add work queue; test coverage 100%

pkg/util/workqueue/doc.go

@@ -0,0 +1,26 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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 provides a simple queue that supports the following
+// features:
+//  * Fair: items processed in the order in which they are added.
+//  * Stingy: a single item will not be processed multiple times concurrently,
+//      and if an item is added multiple times before it can be processed, it
+//      will only be processed once.
+//  * Multiple consumers and producers. In particular, it is allowed for an
+//      item to be reenqueued while it is being processed.
+//  * Shutdown notifications.
+package workqueue