113 lines
2.5 KiB
Go
113 lines
2.5 KiB
Go
/*
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Copyright 2014 CoreOS, Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package stats
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import (
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"sync"
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"time"
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)
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const (
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queueCapacity = 200
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)
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// RequestStats represent the stats for a request.
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// It encapsulates the sending time and the size of the request.
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type RequestStats struct {
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SendingTime time.Time
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Size int
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}
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type statsQueue struct {
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items [queueCapacity]*RequestStats
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size int
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front int
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back int
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totalReqSize int
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rwl sync.RWMutex
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}
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func (q *statsQueue) Len() int {
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return q.size
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}
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func (q *statsQueue) ReqSize() int {
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return q.totalReqSize
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}
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// FrontAndBack gets the front and back elements in the queue
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// We must grab front and back together with the protection of the lock
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func (q *statsQueue) frontAndBack() (*RequestStats, *RequestStats) {
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q.rwl.RLock()
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defer q.rwl.RUnlock()
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if q.size != 0 {
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return q.items[q.front], q.items[q.back]
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}
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return nil, nil
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}
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// Insert function insert a RequestStats into the queue and update the records
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func (q *statsQueue) Insert(p *RequestStats) {
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q.rwl.Lock()
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defer q.rwl.Unlock()
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q.back = (q.back + 1) % queueCapacity
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if q.size == queueCapacity { //dequeue
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q.totalReqSize -= q.items[q.front].Size
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q.front = (q.back + 1) % queueCapacity
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} else {
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q.size++
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}
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q.items[q.back] = p
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q.totalReqSize += q.items[q.back].Size
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}
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// Rate function returns the package rate and byte rate
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func (q *statsQueue) Rate() (float64, float64) {
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front, back := q.frontAndBack()
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if front == nil || back == nil {
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return 0, 0
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}
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if time.Now().Sub(back.SendingTime) > time.Second {
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q.Clear()
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return 0, 0
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}
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sampleDuration := back.SendingTime.Sub(front.SendingTime)
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pr := float64(q.Len()) / float64(sampleDuration) * float64(time.Second)
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br := float64(q.ReqSize()) / float64(sampleDuration) * float64(time.Second)
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return pr, br
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}
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// Clear function clear up the statsQueue
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func (q *statsQueue) Clear() {
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q.rwl.Lock()
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defer q.rwl.Unlock()
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q.back = -1
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q.front = 0
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q.size = 0
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q.totalReqSize = 0
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}
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