Fix crash in sapmexporter, when iterate with range changes to len are…

… not visible

Fixes open-telemetry#3279

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

exporter/sapmexporter/exporter.go

@@ -153,14 +153,13 @@ func filterTokenFromProcess(proc *model.Process) {
 	if proc == nil {
 		return
 	}
-	for i := range proc.Tags {
+	for i := 0; i < len(proc.Tags); {
 		if proc.Tags[i].Key == splunk.SFxAccessTokenLabel {
-			// Switch this tag with last one.
-			lastPos := len(proc.Tags) - 1
-			tmp := proc.Tags[lastPos]
-			proc.Tags[lastPos] = proc.Tags[i]
-			proc.Tags[i] = tmp
-			proc.Tags = proc.Tags[0:lastPos]
+			proc.Tags[i] = proc.Tags[len(proc.Tags)-1]
+			// We do not need to put proc.Tags[i] at the end, as it will be discarded anyway
+			proc.Tags = proc.Tags[:len(proc.Tags)-1]
+			continue
 		}
+		i++
 	}
 }

exporter/sapmexporter/exporter_test.go

@@ -72,9 +72,15 @@ func buildTestTraces(setTokenLabel bool) (traces pdata.Traces) {
 	for i := 0; i < 20; i++ {
 		rs := rss.At(i)
 		resource := rs.Resource()
+		resource.Attributes().InsertString("key1", "value1")
 		if setTokenLabel && i%2 == 1 {
 			tokenLabel := fmt.Sprintf("MyToken%d", i/5)
 			resource.Attributes().InsertString("com.splunk.signalfx.access_token", tokenLabel)
+			resource.Attributes().InsertString("com.splunk.signalfx.access_token", tokenLabel)
+		}
+		// Add one last element every 3rd resource, this way we have cases with token last or not.
+		if i%3 == 1 {
+			resource.Attributes().InsertString("key2", "value2")
 		}
 
 		span := rs.InstrumentationLibrarySpans().AppendEmpty().Spans().AppendEmpty()