Properly handle metric names with lables when printing *_count and *_sum values for Summary

go.mod

@@ -1,3 +1,5 @@
 module github.com/VictoriaMetrics/metrics
 
 require github.com/valyala/histogram v1.0.1
+
+go 1.12

summary.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"io"
 	"math"
+	"strings"
 	"sync"
 	"time"
 
@@ -107,11 +108,20 @@ func (sm *Summary) marshalTo(prefix string, w io.Writer) {
 	sm.mu.Unlock()
 
 	if count > 0 {
-		fmt.Fprintf(w, "%s_sum %g\n", prefix, sum)
-		fmt.Fprintf(w, "%s_count %d\n", prefix, count)
+		name, filters := splitMetricName(prefix)
+		fmt.Fprintf(w, "%s_sum%s %g\n", name, filters, sum)
+		fmt.Fprintf(w, "%s_count%s %d\n", name, filters, count)
 	}
 }
 
+func splitMetricName(name string) (string, string) {
+	n := strings.IndexByte(name, '{')
+	if n < 0 {
+		return name, ""
+	}
+	return name[:n], name[n:]
+}
+
 func (sm *Summary) updateQuantiles() {
 	sm.mu.Lock()
 	sm.quantileValues = sm.curr.Quantiles(sm.quantileValues[:0], sm.quantiles)

summary_test.go

@@ -30,6 +30,7 @@ func TestSummarySerial(t *testing.T) {
 
 	// Make sure the summary prints <prefix>_sum and <prefix>_count on marshalTo call
 	testMarshalTo(t, s, "prefix", fmt.Sprintf("prefix_sum %g\nprefix_count %d\n", s.sum, s.count))
+	testMarshalTo(t, s, `m{foo="bar"}`, fmt.Sprintf("m_sum{foo=\"bar\"} %g\nm_count{foo=\"bar\"} %d\n", s.sum, s.count))
 
 	// Verify s.quantileValues
 	s.updateQuantiles()