Report buffered metrics one final time on Close() (#44)

.travis.yml

@@ -4,7 +4,7 @@ go:
   - 1.5
   - 1.6
   - 1.7
-  - tip
+  - 1.8
 env:
   global:
     - GO15VENDOREXPERIMENT=1

scope.go

@@ -247,6 +247,13 @@ func (s *scope) reportLoopRun() {
 		return
 	}
 
+	s.reportRegistryWithLock()
+
+	s.status.RUnlock()
+}
+
+// reports current registry with scope status lock held
+func (s *scope) reportRegistryWithLock() {
 	s.registry.RLock()
 	if s.reporter != nil {
 		for _, ss := range s.registry.subscopes {
@@ -258,8 +265,6 @@ func (s *scope) reportLoopRun() {
 		}
 	}
 	s.registry.RUnlock()
-
-	s.status.RUnlock()
 }
 
 func (s *scope) Counter(name string) Counter {
@@ -479,8 +484,18 @@ func (s *scope) Snapshot() Snapshot {
 
 func (s *scope) Close() error {
 	s.status.Lock()
+
+	// don't wait to close more than once (panic on double close of
+	// s.status.quit)
+	if s.status.closed {
+		s.status.Unlock()
+		return nil
+	}
+
 	s.status.closed = true
 	close(s.status.quit)
+	s.reportRegistryWithLock()
+
 	s.status.Unlock()
 
 	if closer, ok := s.baseReporter.(io.Closer); ok {

scope_test.go

@@ -693,5 +693,20 @@ func TestScopeAvoidReportLoopRunOnClose(t *testing.T) {
 	assert.NoError(t, closer.Close())
 
 	s.reportLoopRun()
-	assert.Equal(t, int32(1), atomic.LoadInt32(&r.flushes))
+	assert.Equal(t, int32(2), atomic.LoadInt32(&r.flushes))
+}
+
+func TestScopeFlushOnClose(t *testing.T) {
+	r := newTestStatsReporter()
+	root, closer := NewRootScope(ScopeOptions{Reporter: r}, time.Hour)
+
+	r.cg.Add(1)
+	root.Counter("foo").Inc(1)
+	assert.Nil(t, r.counters["foo"])
+
+	assert.NoError(t, closer.Close())
+
+	assert.EqualValues(t, 1, r.counters["foo"].val)
+
+	assert.NoError(t, closer.Close())
 }