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sliding_histogram.go
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sliding_histogram.go
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// Copyright 2015 The Cockroach 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 metric
import (
"time"
"github.com/codahale/hdrhistogram"
)
var _ periodic = &slidingHistogram{}
// A deprecatedWindowedHistogram is a wrapper around an
// hdrhistogram.WindowedHistogram. The caller must enforce proper
// synchronization.
type slidingHistogram struct {
windowed *hdrhistogram.WindowedHistogram
nextT time.Time
duration time.Duration
}
// newSlidingHistogram creates a new windowed HDRHistogram with the given
// parameters. Data is kept in the active window for approximately the given
// duration. See the documentation for hdrhistogram.WindowedHistogram for
// details.
func newSlidingHistogram(duration time.Duration, maxVal int64, sigFigs int) *slidingHistogram {
if duration <= 0 {
panic("cannot create a sliding histogram with nonpositive duration")
}
return &slidingHistogram{
nextT: now(),
duration: duration,
windowed: hdrhistogram.NewWindowed(histWrapNum, 0, maxVal, sigFigs),
}
}
func (h *slidingHistogram) tick() {
h.nextT = h.nextT.Add(h.duration / histWrapNum)
h.windowed.Rotate()
}
func (h *slidingHistogram) nextTick() time.Time {
return h.nextT
}
func (h *slidingHistogram) Current() *hdrhistogram.Histogram {
maybeTick(h)
return h.windowed.Merge()
}
func (h *slidingHistogram) RecordValue(v int64) error {
return h.windowed.Current.RecordValue(v)
}