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avg_over_time.go
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avg_over_time.go
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// Copyright 2019 TiKV Project 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 movingaverage
import (
"time"
"github.com/phf/go-queue/queue"
)
type deltaWithInterval struct {
delta float64
interval time.Duration
}
// AvgOverTime maintains change rate in the last avgInterval.
//
// AvgOverTime takes changes with their own intervals,
// stores recent changes that happened in the last avgInterval,
// then calculates the change rate by (sum of changes) / (sum of intervals).
type AvgOverTime struct {
que *queue.Queue // The element is `deltaWithInterval`, sum of all elements' interval is less than `avgInterval`
margin deltaWithInterval // The last element from `PopFront` in `que`
deltaSum float64 // Including `margin` and all elements in `que`
intervalSum time.Duration // Including `margin` and all elements in `que`
avgInterval time.Duration
}
// NewAvgOverTime returns an AvgOverTime with given interval.
func NewAvgOverTime(interval time.Duration) *AvgOverTime {
return &AvgOverTime{
que: queue.New(),
margin: deltaWithInterval{
delta: 0,
interval: time.Microsecond,
},
deltaSum: 0,
intervalSum: 0,
avgInterval: interval,
}
}
// Get returns change rate in the last interval.
func (aot *AvgOverTime) Get() float64 {
if aot.intervalSum < aot.avgInterval {
return 0
}
marginDelta := aot.margin.delta * (aot.intervalSum.Seconds() - aot.avgInterval.Seconds()) / aot.margin.interval.Seconds()
return (aot.deltaSum - marginDelta) / aot.avgInterval.Seconds()
}
// Clear clears the AvgOverTime.
func (aot *AvgOverTime) Clear() {
for aot.que.Len() > 0 {
aot.que.PopFront()
}
aot.margin = deltaWithInterval{
delta: 0,
interval: time.Microsecond,
}
aot.intervalSum = 0
aot.deltaSum = 0
}
// Add adds recent change to AvgOverTime.
func (aot *AvgOverTime) Add(delta float64, interval time.Duration) {
if interval == 0 {
return
}
aot.que.PushBack(deltaWithInterval{delta, interval})
aot.deltaSum += delta
aot.intervalSum += interval
for aot.intervalSum-aot.margin.interval >= aot.avgInterval {
aot.deltaSum -= aot.margin.delta
aot.intervalSum -= aot.margin.interval
aot.margin = aot.que.PopFront().(deltaWithInterval)
}
}
// Set sets AvgOverTime to the given average.
func (aot *AvgOverTime) Set(avg float64) {
aot.Clear()
aot.margin.delta = avg * aot.avgInterval.Seconds()
aot.margin.interval = aot.avgInterval
aot.deltaSum = aot.margin.delta
aot.intervalSum = aot.avgInterval
aot.que.PushBack(deltaWithInterval{delta: aot.deltaSum, interval: aot.intervalSum})
}
// IsFull returns whether AvgOverTime is full
func (aot *AvgOverTime) IsFull() bool {
return aot.intervalSum >= aot.avgInterval
}
// Clone returns a copy of AvgOverTime
func (aot *AvgOverTime) Clone() *AvgOverTime {
q := queue.New()
for i := 0; i < aot.que.Len(); i++ {
v := aot.que.PopFront()
aot.que.PushBack(v)
q.PushBack(v)
}
margin := deltaWithInterval{
delta: aot.margin.delta,
interval: aot.margin.interval,
}
return &AvgOverTime{
que: q,
margin: margin,
deltaSum: aot.deltaSum,
intervalSum: aot.intervalSum,
avgInterval: aot.avgInterval,
}
}
// GetIntervalSum returns the sum of interval
func (aot *AvgOverTime) GetIntervalSum() time.Duration {
return aot.intervalSum
}
// GetInstantaneous returns the value just added.
func (aot *AvgOverTime) GetInstantaneous() float64 {
if aot.que.Len() == 0 || aot.que.Back() == nil {
return 0
}
return aot.que.Back().(deltaWithInterval).delta
}