fix(pubsub): add attributes before startSpan

Attributes can be used for sampling and so they should be added before
span creation, if possible. See [1].

[1] https://opentelemetry.io/docs/concepts/signals/traces/#attributes

pubsub/iterator.go

@@ -335,14 +335,17 @@ func (it *messageIterator) receive(maxToPull int32) ([]*Message, error) {
 			if m.Attributes != nil {
 				ctx = propagation.TraceContext{}.Extract(ctx, newMessageCarrier(m))
 			}
-			attr := getSubscriberOpts(it.projectID, it.subID, m)
-			_, span := startSpan(ctx, subscribeSpanName, it.subID, attr...)
-			span.SetAttributes(
-				attribute.Bool(eosAttribute, it.enableExactlyOnceDelivery),
-				attribute.String(ackIDAttribute, ackID),
-				semconv.MessagingBatchMessageCount(len(msgs)),
-				semconv.CodeFunction("receive"),
+			opts := getSubscriberOpts(it.projectID, it.subID, m)
+			opts = append(
+				opts,
+				trace.WithAttributes(
+					attribute.Bool(eosAttribute, it.enableExactlyOnceDelivery),
+					attribute.String(ackIDAttribute, ackID),
+					semconv.MessagingBatchMessageCount(len(msgs)),
+					semconv.CodeFunction("receive"),
+				),
 			)
+			_, span := startSpan(ctx, subscribeSpanName, it.subID, opts...)
 			// Always store the subscribe span, even if sampling isn't enabled.
 			// This is useful since we need to propagate the sampling flag
 			// to the callback in Receive, so traces have an unbroken sampling decision.
@@ -658,11 +661,16 @@ func (it *messageIterator) sendAck(m map[string]*AckResult) {
 			// Create the single ack span for this request, and for each
 			// message, add Subscribe<->Ack links.
 			opts := getCommonOptions(it.projectID, it.subID)
-			opts = append(opts, trace.WithLinks(links...))
+			opts = append(
+				opts,
+				trace.WithLinks(links...),
+				trace.WithAttributes(
+					semconv.MessagingBatchMessageCount(len(ackIDs)),
+					semconv.CodeFunction("sendAck"),
+				),
+			)
 			_, ackSpan := startSpan(context.Background(), ackSpanName, it.subID, opts...)
 			defer ackSpan.End()
-			ackSpan.SetAttributes(semconv.MessagingBatchMessageCount(len(ackIDs)),
-				semconv.CodeFunction("sendAck"))
 			if ackSpan.SpanContext().IsSampled() {
 				for _, s := range subscribeSpans {
 					s.AddLink(trace.Link{
@@ -740,16 +748,25 @@ func (it *messageIterator) sendModAck(m map[string]*AckResult, deadline time.Dur
 			// Create the single modack/nack span for this request, and for each
 			// message, add Subscribe<->Modack links.
 			opts := getCommonOptions(it.projectID, it.subID)
-			opts = append(opts, trace.WithLinks(links...))
-			_, mSpan := startSpan(context.Background(), spanName, it.subID, opts...)
-			defer mSpan.End()
+			opts = append(
+				opts,
+				trace.WithLinks(links...),
+				trace.WithAttributes(
+					semconv.MessagingBatchMessageCount(len(ackIDs)),
+					semconv.CodeFunction("sendModAck"),
+				),
+			)
 			if !isNack {
-				mSpan.SetAttributes(
-					semconv.MessagingGCPPubsubMessageAckDeadline(int(deadlineSec)),
-					attribute.Bool(receiptModackAttribute, isReceipt))
+				opts = append(
+					opts,
+					trace.WithAttributes(
+						semconv.MessagingGCPPubsubMessageAckDeadline(int(deadlineSec)),
+						attribute.Bool(receiptModackAttribute, isReceipt),
+					),
+				)
 			}
-			mSpan.SetAttributes(semconv.MessagingBatchMessageCount(len(ackIDs)),
-				semconv.CodeFunction("sendModAck"))
+			_, mSpan := startSpan(context.Background(), spanName, it.subID, opts...)
+			defer mSpan.End()
 			if mSpan.SpanContext().IsSampled() {
 				for _, s := range subscribeSpans {
 					s.AddLink(trace.Link{

pubsub/topic.go

@@ -748,8 +748,8 @@ func (t *Topic) Publish(ctx context.Context, msg *Message) *PublishResult {
 	var createSpan trace.Span
 	if t.enableTracing {
 		opts := getPublishSpanAttributes(t.c.projectID, t.ID(), msg)
+		opts = append(opts, trace.WithAttributes(semconv.CodeFunction("Publish")))
 		ctx, createSpan = startSpan(ctx, createSpanName, t.ID(), opts...)
-		createSpan.SetAttributes(semconv.CodeFunction("Publish"))
 	}
 	ctx, err := tag.New(ctx, tag.Insert(keyStatus, "OK"), tag.Upsert(keyTopic, t.name))
 	if err != nil {
@@ -973,8 +973,14 @@ func (t *Topic) publishMessageBundle(ctx context.Context, bms []*bundledMessage)
 		opts := getCommonOptions(projectID, topicID)
 		// Add link to publish RPC span of createSpan(s).
 		opts = append(opts, trace.WithLinks(links...))
+		opts = append(
+			opts,
+			trace.WithAttributes(
+				semconv.MessagingBatchMessageCount(numMsgs),
+				semconv.CodeFunction("publishMessageBundle"),
+			),
+		)
 		ctx, pSpan = startSpan(ctx, publishRPCSpanName, topicID, opts...)
-		pSpan.SetAttributes(semconv.MessagingBatchMessageCount(numMsgs), semconv.CodeFunction("publishMessageBundle"))
 		defer pSpan.End()
 
 		// Add the reverse link to createSpan(s) of publish RPC span.