go.etcd.io/etcd@v3.3.27+incompatible/etcdserver/stats/queue.go (about) 1 // Copyright 2015 The etcd Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 package stats 16 17 import ( 18 "sync" 19 "time" 20 ) 21 22 const ( 23 queueCapacity = 200 24 ) 25 26 // RequestStats represent the stats for a request. 27 // It encapsulates the sending time and the size of the request. 28 type RequestStats struct { 29 SendingTime time.Time 30 Size int 31 } 32 33 type statsQueue struct { 34 items [queueCapacity]*RequestStats 35 size int 36 front int 37 back int 38 totalReqSize int 39 rwl sync.RWMutex 40 } 41 42 func (q *statsQueue) Len() int { 43 return q.size 44 } 45 46 func (q *statsQueue) ReqSize() int { 47 return q.totalReqSize 48 } 49 50 // FrontAndBack gets the front and back elements in the queue 51 // We must grab front and back together with the protection of the lock 52 func (q *statsQueue) frontAndBack() (*RequestStats, *RequestStats) { 53 q.rwl.RLock() 54 defer q.rwl.RUnlock() 55 if q.size != 0 { 56 return q.items[q.front], q.items[q.back] 57 } 58 return nil, nil 59 } 60 61 // Insert function insert a RequestStats into the queue and update the records 62 func (q *statsQueue) Insert(p *RequestStats) { 63 q.rwl.Lock() 64 defer q.rwl.Unlock() 65 66 q.back = (q.back + 1) % queueCapacity 67 68 if q.size == queueCapacity { //dequeue 69 q.totalReqSize -= q.items[q.front].Size 70 q.front = (q.back + 1) % queueCapacity 71 } else { 72 q.size++ 73 } 74 75 q.items[q.back] = p 76 q.totalReqSize += q.items[q.back].Size 77 78 } 79 80 // Rate function returns the package rate and byte rate 81 func (q *statsQueue) Rate() (float64, float64) { 82 front, back := q.frontAndBack() 83 84 if front == nil || back == nil { 85 return 0, 0 86 } 87 88 if time.Since(back.SendingTime) > time.Second { 89 q.Clear() 90 return 0, 0 91 } 92 93 sampleDuration := back.SendingTime.Sub(front.SendingTime) 94 95 pr := float64(q.Len()) / float64(sampleDuration) * float64(time.Second) 96 97 br := float64(q.ReqSize()) / float64(sampleDuration) * float64(time.Second) 98 99 return pr, br 100 } 101 102 // Clear function clear up the statsQueue 103 func (q *statsQueue) Clear() { 104 q.rwl.Lock() 105 defer q.rwl.Unlock() 106 q.back = -1 107 q.front = 0 108 q.size = 0 109 q.totalReqSize = 0 110 }