add a metric that can be used to notice stuck worker threads

Kubernetes-commit: 6195d1005d81eaa5dd49da744f5beab178340f5a

util/workqueue/metrics_test.go

@@ -0,0 +1,49 @@
+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package workqueue
+
+import (
+	"testing"
+	"time"
+)
+
+type testMetrics struct {
+	added, gotten, finished int64
+
+	updateCalled chan<- struct{}
+}
+
+func (m *testMetrics) add(item t)            { m.added++ }
+func (m *testMetrics) get(item t)            { m.gotten++ }
+func (m *testMetrics) done(item t)           { m.finished++ }
+func (m *testMetrics) updateUnfinishedWork() { m.updateCalled <- struct{}{} }
+
+func TestMetrics(t *testing.T) {
+	ch := make(chan struct{})
+	m := &testMetrics{
+		updateCalled: ch,
+	}
+	q := newQueue("test", m, time.Millisecond)
+	<-ch
+	q.ShutDown()
+	select {
+	case <-time.After(time.Second):
+		return
+	case <-ch:
+		t.Errorf("Unexpected update after shutdown was called.")
+	}
+}