Revert "Revert "Added metrics/debug gathering methods to utils and used them in density ...""

This reverts commit 70500a64a7.

test/e2e/fifo_queue.go

@@ -0,0 +1,75 @@
+/*
+Copyright 2014 The Kubernetes Authors 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 e2e
+
+import (
+	"sync"
+	"time"
+)
+
+type QueueItem struct {
+	createTime string
+	value      interface{}
+}
+
+type QueueItems struct {
+	pos   int
+	mutex *sync.Mutex
+	list  []QueueItem
+}
+
+type FifoQueue QueueItems
+
+func (fq *FifoQueue) Push(elem interface{}) {
+	fq.mutex.Lock()
+	fq.list = append(fq.list, QueueItem{time.Now().String(), elem})
+	fq.mutex.Unlock()
+}
+
+func (fq *FifoQueue) Pop() QueueItem {
+	fq.mutex.Lock()
+	var val QueueItem
+	if len(fq.list)-1 >= fq.pos {
+		val = fq.list[fq.pos]
+		fq.pos++
+	}
+	fq.mutex.Unlock()
+	return val
+}
+
+func (fq FifoQueue) Len() int {
+	return len(fq.list[fq.pos:])
+}
+
+func (fq *FifoQueue) First() QueueItem {
+	return fq.list[fq.pos]
+}
+
+func (fq *FifoQueue) Last() QueueItem {
+	return fq.list[len(fq.list)-1]
+}
+
+func (fq *FifoQueue) Reset() {
+	fq.pos = 0
+}
+
+func newFifoQueue() *FifoQueue {
+	tmp := new(FifoQueue)
+	tmp.mutex = &sync.Mutex{}
+	tmp.pos = 0
+	return tmp
+}