revert the changes for metrics

exporter/splunkhecexporter/client.go

@@ -4,6 +4,7 @@
 package splunkhecexporter // import "github.com/open-telemetry/opentelemetry-collector-contrib/exporter/splunkhecexporter"
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"fmt"
@@ -259,7 +260,7 @@ func (c *client) fillMetricsBuffer(metrics pmetric.Metrics, buf buffer, is iterS
 	var permanentErrors []error
 	jsonStream := jsonStreamPool.Get().(*jsoniter.Stream)
 	defer jsonStreamPool.Put(jsonStream)
-	jsonStream.Reset(buf)
+	tempBuf := bytes.NewBuffer(make([]byte, 0, c.config.MaxContentLengthMetrics))
 	for i := is.resource; i < metrics.ResourceMetrics().Len(); i++ {
 		rm := metrics.ResourceMetrics().At(i)
 		for j := is.library; j < rm.ScopeMetrics().Len(); j++ {
@@ -271,24 +272,20 @@ func (c *client) fillMetricsBuffer(metrics pmetric.Metrics, buf buffer, is iterS
 
 				// Parsing metric record to Splunk event.
 				events := mapMetricToSplunkEvent(rm.Resource(), metric, c.config, c.logger)
-
+				tempBuf.Reset()
 				for _, event := range events {
 					// JSON encoding event and writing to buffer.
-					jsonStream.Error = nil
-					jsonStream.WriteVal(event)
-					if jsonStream.Error != nil {
-						permanentErrors = append(permanentErrors, consumererror.NewPermanent(fmt.Errorf("dropped metric event: %v, error: %w", event, jsonStream.Error)))
-						continue
-					}
-					if uint(jsonStream.Buffered()) > c.config.MaxEventSize {
-						permanentErrors = append(permanentErrors, fmt.Errorf("event size %d exceeds limit %d", jsonStream.Buffered(), c.config.MaxEventSize))
+					b, err := marshalEvent(event, c.config.MaxEventSize, jsonStream)
+					if err != nil {
+						permanentErrors = append(permanentErrors, consumererror.NewPermanent(fmt.Errorf("dropped metric event: %v, error: %w", event, err)))
 						continue
 					}
-
+					tempBuf.Write(b)
 				}
 
 				// Continue adding events to buffer up to capacity.
-				err := jsonStream.Flush()
+				b := tempBuf.Bytes()
+				_, err := buf.Write(b)
 				if err == nil {
 					continue
 				}
@@ -298,11 +295,9 @@ func (c *client) fillMetricsBuffer(metrics pmetric.Metrics, buf buffer, is iterS
 					}
 					permanentErrors = append(permanentErrors, consumererror.NewPermanent(
 						fmt.Errorf("dropped metric event: error: event size %d bytes larger than configured max"+
-							" content length %d bytes", jsonStream.Buffered(), c.config.MaxContentLengthMetrics)))
+							" content length %d bytes", len(b), c.config.MaxContentLengthMetrics)))
 					return iterState{i, j, k + 1, false}, permanentErrors
 				}
-				// flush exited before resetting the buffer of the stream.
-				jsonStream.Reset(buf)
 				permanentErrors = append(permanentErrors, consumererror.NewPermanent(fmt.Errorf(
 					"error writing the event: %w", err)))
 			}
@@ -718,3 +713,17 @@ func buildHTTPHeaders(config *Config, buildInfo component.BuildInfo) map[string]
 		"__splunk_app_version": config.SplunkAppVersion,
 	}
 }
+
+// marshalEvent marshals an event to JSON using a reusable jsoniter stream.
+func marshalEvent(event *splunk.Event, sizeLimit uint, stream *jsoniter.Stream) ([]byte, error) {
+	stream.Reset(nil)
+	stream.Error = nil
+	stream.WriteVal(event)
+	if stream.Error != nil {
+		return nil, stream.Error
+	}
+	if uint(stream.Buffered()) > sizeLimit {
+		return nil, fmt.Errorf("event size %d exceeds limit %d", stream.Buffered(), sizeLimit)
+	}
+	return stream.Buffer(), nil
+}