Ensure that span start <= end

Adds code to detect when a span's end time is less than its start time. This would be caught by a database constraint and prevent the insertion of the span. The new code will swap the start and end times to allow the span's insertion.

Author: jgpruitt

CHANGELOG.md

@@ -17,6 +17,9 @@ We use the following categories for changes:
 ### Added
 - Add Prometheus metrics support for Tracing [#1102]
 
+### Fixed
+- Fix spans with end < start. Start and end are swapped in this case. [#1096]
+
 ## [0.9.0] - 2022-02-02
 
 ### Added

pkg/pgmodel/ingestor/trace/writer.go

@@ -276,8 +276,16 @@ func (t *traceWriterImpl) InsertTraces(ctx context.Context, traces pdata.Traces)
 
 				eventTimeRange := getEventTimeRange(span.Events())
 
-				if maxEndTimestamp < uint64(span.EndTimestamp()) {
-					maxEndTimestamp = uint64(span.EndTimestamp())
+				// postgresql timestamptz only has microsecond precision while time.Time has nanosecond precision
+				start := span.StartTimestamp().AsTime().Truncate(time.Microsecond)
+				end := span.EndTimestamp().AsTime().Truncate(time.Microsecond)
+				// make sure start <= end
+				if end.Before(start) {
+					start, end = end, start
+				}
+
+				if maxEndTimestamp < uint64(end.Unix()) {
+					maxEndTimestamp = uint64(end.Unix())
 				}
 
 				spanBatch.Queue(
@@ -287,8 +295,8 @@ func (t *traceWriterImpl) InsertTraces(ctx context.Context, traces pdata.Traces)
 					getTraceStateValue(span.TraceState()),
 					parentSpanID,
 					operationID,
-					span.StartTimestamp().AsTime(),
-					span.EndTimestamp().AsTime(),
+					start,
+					end,
 					string(jsonTags),
 					span.DroppedAttributesCount(),
 					eventTimeRange,

pkg/tests/end_to_end_tests/dataset_traces_test.go

@@ -136,8 +136,9 @@ func fillSpanOne(span pdata.Span) {
 	span.SetTraceID(pdata.NewTraceID(traceID1))
 	span.SetSpanID(pdata.NewSpanID(generateRandSpanID()))
 	span.SetName("operationA")
-	span.SetStartTimestamp(testSpanStartTimestamp)
-	span.SetEndTimestamp(testSpanEndTimestamp)
+	// test the logic that detects and fixes end < start
+	span.SetStartTimestamp(testSpanEndTimestamp)
+	span.SetEndTimestamp(testSpanStartTimestamp)
 	span.SetDroppedAttributesCount(1)
 	span.SetTraceState("span-trace-state1")
 	initSpanAttributes(span.Attributes())