Adding trace support back in.

Signed-off-by: Scott Nichols <snichols@vmware.com>

cmd/samples/http/receiver-traced/main.go

@@ -0,0 +1,33 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"github.com/cloudevents/sdk-go/pkg/client"
+	"log"
+
+	cloudevents "github.com/cloudevents/sdk-go"
+)
+
+func main() {
+	ctx := context.Background()
+	p, err := cloudevents.NewHTTP()
+	if err != nil {
+		log.Fatalf("failed to create protocol: %s", err.Error())
+	}
+
+	c, err := cloudevents.NewClient(p)
+	if err != nil {
+		log.Fatalf("failed to create client, %v", err)
+	}
+
+	log.Printf("will listen on :8080\n")
+	log.Fatalf("failed to start receiver: %s", c.StartReceiver(ctx, receive))
+}
+
+func receive(ctx context.Context, e cloudevents.Event) {
+	ctx, span := client.TraceSpan(ctx, e)
+	defer span.End()
+
+	fmt.Printf("%s", e)
+}

pkg/client/client_observed.go

@@ -3,6 +3,7 @@ package client
 import (
 	"context"
 	"github.com/cloudevents/sdk-go/pkg/event"
+	"github.com/cloudevents/sdk-go/pkg/extensions"
 	"github.com/cloudevents/sdk-go/pkg/observability"
 	"go.opencensus.io/trace"
 )
@@ -15,34 +16,43 @@ func NewObserved(protocol interface{}, opts ...Option) (Client, error) {
 		return nil, err
 	}
 
-	return &obsClient{client: client}, nil
+	c := &obsClient{client: client}
+
+	if err := c.applyOptions(opts...); err != nil {
+		return nil, err
+	}
+	return c, nil
 }
 
 type obsClient struct {
 	client Client
 
-	disableTracePropagation bool // TODO?
+	addTracing bool
 }
 
-//
-//func (c *ceClient) applyOptions(opts ...Option) error {
-//	for _, fn := range opts {
-//		if err := fn(c); err != nil {
-//			return err
-//		}
-//	}
-//	return nil
-//}
+func (c *obsClient) applyOptions(opts ...Option) error {
+	for _, fn := range opts {
+		if err := fn(c); err != nil {
+			return err
+		}
+	}
+	return nil
+}
 
 // Send transmits the provided event on a preconfigured Protocol. Send returns
 // an error if there was an an issue validating the outbound event or the
 // transport returns an error.
 func (c *obsClient) Send(ctx context.Context, e event.Event) error {
 	ctx, r := observability.NewReporter(ctx, reportSend)
-	ctx, span := trace.StartSpan(ctx, clientSpanName, trace.WithSpanKind(trace.SpanKindClient))
+	ctx, span := trace.StartSpan(ctx, observability.ClientSpanName, trace.WithSpanKind(trace.SpanKindClient))
 	defer span.End()
 	if span.IsRecordingEvents() {
-		span.AddAttributes(eventTraceAttributes(e.Context)...)
+		span.AddAttributes(EventTraceAttributes(&e)...)
+	}
+
+	if c.addTracing {
+		e.Context = e.Context.Clone()
+		extensions.FromSpanContext(span.SpanContext()).AddTracingAttributes(&e)
 	}
 
 	err := c.client.Send(ctx, e)
@@ -57,10 +67,10 @@ func (c *obsClient) Send(ctx context.Context, e event.Event) error {
 
 func (c *obsClient) Request(ctx context.Context, e event.Event) (*event.Event, error) {
 	ctx, r := observability.NewReporter(ctx, reportRequest)
-	ctx, span := trace.StartSpan(ctx, clientSpanName, trace.WithSpanKind(trace.SpanKindClient))
+	ctx, span := trace.StartSpan(ctx, observability.ClientSpanName, trace.WithSpanKind(trace.SpanKindClient))
 	defer span.End()
 	if span.IsRecordingEvents() {
-		span.AddAttributes(eventTraceAttributes(e.Context)...)
+		span.AddAttributes(EventTraceAttributes(&e)...)
 	}
 
 	resp, err := c.client.Request(ctx, e)

pkg/client/client_test.go

@@ -43,7 +43,7 @@ func simpleBinaryClient(target string) client.Client {
 		return nil
 	}
 
-	c, err := client.New(p, client.WithoutTracePropagation(), client.WithForceBinary())
+	c, err := client.New(p, client.WithForceBinary())
 	if err != nil {
 		return nil
 	}
@@ -57,7 +57,7 @@ func simpleTracingBinaryClient(target string) client.Client {
 		return nil
 	}
 
-	c, err := client.New(p)
+	c, err := client.NewObserved(p, client.WithTracePropagation())
 	if err != nil {
 		return nil
 	}
@@ -71,7 +71,7 @@ func simpleStructuredClient(target string) client.Client {
 		return nil
 	}
 
-	c, err := client.New(p, client.WithoutTracePropagation(), client.WithForceStructured())
+	c, err := client.New(p, client.WithForceStructured())
 	if err != nil {
 		return nil
 	}
@@ -187,8 +187,6 @@ func TestClientSend(t *testing.T) {
 }
 
 func TestTracingClientSend(t *testing.T) {
-	t.Skip("skipping tracing tests for now, need to rework this for sdk v2")
-
 	now := time.Now()
 
 	testCases := map[string]struct {
@@ -475,8 +473,6 @@ func TestClientReceive(t *testing.T) {
 }
 
 func TestTracedClientReceive(t *testing.T) {
-	t.Skip("TODO: need to re-add tracedClient features into httpb")
-
 	now := time.Now()
 
 	testCases := map[string]struct {
@@ -518,9 +514,11 @@ func TestTracedClientReceive(t *testing.T) {
 
 			ctx, cancel := context.WithCancel(context.TODO())
 			go func() {
-				err = c.StartReceiver(ctx, func(ctx context.Context, event event.Event) (*event.Event, transport.Result) {
+				err = c.StartReceiver(ctx, func(ctx context.Context, e event.Event) (*event.Event, transport.Result) {
 					go func() {
-						spanContexts <- trace.FromContext(ctx).SpanContext()
+						_, span := client.TraceSpan(ctx, e)
+						defer span.End()
+						spanContexts <- span.SpanContext()
 					}()
 					return nil, nil
 				})
@@ -531,10 +529,10 @@ func TestTracedClientReceive(t *testing.T) {
 			time.Sleep(5 * time.Millisecond) // let the server start
 
 			target := fmt.Sprintf("http://localhost:%d", p.GetPort())
-			client := simpleBinaryClient(target)
+			sender := simpleTracingBinaryClient(target)
 
 			ctx, span := trace.StartSpan(context.TODO(), "test-span")
-			err = client.Send(ctx, tc.event)
+			err = sender.Send(ctx, tc.event)
 			span.End()
 
 			if err != nil {

pkg/client/invoker.go

@@ -31,7 +31,7 @@ func newReceiveInvoker(fn interface{}, fns ...EventDefaulter) (Invoker, error) {
 
 type receiveInvoker struct {
 	fn                *receiverFn
-	eventDefaulterFns []EventDefaulter // TODO: set these.
+	eventDefaulterFns []EventDefaulter
 }
 
 func (r *receiveInvoker) Invoke(ctx context.Context, m binding.Message, respFn transport.ResponseFn) (err error) {

pkg/client/observability.go

@@ -1,7 +1,9 @@
 package client
 
 import (
+	"context"
 	"github.com/cloudevents/sdk-go/pkg/event"
+	"github.com/cloudevents/sdk-go/pkg/extensions"
 	"github.com/cloudevents/sdk-go/pkg/observability"
 	"go.opencensus.io/stats"
 	"go.opencensus.io/stats/view"
@@ -31,8 +33,6 @@ type observed int32
 var _ observability.Observable = observed(0)
 
 const (
-	clientSpanName = "cloudevents.client"
-
 	specversionAttr     = "cloudevents.specversion"
 	typeAttr            = "cloudevents.type"
 	sourceAttr          = "cloudevents.source"
@@ -63,17 +63,32 @@ func (o observed) LatencyMs() *stats.Float64Measure {
 	return LatencyMs
 }
 
-func eventTraceAttributes(e event.EventContextReader) []trace.Attribute {
+func EventTraceAttributes(e event.EventReader) []trace.Attribute {
 	as := []trace.Attribute{
-		trace.StringAttribute(specversionAttr, e.GetSpecVersion()),
-		trace.StringAttribute(typeAttr, e.GetType()),
-		trace.StringAttribute(sourceAttr, e.GetSource()),
+		trace.StringAttribute(specversionAttr, e.SpecVersion()),
+		trace.StringAttribute(typeAttr, e.Type()),
+		trace.StringAttribute(sourceAttr, e.Source()),
 	}
-	if sub := e.GetSubject(); sub != "" {
+	if sub := e.Subject(); sub != "" {
 		as = append(as, trace.StringAttribute(subjectAttr, sub))
 	}
-	if dct := e.GetDataContentType(); dct != "" {
+	if dct := e.DataContentType(); dct != "" {
 		as = append(as, trace.StringAttribute(datacontenttypeAttr, dct))
 	}
 	return as
 }
+
+// TraceSpan returns context and trace.Span based on event. Caller must call span.End()
+func TraceSpan(ctx context.Context, e event.Event) (context.Context, *trace.Span) {
+	var span *trace.Span
+	if ext, ok := extensions.GetDistributedTracingExtension(e); ok {
+		ctx, span = ext.StartChildSpan(ctx, observability.ClientSpanName, trace.WithSpanKind(trace.SpanKindServer))
+	}
+	if span == nil {
+		ctx, span = trace.StartSpan(ctx, observability.ClientSpanName, trace.WithSpanKind(trace.SpanKindServer))
+	}
+	if span.IsRecordingEvents() {
+		span.AddAttributes(EventTraceAttributes(&e)...)
+	}
+	return ctx, span
+}

pkg/client/options.go

@@ -6,56 +6,68 @@ import (
 )
 
 // Option is the function signature required to be considered an client.Option.
-type Option func(*ceClient) error
+type Option func(interface{}) error
 
 // WithEventDefaulter adds an event defaulter to the end of the defaulter chain.
 func WithEventDefaulter(fn EventDefaulter) Option {
-	return func(c *ceClient) error {
-		if fn == nil {
-			return fmt.Errorf("client option was given an nil event defaulter")
+	return func(i interface{}) error {
+		if c, ok := i.(*ceClient); ok {
+			if fn == nil {
+				return fmt.Errorf("client option was given an nil event defaulter")
+			}
+			c.eventDefaulterFns = append(c.eventDefaulterFns, fn)
 		}
-		c.eventDefaulterFns = append(c.eventDefaulterFns, fn)
 		return nil
 	}
 }
 
 func WithForceBinary() Option {
-	return func(c *ceClient) error {
-		c.outboundContextDecorators = append(c.outboundContextDecorators, binding.WithForceBinary)
+	return func(i interface{}) error {
+		if c, ok := i.(*ceClient); ok {
+			c.outboundContextDecorators = append(c.outboundContextDecorators, binding.WithForceBinary)
+		}
 		return nil
 	}
 }
 
 func WithForceStructured() Option {
-	return func(c *ceClient) error {
-		c.outboundContextDecorators = append(c.outboundContextDecorators, binding.WithForceStructured)
+	return func(i interface{}) error {
+		if c, ok := i.(*ceClient); ok {
+			c.outboundContextDecorators = append(c.outboundContextDecorators, binding.WithForceStructured)
+		}
 		return nil
 	}
 }
 
 // WithUUIDs adds DefaultIDToUUIDIfNotSet event defaulter to the end of the
 // defaulter chain.
 func WithUUIDs() Option {
-	return func(c *ceClient) error {
-		c.eventDefaulterFns = append(c.eventDefaulterFns, DefaultIDToUUIDIfNotSet)
+	return func(i interface{}) error {
+		if c, ok := i.(*ceClient); ok {
+			c.eventDefaulterFns = append(c.eventDefaulterFns, DefaultIDToUUIDIfNotSet)
+		}
 		return nil
 	}
 }
 
 // WithTimeNow adds DefaultTimeToNowIfNotSet event defaulter to the end of the
 // defaulter chain.
 func WithTimeNow() Option {
-	return func(c *ceClient) error {
-		c.eventDefaulterFns = append(c.eventDefaulterFns, DefaultTimeToNowIfNotSet)
+	return func(i interface{}) error {
+		if c, ok := i.(*ceClient); ok {
+			c.eventDefaulterFns = append(c.eventDefaulterFns, DefaultTimeToNowIfNotSet)
+		}
 		return nil
 	}
 }
 
-// WithoutTracePropagation disables automatic trace propagation via
-// the distributed tracing extension.
-func WithoutTracePropagation() Option {
-	return func(c *ceClient) error {
-		//c.disableTracePropagation = true
+// WithTracePropagation enables trace propagation via the distributed tracing
+// extension.
+func WithTracePropagation() Option {
+	return func(i interface{}) error {
+		if c, ok := i.(*obsClient); ok {
+			c.addTracing = true
+		}
 		return nil
 	}
 }

pkg/extensions/distributed_tracing_extension.go

@@ -21,7 +21,7 @@ const (
 
 // EventTracer interface allows setting extension for cloudevents context.
 type EventTracer interface {
-	SetExtension(k string, v interface{}) error
+	SetExtension(k string, v interface{})
 }
 
 // DistributedTracingExtension represents the extension for cloudevents context
@@ -31,7 +31,7 @@ type DistributedTracingExtension struct {
 }
 
 // AddTracingAttributes adds the tracing attributes traceparent and tracestate to the cloudevents context
-func (d DistributedTracingExtension) AddTracingAttributes(ec EventTracer) error {
+func (d DistributedTracingExtension) AddTracingAttributes(ec EventTracer) {
 	if d.TraceParent != "" {
 		value := reflect.ValueOf(d)
 		typeOf := value.Type()
@@ -42,12 +42,9 @@ func (d DistributedTracingExtension) AddTracingAttributes(ec EventTracer) error
 			if k == TraceStateExtension && v == "" {
 				continue
 			}
-			if err := ec.SetExtension(k, v); err != nil {
-				return err
-			}
+			ec.SetExtension(k, v)
 		}
 	}
-	return nil
 }
 
 func GetDistributedTracingExtension(event event.Event) (DistributedTracingExtension, bool) {

pkg/observability/keys.go

@@ -12,6 +12,9 @@ var (
 )
 
 const (
+	// ClientSpanName is the key used to start spans from the client.
+	ClientSpanName = "cloudevents.client"
+
 	// ResultError is a shared result tag value for error.
 	ResultError = "error"
 	// ResultOK is a shared result tag value for success.