Set default reporting interval (#226)

* Enforce minimum reporting interval

* Add new RootScope constructor with default interval

scope.go

@@ -39,7 +39,8 @@ const (
 	// OmitInternalMetrics turns off internal metrics submission.
 	OmitInternalMetrics
 
-	_defaultInitialSliceSize = 16
+	_defaultInitialSliceSize  = 16
+	_defaultReportingInterval = 2 * time.Second
 )
 
 var (
@@ -124,6 +125,12 @@ func NewRootScope(opts ScopeOptions, interval time.Duration) (Scope, io.Closer)
 	return s, s
 }
 
+// NewRootScopeWithDefaultInterval invokes NewRootScope with the default
+// reporting interval of 2s.
+func NewRootScopeWithDefaultInterval(opts ScopeOptions) (Scope, io.Closer) {
+	return NewRootScope(opts, _defaultReportingInterval)
+}
+
 // NewTestScope creates a new Scope without a stats reporter with the
 // given prefix and adds the ability to take snapshots of metrics emitted
 // to it.

scope_test.go

@@ -395,6 +395,26 @@ func TestWriteReportLoop(t *testing.T) {
 	r.WaitAll()
 }
 
+func TestWriteReportLoopDefaultInterval(t *testing.T) {
+	r := newTestStatsReporter()
+	s, closer := NewRootScopeWithDefaultInterval(
+		ScopeOptions{Reporter: r, MetricsOption: OmitInternalMetrics},
+	)
+	defer closer.Close()
+
+	r.cg.Add(1)
+	s.Counter("bar").Inc(1)
+	r.gg.Add(1)
+	s.Gauge("zed").Update(1)
+	r.tg.Add(1)
+	s.Timer("ticky").Record(time.Millisecond * 175)
+	r.hg.Add(1)
+	s.Histogram("baz", MustMakeLinearValueBuckets(0, 10, 10)).
+		RecordValue(42.42)
+
+	r.WaitAll()
+}
+
 func TestCachedReportLoop(t *testing.T) {
 	r := newTestStatsReporter()
 	s, closer := NewRootScope(ScopeOptions{CachedReporter: r, MetricsOption: OmitInternalMetrics}, 10)