Add examples for Histogram

histogram_example_test.go

@@ -0,0 +1,27 @@
+package metrics_test
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/VictoriaMetrics/metrics"
+)
+
+func ExampleHistogram() {
+	// Define a histogram in global scope.
+	var h = metrics.NewHistogram(`request_duration_seconds{path="/foo/bar"}`)
+
+	// Update the histogram with the duration of processRequest call.
+	startTime := time.Now()
+	processRequest()
+	h.UpdateDuration(startTime)
+}
+
+func ExampleHistogram_vec() {
+	for i := 0; i < 3; i++ {
+		// Dynamically construct metric name and pass it to GetOrCreateHistogram.
+		name := fmt.Sprintf(`response_size_bytes{path=%q}`, "/foo/bar")
+		response := processRequest()
+		metrics.GetOrCreateHistogram(name).Update(float64(len(response)))
+	}
+}