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cmd/trace: factor out durationHistogram
This code will be useful for the new tracer, and there's no need to duplicate it. This change copies it to internal/trace/traceviewer, adds some comments, and renames it to TimeHistogram. While we're here, let's get rid of the unused String method which has a comment talking about how awful the rendering is. Also, let's get rid of uses of niceDuration. We'd have to bring it with us in the move and I don't think it's worth it. The difference between the default time.Duration rendering and the niceDuration rendering is usually a few extra digits of precision. Yes, it's noisier, but AFAICT it's not substantially worse. It doesn't seem worth the new API, even if it's just internal. We can also always bring it back later. For #60773. For #63960. Change-Id: I795f58f579f1d503c540c3a40bed12e52bce38e2 Reviewed-on: https://go-review.googlesource.com/c/go/+/542001 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Michael Knyszek <mknyszek@google.com> Reviewed-by: Michael Pratt <mpratt@google.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,86 @@ | ||
| // Copyright 2023 The Go Authors. All rights reserved. | ||
| // Use of this source code is governed by a BSD-style | ||
| // license that can be found in the LICENSE file. | ||
|
|
||
| package traceviewer | ||
|
|
||
| import ( | ||
| "fmt" | ||
| "html/template" | ||
| "math" | ||
| "strings" | ||
| "time" | ||
| ) | ||
|
|
||
| // TimeHistogram is an high-dynamic-range histogram for durations. | ||
| type TimeHistogram struct { | ||
| Count int | ||
| Buckets []int | ||
| MinBucket, MaxBucket int | ||
| } | ||
|
|
||
| // Five buckets for every power of 10. | ||
| var logDiv = math.Log(math.Pow(10, 1.0/5)) | ||
|
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| // Add adds a single sample to the histogram. | ||
| func (h *TimeHistogram) Add(d time.Duration) { | ||
| var bucket int | ||
| if d > 0 { | ||
| bucket = int(math.Log(float64(d)) / logDiv) | ||
| } | ||
| if len(h.Buckets) <= bucket { | ||
| h.Buckets = append(h.Buckets, make([]int, bucket-len(h.Buckets)+1)...) | ||
| h.Buckets = h.Buckets[:cap(h.Buckets)] | ||
| } | ||
| h.Buckets[bucket]++ | ||
| if bucket < h.MinBucket || h.MaxBucket == 0 { | ||
| h.MinBucket = bucket | ||
| } | ||
| if bucket > h.MaxBucket { | ||
| h.MaxBucket = bucket | ||
| } | ||
| h.Count++ | ||
| } | ||
|
|
||
| // BucketMin returns the minimum duration value for a provided bucket. | ||
| func (h *TimeHistogram) BucketMin(bucket int) time.Duration { | ||
| return time.Duration(math.Exp(float64(bucket) * logDiv)) | ||
| } | ||
|
|
||
| // ToHTML renders the histogram as HTML. | ||
| func (h *TimeHistogram) ToHTML(urlmaker func(min, max time.Duration) string) template.HTML { | ||
| if h == nil || h.Count == 0 { | ||
| return template.HTML("") | ||
| } | ||
|
|
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| const barWidth = 400 | ||
|
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| maxCount := 0 | ||
| for _, count := range h.Buckets { | ||
| if count > maxCount { | ||
| maxCount = count | ||
| } | ||
| } | ||
|
|
||
| w := new(strings.Builder) | ||
| fmt.Fprintf(w, `<table>`) | ||
| for i := h.MinBucket; i <= h.MaxBucket; i++ { | ||
| // Tick label. | ||
| if h.Buckets[i] > 0 { | ||
| fmt.Fprintf(w, `<tr><td class="histoTime" align="right"><a href=%s>%s</a></td>`, urlmaker(h.BucketMin(i), h.BucketMin(i+1)), h.BucketMin(i)) | ||
| } else { | ||
| fmt.Fprintf(w, `<tr><td class="histoTime" align="right">%s</td>`, h.BucketMin(i)) | ||
| } | ||
| // Bucket bar. | ||
| width := h.Buckets[i] * barWidth / maxCount | ||
| fmt.Fprintf(w, `<td><div style="width:%dpx;background:blue;position:relative"> </div></td>`, width) | ||
| // Bucket count. | ||
| fmt.Fprintf(w, `<td align="right"><div style="position:relative">%d</div></td>`, h.Buckets[i]) | ||
| fmt.Fprintf(w, "</tr>\n") | ||
|
|
||
| } | ||
| // Final tick label. | ||
| fmt.Fprintf(w, `<tr><td align="right">%s</td></tr>`, h.BucketMin(h.MaxBucket+1)) | ||
| fmt.Fprintf(w, `</table>`) | ||
| return template.HTML(w.String()) | ||
| } |