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package hdrhistogram_test
import (
"bytes"
"fmt"
hdrhistogram "github.com/HdrHistogram/hdrhistogram-go"
"io/ioutil"
)
// The log format encodes into a single file, multiple histograms with optional shared meta data.
// The following example showcases reading a log file into a slice of histograms
// nolint
func ExampleNewHistogramLogReader() {
}
// The log format encodes into a single file, multiple histograms with optional shared meta data.
// The following example showcases writing multiple histograms into a log file and then
// processing them again to confirm a proper encode-decode flow
// nolint
func ExampleNewHistogramLogWriter() {
var buff bytes.Buffer
// Create a histogram log writer to write to a bytes.Buffer
writer := hdrhistogram.NewHistogramLogWriter(&buff)
writer.OutputLogFormatVersion()
writer.OutputStartTime(0)
writer.OutputLegend()
// Lets create 3 distinct histograms to exemply the logwriter features
// each one with a time-frame of 60 secs ( 60000 ms )
hist1 := hdrhistogram.New(1, 30000000, 3)
hist1.SetStartTimeMs(0)
hist1.SetEndTimeMs(60000)
for _, sample := range []int64{10, 20, 30, 40} {
hist1.RecordValue(sample)
}
hist2 := hdrhistogram.New(1, 3000, 3)
hist1.SetStartTimeMs(60001)
hist1.SetEndTimeMs(120000)
for _, sample := range []int64{50, 70, 80, 60} {
hist2.RecordValue(sample)
}
hist3 := hdrhistogram.New(1, 30000, 3)
hist1.SetStartTimeMs(120001)
hist1.SetEndTimeMs(180000)
for _, sample := range []int64{90, 100} {
hist3.RecordValue(sample)
}
writer.OutputIntervalHistogram(hist1)
writer.OutputIntervalHistogram(hist2)
writer.OutputIntervalHistogram(hist3)
ioutil.WriteFile("example.logV2.hlog", buff.Bytes(), 0644)
// read check
// Lets read all again and confirm that the total sample count is 10
dat, _ := ioutil.ReadFile("example.logV2.hlog")
r := bytes.NewReader(dat)
// Create a histogram log reader
reader := hdrhistogram.NewHistogramLogReader(r)
var histograms []*hdrhistogram.Histogram = make([]*hdrhistogram.Histogram, 0)
// Read all histograms in the file
for hist, err := reader.NextIntervalHistogram(); hist != nil && err == nil; hist, err = reader.NextIntervalHistogram() {
histograms = append(histograms, hist)
}
fmt.Printf("Read a total of %d histograms\n", len(histograms))
min := reader.RangeObservedMin()
max := reader.RangeObservedMax()
sigdigits := 3
overallHistogram := hdrhistogram.New(min, max, sigdigits)
//// We can then merge all histograms into one and retrieve overall metrics
for _, hist := range histograms {
overallHistogram.Merge(hist)
}
fmt.Printf("Overall count: %d samples\n", overallHistogram.TotalCount())
// Output:
// Read a total of 3 histograms
// Overall count: 10 samples
}
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