go.etcd.io/etcd@v3.3.27+incompatible/etcdserver/stats/leader.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  	"encoding/json"
    19  	"math"
    20  	"sync"
    21  	"time"
    22  )
    23  
    24  // LeaderStats is used by the leader in an etcd cluster, and encapsulates
    25  // statistics about communication with its followers
    26  type LeaderStats struct {
    27  	leaderStats
    28  	sync.Mutex
    29  }
    30  
    31  type leaderStats struct {
    32  	// Leader is the ID of the leader in the etcd cluster.
    33  	// TODO(jonboulle): clarify that these are IDs, not names
    34  	Leader    string                    `json:"leader"`
    35  	Followers map[string]*FollowerStats `json:"followers"`
    36  }
    37  
    38  // NewLeaderStats generates a new LeaderStats with the given id as leader
    39  func NewLeaderStats(id string) *LeaderStats {
    40  	return &LeaderStats{
    41  		leaderStats: leaderStats{
    42  			Leader:    id,
    43  			Followers: make(map[string]*FollowerStats),
    44  		},
    45  	}
    46  }
    47  
    48  func (ls *LeaderStats) JSON() []byte {
    49  	ls.Lock()
    50  	stats := ls.leaderStats
    51  	ls.Unlock()
    52  	b, err := json.Marshal(stats)
    53  	// TODO(jonboulle): appropriate error handling?
    54  	if err != nil {
    55  		plog.Errorf("error marshalling leader stats (%v)", err)
    56  	}
    57  	return b
    58  }
    59  
    60  func (ls *LeaderStats) Follower(name string) *FollowerStats {
    61  	ls.Lock()
    62  	defer ls.Unlock()
    63  	fs, ok := ls.Followers[name]
    64  	if !ok {
    65  		fs = &FollowerStats{}
    66  		fs.Latency.Minimum = 1 << 63
    67  		ls.Followers[name] = fs
    68  	}
    69  	return fs
    70  }
    71  
    72  // FollowerStats encapsulates various statistics about a follower in an etcd cluster
    73  type FollowerStats struct {
    74  	Latency LatencyStats `json:"latency"`
    75  	Counts  CountsStats  `json:"counts"`
    76  
    77  	sync.Mutex
    78  }
    79  
    80  // LatencyStats encapsulates latency statistics.
    81  type LatencyStats struct {
    82  	Current           float64 `json:"current"`
    83  	Average           float64 `json:"average"`
    84  	averageSquare     float64
    85  	StandardDeviation float64 `json:"standardDeviation"`
    86  	Minimum           float64 `json:"minimum"`
    87  	Maximum           float64 `json:"maximum"`
    88  }
    89  
    90  // CountsStats encapsulates raft statistics.
    91  type CountsStats struct {
    92  	Fail    uint64 `json:"fail"`
    93  	Success uint64 `json:"success"`
    94  }
    95  
    96  // Succ updates the FollowerStats with a successful send
    97  func (fs *FollowerStats) Succ(d time.Duration) {
    98  	fs.Lock()
    99  	defer fs.Unlock()
   100  
   101  	total := float64(fs.Counts.Success) * fs.Latency.Average
   102  	totalSquare := float64(fs.Counts.Success) * fs.Latency.averageSquare
   103  
   104  	fs.Counts.Success++
   105  
   106  	fs.Latency.Current = float64(d) / (1000000.0)
   107  
   108  	if fs.Latency.Current > fs.Latency.Maximum {
   109  		fs.Latency.Maximum = fs.Latency.Current
   110  	}
   111  
   112  	if fs.Latency.Current < fs.Latency.Minimum {
   113  		fs.Latency.Minimum = fs.Latency.Current
   114  	}
   115  
   116  	fs.Latency.Average = (total + fs.Latency.Current) / float64(fs.Counts.Success)
   117  	fs.Latency.averageSquare = (totalSquare + fs.Latency.Current*fs.Latency.Current) / float64(fs.Counts.Success)
   118  
   119  	// sdv = sqrt(avg(x^2) - avg(x)^2)
   120  	fs.Latency.StandardDeviation = math.Sqrt(fs.Latency.averageSquare - fs.Latency.Average*fs.Latency.Average)
   121  }
   122  
   123  // Fail updates the FollowerStats with an unsuccessful send
   124  func (fs *FollowerStats) Fail() {
   125  	fs.Lock()
   126  	defer fs.Unlock()
   127  	fs.Counts.Fail++
   128  }