Merge pull request #4 from juvenn/feat/auto-remove

Auto remove metric from registry

.github/CODEOWNERS

@@ -0,0 +1,2 @@
+
+* @juvenn

emitters/reporter_test.go

@@ -19,19 +19,21 @@ func TestReportToFile(t *testing.T) {
 	stdout := NewStdoutEmitter()
 	rep, err := exporters.NewReporter(reg, 800*time.Millisecond,
 		exporters.WithLabels("host", "localhost"),
-		exporters.WithAutoReset(true),
+		exporters.WithAutoRemove(true),
 		exporters.WithEmitters(piper, stdout))
 	if err != nil {
 		t.Fatalf("%#v\n", err)
 	}
 	rep.Start()
-	counter := metrics.NewCounter()
-	reg.Register("req", counter)
+	counter := metrics.GetOrRegisterCounter("req", reg)
 	counter.Inc(1)
 	go func() {
 		time.Sleep(1 * time.Second)
 		rep.Close()
 	}()
+	time.Sleep(900 * time.Millisecond)
+	counter = metrics.GetOrRegisterCounter("req", reg)
+	counter.Inc(2)
 
 	scanner := bufio.NewScanner(pr)
 	data := make([]exporters.Metric, 0, 8)
@@ -44,7 +46,7 @@ func TestReportToFile(t *testing.T) {
 		}
 		data = append(data, *metric)
 	}
-	if len(data) != 2 {
+	if len(data) < 2 {
 		t.Fatalf("Should report 2 times with last graceful report but got %d", len(data))
 	}
 	for _, metric := range data {
@@ -58,7 +60,7 @@ func TestReportToFile(t *testing.T) {
 			t.Errorf("Labels.host localhost != %s\n", host)
 		}
 	}
-	if count := data[1].Fields["count"]; count != 0 {
-		t.Errorf("Counter should be reset to 0, but got %f\n", count)
+	if val := data[1].Fields["count"]; val != 2 {
+		t.Errorf("Counter should be reset and incremented, but got %f\n", val)
 	}
 }

metric.go

@@ -27,17 +27,14 @@ type Metric struct {
 	Fields map[string]float64 `json:"fields"`
 }
 
-func CollectMetric(name string, metric any, reset bool) *Metric {
+func CollectMetric(name string, metric any) *Metric {
 	now := time.Now()
 	switch metric := metric.(type) {
 	case metrics.Counter:
 		ms := metric.Snapshot()
 		fields := map[string]float64{
 			"count": float64(ms.Count()),
 		}
-		if reset {
-			metric.Clear()
-		}
 		return &Metric{Name: name, Type: TypeCounter, Time: now, Fields: fields}
 	case metrics.Histogram:
 		ms := metric.Snapshot()
@@ -56,9 +53,6 @@ func CollectMetric(name string, metric any, reset bool) *Metric {
 			"p999":     ps[4],
 			"p9999":    ps[5],
 		}
-		if reset {
-			metric.Clear()
-		}
 		return &Metric{Name: name, Type: TypeHistogram, Time: now, Fields: fields}
 	case metrics.Meter:
 		ms := metric.Snapshot()

reporter.go

@@ -10,19 +10,23 @@ import (
 
 // A reporter periodically cut metrics and publish to given publishers.
 type Reporter struct {
-	registry  metrics.Registry
-	interval  time.Duration // poll and report interval
-	autoReset bool          // auto reset metric such as counter
-	emitters  []Emitter
-	exit      chan struct{}     // signal when shutting down
-	labels    map[string]string // global labels attach to each metric
-	logf      func(format string, a ...any)
+	registry   metrics.Registry
+	interval   time.Duration // poll and report interval
+	autoRemove bool          // auto remove metric such as counter
+	emitters   []Emitter
+	exit       chan struct{}     // signal when shutting down
+	labels     map[string]string // global labels attach to each metric
+	logf       func(format string, a ...any)
 }
 
 func (rep *Reporter) pollMetrics() []*Metric {
 	points := make([]*Metric, 0, 128)
 	rep.registry.Each(func(name string, metrik any) {
-		metric := CollectMetric(name, metrik, rep.autoReset)
+		metric := CollectMetric(name, metrik)
+		if rep.autoRemove {
+			// remove metric to keep zero metrics from hanging all time
+			rep.registry.Unregister(name)
+		}
 		if metric != nil {
 			if metric.Labels == nil && len(rep.labels) > 0 {
 				metric.Labels = make(map[string]string)
@@ -112,10 +116,10 @@ func WithPollInterval(interval time.Duration) Option {
 	}
 }
 
-// Auto reset metric after each report, such as Counter.
-func WithAutoReset(flag bool) Option {
+// Auto remove metric after each report, such as Counter.
+func WithAutoRemove(flag bool) Option {
 	return func(rep *Reporter) {
-		rep.autoReset = flag
+		rep.autoRemove = flag
 	}
 }