51 lines
971 B
Go
51 lines
971 B
Go
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package main
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import (
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"log"
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"net/http"
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"sync"
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"time"
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"github.com/wcharczuk/go-chart/util"
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chart "github.com/wcharczuk/go-chart"
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)
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var lock sync.Mutex
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var graph *chart.Chart
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var ts *chart.TimeSeries
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func addData(t time.Time, e time.Duration) {
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lock.Lock()
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ts.XValues = append(ts.XValues, t)
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ts.YValues = append(ts.YValues, util.Time.Millis(e))
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lock.Unlock()
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}
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func drawChart(res http.ResponseWriter, req *http.Request) {
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start := time.Now()
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defer func() {
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addData(start, time.Since(start))
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}()
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if len(ts.XValues) == 0 {
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http.Error(res, "no data (yet)", http.StatusBadRequest)
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return
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}
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res.Header().Set("Content-Type", "image/png")
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if err := graph.Render(chart.PNG, res); err != nil {
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log.Printf("%v", err)
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}
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}
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func main() {
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ts = &chart.TimeSeries{
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XValues: []time.Time{},
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YValues: []float64{},
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}
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graph = &chart.Chart{
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Series: []chart.Series{ts},
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}
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http.HandleFunc("/", drawChart)
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log.Fatal(http.ListenAndServe(":8080", nil))
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}
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