Limit GetMetricStatistics to 10 per second

closes #1197

internal/limiter/limiter_test.go

@@ -0,0 +1,54 @@
+package limiter
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRateLimiter(t *testing.T) {
+	r := NewRateLimiter(5, time.Second)
+	ticker := time.NewTicker(time.Millisecond * 75)
+
+	// test that we can only get 5 receives from the rate limiter
+	counter := 0
+outer:
+	for {
+		select {
+		case <-r.C:
+			counter++
+		case <-ticker.C:
+			break outer
+		}
+	}
+
+	assert.Equal(t, 5, counter)
+	r.Stop()
+	// verify that the Stop function closes the channel.
+	_, ok := <-r.C
+	assert.False(t, ok)
+}
+
+func TestRateLimiterMultipleIterations(t *testing.T) {
+	r := NewRateLimiter(5, time.Millisecond*50)
+	ticker := time.NewTicker(time.Millisecond * 250)
+
+	// test that we can get 15 receives from the rate limiter
+	counter := 0
+outer:
+	for {
+		select {
+		case <-ticker.C:
+			break outer
+		case <-r.C:
+			counter++
+		}
+	}
+
+	assert.True(t, counter > 10)
+	r.Stop()
+	// verify that the Stop function closes the channel.
+	_, ok := <-r.C
+	assert.False(t, ok)
+}