queue.go

Documentation: go.etcd.io/etcd/server/v3/etcdserver/api/v2stats

     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 v2stats
    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  }
   111
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