khenaidoo | d948f77 | 2021-08-11 17:49:24 -0400 | [diff] [blame^] | 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 | } |