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Signed-off-by: husharp <jinhao.hu@pingcap.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,172 @@ | ||
| // Copyright 2024 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 trend | ||
|
|
||
| import ( | ||
| "container/list" | ||
| "go.uber.org/zap" | ||
| "math" | ||
| "sync" | ||
| "time" | ||
|
|
||
| "github.com/pingcap/log" | ||
| ) | ||
|
|
||
| // SampleValue is a sample value. | ||
| type SampleValue struct { | ||
| value float64 | ||
| time time.Time | ||
| } | ||
|
|
||
| // SampleWindow is a window of sample values. | ||
| type SampleWindow struct { | ||
| sum float64 | ||
| values *list.List | ||
| duration time.Duration | ||
| } | ||
|
|
||
| // NewSampleWindow creates a new instance of SampleWindow. | ||
| func NewSampleWindow(duration time.Duration) *SampleWindow { | ||
| return &SampleWindow{ | ||
| sum: 0, | ||
| values: list.New(), | ||
| duration: duration, | ||
| } | ||
| } | ||
|
|
||
| // Record adds a new sample value and maintains the window constraints. | ||
| func (sw *SampleWindow) Record(value float64, now time.Time) { | ||
| sw.values.PushBack(SampleValue{value: value, time: now}) | ||
| sw.sum += value | ||
|
|
||
| for sw.values.Len() > 0 { | ||
| front := sw.values.Front().Value.(SampleValue) | ||
| if now.Sub(front.time) >= sw.duration { | ||
| sw.values.Remove(sw.values.Front()) | ||
| sw.sum -= front.value | ||
| } else { | ||
| break | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Avg calculates the average of the values in the window. | ||
| func (sw *SampleWindow) Avg() float64 { | ||
| if sw.values.Len() == 0 { | ||
| return 0.0 | ||
| } | ||
| log.Info("sw.sum", zap.Float64("sw.sum", sw.sum), zap.Int("sw.values.Len()", sw.values.Len())) | ||
| return sw.sum / float64(sw.values.Len()) | ||
| } | ||
|
|
||
| func (sw *SampleWindow) reset(capacity int64) { | ||
| sw.sum = 0 | ||
| sw.values.Init() | ||
| sw.duration = time.Duration(capacity) | ||
| } | ||
|
|
||
| // Trend is a trend of a value. | ||
| type Trend struct { | ||
| sync.RWMutex | ||
|
|
||
| smallWindow *SampleWindow | ||
| bigWindow *SampleWindow | ||
|
|
||
| changed bool | ||
| cache float64 | ||
| } | ||
|
|
||
| // NewTrend creates a new instance of Trend. | ||
| func NewTrend(dur time.Duration) *Trend { | ||
| return &Trend{ | ||
| smallWindow: NewSampleWindow(dur), | ||
| bigWindow: NewSampleWindow(dur * 2), | ||
| changed: false, | ||
| cache: 0.0, | ||
| } | ||
| } | ||
|
|
||
| // Record adds a new sample value and maintains the window constraints. | ||
| func (t *Trend) Record(value float64, now time.Time) { | ||
| t.Lock() | ||
| defer t.Unlock() | ||
|
|
||
| t.changed = true | ||
| t.smallWindow.Record(value, now) | ||
| t.bigWindow.Record(value, now) | ||
| } | ||
|
|
||
| // TODO: unSensitiveCause reduce influence of spike | ||
| const unSensitiveCause = 0.0 | ||
|
|
||
| // AvgRate calculates the average rate of the values in the window. | ||
| func (t *Trend) AvgRate() float64 { | ||
| t.Lock() | ||
| defer t.Unlock() | ||
|
|
||
| if !t.changed { | ||
| return t.cache | ||
| } | ||
|
|
||
| t.cache = laLbRate(t.smallWindow.Avg(), t.bigWindow.Avg(), unSensitiveCause) | ||
| log.Info("trend", zap.Float64("t.cache", t.cache), zap.Float64("smallWindow.Avg()", t.smallWindow.Avg()), zap.Float64("bigWindow.Avg()", t.bigWindow.Avg())) | ||
| return t.cache | ||
| } | ||
|
|
||
| // Reset resets the trend. | ||
| func (t *Trend) Reset() { | ||
| t.Lock() | ||
| defer t.Unlock() | ||
|
|
||
| t.smallWindow.reset(10) | ||
| t.bigWindow.reset(30) | ||
| t.changed = false | ||
| t.cache = 0.0 | ||
| } | ||
|
|
||
| // laLbRateSimple is a simple version of LaLbRate. | ||
| // func laLbRateSimple(laAvg float64, lbAvg float64) float64 { | ||
| // return (laAvg - lbAvg) / laAvg | ||
| // } | ||
|
|
||
| func laLbRate(laAvg float64, lbAvg float64, marginError float64) float64 { | ||
| if lbAvg < math.SmallestNonzeroFloat64 { | ||
| return 0.0 | ||
| } | ||
| increased := laAvg - lbAvg | ||
| if math.Abs(increased) < math.SmallestNonzeroFloat64 { | ||
| return 0.0 | ||
| } | ||
| if laAvg < lbAvg { | ||
| if -increased > marginError { | ||
| increased = -increased - marginError | ||
| } else { | ||
| increased = 0.0 | ||
| } | ||
| } else if increased > marginError { | ||
| increased -= marginError | ||
| } else { | ||
| increased = 0.0 | ||
| } | ||
| incSq := increased * increased | ||
| if laAvg < lbAvg { | ||
| incSq = -incSq | ||
| } | ||
| res := laAvg * incSq / math.Sqrt(lbAvg) | ||
| if laAvg < lbAvg { | ||
| return -math.Sqrt(-res) | ||
| } | ||
| return math.Sqrt(res) | ||
| } | ||
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