Add initial controller boilerplate and example controller

Signed-off-by: Monis Khan <mok@vmware.com>

internal/controller/queue.go

@@ -0,0 +1,41 @@
+/*
+Copyright 2020 VMware, Inc.
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package controller
+
+import (
+	"time"
+
+	"k8s.io/client-go/util/workqueue"
+)
+
+type Queue interface {
+	// Add immediately adds a key to the queue and marks it as needing processing.
+	Add(key Key)
+
+	// AddRateLimited adds a key to the queue after the rate limiter says it is ok.
+	AddRateLimited(key Key)
+
+	// AddAfter adds a key to the queue after the indicated duration has passed.
+	AddAfter(key Key, duration time.Duration)
+}
+
+var _ Queue = &queueWrapper{}
+
+type queueWrapper struct {
+	queue workqueue.RateLimitingInterface
+}
+
+func (q *queueWrapper) Add(key Key) {
+	q.queue.Add(key)
+}
+
+func (q *queueWrapper) AddRateLimited(key Key) {
+	q.queue.AddRateLimited(key)
+}
+
+func (q *queueWrapper) AddAfter(key Key, duration time.Duration) {
+	q.queue.AddAfter(key, duration)
+}