[chore] [exporter/prometheusremotewrite] Do not repeat marshal proto …

…on retry (open-telemetry#29584)

**Description:** <Describe what has changed.>
Do not repeat marshal proto on retry.

**Link to tracking Issue:** <Issue number if applicable>
n/a
**Testing:** <Describe what testing was performed and which tests were
added.>
n/a
**Documentation:** <Describe the documentation added.>
n/a

exporter/prometheusremotewriteexporter/exporter.go

@@ -226,16 +226,16 @@ func (prwe *prwExporter) export(ctx context.Context, requests []*prompb.WriteReq
 }
 
 func (prwe *prwExporter) execute(ctx context.Context, writeReq *prompb.WriteRequest) error {
+ // Uses proto.Marshal to convert the WriteRequest into bytes array
+ data, errMarshal := proto.Marshal(writeReq)
+ if errMarshal != nil {
+ return consumererror.NewPermanent(errMarshal)
+ }
+ buf := make([]byte, len(data), cap(data))
+ compressedData := snappy.Encode(buf, data)
+
  // executeFunc can be used for backoff and non backoff scenarios.
  executeFunc := func() error {
- // Uses proto.Marshal to convert the WriteRequest into bytes array
- data, err := proto.Marshal(writeReq)
- if err != nil {
- return backoff.Permanent(consumererror.NewPermanent(err))
- }
- buf := make([]byte, len(data), cap(data))
- compressedData := snappy.Encode(buf, data)
-
  // Create the HTTP POST request to send to the endpoint
  req, err := http.NewRequestWithContext(ctx, "POST", prwe.endpointURL.String(), bytes.NewReader(compressedData))
  if err != nil {