tracing: link child into parent, even if not verbose

Prior to this change, when a child was derived from a local parent, we
would not register the child with the parent. In effect, this meant that
any payloads in the child would not be collected.

Release note: None

pkg/util/tracing/crdbspan.go

@@ -98,12 +98,16 @@ func (s *crdbSpan) recordingType() RecordingType {
 // If separate recording is specified, the child is not registered with the
 // parent. Thus, the parent's recording will not include this child.
 func (s *crdbSpan) enableRecording(parent *crdbSpan, recType RecordingType) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	s.mu.recording.recordingType.swap(recType)
 	if parent != nil {
 		parent.addChild(s)
 	}
+	if recType == RecordingOff {
+		return
+	}
+
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.mu.recording.recordingType.swap(recType)
 	if recType == RecordingVerbose {
 		s.setBaggageItemLocked(verboseTracingBaggageKey, "1")
 	}

pkg/util/tracing/span_test.go

@@ -196,3 +196,19 @@ func TestSpan_LogStructured(t *testing.T) {
 	require.NoError(t, types.UnmarshalAny(item, &d1))
 	require.IsType(t, (*types.Int32Value)(nil), d1.Message)
 }
+
+func TestNonVerboseChildSpanRegisteredWithParent(t *testing.T) {
+	tr := NewTracer()
+	tr._mode = int32(modeBackground)
+	sp := tr.StartSpan("root", WithForceRealSpan())
+	defer sp.Finish()
+	ch := tr.StartSpan("child", WithParentAndAutoCollection(sp), WithForceRealSpan())
+	defer ch.Finish()
+	require.Len(t, sp.crdb.mu.recording.children, 1)
+	require.Equal(t, ch.crdb, sp.crdb.mu.recording.children[0])
+	ch.LogStructured(&types.Int32Value{Value: 5})
+	// Check that the child span (incl its payload) is in the recording.
+	rec := sp.GetRecording()
+	require.Len(t, rec, 2)
+	require.Len(t, rec[1].InternalStructured, 1)
+}

pkg/util/tracing/tracer.go

@@ -394,16 +394,16 @@ func (t *Tracer) startSpanGeneric(
 
 	s := &helper.span
 
-	// Start recording if necessary. We inherit the recording type of the local parent, if any,
-	// over the remote parent, if any. If neither are specified, we're not recording.
-	recordingType := opts.recordingType()
-
-	if recordingType != RecordingOff {
+	{
+		// Link the newly created span to the parent, if necessary,
+		// and start recording, if requested.
+		// We inherit the recording type of the local parent, if any,
+		// over the remote parent, if any. If neither are specified, we're not recording.
 		var p *crdbSpan
 		if opts.Parent != nil {
 			p = opts.Parent.crdb
 		}
-		s.crdb.enableRecording(p, recordingType)
+		s.crdb.enableRecording(p, opts.recordingType())
 	}
 
 	// Set initial tags. These will propagate to the crdbSpan, ot, and netTr