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// Copyright 2015 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package v2stats
import (
"encoding/json"
"math"
"sync"
"time"
"go.uber.org/zap"
)
// LeaderStats is used by the leader in an etcd cluster, and encapsulates
// statistics about communication with its followers
type LeaderStats struct {
lg *zap.Logger
leaderStats
sync.Mutex
}
type leaderStats struct {
// Leader is the ID of the leader in the etcd cluster.
// TODO(jonboulle): clarify that these are IDs, not names
Leader string `json:"leader"`
Followers map[string]*FollowerStats `json:"followers"`
}
// NewLeaderStats generates a new LeaderStats with the given id as leader
func NewLeaderStats(lg *zap.Logger, id string) *LeaderStats {
if lg == nil {
lg = zap.NewNop()
}
return &LeaderStats{
lg: lg,
leaderStats: leaderStats{
Leader: id,
Followers: make(map[string]*FollowerStats),
},
}
}
func (ls *LeaderStats) JSON() []byte {
ls.Lock()
stats := ls.leaderStats
ls.Unlock()
b, err := json.Marshal(stats)
// TODO(jonboulle): appropriate error handling?
if err != nil {
ls.lg.Error("failed to marshal leader stats", zap.Error(err))
}
return b
}
func (ls *LeaderStats) Follower(name string) *FollowerStats {
ls.Lock()
defer ls.Unlock()
fs, ok := ls.Followers[name]
if !ok {
fs = &FollowerStats{}
fs.Latency.Minimum = 1 << 63
ls.Followers[name] = fs
}
return fs
}
// FollowerStats encapsulates various statistics about a follower in an etcd cluster
type FollowerStats struct {
Latency LatencyStats `json:"latency"`
Counts CountsStats `json:"counts"`
sync.Mutex
}
// LatencyStats encapsulates latency statistics.
type LatencyStats struct {
Current float64 `json:"current"`
Average float64 `json:"average"`
averageSquare float64
StandardDeviation float64 `json:"standardDeviation"`
Minimum float64 `json:"minimum"`
Maximum float64 `json:"maximum"`
}
// CountsStats encapsulates raft statistics.
type CountsStats struct {
Fail uint64 `json:"fail"`
Success uint64 `json:"success"`
}
// Succ updates the FollowerStats with a successful send
func (fs *FollowerStats) Succ(d time.Duration) {
fs.Lock()
defer fs.Unlock()
total := float64(fs.Counts.Success) * fs.Latency.Average
totalSquare := float64(fs.Counts.Success) * fs.Latency.averageSquare
fs.Counts.Success++
fs.Latency.Current = float64(d) / (1000000.0)
if fs.Latency.Current > fs.Latency.Maximum {
fs.Latency.Maximum = fs.Latency.Current
}
if fs.Latency.Current < fs.Latency.Minimum {
fs.Latency.Minimum = fs.Latency.Current
}
fs.Latency.Average = (total + fs.Latency.Current) / float64(fs.Counts.Success)
fs.Latency.averageSquare = (totalSquare + fs.Latency.Current*fs.Latency.Current) / float64(fs.Counts.Success)
// sdv = sqrt(avg(x^2) - avg(x)^2)
fs.Latency.StandardDeviation = math.Sqrt(fs.Latency.averageSquare - fs.Latency.Average*fs.Latency.Average)
}
// Fail updates the FollowerStats with an unsuccessful send
func (fs *FollowerStats) Fail() {
fs.Lock()
defer fs.Unlock()
fs.Counts.Fail++
}
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