Check for nil before using struct (#6238)

* Check for nil before using struct

Signed-off-by: Andres Taylor <andres@planetscale.com>

go/vt/vttablet/tabletserver/txlogz.go

@@ -120,25 +120,33 @@ func txlogzHandler(w http.ResponseWriter, req *http.Request) {
  log.Error(err)
  continue
  }
- duration := txc.txProps.EndTime.Sub(txc.txProps.StartTime).Seconds()
- var level string
- if duration < 0.1 {
- level = "low"
- } else if duration < 1.0 {
- level = "medium"
- } else {
- level = "high"
- }
- tmplData := struct {
- *StatefulConnection
- Duration float64
- ColorLevel string
- }{txc, duration, level}
- if err := txlogzTmpl.Execute(w, tmplData); err != nil {
- log.Errorf("txlogz: couldn't execute template: %v", err)
+ // not all StatefulConnections contain transactions
+ if txc.txProps != nil {
+ writeTransactionData(w, txc)
  }
  case <-tmr.C:
  return
  }
  }
 }
+
+func writeTransactionData(w http.ResponseWriter, txc *StatefulConnection) {
+ props := txc.txProps
+ var level string
+ duration := props.EndTime.Sub(props.StartTime).Seconds()
+ if duration < 0.1 {
+ level = "low"
+ } else if duration < 1.0 {
+ level = "medium"
+ } else {
+ level = "high"
+ }
+ tmplData := struct {
+ *StatefulConnection
+ Duration float64
+ ColorLevel string
+ }{txc, duration, level}
+ if err := txlogzTmpl.Execute(w, tmplData); err != nil {
+ log.Errorf("txlogz: couldn't execute template: %v", err)
+ }
+}