)}}, clientSpan.attributesList)
+				
+				assert.Equal(t, errorMethod, serverSpan.name)
+				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(3)}}, serverSpan.attributesList)
+			} else {
+				assert.Equal(t, codes.OK, clientSpan.statusCode)
+				assert.Equal(t, method, clientSpan.name)
+				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(0)}}, clientSpan.attributesList)
+				
+				assert.Equal(t, method, serverSpan.name)
+				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(0)}}, serverSpan.attributesList)
+			}
+		})
+	}
+}
+
+func (s *tracingSuite) TestPingList() {
+	t := s.T()
+	method := "/testing.testpb.v1.TestService/PingList"
+	
+	stream, err := s.Client.PingList(s.SimpleCtx(), &testpb.PingListRequest{Value: "something"})
+	require.NoError(t, err)
+	
+	for {
+		_, err := stream.Recv()
+		if err == io.EOF {
+			break
+		}
+		require.NoError(t, err)
+	}
+	
+	clientSpans := s.tracer.ListSpan(tracing.SpanKindClient)
+	serverSpans := s.tracer.ListSpan(tracing.SpanKindServer)
+	require.Len(t, clientSpans, 1)
+	require.Len(t, serverSpans, 1)
+	
+	clientSpan := clientSpans[0]
+	assert.True(t, clientSpan.end)
+	assert.Equal(t, 1, clientSpan.msgSendCounter)
+	assert.Equal(t, testpb.ListResponseCount+1, clientSpan.msgReceivedCounter)
+	assert.Equal(t, codes.OK, clientSpan.statusCode)
+	assert.Equal(t, method, clientSpan.name)
+	
+	serverSpan := serverSpans[0]
+	assert.True(t, serverSpan.end)
+	assert.Equal(t, testpb.ListResponseCount, serverSpan.msgSendCounter)
+	assert.Equal(t, 1, serverSpan.msgReceivedCounter)
+	assert.Equal(t, codes.OK, serverSpan.statusCode)
+	assert.Equal(t, method, serverSpan.name)
+}
+
+func TestSuite(t *testing.T) {
+	tracer := newMockTracer()
+	
+	s := tracingSuite{
+		InterceptorTestSuite: &testpb.InterceptorTestSuite{
+			TestService: &testpb.TestPingService{T: t},
+		},
+		tracer: tracer,
+	}
+	s.InterceptorTestSuite.ClientOpts = []grpc.DialOption{
+		grpc.WithUnaryInterceptor(tracing.UnaryClientInterceptor(tracer)),
+		grpc.WithStreamInterceptor(tracing.StreamClientInterceptor(tracer)),
+	}
+	s.InterceptorTestSuite.ServerOpts = []grpc.ServerOption{
+		grpc.ChainUnaryInterceptor(
+			tags.UnaryServerInterceptor(tags.WithFieldExtractor(tags.CodeGenRequestFieldExtractor)),
+			tracing.UnaryServerInterceptor(tracer),
+		),
+		grpc.ChainStreamInterceptor(
+			tags.StreamServerInterceptor(tags.WithFieldExtractor(tags.CodeGenRequestFieldExtractor)),
+			tracing.StreamServerInterceptor(tracer),
+		),
+	}
+	
+	suite.Run(t, &s)
+}
diff --git a/interceptors/tracing/kv/value.go b/interceptors/tracing/kv/value.go
new file mode 100644
index 000000000..224f95070
--- /dev/null
+++ b/interceptors/tracing/kv/value.go
@@ -0,0 +1,171 @@
+package kv
+
+import (
+	"math"
+)
+
+// KeyValue holds a key and value pair.
+type KeyValue struct {
+	Key   Key
+	Value Value
+}
+
+type Key string
+
+// Bool creates a KeyValue instance with a BOOL Value.
+//
+// If creating both key and a bool value at the same time, then
+// instead of calling kv.Key(name).Bool(value) consider using a
+// convenience function provided by the api/key package -
+// key.Bool(name, value).
+func (k Key) Bool(v bool) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: boolValue(v),
+	}
+}
+
+// Int64 creates a KeyValue instance with an INT64 Value.
+//
+// If creating both key and an int64 value at the same time, then
+// instead of calling kv.Key(name).Int64(value) consider using a
+// convenience function provided by the api/key package -
+// key.Int64(name, value).
+func (k Key) Int64(v int64) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: int64Value(v),
+	}
+}
+
+// Float64 creates a KeyValue instance with a FLOAT64 Value.
+//
+// If creating both key and a float64 value at the same time, then
+// instead of calling kv.Key(name).Float64(value) consider using a
+// convenience function provided by the api/key package -
+// key.Float64(name, value).
+func (k Key) Float64(v float64) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: float64Value(v),
+	}
+}
+
+// String creates a KeyValue instance with a STRING Value.
+//
+// If creating both key and a string value at the same time, then
+// instead of calling kv.Key(name).String(value) consider using a
+// convenience function provided by the api/key package -
+// key.String(name, value).
+func (k Key) String(v string) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: stringValue(v),
+	}
+}
+
+// Int creates a KeyValue instance with either an INT32 or an INT64
+// Value, depending on whether the int type is 32 or 64 bits wide.
+//
+// If creating both key and an int value at the same time, then
+// instead of calling kv.Key(name).Int(value) consider using a
+// convenience function provided by the api/key package -
+// key.Int(name, value).
+func (k Key) Int(v int) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: intValue(v),
+	}
+}
+
+// ValueType describes the type of the data Value holds.
+type ValueType int
+
+const (
+	INVALID ValueType = iota // No value.
+	// BOOL is a boolean Type Value.
+	BOOL
+	// INT64 is a 64-bit signed integral Type Value.
+	INT64
+	// FLOAT64 is a 64-bit floating point Type Value.
+	FLOAT64
+	// STRING is a string Type Value.
+	STRING
+)
+
+type Value struct {
+	vtype    ValueType
+	numeric  uint64
+	stringly string
+}
+
+func boolTowRaw(b bool) uint64 {
+	if b {
+		return 1
+	}
+	return 0
+}
+
+func rawToBool(r uint64) bool {
+	return r != 0
+}
+
+func boolValue(v bool) Value {
+	return Value{
+		vtype:   BOOL,
+		numeric: boolTowRaw(v),
+	}
+}
+
+func int64Value(v int64) Value {
+	return Value{
+		vtype:   INT64,
+		numeric: uint64(v),
+	}
+}
+
+func float64Value(v float64) Value {
+	return Value{
+		vtype:   FLOAT64,
+		numeric: math.Float64bits(v),
+	}
+}
+
+func stringValue(v string) Value {
+	return Value{
+		vtype:    STRING,
+		stringly: v,
+	}
+}
+
+// intValue creates an INT64 Value.
+func intValue(v int) Value {
+	return int64Value(int64(v))
+}
+
+func (v Value) AsBool() bool {
+	return rawToBool(v.numeric)
+}
+
+// AsInt64 returns the int64 value. Make sure that the Value's type is
+// INT64.
+func (v Value) AsInt64() int64 {
+	return int64(v.numeric)
+}
+
+// AsFloat64 returns the float64 value. Make sure that the Value's
+// type is FLOAT64.
+func (v Value) AsFloat64() float64 {
+	return math.Float64frombits(v.numeric)
+}
+
+// AsString returns the string value. Make sure that the Value's type
+// is STRING.
+func (v Value) AsString() string {
+	return v.stringly
+}
+
+// Type returns a type of the Value.
+func (v Value) Type() ValueType {
+	return v.vtype
+}
diff --git a/interceptors/tracing/kv/value_test.go b/interceptors/tracing/kv/value_test.go
new file mode 100644
index 000000000..34c48687b
--- /dev/null
+++ b/interceptors/tracing/kv/value_test.go
@@ -0,0 +1,56 @@
+package kv
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestKey(t *testing.T) {
+	testCases := []struct {
+		name          string
+		keyValue      KeyValue
+		expectedValue interface{}
+	}{
+		{
+			name:          "true",
+			keyValue:      Key("bool").Bool(true),
+			expectedValue: true,
+		},
+		{
+			name:          "false",
+			keyValue:      Key("bool").Bool(false),
+			expectedValue: false,
+		},
+		{
+			name:          "int64",
+			keyValue:      Key("int64").Int64(43),
+			expectedValue: int64(43),
+		},
+		{
+			name:          "float64",
+			keyValue:      Key("float64").Float64(43),
+			expectedValue: float64(43),
+		},
+		{
+			name:          "string",
+			keyValue:      Key("string").String("foo"),
+			expectedValue: "foo",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			switch tc.keyValue.Value.Type() {
+			case BOOL:
+				assert.Equal(t, tc.expectedValue, tc.keyValue.Value.AsBool())
+			case INT64:
+				assert.Equal(t, tc.expectedValue, tc.keyValue.Value.AsInt64())
+			case FLOAT64:
+				assert.Equal(t, tc.expectedValue, tc.keyValue.Value.AsFloat64())
+			case STRING:
+				assert.Equal(t, tc.expectedValue, tc.keyValue.Value.AsString())
+			}
+		})
+	}
+}
diff --git a/interceptors/tracing/reporter.go b/interceptors/tracing/reporter.go
new file mode 100644
index 000000000..d8b5df61d
--- /dev/null
+++ b/interceptors/tracing/reporter.go
@@ -0,0 +1,65 @@
+package tracing
+
+import (
+	"context"
+	"io"
+	"time"
+
+	"github.com/golang/protobuf/proto"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing/kv"
+)
+
+type reporter struct {
+	ctx  context.Context
+	span Span
+
+	receivedMessageID int
+	sentMessageID     int
+}
+
+func (o *reporter) PostCall(err error, _ time.Duration) {
+	// Finish span.
+	if err != nil && err != io.EOF {
+		s, _ := status.FromError(err)
+		o.span.SetStatus(s.Code(), s.Message())
+		o.span.SetAttributes(statusCodeAttr(s.Code()))
+	} else {
+		o.span.SetAttributes(statusCodeAttr(codes.OK))
+	}
+	o.span.End()
+}
+
+func (o *reporter) PostMsgSend(payload interface{}, err error, d time.Duration) {
+	o.sentMessageID++
+
+	addEvent(o.span, RPCMessageTypeSent, o.sentMessageID, payload)
+}
+
+func (o *reporter) PostMsgReceive(payload interface{}, err error, d time.Duration) {
+	o.receivedMessageID++
+
+	addEvent(o.span, RPCMessageTypeReceived, o.receivedMessageID, payload)
+}
+
+func addEvent(span Span, messageType kv.KeyValue, messageID int, payload interface{}) {
+	if p, ok := payload.(proto.Message); ok {
+		span.AddEvent("message",
+			messageType,
+			rpcMessageIDKey.Int(messageID),
+			rpcMessageUncompressedSizeKey.Int(proto.Size(p)),
+		)
+	} else {
+		span.AddEvent("message",
+			messageType,
+			rpcMessageIDKey.Int(messageID),
+		)
+	}
+}
+
+// statusCodeAttr returns status code attribute based on given gRPC code
+func statusCodeAttr(c codes.Code) kv.KeyValue {
+	return grpcStatusCodeKey.Int64(int64(c))
+}
\ No newline at end of file
diff --git a/interceptors/tracing/tracing.go b/interceptors/tracing/tracing.go
new file mode 100644
index 000000000..3415ecce3
--- /dev/null
+++ b/interceptors/tracing/tracing.go
@@ -0,0 +1,57 @@
+package tracing
+
+import (
+	"context"
+	
+	"google.golang.org/grpc/codes"
+	
+	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing/kv"
+)
+
+const (
+	// Type of message transmitted or received.
+	rpcMessageTypeKey = kv.Key("message.type")
+	
+	// Identifier of message transmitted or received.
+	rpcMessageIDKey = kv.Key("message.id")
+	
+	// The uncompressed size of the message transmitted or received in
+	// bytes.
+	rpcMessageUncompressedSizeKey = kv.Key("message.uncompressed_size")
+	
+	// grpcStatusCodeKey is convention for numeric status code of a gRPC request.
+	grpcStatusCodeKey = kv.Key("rpc.grpc.status_code")
+)
+
+var (
+	RPCMessageTypeSent     = rpcMessageTypeKey.String("SENT")
+	RPCMessageTypeReceived = rpcMessageTypeKey.String("RECEIVED")
+)
+
+type Tracer interface {
+	Start(ctx context.Context, spanName string, kind SpanKind) (context.Context, Span)
+}
+
+type Span interface {
+	// End completes the span. No updates are allowed to span after it
+	// ends. The only exception is setting status of the span.
+	End()
+	
+	// SetStatus sets the status of the span in the form of a code
+	// and a message. SetStatus overrides the value of previous
+	// calls to SetStatus on the Span.
+	//
+	// The default span status is OK, so it is not necessary to
+	// explicitly set an OK status on successful Spans unless it
+	// is to add an OK message or to override a previous status on the Span.
+	SetStatus(code codes.Code, msg string)
+	
+	// AddEvent adds an event to the span.
+	// Middleware will call it while receiving or sending messages.
+	AddEvent(name string, attrs ...kv.KeyValue)
+	
+	// SetAttributes sets kv as attributes of the Span. If a key from kv
+	// already exists for an attribute of the Span it should be overwritten with
+	// the value contained in kv.
+	SetAttributes(attrs ...kv.KeyValue)
+}

From be1e9916b6a7a37a94368d9263909652e1d56b9b Mon Sep 17 00:00:00 2001
From: Sam Xie <sam@samxie.me>
Date: Sun, 8 Aug 2021 23:46:40 +0800
Subject: [PATCH 2/8] Fix CI

---
 interceptors/tracing/interceptors.go      |  3 ++
 interceptors/tracing/interceptors_test.go | 63 ++++++++++++-----------
 interceptors/tracing/kv/value.go          |  3 ++
 interceptors/tracing/kv/value_test.go     |  3 ++
 interceptors/tracing/reporter.go          |  7 ++-
 interceptors/tracing/tracing.go           | 19 ++++---
 6 files changed, 58 insertions(+), 40 deletions(-)

diff --git a/interceptors/tracing/interceptors.go b/interceptors/tracing/interceptors.go
index 681d581ae..a30fd3d27 100644
--- a/interceptors/tracing/interceptors.go
+++ b/interceptors/tracing/interceptors.go
@@ -1,3 +1,6 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
 package tracing
 
 import (
diff --git a/interceptors/tracing/interceptors_test.go b/interceptors/tracing/interceptors_test.go
index 99d592964..e09a499cb 100644
--- a/interceptors/tracing/interceptors_test.go
+++ b/interceptors/tracing/interceptors_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
 package tracing_test
 
 import (
@@ -6,14 +9,14 @@ import (
 	"strconv"
 	"sync/atomic"
 	"testing"
-	
+
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/stretchr/testify/suite"
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/metadata"
-	
+
 	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tags"
 	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing"
 	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing/kv"
@@ -33,7 +36,7 @@ func extractFromContext(ctx context.Context, kind tracing.SpanKind) *mockSpan {
 	} else {
 		m, _ = metadata.FromIncomingContext(ctx)
 	}
-	
+
 	traceIDValues := m.Get(traceIDHeaderKey)
 	if len(traceIDValues) == 0 {
 		return nil
@@ -42,7 +45,7 @@ func extractFromContext(ctx context.Context, kind tracing.SpanKind) *mockSpan {
 	if len(spanIDValues) == 0 {
 		return nil
 	}
-	
+
 	return &mockSpan{
 		traceID: traceIDValues[0],
 		spanID:  spanIDValues[0],
@@ -57,10 +60,10 @@ func injectWithContext(ctx context.Context, span *mockSpan, kind tracing.SpanKin
 		m, _ = metadata.FromIncomingContext(ctx)
 	}
 	m = m.Copy()
-	
+
 	m.Set(traceIDHeaderKey, span.traceID)
 	m.Set(spanIDHeaderKey, span.spanID)
-	
+
 	ctx = metadata.NewOutgoingContext(ctx, m)
 	return ctx
 }
@@ -101,7 +104,7 @@ func (t *mockTracer) Start(ctx context.Context, spanName string, kind tracing.Sp
 		kind:       kind,
 		statusCode: codes.OK,
 	}
-	
+
 	// parentSpan := spanFromContext(ctx)
 	parentSpan := extractFromContext(ctx, kind)
 	if parentSpan != nil {
@@ -111,9 +114,9 @@ func (t *mockTracer) Start(ctx context.Context, spanName string, kind tracing.Sp
 	} else {
 		span.traceID = genID()
 	}
-	
+
 	t.spanStore[span.spanID] = &span
-	
+
 	// ctx = contextWithSpan(ctx, &span)
 	if kind == tracing.SpanKindClient {
 		ctx = injectWithContext(ctx, &span, kind)
@@ -126,14 +129,14 @@ type mockSpan struct {
 	traceID      string
 	spanID       string
 	parentSpanID string
-	
+
 	name string
 	kind tracing.SpanKind
 	end  bool
-	
+
 	statusCode    codes.Code
 	statusMessage string
-	
+
 	msgSendCounter     int
 	msgReceivedCounter int
 	eventNameList      []string
@@ -155,7 +158,7 @@ func (s *mockSpan) SetStatus(code codes.Code, message string) {
 
 func (s *mockSpan) AddEvent(name string, attrs ...kv.KeyValue) {
 	s.eventNameList = append(s.eventNameList, name)
-	
+
 	for _, v := range attrs {
 		switch v {
 		case tracing.RPCMessageTypeSent:
@@ -179,7 +182,7 @@ func (s *tracingSuite) TestPing() {
 	method := "/testing.testpb.v1.TestService/Ping"
 	errorMethod := "/testing.testpb.v1.TestService/PingError"
 	t := s.T()
-	
+
 	testCases := []struct {
 		name         string
 		error        bool
@@ -195,11 +198,11 @@ func (s *tracingSuite) TestPing() {
 			errorMessage: "Userspace error.",
 		},
 	}
-	
+
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
 			s.tracer.Reset()
-			
+
 			var err error
 			if tc.error {
 				req := &testpb.PingErrorRequest{ErrorCodeReturned: uint32(codes.InvalidArgument)}
@@ -213,40 +216,40 @@ func (s *tracingSuite) TestPing() {
 			} else {
 				require.NoError(t, err)
 			}
-			
+
 			clientSpans := s.tracer.ListSpan(tracing.SpanKindClient)
 			serverSpans := s.tracer.ListSpan(tracing.SpanKindServer)
 			require.Len(t, clientSpans, 1)
 			require.Len(t, serverSpans, 1)
-			
+
 			clientSpan := clientSpans[0]
 			assert.True(t, clientSpan.end)
 			assert.Equal(t, 1, clientSpan.msgSendCounter)
 			assert.Equal(t, 1, clientSpan.msgReceivedCounter)
 			assert.Equal(t, []string{"message", "message"}, clientSpan.eventNameList)
-			
+
 			serverSpan := serverSpans[0]
 			assert.True(t, serverSpan.end)
 			assert.Equal(t, 1, serverSpan.msgSendCounter)
 			assert.Equal(t, 1, serverSpan.msgReceivedCounter)
 			assert.Equal(t, []string{"message", "message"}, serverSpan.eventNameList)
-			
+
 			assert.Equal(t, clientSpan.traceID, serverSpan.traceID)
 			assert.Equal(t, clientSpan.spanID, serverSpan.parentSpanID)
-			
+
 			if tc.error {
 				assert.Equal(t, codes.InvalidArgument, clientSpan.statusCode)
 				assert.Equal(t, tc.errorMessage, clientSpan.statusMessage)
 				assert.Equal(t, errorMethod, clientSpan.name)
 				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(3)}}, clientSpan.attributesList)
-				
+
 				assert.Equal(t, errorMethod, serverSpan.name)
 				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(3)}}, serverSpan.attributesList)
 			} else {
 				assert.Equal(t, codes.OK, clientSpan.statusCode)
 				assert.Equal(t, method, clientSpan.name)
 				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(0)}}, clientSpan.attributesList)
-				
+
 				assert.Equal(t, method, serverSpan.name)
 				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(0)}}, serverSpan.attributesList)
 			}
@@ -257,10 +260,10 @@ func (s *tracingSuite) TestPing() {
 func (s *tracingSuite) TestPingList() {
 	t := s.T()
 	method := "/testing.testpb.v1.TestService/PingList"
-	
+
 	stream, err := s.Client.PingList(s.SimpleCtx(), &testpb.PingListRequest{Value: "something"})
 	require.NoError(t, err)
-	
+
 	for {
 		_, err := stream.Recv()
 		if err == io.EOF {
@@ -268,19 +271,19 @@ func (s *tracingSuite) TestPingList() {
 		}
 		require.NoError(t, err)
 	}
-	
+
 	clientSpans := s.tracer.ListSpan(tracing.SpanKindClient)
 	serverSpans := s.tracer.ListSpan(tracing.SpanKindServer)
 	require.Len(t, clientSpans, 1)
 	require.Len(t, serverSpans, 1)
-	
+
 	clientSpan := clientSpans[0]
 	assert.True(t, clientSpan.end)
 	assert.Equal(t, 1, clientSpan.msgSendCounter)
 	assert.Equal(t, testpb.ListResponseCount+1, clientSpan.msgReceivedCounter)
 	assert.Equal(t, codes.OK, clientSpan.statusCode)
 	assert.Equal(t, method, clientSpan.name)
-	
+
 	serverSpan := serverSpans[0]
 	assert.True(t, serverSpan.end)
 	assert.Equal(t, testpb.ListResponseCount, serverSpan.msgSendCounter)
@@ -291,7 +294,7 @@ func (s *tracingSuite) TestPingList() {
 
 func TestSuite(t *testing.T) {
 	tracer := newMockTracer()
-	
+
 	s := tracingSuite{
 		InterceptorTestSuite: &testpb.InterceptorTestSuite{
 			TestService: &testpb.TestPingService{T: t},
@@ -312,6 +315,6 @@ func TestSuite(t *testing.T) {
 			tracing.StreamServerInterceptor(tracer),
 		),
 	}
-	
+
 	suite.Run(t, &s)
 }
diff --git a/interceptors/tracing/kv/value.go b/interceptors/tracing/kv/value.go
index 224f95070..82e37caca 100644
--- a/interceptors/tracing/kv/value.go
+++ b/interceptors/tracing/kv/value.go
@@ -1,3 +1,6 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
 package kv
 
 import (
diff --git a/interceptors/tracing/kv/value_test.go b/interceptors/tracing/kv/value_test.go
index 34c48687b..29edfc657 100644
--- a/interceptors/tracing/kv/value_test.go
+++ b/interceptors/tracing/kv/value_test.go
@@ -1,3 +1,6 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
 package kv
 
 import (
diff --git a/interceptors/tracing/reporter.go b/interceptors/tracing/reporter.go
index d8b5df61d..231e8ff9a 100644
--- a/interceptors/tracing/reporter.go
+++ b/interceptors/tracing/reporter.go
@@ -1,3 +1,6 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
 package tracing
 
 import (
@@ -5,9 +8,9 @@ import (
 	"io"
 	"time"
 
-	"github.com/golang/protobuf/proto"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/proto"
 
 	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing/kv"
 )
@@ -62,4 +65,4 @@ func addEvent(span Span, messageType kv.KeyValue, messageID int, payload interfa
 // statusCodeAttr returns status code attribute based on given gRPC code
 func statusCodeAttr(c codes.Code) kv.KeyValue {
 	return grpcStatusCodeKey.Int64(int64(c))
-}
\ No newline at end of file
+}
diff --git a/interceptors/tracing/tracing.go b/interceptors/tracing/tracing.go
index 3415ecce3..84f71c46a 100644
--- a/interceptors/tracing/tracing.go
+++ b/interceptors/tracing/tracing.go
@@ -1,24 +1,27 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
 package tracing
 
 import (
 	"context"
-	
+
 	"google.golang.org/grpc/codes"
-	
+
 	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing/kv"
 )
 
 const (
 	// Type of message transmitted or received.
 	rpcMessageTypeKey = kv.Key("message.type")
-	
+
 	// Identifier of message transmitted or received.
 	rpcMessageIDKey = kv.Key("message.id")
-	
+
 	// The uncompressed size of the message transmitted or received in
 	// bytes.
 	rpcMessageUncompressedSizeKey = kv.Key("message.uncompressed_size")
-	
+
 	// grpcStatusCodeKey is convention for numeric status code of a gRPC request.
 	grpcStatusCodeKey = kv.Key("rpc.grpc.status_code")
 )
@@ -36,7 +39,7 @@ type Span interface {
 	// End completes the span. No updates are allowed to span after it
 	// ends. The only exception is setting status of the span.
 	End()
-	
+
 	// SetStatus sets the status of the span in the form of a code
 	// and a message. SetStatus overrides the value of previous
 	// calls to SetStatus on the Span.
@@ -45,11 +48,11 @@ type Span interface {
 	// explicitly set an OK status on successful Spans unless it
 	// is to add an OK message or to override a previous status on the Span.
 	SetStatus(code codes.Code, msg string)
-	
+
 	// AddEvent adds an event to the span.
 	// Middleware will call it while receiving or sending messages.
 	AddEvent(name string, attrs ...kv.KeyValue)
-	
+
 	// SetAttributes sets kv as attributes of the Span. If a key from kv
 	// already exists for an attribute of the Span it should be overwritten with
 	// the value contained in kv.

From d0650ba634aa1f36f500077dfdd443280f90f957 Mon Sep 17 00:00:00 2001
From: Sam Xie <sam@samxie.me>
Date: Wed, 25 Aug 2021 17:24:44 +0800
Subject: [PATCH 3/8] Follow dependencies changes

---
 interceptors/tracing/interceptors.go      | 33 +++++++++--------------
 interceptors/tracing/interceptors_test.go |  3 ---
 2 files changed, 13 insertions(+), 23 deletions(-)

diff --git a/interceptors/tracing/interceptors.go b/interceptors/tracing/interceptors.go
index a30fd3d27..e2f91d768 100644
--- a/interceptors/tracing/interceptors.go
+++ b/interceptors/tracing/interceptors.go
@@ -18,45 +18,38 @@ const (
 	SpanKindClient SpanKind = "client"
 )
 
-type reportable struct {
-	tracer Tracer
-}
-
-func (r *reportable) ServerReporter(ctx context.Context, _ interface{}, typ interceptors.GRPCType, service string, method string) (interceptors.Reporter, context.Context) {
-	return r.reporter(ctx, service, method, SpanKindServer)
-}
-
-func (r *reportable) ClientReporter(ctx context.Context, _ interface{}, typ interceptors.GRPCType, service string, method string) (interceptors.Reporter, context.Context) {
-	return r.reporter(ctx, service, method, SpanKindClient)
-}
-
-func (r *reportable) reporter(ctx context.Context, service string, method string, kind SpanKind) (interceptors.Reporter, context.Context) {
-	newCtx, span := r.tracer.Start(ctx, interceptors.FullMethod(service, method), kind)
-	reporter := reporter{ctx: newCtx, span: span}
+func reportable(tracer Tracer) interceptors.CommonReportableFunc {
+	return func(ctx context.Context, c interceptors.CallMeta, isClient bool) (interceptors.Reporter, context.Context) {
+		kind := SpanKindServer
+		if isClient {
+			kind = SpanKindClient
+		}
 
-	return &reporter, newCtx
+		newCtx, span := tracer.Start(ctx, c.FullMethod(), kind)
+		return &reporter{ctx: newCtx, span: span}, newCtx
+	}
 }
 
 // UnaryClientInterceptor returns a new unary client interceptor that optionally traces the execution of external gRPC calls.
 // Tracer will use tags (from tags package) available in current context as fields.
 func UnaryClientInterceptor(tracer Tracer) grpc.UnaryClientInterceptor {
-	return interceptors.UnaryClientInterceptor(&reportable{tracer: tracer})
+	return interceptors.UnaryClientInterceptor(reportable(tracer))
 }
 
 // StreamClientInterceptor returns a new streaming client interceptor that optionally traces the execution of external gRPC calls.
 // Tracer will use tags (from tags package) available in current context as fields.
 func StreamClientInterceptor(tracer Tracer) grpc.StreamClientInterceptor {
-	return interceptors.StreamClientInterceptor(&reportable{tracer: tracer})
+	return interceptors.StreamClientInterceptor(reportable(tracer))
 }
 
 // UnaryServerInterceptor returns a new unary server interceptors that optionally traces endpoint handling.
 // Tracer will use tags (from tags package) available in current context as fields.
 func UnaryServerInterceptor(tracer Tracer) grpc.UnaryServerInterceptor {
-	return interceptors.UnaryServerInterceptor(&reportable{tracer: tracer})
+	return interceptors.UnaryServerInterceptor(reportable(tracer))
 }
 
 // StreamServerInterceptor returns a new stream server interceptors that optionally traces endpoint handling.
 // Tracer will use tags (from tags package) available in current context as fields.
 func StreamServerInterceptor(tracer Tracer) grpc.StreamServerInterceptor {
-	return interceptors.StreamServerInterceptor(&reportable{tracer: tracer})
+	return interceptors.StreamServerInterceptor(reportable(tracer))
 }
diff --git a/interceptors/tracing/interceptors_test.go b/interceptors/tracing/interceptors_test.go
index e09a499cb..3f25e4eac 100644
--- a/interceptors/tracing/interceptors_test.go
+++ b/interceptors/tracing/interceptors_test.go
@@ -17,7 +17,6 @@ import (
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/metadata"
 
-	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tags"
 	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing"
 	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing/kv"
 	"github.com/grpc-ecosystem/go-grpc-middleware/v2/testing/testpb"
@@ -307,11 +306,9 @@ func TestSuite(t *testing.T) {
 	}
 	s.InterceptorTestSuite.ServerOpts = []grpc.ServerOption{
 		grpc.ChainUnaryInterceptor(
-			tags.UnaryServerInterceptor(tags.WithFieldExtractor(tags.CodeGenRequestFieldExtractor)),
 			tracing.UnaryServerInterceptor(tracer),
 		),
 		grpc.ChainStreamInterceptor(
-			tags.StreamServerInterceptor(tags.WithFieldExtractor(tags.CodeGenRequestFieldExtractor)),
 			tracing.StreamServerInterceptor(tracer),
 		),
 	}

From 822802af57d7df9747f123c7df09ae91c9b6ec50 Mon Sep 17 00:00:00 2001
From: Sam Xie <sam@samxie.me>
Date: Wed, 25 Aug 2021 17:31:35 +0800
Subject: [PATCH 4/8] Fix comments

---
 interceptors/tracing/reporter.go | 2 --
 1 file changed, 2 deletions(-)

diff --git a/interceptors/tracing/reporter.go b/interceptors/tracing/reporter.go
index 231e8ff9a..a80298431 100644
--- a/interceptors/tracing/reporter.go
+++ b/interceptors/tracing/reporter.go
@@ -37,13 +37,11 @@ func (o *reporter) PostCall(err error, _ time.Duration) {
 
 func (o *reporter) PostMsgSend(payload interface{}, err error, d time.Duration) {
 	o.sentMessageID++
-
 	addEvent(o.span, RPCMessageTypeSent, o.sentMessageID, payload)
 }
 
 func (o *reporter) PostMsgReceive(payload interface{}, err error, d time.Duration) {
 	o.receivedMessageID++
-
 	addEvent(o.span, RPCMessageTypeReceived, o.receivedMessageID, payload)
 }
 

From 7854af0f0b454e1a3c4de17cda70a15d47e023e5 Mon Sep 17 00:00:00 2001
From: Sam Xie <sam@samxie.me>
Date: Tue, 31 Aug 2021 11:20:38 +0800
Subject: [PATCH 5/8] Avoid redundant else and return early

---
 interceptors/tracing/reporter.go | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/interceptors/tracing/reporter.go b/interceptors/tracing/reporter.go
index a80298431..b54fc45eb 100644
--- a/interceptors/tracing/reporter.go
+++ b/interceptors/tracing/reporter.go
@@ -52,12 +52,12 @@ func addEvent(span Span, messageType kv.KeyValue, messageID int, payload interfa
 			rpcMessageIDKey.Int(messageID),
 			rpcMessageUncompressedSizeKey.Int(proto.Size(p)),
 		)
-	} else {
-		span.AddEvent("message",
-			messageType,
-			rpcMessageIDKey.Int(messageID),
-		)
+		return
 	}
+	span.AddEvent("message",
+		messageType,
+		rpcMessageIDKey.Int(messageID),
+	)
 }
 
 // statusCodeAttr returns status code attribute based on given gRPC code

From 135fdbd2fa40f425dfae57269632022a2e138918 Mon Sep 17 00:00:00 2001
From: Sam Xie <xsambundy@gmail.com>
Date: Wed, 1 Sep 2021 11:01:32 +0800
Subject: [PATCH 6/8] Update interceptors/tracing/interceptors_test.go

Co-authored-by: Yash Sharma <yashrsharma44@gmail.com>
---
 interceptors/tracing/interceptors_test.go | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/interceptors/tracing/interceptors_test.go b/interceptors/tracing/interceptors_test.go
index 3f25e4eac..9989f34c8 100644
--- a/interceptors/tracing/interceptors_test.go
+++ b/interceptors/tracing/interceptors_test.go
@@ -104,7 +104,6 @@ func (t *mockTracer) Start(ctx context.Context, spanName string, kind tracing.Sp
 		statusCode: codes.OK,
 	}
 
-	// parentSpan := spanFromContext(ctx)
 	parentSpan := extractFromContext(ctx, kind)
 	if parentSpan != nil {
 		// Fetch span from context as parent span
@@ -115,8 +114,6 @@ func (t *mockTracer) Start(ctx context.Context, spanName string, kind tracing.Sp
 	}
 
 	t.spanStore[span.spanID] = &span
-
-	// ctx = contextWithSpan(ctx, &span)
 	if kind == tracing.SpanKindClient {
 		ctx = injectWithContext(ctx, &span, kind)
 	}

From 9202a1567c91319d19b44adbf2814b8d80914baa Mon Sep 17 00:00:00 2001
From: Sam Xie <sam@samxie.me>
Date: Thu, 14 Apr 2022 22:30:50 +0800
Subject: [PATCH 7/8] Remove kv package

---
 interceptors/tracing/interceptors_test.go |  15 +-
 interceptors/tracing/kv.go                |  21 +++
 interceptors/tracing/kv/value.go          | 174 ----------------------
 interceptors/tracing/kv/value_test.go     |  59 --------
 interceptors/tracing/reporter.go          |  14 +-
 interceptors/tracing/tracing.go           |  18 +--
 6 files changed, 42 insertions(+), 259 deletions(-)
 create mode 100644 interceptors/tracing/kv.go
 delete mode 100644 interceptors/tracing/kv/value.go
 delete mode 100644 interceptors/tracing/kv/value_test.go

diff --git a/interceptors/tracing/interceptors_test.go b/interceptors/tracing/interceptors_test.go
index 9989f34c8..f4e91cf52 100644
--- a/interceptors/tracing/interceptors_test.go
+++ b/interceptors/tracing/interceptors_test.go
@@ -18,7 +18,6 @@ import (
 	"google.golang.org/grpc/metadata"
 
 	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing"
-	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing/kv"
 	"github.com/grpc-ecosystem/go-grpc-middleware/v2/testing/testpb"
 )
 
@@ -136,10 +135,10 @@ type mockSpan struct {
 	msgSendCounter     int
 	msgReceivedCounter int
 	eventNameList      []string
-	attributesList     [][]kv.KeyValue
+	attributesList     [][]tracing.KeyValue
 }
 
-func (s *mockSpan) SetAttributes(attrs ...kv.KeyValue) {
+func (s *mockSpan) SetAttributes(attrs ...tracing.KeyValue) {
 	s.attributesList = append(s.attributesList, attrs)
 }
 
@@ -152,7 +151,7 @@ func (s *mockSpan) SetStatus(code codes.Code, message string) {
 	s.statusMessage = message
 }
 
-func (s *mockSpan) AddEvent(name string, attrs ...kv.KeyValue) {
+func (s *mockSpan) AddEvent(name string, attrs ...tracing.KeyValue) {
 	s.eventNameList = append(s.eventNameList, name)
 
 	for _, v := range attrs {
@@ -237,17 +236,17 @@ func (s *tracingSuite) TestPing() {
 				assert.Equal(t, codes.InvalidArgument, clientSpan.statusCode)
 				assert.Equal(t, tc.errorMessage, clientSpan.statusMessage)
 				assert.Equal(t, errorMethod, clientSpan.name)
-				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(3)}}, clientSpan.attributesList)
+				assert.Equal(t, [][]tracing.KeyValue{{tracing.Key("rpc.grpc.status_code").Value(int64(3))}}, clientSpan.attributesList)
 
 				assert.Equal(t, errorMethod, serverSpan.name)
-				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(3)}}, serverSpan.attributesList)
+				assert.Equal(t, [][]tracing.KeyValue{{tracing.Key("rpc.grpc.status_code").Value(int64(3))}}, serverSpan.attributesList)
 			} else {
 				assert.Equal(t, codes.OK, clientSpan.statusCode)
 				assert.Equal(t, method, clientSpan.name)
-				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(0)}}, clientSpan.attributesList)
+				assert.Equal(t, [][]tracing.KeyValue{{tracing.Key("rpc.grpc.status_code").Value(int64(0))}}, clientSpan.attributesList)
 
 				assert.Equal(t, method, serverSpan.name)
-				assert.Equal(t, [][]kv.KeyValue{{kv.Key("rpc.grpc.status_code").Int64(0)}}, serverSpan.attributesList)
+				assert.Equal(t, [][]tracing.KeyValue{{tracing.Key("rpc.grpc.status_code").Value(int64(0))}}, serverSpan.attributesList)
 			}
 		})
 	}
diff --git a/interceptors/tracing/kv.go b/interceptors/tracing/kv.go
new file mode 100644
index 000000000..30e59527d
--- /dev/null
+++ b/interceptors/tracing/kv.go
@@ -0,0 +1,21 @@
+// Copyright (c) The go-grpc-middleware Authors.
+// Licensed under the Apache License 2.0.
+
+package tracing
+
+type Key string
+
+// KeyValue holds a key and value pair.
+type KeyValue struct {
+	Key   Key
+	Value interface{}
+}
+
+// Value creates a KeyValue instance with a Value.
+// It supports string, bool, int, int64, float64, string.
+func (k Key) Value(v interface{}) KeyValue {
+	return KeyValue{
+		Key:   k,
+		Value: v,
+	}
+}
diff --git a/interceptors/tracing/kv/value.go b/interceptors/tracing/kv/value.go
deleted file mode 100644
index 82e37caca..000000000
--- a/interceptors/tracing/kv/value.go
+++ /dev/null
@@ -1,174 +0,0 @@
-// Copyright (c) The go-grpc-middleware Authors.
-// Licensed under the Apache License 2.0.
-
-package kv
-
-import (
-	"math"
-)
-
-// KeyValue holds a key and value pair.
-type KeyValue struct {
-	Key   Key
-	Value Value
-}
-
-type Key string
-
-// Bool creates a KeyValue instance with a BOOL Value.
-//
-// If creating both key and a bool value at the same time, then
-// instead of calling kv.Key(name).Bool(value) consider using a
-// convenience function provided by the api/key package -
-// key.Bool(name, value).
-func (k Key) Bool(v bool) KeyValue {
-	return KeyValue{
-		Key:   k,
-		Value: boolValue(v),
-	}
-}
-
-// Int64 creates a KeyValue instance with an INT64 Value.
-//
-// If creating both key and an int64 value at the same time, then
-// instead of calling kv.Key(name).Int64(value) consider using a
-// convenience function provided by the api/key package -
-// key.Int64(name, value).
-func (k Key) Int64(v int64) KeyValue {
-	return KeyValue{
-		Key:   k,
-		Value: int64Value(v),
-	}
-}
-
-// Float64 creates a KeyValue instance with a FLOAT64 Value.
-//
-// If creating both key and a float64 value at the same time, then
-// instead of calling kv.Key(name).Float64(value) consider using a
-// convenience function provided by the api/key package -
-// key.Float64(name, value).
-func (k Key) Float64(v float64) KeyValue {
-	return KeyValue{
-		Key:   k,
-		Value: float64Value(v),
-	}
-}
-
-// String creates a KeyValue instance with a STRING Value.
-//
-// If creating both key and a string value at the same time, then
-// instead of calling kv.Key(name).String(value) consider using a
-// convenience function provided by the api/key package -
-// key.String(name, value).
-func (k Key) String(v string) KeyValue {
-	return KeyValue{
-		Key:   k,
-		Value: stringValue(v),
-	}
-}
-
-// Int creates a KeyValue instance with either an INT32 or an INT64
-// Value, depending on whether the int type is 32 or 64 bits wide.
-//
-// If creating both key and an int value at the same time, then
-// instead of calling kv.Key(name).Int(value) consider using a
-// convenience function provided by the api/key package -
-// key.Int(name, value).
-func (k Key) Int(v int) KeyValue {
-	return KeyValue{
-		Key:   k,
-		Value: intValue(v),
-	}
-}
-
-// ValueType describes the type of the data Value holds.
-type ValueType int
-
-const (
-	INVALID ValueType = iota // No value.
-	// BOOL is a boolean Type Value.
-	BOOL
-	// INT64 is a 64-bit signed integral Type Value.
-	INT64
-	// FLOAT64 is a 64-bit floating point Type Value.
-	FLOAT64
-	// STRING is a string Type Value.
-	STRING
-)
-
-type Value struct {
-	vtype    ValueType
-	numeric  uint64
-	stringly string
-}
-
-func boolTowRaw(b bool) uint64 {
-	if b {
-		return 1
-	}
-	return 0
-}
-
-func rawToBool(r uint64) bool {
-	return r != 0
-}
-
-func boolValue(v bool) Value {
-	return Value{
-		vtype:   BOOL,
-		numeric: boolTowRaw(v),
-	}
-}
-
-func int64Value(v int64) Value {
-	return Value{
-		vtype:   INT64,
-		numeric: uint64(v),
-	}
-}
-
-func float64Value(v float64) Value {
-	return Value{
-		vtype:   FLOAT64,
-		numeric: math.Float64bits(v),
-	}
-}
-
-func stringValue(v string) Value {
-	return Value{
-		vtype:    STRING,
-		stringly: v,
-	}
-}
-
-// intValue creates an INT64 Value.
-func intValue(v int) Value {
-	return int64Value(int64(v))
-}
-
-func (v Value) AsBool() bool {
-	return rawToBool(v.numeric)
-}
-
-// AsInt64 returns the int64 value. Make sure that the Value's type is
-// INT64.
-func (v Value) AsInt64() int64 {
-	return int64(v.numeric)
-}
-
-// AsFloat64 returns the float64 value. Make sure that the Value's
-// type is FLOAT64.
-func (v Value) AsFloat64() float64 {
-	return math.Float64frombits(v.numeric)
-}
-
-// AsString returns the string value. Make sure that the Value's type
-// is STRING.
-func (v Value) AsString() string {
-	return v.stringly
-}
-
-// Type returns a type of the Value.
-func (v Value) Type() ValueType {
-	return v.vtype
-}
diff --git a/interceptors/tracing/kv/value_test.go b/interceptors/tracing/kv/value_test.go
deleted file mode 100644
index 29edfc657..000000000
--- a/interceptors/tracing/kv/value_test.go
+++ /dev/null
@@ -1,59 +0,0 @@
-// Copyright (c) The go-grpc-middleware Authors.
-// Licensed under the Apache License 2.0.
-
-package kv
-
-import (
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-)
-
-func TestKey(t *testing.T) {
-	testCases := []struct {
-		name          string
-		keyValue      KeyValue
-		expectedValue interface{}
-	}{
-		{
-			name:          "true",
-			keyValue:      Key("bool").Bool(true),
-			expectedValue: true,
-		},
-		{
-			name:          "false",
-			keyValue:      Key("bool").Bool(false),
-			expectedValue: false,
-		},
-		{
-			name:          "int64",
-			keyValue:      Key("int64").Int64(43),
-			expectedValue: int64(43),
-		},
-		{
-			name:          "float64",
-			keyValue:      Key("float64").Float64(43),
-			expectedValue: float64(43),
-		},
-		{
-			name:          "string",
-			keyValue:      Key("string").String("foo"),
-			expectedValue: "foo",
-		},
-	}
-
-	for _, tc := range testCases {
-		t.Run(tc.name, func(t *testing.T) {
-			switch tc.keyValue.Value.Type() {
-			case BOOL:
-				assert.Equal(t, tc.expectedValue, tc.keyValue.Value.AsBool())
-			case INT64:
-				assert.Equal(t, tc.expectedValue, tc.keyValue.Value.AsInt64())
-			case FLOAT64:
-				assert.Equal(t, tc.expectedValue, tc.keyValue.Value.AsFloat64())
-			case STRING:
-				assert.Equal(t, tc.expectedValue, tc.keyValue.Value.AsString())
-			}
-		})
-	}
-}
diff --git a/interceptors/tracing/reporter.go b/interceptors/tracing/reporter.go
index b54fc45eb..e38b31180 100644
--- a/interceptors/tracing/reporter.go
+++ b/interceptors/tracing/reporter.go
@@ -11,8 +11,6 @@ import (
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 	"google.golang.org/protobuf/proto"
-
-	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing/kv"
 )
 
 type reporter struct {
@@ -45,22 +43,22 @@ func (o *reporter) PostMsgReceive(payload interface{}, err error, d time.Duratio
 	addEvent(o.span, RPCMessageTypeReceived, o.receivedMessageID, payload)
 }
 
-func addEvent(span Span, messageType kv.KeyValue, messageID int, payload interface{}) {
+func addEvent(span Span, messageType KeyValue, messageID int, payload interface{}) {
 	if p, ok := payload.(proto.Message); ok {
 		span.AddEvent("message",
 			messageType,
-			rpcMessageIDKey.Int(messageID),
-			rpcMessageUncompressedSizeKey.Int(proto.Size(p)),
+			rpcMessageIDKey.Value(messageID),
+			rpcMessageUncompressedSizeKey.Value(proto.Size(p)),
 		)
 		return
 	}
 	span.AddEvent("message",
 		messageType,
-		rpcMessageIDKey.Int(messageID),
+		rpcMessageIDKey.Value(messageID),
 	)
 }
 
 // statusCodeAttr returns status code attribute based on given gRPC code
-func statusCodeAttr(c codes.Code) kv.KeyValue {
-	return grpcStatusCodeKey.Int64(int64(c))
+func statusCodeAttr(c codes.Code) KeyValue {
+	return grpcStatusCodeKey.Value(int64(c))
 }
diff --git a/interceptors/tracing/tracing.go b/interceptors/tracing/tracing.go
index 84f71c46a..08299ce1d 100644
--- a/interceptors/tracing/tracing.go
+++ b/interceptors/tracing/tracing.go
@@ -7,28 +7,26 @@ import (
 	"context"
 
 	"google.golang.org/grpc/codes"
-
-	"github.com/grpc-ecosystem/go-grpc-middleware/v2/interceptors/tracing/kv"
 )
 
 const (
 	// Type of message transmitted or received.
-	rpcMessageTypeKey = kv.Key("message.type")
+	rpcMessageTypeKey = Key("message.type")
 
 	// Identifier of message transmitted or received.
-	rpcMessageIDKey = kv.Key("message.id")
+	rpcMessageIDKey = Key("message.id")
 
 	// The uncompressed size of the message transmitted or received in
 	// bytes.
-	rpcMessageUncompressedSizeKey = kv.Key("message.uncompressed_size")
+	rpcMessageUncompressedSizeKey = Key("message.uncompressed_size")
 
 	// grpcStatusCodeKey is convention for numeric status code of a gRPC request.
-	grpcStatusCodeKey = kv.Key("rpc.grpc.status_code")
+	grpcStatusCodeKey = Key("rpc.grpc.status_code")
 )
 
 var (
-	RPCMessageTypeSent     = rpcMessageTypeKey.String("SENT")
-	RPCMessageTypeReceived = rpcMessageTypeKey.String("RECEIVED")
+	RPCMessageTypeSent     = rpcMessageTypeKey.Value("SENT")
+	RPCMessageTypeReceived = rpcMessageTypeKey.Value("RECEIVED")
 )
 
 type Tracer interface {
@@ -51,10 +49,10 @@ type Span interface {
 
 	// AddEvent adds an event to the span.
 	// Middleware will call it while receiving or sending messages.
-	AddEvent(name string, attrs ...kv.KeyValue)
+	AddEvent(name string, attrs ...KeyValue)
 
 	// SetAttributes sets kv as attributes of the Span. If a key from kv
 	// already exists for an attribute of the Span it should be overwritten with
 	// the value contained in kv.
-	SetAttributes(attrs ...kv.KeyValue)
+	SetAttributes(attrs ...KeyValue)
 }

From 545d37aa07ed8705b1e413eb0a7acb8356c8ec0e Mon Sep 17 00:00:00 2001
From: Sam Xie <sam@samxie.me>
Date: Fri, 22 Apr 2022 00:14:49 +0800
Subject: [PATCH 8/8] Remove keyvalue

---
 interceptors/tracing/interceptors_test.go | 37 ++++++++++++++---------
 interceptors/tracing/kv.go                | 21 -------------
 interceptors/tracing/reporter.go          | 16 +++++-----
 interceptors/tracing/tracing.go           | 24 +++++++--------
 4 files changed, 43 insertions(+), 55 deletions(-)
 delete mode 100644 interceptors/tracing/kv.go

diff --git a/interceptors/tracing/interceptors_test.go b/interceptors/tracing/interceptors_test.go
index f4e91cf52..f74854ca4 100644
--- a/interceptors/tracing/interceptors_test.go
+++ b/interceptors/tracing/interceptors_test.go
@@ -135,11 +135,11 @@ type mockSpan struct {
 	msgSendCounter     int
 	msgReceivedCounter int
 	eventNameList      []string
-	attributesList     [][]tracing.KeyValue
+	attributesList     [][]interface{}
 }
 
-func (s *mockSpan) SetAttributes(attrs ...tracing.KeyValue) {
-	s.attributesList = append(s.attributesList, attrs)
+func (s *mockSpan) SetAttributes(keyvals ...interface{}) {
+	s.attributesList = append(s.attributesList, keyvals)
 }
 
 func (s *mockSpan) End() {
@@ -151,15 +151,24 @@ func (s *mockSpan) SetStatus(code codes.Code, message string) {
 	s.statusMessage = message
 }
 
-func (s *mockSpan) AddEvent(name string, attrs ...tracing.KeyValue) {
+func (s *mockSpan) AddEvent(name string, keyvals ...interface{}) {
 	s.eventNameList = append(s.eventNameList, name)
 
-	for _, v := range attrs {
-		switch v {
-		case tracing.RPCMessageTypeSent:
-			s.msgSendCounter++
-		case tracing.RPCMessageTypeReceived:
-			s.msgReceivedCounter++
+	if len(keyvals)%2 == 1 {
+		keyvals = append(keyvals, nil)
+	}
+
+	for i := 0; i < len(keyvals); i += 2 {
+		k, keyOK := keyvals[i].(string)
+		v, valueOK := keyvals[i+1].(string)
+
+		if keyOK && valueOK && k == "message.type" {
+			switch v {
+			case tracing.RPCMessageTypeSent:
+				s.msgSendCounter++
+			case tracing.RPCMessageTypeReceived:
+				s.msgReceivedCounter++
+			}
 		}
 	}
 }
@@ -236,17 +245,17 @@ func (s *tracingSuite) TestPing() {
 				assert.Equal(t, codes.InvalidArgument, clientSpan.statusCode)
 				assert.Equal(t, tc.errorMessage, clientSpan.statusMessage)
 				assert.Equal(t, errorMethod, clientSpan.name)
-				assert.Equal(t, [][]tracing.KeyValue{{tracing.Key("rpc.grpc.status_code").Value(int64(3))}}, clientSpan.attributesList)
+				assert.Equal(t, [][]interface{}{{[]interface{}{"rpc.grpc.status_code", int64(3)}}}, clientSpan.attributesList)
 
 				assert.Equal(t, errorMethod, serverSpan.name)
-				assert.Equal(t, [][]tracing.KeyValue{{tracing.Key("rpc.grpc.status_code").Value(int64(3))}}, serverSpan.attributesList)
+				assert.Equal(t, [][]interface{}{{[]interface{}{"rpc.grpc.status_code", int64(3)}}}, serverSpan.attributesList)
 			} else {
 				assert.Equal(t, codes.OK, clientSpan.statusCode)
 				assert.Equal(t, method, clientSpan.name)
-				assert.Equal(t, [][]tracing.KeyValue{{tracing.Key("rpc.grpc.status_code").Value(int64(0))}}, clientSpan.attributesList)
+				assert.Equal(t, [][]interface{}{{[]interface{}{"rpc.grpc.status_code", int64(0)}}}, clientSpan.attributesList)
 
 				assert.Equal(t, method, serverSpan.name)
-				assert.Equal(t, [][]tracing.KeyValue{{tracing.Key("rpc.grpc.status_code").Value(int64(0))}}, serverSpan.attributesList)
+				assert.Equal(t, [][]interface{}{{[]interface{}{"rpc.grpc.status_code", int64(0)}}}, serverSpan.attributesList)
 			}
 		})
 	}
diff --git a/interceptors/tracing/kv.go b/interceptors/tracing/kv.go
deleted file mode 100644
index 30e59527d..000000000
--- a/interceptors/tracing/kv.go
+++ /dev/null
@@ -1,21 +0,0 @@
-// Copyright (c) The go-grpc-middleware Authors.
-// Licensed under the Apache License 2.0.
-
-package tracing
-
-type Key string
-
-// KeyValue holds a key and value pair.
-type KeyValue struct {
-	Key   Key
-	Value interface{}
-}
-
-// Value creates a KeyValue instance with a Value.
-// It supports string, bool, int, int64, float64, string.
-func (k Key) Value(v interface{}) KeyValue {
-	return KeyValue{
-		Key:   k,
-		Value: v,
-	}
-}
diff --git a/interceptors/tracing/reporter.go b/interceptors/tracing/reporter.go
index e38b31180..4a0e40ebd 100644
--- a/interceptors/tracing/reporter.go
+++ b/interceptors/tracing/reporter.go
@@ -43,22 +43,22 @@ func (o *reporter) PostMsgReceive(payload interface{}, err error, d time.Duratio
 	addEvent(o.span, RPCMessageTypeReceived, o.receivedMessageID, payload)
 }
 
-func addEvent(span Span, messageType KeyValue, messageID int, payload interface{}) {
+func addEvent(span Span, messageType string, messageID int, payload interface{}) {
 	if p, ok := payload.(proto.Message); ok {
 		span.AddEvent("message",
-			messageType,
-			rpcMessageIDKey.Value(messageID),
-			rpcMessageUncompressedSizeKey.Value(proto.Size(p)),
+			rpcMessageTypeKey, messageType,
+			rpcMessageIDKey, messageID,
+			rpcMessageUncompressedSizeKey, proto.Size(p),
 		)
 		return
 	}
 	span.AddEvent("message",
-		messageType,
-		rpcMessageIDKey.Value(messageID),
+		rpcMessageTypeKey, messageType,
+		rpcMessageIDKey, messageID,
 	)
 }
 
 // statusCodeAttr returns status code attribute based on given gRPC code
-func statusCodeAttr(c codes.Code) KeyValue {
-	return grpcStatusCodeKey.Value(int64(c))
+func statusCodeAttr(c codes.Code) []interface{} {
+	return []interface{}{grpcStatusCodeKey, int64(c)}
 }
diff --git a/interceptors/tracing/tracing.go b/interceptors/tracing/tracing.go
index 08299ce1d..bd47d20db 100644
--- a/interceptors/tracing/tracing.go
+++ b/interceptors/tracing/tracing.go
@@ -11,22 +11,22 @@ import (
 
 const (
 	// Type of message transmitted or received.
-	rpcMessageTypeKey = Key("message.type")
+	rpcMessageTypeKey = "message.type"
 
 	// Identifier of message transmitted or received.
-	rpcMessageIDKey = Key("message.id")
+	rpcMessageIDKey = "message.id"
 
 	// The uncompressed size of the message transmitted or received in
 	// bytes.
-	rpcMessageUncompressedSizeKey = Key("message.uncompressed_size")
+	rpcMessageUncompressedSizeKey = "message.uncompressed_size"
 
 	// grpcStatusCodeKey is convention for numeric status code of a gRPC request.
-	grpcStatusCodeKey = Key("rpc.grpc.status_code")
+	grpcStatusCodeKey = "rpc.grpc.status_code"
 )
 
-var (
-	RPCMessageTypeSent     = rpcMessageTypeKey.Value("SENT")
-	RPCMessageTypeReceived = rpcMessageTypeKey.Value("RECEIVED")
+const (
+	RPCMessageTypeSent     = "SENT"
+	RPCMessageTypeReceived = "RECEIVED"
 )
 
 type Tracer interface {
@@ -47,12 +47,12 @@ type Span interface {
 	// is to add an OK message or to override a previous status on the Span.
 	SetStatus(code codes.Code, msg string)
 
-	// AddEvent adds an event to the span.
+	// AddEvent adds an event to the span with key/value pairs as attributes.
 	// Middleware will call it while receiving or sending messages.
-	AddEvent(name string, attrs ...KeyValue)
+	AddEvent(name string, keyvals ...interface{})
 
-	// SetAttributes sets kv as attributes of the Span. If a key from kv
+	// SetAttributes sets key/value pairs as attributes. If a key
 	// already exists for an attribute of the Span it should be overwritten with
-	// the value contained in kv.
-	SetAttributes(attrs ...KeyValue)
+	// the value.
+	SetAttributes(keyvals ...interface{})
 }