improve tracing

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

carrier.go

@@ -2,6 +2,7 @@ package kgo
 
 import (
 	"github.com/twmb/franz-go/pkg/kgo"
+	"go.unistack.org/micro/v3/metadata"
 )
 
 // RecordCarrier injects and extracts traces from a kgo.Record.
@@ -51,3 +52,25 @@ func (c RecordCarrier) Keys() []string {
 	}
 	return out
 }
+
+func setHeaders(r *kgo.Record, md metadata.Metadata) {
+	seen := make(map[string]struct{})
+loop:
+	for k, v := range md {
+		for i := 0; i < len(r.Headers); i++ {
+			if r.Headers[i].Key == k {
+				// Key exist, update the value.
+				r.Headers[i].Value = []byte(v)
+				continue loop
+			} else if _, ok := seen[k]; ok {
+				continue loop
+			}
+			// Key does not exist, append new header.
+			r.Headers = append(r.Headers, kgo.RecordHeader{
+				Key:   k,
+				Value: []byte(v),
+			})
+			seen[k] = struct{}{}
+		}
+	}
+}

kgo.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"fmt"
 	"math/rand"
+	"net/http"
 	"strings"
 	"sync"
 	"time"
@@ -62,7 +63,7 @@ type Broker struct {
 	connected bool
 	sync.RWMutex
 	opts broker.Options
-	subs []*subscriber
+	subs []*Subscriber
 }
 
 func (k *Broker) Address() string {
@@ -275,7 +276,7 @@ func (k *Broker) publish(ctx context.Context, msgs []*broker.Message, opts ...br
 		if options.BodyOnly || k.opts.Codec.String() == "noop" {
 			rec.Value = msg.Body
 			for k, v := range msg.Header {
-				rec.Headers = append(rec.Headers, kgo.RecordHeader{Key: k, Value: []byte(v)})
+				rec.Headers = append(rec.Headers, kgo.RecordHeader{Key: http.CanonicalHeaderKey(k), Value: []byte(v)})
 			}
 		} else {
 			rec.Value, err = k.opts.Codec.Marshal(msg)
@@ -364,7 +365,7 @@ func (k *Broker) Subscribe(ctx context.Context, topic string, handler broker.Han
 		}
 	}
 
-	sub := &subscriber{
+	sub := &Subscriber{
 		topic:     topic,
 		opts:      options,
 		handler:   handler,

subscriber.go

@@ -33,7 +33,7 @@ type consumer struct {
 	recs      chan kgo.FetchTopicPartition
 }
 
-type subscriber struct {
+type Subscriber struct {
 	c         *kgo.Client
 	topic     string
 	htracer   *hookTracer
@@ -46,19 +46,19 @@ type subscriber struct {
 	sync.RWMutex
 }
 
-func (s *subscriber) Client() *kgo.Client {
+func (s *Subscriber) Client() *kgo.Client {
 	return s.c
 }
 
-func (s *subscriber) Options() broker.SubscribeOptions {
+func (s *Subscriber) Options() broker.SubscribeOptions {
 	return s.opts
 }
 
-func (s *subscriber) Topic() string {
+func (s *Subscriber) Topic() string {
 	return s.topic
 }
 
-func (s *subscriber) Unsubscribe(ctx context.Context) error {
+func (s *Subscriber) Unsubscribe(ctx context.Context) error {
 	if s.closed {
 		return nil
 	}
@@ -80,7 +80,7 @@ func (s *subscriber) Unsubscribe(ctx context.Context) error {
 	return nil
 }
 
-func (s *subscriber) poll(ctx context.Context) {
+func (s *Subscriber) poll(ctx context.Context) {
 	maxInflight := DefaultSubscribeMaxInflight
 	if s.opts.Context != nil {
 		if n, ok := s.opts.Context.Value(subscribeMaxInflightKey{}).(int); n > 0 && ok {
@@ -148,7 +148,7 @@ func (s *subscriber) poll(ctx context.Context) {
 	}
 }
 
-func (s *subscriber) killConsumers(ctx context.Context, lost map[string][]int32) {
+func (s *Subscriber) killConsumers(ctx context.Context, lost map[string][]int32) {
 	var wg sync.WaitGroup
 	defer wg.Wait()
 
@@ -165,12 +165,12 @@ func (s *subscriber) killConsumers(ctx context.Context, lost map[string][]int32)
 	}
 }
 
-func (s *subscriber) lost(ctx context.Context, _ *kgo.Client, lost map[string][]int32) {
+func (s *Subscriber) lost(ctx context.Context, _ *kgo.Client, lost map[string][]int32) {
 	s.kopts.Logger.Debugf(ctx, "[kgo] lost %#+v", lost)
 	s.killConsumers(ctx, lost)
 }
 
-func (s *subscriber) revoked(ctx context.Context, c *kgo.Client, revoked map[string][]int32) {
+func (s *Subscriber) revoked(ctx context.Context, c *kgo.Client, revoked map[string][]int32) {
 	s.kopts.Logger.Debugf(ctx, "[kgo] revoked %#+v", revoked)
 	s.killConsumers(ctx, revoked)
 	if err := c.CommitMarkedOffsets(ctx); err != nil {
@@ -178,7 +178,7 @@ func (s *subscriber) revoked(ctx context.Context, c *kgo.Client, revoked map[str
 	}
 }
 
-func (s *subscriber) assigned(_ context.Context, c *kgo.Client, assigned map[string][]int32) {
+func (s *Subscriber) assigned(_ context.Context, c *kgo.Client, assigned map[string][]int32) {
 	for topic, partitions := range assigned {
 		for _, partition := range partitions {
 			pc := &consumer{

tracer.go

@@ -58,12 +58,15 @@ func (m *hookTracer) OnProduceRecordBuffered(r *kgo.Record) {
 		md.Set(h.Key, string(h.Value))
 	}
 
-	// Start the "publish" span.
-	ctx, _ := m.tracer.Start(metadata.NewOutgoingContext(r.Context, md), r.Topic+" publish", opts...)
-	// Inject the span context into the record.
-	// t.propagators.Inject(ctx, NewRecordCarrier(r))
-	// Update the record context.
-	r.Context = ctx
+	if !ok {
+		r.Context, _ = m.tracer.Start(metadata.NewOutgoingContext(r.Context, md), r.Topic+" publish", opts...)
+	} else {
+		r.Context, _ = m.tracer.Start(r.Context, r.Topic+" publish", opts...)
+	}
+
+	md, _ = metadata.FromOutgoingContext(r.Context)
+
+	setHeaders(r, md)
 }
 
 // OnProduceRecordUnbuffered continues and ends the "publish" span for an
@@ -72,14 +75,15 @@ func (m *hookTracer) OnProduceRecordBuffered(r *kgo.Record) {
 // It sets attributes with values unset when producing and records any error
 // that occurred during the publish operation.
 func (m *hookTracer) OnProduceRecordUnbuffered(r *kgo.Record, err error) {
-	span, _ := tracer.SpanFromContext(r.Context)
-	span.AddLabels(
-		semconv.MessagingKafkaDestinationPartition(int(r.Partition)),
-	)
-	if err != nil {
-		span.SetStatus(tracer.SpanStatusError, err.Error())
+	if span, ok := tracer.SpanFromContext(r.Context); ok {
+		span.AddLabels(
+			semconv.MessagingKafkaDestinationPartition(int(r.Partition)),
+		)
+		if err != nil {
+			span.SetStatus(tracer.SpanStatusError, err.Error())
+		}
+		span.Finish()
 	}
-	span.Finish()
 }
 
 // OnFetchRecordBuffered starts a new span for the "receive" operation on a
@@ -121,12 +125,15 @@ func (m *hookTracer) OnFetchRecordBuffered(r *kgo.Record) {
 		md.Set(h.Key, string(h.Value))
 	}
 
-	// Extract the span context from the record.
-	// ctx := t.propagators.Extract(r.Context, NewRecordCarrier(r))
-	// Start the "receive" span.
-	newCtx, _ := m.tracer.Start(metadata.NewIncomingContext(r.Context, md), r.Topic+" receive", opts...)
-	// Update the record context.
-	r.Context = newCtx
+	if !ok {
+		r.Context, _ = m.tracer.Start(metadata.NewIncomingContext(r.Context, md), r.Topic+" receive", opts...)
+	} else {
+		r.Context, _ = m.tracer.Start(r.Context, r.Topic+" receive", opts...)
+	}
+
+	md, _ = metadata.FromIncomingContext(r.Context)
+
+	setHeaders(r, md)
 }
 
 // OnFetchRecordUnbuffered continues and ends the "receive" span for an