Source: templates.go in package go.opencensus.io/zpages

Copyright 2017, OpenCensus 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 zpages

import (
	"fmt"
	"html/template"
	"io/ioutil"
	"log"
	"strconv"
	"time"

	"go.opencensus.io/trace"
	"go.opencensus.io/zpages/internal"
)

var (
	fs                = internal.FS(false)
	templateFunctions = template.FuncMap{
		"count":    countFormatter,
		"ms":       msFormatter,
		"rate":     rateFormatter,
		"datarate": dataRateFormatter,
		"even":     even,
		"traceid":  traceIDFormatter,
	}
	headerTemplate       = parseTemplate("header")
	summaryTableTemplate = parseTemplate("summary")
	statsTemplate        = parseTemplate("rpcz")
	tracesTableTemplate  = parseTemplate("traces")
	footerTemplate       = parseTemplate("footer")
)

func parseTemplate(name string) *template.Template {
	f, err := fs.Open("/templates/" + name + ".html")
	if err != nil {
		log.Panicf("%v: %v", name, err)
	}
	defer f.Close()
	text, err := ioutil.ReadAll(f)
	if err != nil {
		log.Panicf("%v: %v", name, err)
	}
	return template.Must(template.New(name).Funcs(templateFunctions).Parse(string(text)))
}

func countFormatter(num uint64) string {
	if num <= 0 {
		return " "
	}
	var floatVal float64
	var suffix string

	if num >= 1e18 {
		floatVal = float64(num) / 1e18
		suffix = " E "
	} else if num >= 1e15 {
		floatVal = float64(num) / 1e15
		suffix = " P "
	} else if num >= 1e12 {
		floatVal = float64(num) / 1e12
		suffix = " T "
	} else if num >= 1e9 {
		floatVal = float64(num) / 1e9
		suffix = " G "
	} else if num >= 1e6 {
		floatVal = float64(num) / 1e6
		suffix = " M "
	}

	if floatVal != 0 {
		return fmt.Sprintf("%1.3f%s", floatVal, suffix)
	}
	return fmt.Sprint(num)
}

func msFormatter(d time.Duration) string {
	if d == 0 {
		return "0"
	}
	if d < 10*time.Millisecond {
		return fmt.Sprintf("%.3f", float64(d)*1e-6)
	}
	return strconv.Itoa(int(d / time.Millisecond))
}

func rateFormatter(r float64) string {
	return fmt.Sprintf("%.3f", r)
}

func dataRateFormatter(b float64) string {
	return fmt.Sprintf("%.3f", b/1e6)
}

func traceIDFormatter(r traceRow) template.HTML {
	sc := r.SpanContext
	if sc == (trace.SpanContext{}) {
		return ""
	}
	col := "black"
	if sc.TraceOptions.IsSampled() {
		col = "blue"
	}
	if r.ParentSpanID != (trace.SpanID{}) {
		return template.HTML(fmt.Sprintf(`trace_id: <b style="color:%s">%s</b> span_id: %s parent_span_id: %s`, col, sc.TraceID, sc.SpanID, r.ParentSpanID))
	}
	return template.HTML(fmt.Sprintf(`trace_id: <b style="color:%s">%s</b> span_id: %s`, col, sc.TraceID, sc.SpanID))
}

func even(x int) bool {
	return x%2 == 0