etcdserver/*: move internal v2 packages

Signed-off-by: Gyuho Lee <gyuhox@gmail.com>

etcdserver/api/v2stats/queue.go

@@ -0,0 +1,110 @@
+// Copyright 2015 The etcd 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 v2stats
+
+import (
+	"sync"
+	"time"
+)
+
+const (
+	queueCapacity = 200
+)
+
+// RequestStats represent the stats for a request.
+// It encapsulates the sending time and the size of the request.
+type RequestStats struct {
+	SendingTime time.Time
+	Size        int
+}
+
+type statsQueue struct {
+	items        [queueCapacity]*RequestStats
+	size         int
+	front        int
+	back         int
+	totalReqSize int
+	rwl          sync.RWMutex
+}
+
+func (q *statsQueue) Len() int {
+	return q.size
+}
+
+func (q *statsQueue) ReqSize() int {
+	return q.totalReqSize
+}
+
+// FrontAndBack gets the front and back elements in the queue
+// We must grab front and back together with the protection of the lock
+func (q *statsQueue) frontAndBack() (*RequestStats, *RequestStats) {
+	q.rwl.RLock()
+	defer q.rwl.RUnlock()
+	if q.size != 0 {
+		return q.items[q.front], q.items[q.back]
+	}
+	return nil, nil
+}
+
+// Insert function insert a RequestStats into the queue and update the records
+func (q *statsQueue) Insert(p *RequestStats) {
+	q.rwl.Lock()
+	defer q.rwl.Unlock()
+
+	q.back = (q.back + 1) % queueCapacity
+
+	if q.size == queueCapacity { //dequeue
+		q.totalReqSize -= q.items[q.front].Size
+		q.front = (q.back + 1) % queueCapacity
+	} else {
+		q.size++
+	}
+
+	q.items[q.back] = p
+	q.totalReqSize += q.items[q.back].Size
+
+}
+
+// Rate function returns the package rate and byte rate
+func (q *statsQueue) Rate() (float64, float64) {
+	front, back := q.frontAndBack()
+
+	if front == nil || back == nil {
+		return 0, 0
+	}
+
+	if time.Since(back.SendingTime) > time.Second {
+		q.Clear()
+		return 0, 0
+	}
+
+	sampleDuration := back.SendingTime.Sub(front.SendingTime)
+
+	pr := float64(q.Len()) / float64(sampleDuration) * float64(time.Second)
+
+	br := float64(q.ReqSize()) / float64(sampleDuration) * float64(time.Second)
+
+	return pr, br
+}
+
+// Clear function clear up the statsQueue
+func (q *statsQueue) Clear() {
+	q.rwl.Lock()
+	defer q.rwl.Unlock()
+	q.back = -1
+	q.front = 0
+	q.size = 0
+	q.totalReqSize = 0
+}