update logic

config.go

@@ -25,8 +25,6 @@ type PushConfig struct {
 	// ExtraLabels may contain comma-separated list of `label="value"` labels, which will be added
 	// to all the metrics before pushing them to PushURL.
 	ExtraLabels string
-	// WriteMetrics defines the function to write metrics
-	WriteMetrics func(w io.Writer)
 
 	pushURL *url.URL
 }
@@ -50,7 +48,10 @@ func (pc *PushConfig) Validate() error {
 }
 
 // Push run request to the defined PushURL every Interval
-func (pc *PushConfig) Push() {
+func (pc *PushConfig) Push(writeMetrics func(w io.Writer)) {
+	if writeMetrics == nil {
+		panic(fmt.Errorf("write metrics function not defined"))
+	}
 	pushURLRedacted := pc.pushURL.Redacted()
 	// by default set interval to one second
 	if pc.Interval == 0 {
@@ -71,7 +72,7 @@ func (pc *PushConfig) Push() {
 	zw := gzip.NewWriter(&bb)
 	for range ticker.C {
 		bb.Reset()
-		pc.WriteMetrics(&bb)
+		writeMetrics(&bb)
 		if len(pc.ExtraLabels) > 0 {
 			tmpBuf = addExtraLabels(tmpBuf[:0], bb.Bytes(), pc.ExtraLabels)
 			bb.Reset()

push.go

@@ -58,10 +58,10 @@ func InitPushWithConfig(pushConfig *PushConfig, pushProcessMetrics bool) error {
 	if err := pushConfig.Validate(); err != nil {
 		return err
 	}
-	pushConfig.WriteMetrics = func(w io.Writer) {
+	f := func(w io.Writer) {
 		WritePrometheus(w, pushProcessMetrics)
 	}
-	go pushConfig.Push()
+	go pushConfig.Push(f)
 	return nil
 }
 
@@ -94,10 +94,10 @@ func (s *Set) InitPushWithConfig(pushConfig *PushConfig) error {
 	if err := pushConfig.Validate(); err != nil {
 		return err
 	}
-	pushConfig.WriteMetrics = func(w io.Writer) {
+	f := func(w io.Writer) {
 		s.WritePrometheus(w)
 	}
-	go pushConfig.Push()
+	go pushConfig.Push(f)
 	return nil
 }
 
@@ -118,25 +118,20 @@ func (s *Set) InitPushWithConfig(pushConfig *PushConfig) error {
 // It is OK calling InitPushExt multiple times with different writeMetrics -
 // in this case all the metrics generated by writeMetrics callbacks are written to pushURL.
 func InitPushExt(pushURL string, interval time.Duration, extraLabels string, writeMetrics func(w io.Writer)) error {
-	pc := &PushConfig{
-		PushURL:      pushURL,
-		Interval:     interval,
-		ExtraLabels:  extraLabels,
-		WriteMetrics: writeMetrics,
-	}
-	return InitPushExtWithConfig(pc)
+	pc := &PushConfig{PushURL: pushURL, Interval: interval, ExtraLabels: extraLabels}
+	return InitPushExtWithConfig(pc, writeMetrics)
 }
 
 // InitPushExtWithConfig sets up periodic push for metrics obtained by calling writeMetrics with the given interval
 // defined in the PushConfig.
 //
 // It is OK calling InitPushExtWithConfig multiple times with different writeMetrics -
 // in this case all the metrics generated by writeMetrics callbacks are written to PushURL.
-func InitPushExtWithConfig(pushConfig *PushConfig) error {
+func InitPushExtWithConfig(pushConfig *PushConfig, writeMetrics func(w io.Writer)) error {
 	if err := pushConfig.Validate(); err != nil {
 		return err
 	}
-	go pushConfig.Push()
+	go pushConfig.Push(writeMetrics)
 	return nil
 }