From ccc44f0c1e03bda047b90f2452e6babbf9924cb3 Mon Sep 17 00:00:00 2001
From: linfn <linfeng.lu@hotmail.com>
Date: Thu, 11 May 2023 12:43:09 +0800
Subject: [PATCH] [receiver/skywalking]: fix parentSpanId lost when crossing
 segments

---
 .../skywalkingproto_to_traces.go              |  8 ++++-
 .../skywalkingproto_to_traces_test.go         | 35 +++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/receiver/skywalkingreceiver/skywalkingproto_to_traces.go b/receiver/skywalkingreceiver/skywalkingproto_to_traces.go
index efdc7f881fde2..f1a104f14e013 100644
--- a/receiver/skywalkingreceiver/skywalkingproto_to_traces.go
+++ b/receiver/skywalkingreceiver/skywalkingproto_to_traces.go
@@ -117,9 +117,15 @@ func swSpanToSpan(traceID string, segmentID string, span *agentV3.SpanObject, de
 	// so use segmentId to convert to an unique otel-span
 	dest.SetSpanID(segmentIDToSpanID(segmentID, uint32(span.GetSpanId())))
 
-	// parent spanid = -1, means(root span) no parent span in skywalking,so just make otlp's parent span id empty.
+	// parent spanid = -1, means(root span) no parent span in current skywalking segment, so it is necessary to search for the parent segment.
 	if span.ParentSpanId != -1 {
 		dest.SetParentSpanID(segmentIDToSpanID(segmentID, uint32(span.GetParentSpanId())))
+	} else {
+		// TODO: SegmentReference references usually have only one element, but in batch consumer case, such as in MQ or async batch process, it could be multiple.
+		// We only handle one element for now.
+		if len(span.Refs) == 1 {
+			dest.SetParentSpanID(segmentIDToSpanID(span.Refs[0].GetParentTraceSegmentId(), uint32(span.Refs[0].GetParentSpanId())))
+		}
 	}
 
 	dest.SetName(span.OperationName)
diff --git a/receiver/skywalkingreceiver/skywalkingproto_to_traces_test.go b/receiver/skywalkingreceiver/skywalkingproto_to_traces_test.go
index 5262a32be43e5..b4f93d6181d42 100644
--- a/receiver/skywalkingreceiver/skywalkingproto_to_traces_test.go
+++ b/receiver/skywalkingreceiver/skywalkingproto_to_traces_test.go
@@ -309,6 +309,41 @@ func Test_segmentIdToSpanId_Unique(t *testing.T) {
 	assert.NotEqual(t, results[0], results[1])
 }
 
+func Test_swSpanToSpan_ParentSpanId(t *testing.T) {
+	type args struct {
+		span *agentV3.SpanObject
+	}
+	tests := []struct {
+		name string
+		args args
+		want pcommon.SpanID
+	}{
+		{
+			name: "mock-sw-span-with-parent-segment",
+			args: args{span: &agentV3.SpanObject{
+				ParentSpanId: -1,
+				Refs: []*agentV3.SegmentReference{{
+					ParentTraceSegmentId: "4f2f27748b8e44ecaf18fe0347194e86.33.16560607369950066",
+					ParentSpanId:         123,
+				}}}},
+			want: [8]byte{233, 196, 85, 168, 37, 66, 48, 106},
+		},
+		{
+			name: "mock-sw-span-without-parent-segment",
+			args: args{span: &agentV3.SpanObject{Refs: []*agentV3.SegmentReference{{
+				ParentSpanId: -1,
+			}}}},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			dest := ptrace.NewSpan()
+			swSpanToSpan("de5980b8-fce3-4a37-aab9-b4ac3af7eedd", "", tt.args.span, dest)
+			assert.Equal(t, tt.want, dest.ParentSpanID())
+		})
+	}
+}
+
 func generateTracesOneEmptyResourceSpans() ptrace.Span {
 	td := ptrace.NewTraces()
 	resourceSpan := td.ResourceSpans().AppendEmpty()