src/cmd/trace/v2/tasks.go - toolchain/go - Git at Google

 // 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 trace

 import (
 	"bytes"
 	"cmp"
 	"fmt"
 	"html/template"
 	"internal/trace"
 	"internal/trace/traceviewer"
 	tracev2 "internal/trace/v2"
 	"log"
 	"net/http"
 	"slices"
 	"strings"
 	"time"
 )

 // UserTasksHandlerFunc returns a HandlerFunc that reports all tasks found in the trace.
 func UserTasksHandlerFunc(t *parsedTrace) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		tasks := t.summary.Tasks

 		// Summarize groups of tasks with the same name.
 		summary := make(map[string]taskStats)
 		for _, task := range tasks {
 			stats, ok := summary[task.Name]
 			if !ok {
 				stats.Type = task.Name
 			}
 			stats.add(task)
 			summary[task.Name] = stats
 		}

 		// Sort tasks by type.
 		userTasks := make([]taskStats, 0, len(summary))
 		for _, stats := range summary {
 			userTasks = append(userTasks, stats)
 		}
 		slices.SortFunc(userTasks, func(a, b taskStats) int {
 			return cmp.Compare(a.Type, b.Type)
 		})

 		// Emit table.
 		err := templUserTaskTypes.Execute(w, userTasks)
 		if err != nil {
 			http.Error(w, fmt.Sprintf("failed to execute template: %v", err), http.StatusInternalServerError)
 			return
 		}
 	}
 }

 type taskStats struct {
 	Type      string
 	Count     int                       // Complete + incomplete tasks
 	Histogram traceviewer.TimeHistogram // Complete tasks only
 }

 func (s *taskStats) UserTaskURL(complete bool) func(min, max time.Duration) string {
 	return func(min, max time.Duration) string {
 		return fmt.Sprintf("/usertask?type=%s&complete=%v&latmin=%v&latmax=%v", template.URLQueryEscaper(s.Type), template.URLQueryEscaper(complete), template.URLQueryEscaper(min), template.URLQueryEscaper(max))
 	}
 }

 func (s *taskStats) add(task *trace.UserTaskSummary) {
 	s.Count++
 	if task.Complete() {
 		s.Histogram.Add(task.End.Time().Sub(task.Start.Time()))
 	}
 }

 var templUserTaskTypes = template.Must(template.New("").Parse(`
 <!DOCTYPE html>
 <title>Tasks</title>
 <style>` + traceviewer.CommonStyle + `
 .histoTime {
   width: 20%;
   white-space:nowrap;
 }
 th {
   background-color: #050505;
   color: #fff;
 }
 table {
   border-collapse: collapse;
 }
 td,
 th {
   padding-left: 8px;
   padding-right: 8px;
   padding-top: 4px;
   padding-bottom: 4px;
 }
 </style>
 <body>
 Search log text: <form action="/usertask"><input name="logtext" type="text"><input type="submit"></form><br>
 <table border="1" sortable="1">
 <tr>
 <th>Task type</th>
 <th>Count</th>
 <th>Duration distribution (complete tasks)</th>
 </tr>
 {{range $}}
   <tr>
     <td>{{.Type}}</td>
     <td><a href="/usertask?type={{.Type}}">{{.Count}}</a></td>
     <td>{{.Histogram.ToHTML (.UserTaskURL true)}}</td>
   </tr>
 {{end}}
 </table>
 </body>
 </html>
 `))

 // UserTaskHandlerFunc returns a HandlerFunc that presents the details of the selected tasks.
 func UserTaskHandlerFunc(t *parsedTrace) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		filter, err := newTaskFilter(r)
 		if err != nil {
 			http.Error(w, err.Error(), http.StatusBadRequest)
 			return
 		}
 		type event struct {
 			WhenString string
 			Elapsed    time.Duration
 			Goroutine  tracev2.GoID
 			What       string
 			// TODO: include stack trace of creation time
 		}
 		type task struct {
 			WhenString string
 			ID         tracev2.TaskID
 			Duration   time.Duration
 			Complete   bool
 			Events     []event
 			Start, End time.Duration // Time since the beginning of the trace
 			GCTime     time.Duration
 		}
 		var tasks []task
 		for _, summary := range t.summary.Tasks {
 			if !filter.match(t, summary) {
 				continue
 			}

 			// Collect all the events for the task.
 			var rawEvents []*tracev2.Event
 			if summary.Start != nil {
 				rawEvents = append(rawEvents, summary.Start)
 			}
 			if summary.End != nil {
 				rawEvents = append(rawEvents, summary.End)
 			}
 			rawEvents = append(rawEvents, summary.Logs...)
 			for _, r := range summary.Regions {
 				if r.Start != nil {
 					rawEvents = append(rawEvents, r.Start)
 				}
 				if r.End != nil {
 					rawEvents = append(rawEvents, r.End)
 				}
 			}

 			// Sort them.
 			slices.SortStableFunc(rawEvents, func(a, b *tracev2.Event) int {
 				return cmp.Compare(a.Time(), b.Time())
 			})

 			// Summarize them.
 			var events []event
 			last := t.startTime()
 			for _, ev := range rawEvents {
 				what := describeEvent(ev)
 				if what == "" {
 					continue
 				}
 				sinceStart := ev.Time().Sub(t.startTime())
 				events = append(events, event{
 					WhenString: fmt.Sprintf("%2.9f", sinceStart.Seconds()),
 					Elapsed:    ev.Time().Sub(last),
 					What:       what,
 					Goroutine:  primaryGoroutine(ev),
 				})
 				last = ev.Time()
 			}
 			taskSpan := taskInterval(t, summary)
 			taskStart := taskSpan.start.Sub(t.startTime())

 			// Produce the task summary.
 			tasks = append(tasks, task{
 				WhenString: fmt.Sprintf("%2.9fs", taskStart.Seconds()),
 				Duration:   taskSpan.duration(),
 				ID:         summary.ID,
 				Complete:   summary.Complete(),
 				Events:     events,
 				Start:      taskStart,
 				End:        taskStart + taskSpan.duration(),
 			})
 		}
 		// Sort the tasks by duration.
 		slices.SortFunc(tasks, func(a, b task) int {
 			return cmp.Compare(a.Duration, b.Duration)
 		})

 		// Emit table.
 		err = templUserTaskType.Execute(w, struct {
 			Name  string
 			Tasks []task
 		}{
 			Name:  filter.name,
 			Tasks: tasks,
 		})
 		if err != nil {
 			log.Printf("failed to execute template: %v", err)
 			http.Error(w, fmt.Sprintf("failed to execute template: %v", err), http.StatusInternalServerError)
 			return
 		}
 	}
 }

 var templUserTaskType = template.Must(template.New("userTask").Funcs(template.FuncMap{
 	"elapsed":       elapsed,
 	"asMillisecond": asMillisecond,
 	"trimSpace":     strings.TrimSpace,
 }).Parse(`
 <!DOCTYPE html>
 <title>Tasks: {{.Name}}</title>
 <style>` + traceviewer.CommonStyle + `
 body {
   font-family: sans-serif;
 }
 table#req-status td.family {
   padding-right: 2em;
 }
 table#req-status td.active {
   padding-right: 1em;
 }
 table#req-status td.empty {
   color: #aaa;
 }
 table#reqs {
   margin-top: 1em;
   border-collapse: collapse;
 }
 table#reqs tr.first {
   font-weight: bold;
 }
 table#reqs td {
   font-family: monospace;
 }
 table#reqs td.when {
   text-align: right;
   white-space: nowrap;
 }
 table#reqs td.elapsed {
   padding: 0 0.5em;
   text-align: right;
   white-space: pre;
   width: 10em;
 }
 address {
   font-size: smaller;
   margin-top: 5em;
 }
 </style>
 <body>

 <h2>User Task: {{.Name}}</h2>

 Search log text: <form onsubmit="window.location.search+='&logtext='+window.logtextinput.value; return false">
 <input name="logtext" id="logtextinput" type="text"><input type="submit">
 </form><br>

 <table id="reqs">
 	<tr>
 		<th>When</th>
 		<th>Elapsed</th>
 		<th>Goroutine</th>
 		<th>Events</th>
 	</tr>
 	{{range $el := $.Tasks}}
 	<tr class="first">
 		<td class="when">{{$el.WhenString}}</td>
 		<td class="elapsed">{{$el.Duration}}</td>
 		<td></td>
 		<td>
 			<a href="/trace?focustask={{$el.ID}}#{{asMillisecond $el.Start}}:{{asMillisecond $el.End}}">Task {{$el.ID}}</a>
 			<a href="/trace?taskid={{$el.ID}}#{{asMillisecond $el.Start}}:{{asMillisecond $el.End}}">(goroutine view)</a>
 			({{if .Complete}}complete{{else}}incomplete{{end}})
 		</td>
 	</tr>
 	{{range $el.Events}}
 	<tr>
 		<td class="when">{{.WhenString}}</td>
 		<td class="elapsed">{{elapsed .Elapsed}}</td>
 		<td class="goid">{{.Goroutine}}</td>
 		<td>{{.What}}</td>
 	</tr>
 	{{end}}
     {{end}}
 </body>
 </html>
 `))

 // taskFilter represents a task filter specified by a user of cmd/trace.
 type taskFilter struct {
 	name string
 	cond []func(*parsedTrace, *trace.UserTaskSummary) bool
 }

 // match returns true if a task, described by its ID and summary, matches
 // the filter.
 func (f *taskFilter) match(t *parsedTrace, task *trace.UserTaskSummary) bool {
 	if t == nil {
 		return false
 	}
 	for _, c := range f.cond {
 		if !c(t, task) {
 			return false
 		}
 	}
 	return true
 }

 // newTaskFilter creates a new task filter from URL query variables.
 func newTaskFilter(r *http.Request) (*taskFilter, error) {
 	if err := r.ParseForm(); err != nil {
 		return nil, err
 	}

 	var name []string
 	var conditions []func(*parsedTrace, *trace.UserTaskSummary) bool

 	param := r.Form
 	if typ, ok := param["type"]; ok && len(typ) > 0 {
 		name = append(name, fmt.Sprintf("%q", typ[0]))
 		conditions = append(conditions, func(_ *parsedTrace, task *trace.UserTaskSummary) bool {
 			return task.Name == typ[0]
 		})
 	}
 	if complete := r.FormValue("complete"); complete == "1" {
 		name = append(name, "complete")
 		conditions = append(conditions, func(_ *parsedTrace, task *trace.UserTaskSummary) bool {
 			return task.Complete()
 		})
 	} else if complete == "0" {
 		name = append(name, "incomplete")
 		conditions = append(conditions, func(_ *parsedTrace, task *trace.UserTaskSummary) bool {
 			return !task.Complete()
 		})
 	}
 	if lat, err := time.ParseDuration(r.FormValue("latmin")); err == nil {
 		name = append(name, fmt.Sprintf("latency >= %s", lat))
 		conditions = append(conditions, func(t *parsedTrace, task *trace.UserTaskSummary) bool {
 			return task.Complete() && taskInterval(t, task).duration() >= lat
 		})
 	}
 	if lat, err := time.ParseDuration(r.FormValue("latmax")); err == nil {
 		name = append(name, fmt.Sprintf("latency <= %s", lat))
 		conditions = append(conditions, func(t *parsedTrace, task *trace.UserTaskSummary) bool {
 			return task.Complete() && taskInterval(t, task).duration() <= lat
 		})
 	}
 	if text := r.FormValue("logtext"); text != "" {
 		name = append(name, fmt.Sprintf("log contains %q", text))
 		conditions = append(conditions, func(_ *parsedTrace, task *trace.UserTaskSummary) bool {
 			return taskMatches(task, text)
 		})
 	}

 	return &taskFilter{name: strings.Join(name, ","), cond: conditions}, nil
 }

 func taskInterval(t *parsedTrace, s *trace.UserTaskSummary) interval {
 	var i interval
 	if s.Start != nil {
 		i.start = s.Start.Time()
 	} else {
 		i.start = t.startTime()
 	}
 	if s.End != nil {
 		i.end = s.End.Time()
 	} else {
 		i.end = t.endTime()
 	}
 	return i
 }

 func taskMatches(t *trace.UserTaskSummary, text string) bool {
 	matches := func(s string) bool {
 		return strings.Contains(s, text)
 	}
 	if matches(t.Name) {
 		return true
 	}
 	for _, r := range t.Regions {
 		if matches(r.Name) {
 			return true
 		}
 	}
 	for _, ev := range t.Logs {
 		log := ev.Log()
 		if matches(log.Category) {
 			return true
 		}
 		if matches(log.Message) {
 			return true
 		}
 	}
 	return false
 }

 func describeEvent(ev *tracev2.Event) string {
 	switch ev.Kind() {
 	case tracev2.EventStateTransition:
 		st := ev.StateTransition()
 		if st.Resource.Kind != tracev2.ResourceGoroutine {
 			return ""
 		}
 		old, new := st.Goroutine()
 		return fmt.Sprintf("%s -> %s", old, new)
 	case tracev2.EventRegionBegin:
 		return fmt.Sprintf("region %q begin", ev.Region().Type)
 	case tracev2.EventRegionEnd:
 		return fmt.Sprintf("region %q end", ev.Region().Type)
 	case tracev2.EventTaskBegin:
 		t := ev.Task()
 		return fmt.Sprintf("task %q (D %d, parent %d) begin", t.Type, t.ID, t.Parent)
 	case tracev2.EventTaskEnd:
 		return "task end"
 	case tracev2.EventLog:
 		log := ev.Log()
 		if log.Category != "" {
 			return fmt.Sprintf("log %q", log.Message)
 		}
 		return fmt.Sprintf("log (category: %s): %q", log.Category, log.Message)
 	}
 	return ""
 }

 func primaryGoroutine(ev *tracev2.Event) tracev2.GoID {
 	if ev.Kind() != tracev2.EventStateTransition {
 		return ev.Goroutine()
 	}
 	st := ev.StateTransition()
 	if st.Resource.Kind != tracev2.ResourceGoroutine {
 		return tracev2.NoGoroutine
 	}
 	return st.Resource.Goroutine()
 }

 func elapsed(d time.Duration) string {
 	b := fmt.Appendf(nil, "%.9f", d.Seconds())

 	// For subsecond durations, blank all zeros before decimal point,
 	// and all zeros between the decimal point and the first non-zero digit.
 	if d < time.Second {
 		dot := bytes.IndexByte(b, '.')
 		for i := 0; i < dot; i++ {
 			b[i] = ' '
 		}
 		for i := dot + 1; i < len(b); i++ {
 			if b[i] == '0' {
 				b[i] = ' '
 			} else {
 				break
 			}
 		}
 	}
 	return string(b)
 }

 func asMillisecond(d time.Duration) float64 {
 	return float64(d.Nanoseconds()) / float64(time.Millisecond)
 }
	// 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 trace

	import (
	"bytes"
	"cmp"
	"fmt"
	"html/template"
	"internal/trace"
	"internal/trace/traceviewer"
	tracev2 "internal/trace/v2"
	"log"
	"net/http"
	"slices"
	"strings"
	"time"
	)

	// UserTasksHandlerFunc returns a HandlerFunc that reports all tasks found in the trace.
	func UserTasksHandlerFunc(t *parsedTrace) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	tasks := t.summary.Tasks

	// Summarize groups of tasks with the same name.
	summary := make(map[string]taskStats)
	for _, task := range tasks {
	stats, ok := summary[task.Name]
	if !ok {
	stats.Type = task.Name
	}
	stats.add(task)
	summary[task.Name] = stats
	}

	// Sort tasks by type.
	userTasks := make([]taskStats, 0, len(summary))
	for _, stats := range summary {
	userTasks = append(userTasks, stats)
	}
	slices.SortFunc(userTasks, func(a, b taskStats) int {
	return cmp.Compare(a.Type, b.Type)
	})

	// Emit table.
	err := templUserTaskTypes.Execute(w, userTasks)
	if err != nil {
	http.Error(w, fmt.Sprintf("failed to execute template: %v", err), http.StatusInternalServerError)
	return
	}
	}
	}

	type taskStats struct {
	Type string
	Count int // Complete + incomplete tasks
	Histogram traceviewer.TimeHistogram // Complete tasks only
	}

	func (s *taskStats) UserTaskURL(complete bool) func(min, max time.Duration) string {
	return func(min, max time.Duration) string {
	return fmt.Sprintf("/usertask?type=%s&complete=%v&latmin=%v&latmax=%v", template.URLQueryEscaper(s.Type), template.URLQueryEscaper(complete), template.URLQueryEscaper(min), template.URLQueryEscaper(max))
	}
	}

	func (s taskStats) add(task trace.UserTaskSummary) {
	s.Count++
	if task.Complete() {
	s.Histogram.Add(task.End.Time().Sub(task.Start.Time()))
	}
	}

	var templUserTaskTypes = template.Must(template.New("").Parse(`
	<!DOCTYPE html>
	<title>Tasks</title>
	<style>` + traceviewer.CommonStyle + `
	.histoTime {
	width: 20%;
	white-space:nowrap;
	}
	th {
	background-color: #050505;
	color: #fff;
	}
	table {
	border-collapse: collapse;
	}
	td,
	th {
	padding-left: 8px;
	padding-right: 8px;
	padding-top: 4px;
	padding-bottom: 4px;
	}
	</style>
	<body>
	Search log text: <form action="/usertask"><input name="logtext" type="text"><input type="submit"></form><br>
	<table border="1" sortable="1">
	<tr>
	<th>Task type</th>
	<th>Count</th>
	<th>Duration distribution (complete tasks)</th>
	</tr>
	{{range $}}
	<tr>
	<td>{{.Type}}</td>
	<td><a href="/usertask?type={{.Type}}">{{.Count}}</a></td>
	<td>{{.Histogram.ToHTML (.UserTaskURL true)}}</td>
	</tr>
	{{end}}
	</table>
	</body>
	</html>
	`))

	// UserTaskHandlerFunc returns a HandlerFunc that presents the details of the selected tasks.
	func UserTaskHandlerFunc(t *parsedTrace) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
	filter, err := newTaskFilter(r)
	if err != nil {
	http.Error(w, err.Error(), http.StatusBadRequest)
	return
	}
	type event struct {
	WhenString string
	Elapsed time.Duration
	Goroutine tracev2.GoID
	What string
	// TODO: include stack trace of creation time
	}
	type task struct {
	WhenString string
	ID tracev2.TaskID
	Duration time.Duration
	Complete bool
	Events []event
	Start, End time.Duration // Time since the beginning of the trace
	GCTime time.Duration
	}
	var tasks []task
	for _, summary := range t.summary.Tasks {
	if !filter.match(t, summary) {
	continue
	}

	// Collect all the events for the task.
	var rawEvents []*tracev2.Event
	if summary.Start != nil {
	rawEvents = append(rawEvents, summary.Start)
	}
	if summary.End != nil {
	rawEvents = append(rawEvents, summary.End)
	}
	rawEvents = append(rawEvents, summary.Logs...)
	for _, r := range summary.Regions {
	if r.Start != nil {
	rawEvents = append(rawEvents, r.Start)
	}
	if r.End != nil {
	rawEvents = append(rawEvents, r.End)
	}
	}

	// Sort them.
	slices.SortStableFunc(rawEvents, func(a, b *tracev2.Event) int {
	return cmp.Compare(a.Time(), b.Time())
	})

	// Summarize them.
	var events []event
	last := t.startTime()
	for _, ev := range rawEvents {
	what := describeEvent(ev)
	if what == "" {
	continue
	}
	sinceStart := ev.Time().Sub(t.startTime())
	events = append(events, event{
	WhenString: fmt.Sprintf("%2.9f", sinceStart.Seconds()),
	Elapsed: ev.Time().Sub(last),
	What: what,
	Goroutine: primaryGoroutine(ev),
	})
	last = ev.Time()
	}
	taskSpan := taskInterval(t, summary)
	taskStart := taskSpan.start.Sub(t.startTime())

	// Produce the task summary.
	tasks = append(tasks, task{
	WhenString: fmt.Sprintf("%2.9fs", taskStart.Seconds()),
	Duration: taskSpan.duration(),
	ID: summary.ID,
	Complete: summary.Complete(),
	Events: events,
	Start: taskStart,
	End: taskStart + taskSpan.duration(),
	})
	}
	// Sort the tasks by duration.
	slices.SortFunc(tasks, func(a, b task) int {
	return cmp.Compare(a.Duration, b.Duration)
	})

	// Emit table.
	err = templUserTaskType.Execute(w, struct {
	Name string
	Tasks []task
	}{
	Name: filter.name,
	Tasks: tasks,
	})
	if err != nil {
	log.Printf("failed to execute template: %v", err)
	http.Error(w, fmt.Sprintf("failed to execute template: %v", err), http.StatusInternalServerError)
	return
	}
	}
	}

	var templUserTaskType = template.Must(template.New("userTask").Funcs(template.FuncMap{
	"elapsed": elapsed,
	"asMillisecond": asMillisecond,
	"trimSpace": strings.TrimSpace,
	}).Parse(`
	<!DOCTYPE html>
	<title>Tasks: {{.Name}}</title>
	<style>` + traceviewer.CommonStyle + `
	body {
	font-family: sans-serif;
	}
	table#req-status td.family {
	padding-right: 2em;
	}
	table#req-status td.active {
	padding-right: 1em;
	}
	table#req-status td.empty {
	color: #aaa;
	}
	table#reqs {
	margin-top: 1em;
	border-collapse: collapse;
	}
	table#reqs tr.first {
	font-weight: bold;
	}
	table#reqs td {
	font-family: monospace;
	}
	table#reqs td.when {
	text-align: right;
	white-space: nowrap;
	}
	table#reqs td.elapsed {
	padding: 0 0.5em;
	text-align: right;
	white-space: pre;
	width: 10em;
	}
	address {
	font-size: smaller;
	margin-top: 5em;
	}
	</style>
	<body>

	<h2>User Task: {{.Name}}</h2>

	Search log text: <form onsubmit="window.location.search+='&logtext='+window.logtextinput.value; return false">
	<input name="logtext" id="logtextinput" type="text"><input type="submit">
	</form><br>

	<table id="reqs">
	<tr>
	<th>When</th>
	<th>Elapsed</th>
	<th>Goroutine</th>
	<th>Events</th>
	</tr>
	{{range $el := $.Tasks}}
	<tr class="first">
	<td class="when">{{$el.WhenString}}</td>
	<td class="elapsed">{{$el.Duration}}</td>
	<td></td>
	<td>
	<a href="/trace?focustask={{$el.ID}}#{{asMillisecond $el.Start}}:{{asMillisecond $el.End}}">Task {{$el.ID}}</a>
	<a href="/trace?taskid={{$el.ID}}#{{asMillisecond $el.Start}}:{{asMillisecond $el.End}}">(goroutine view)</a>
	({{if .Complete}}complete{{else}}incomplete{{end}})
	</td>
	</tr>
	{{range $el.Events}}
	<tr>
	<td class="when">{{.WhenString}}</td>
	<td class="elapsed">{{elapsed .Elapsed}}</td>
	<td class="goid">{{.Goroutine}}</td>
	<td>{{.What}}</td>
	</tr>
	{{end}}
	{{end}}
	</body>
	</html>
	`))

	// taskFilter represents a task filter specified by a user of cmd/trace.
	type taskFilter struct {
	name string
	cond []func(parsedTrace, trace.UserTaskSummary) bool
	}

	// match returns true if a task, described by its ID and summary, matches
	// the filter.
	func (f taskFilter) match(t parsedTrace, task *trace.UserTaskSummary) bool {
	if t == nil {
	return false
	}
	for _, c := range f.cond {
	if !c(t, task) {
	return false
	}
	}
	return true
	}

	// newTaskFilter creates a new task filter from URL query variables.
	func newTaskFilter(r http.Request) (taskFilter, error) {
	if err := r.ParseForm(); err != nil {
	return nil, err
	}

	var name []string
	var conditions []func(parsedTrace, trace.UserTaskSummary) bool

	param := r.Form
	if typ, ok := param["type"]; ok && len(typ) > 0 {
	name = append(name, fmt.Sprintf("%q", typ[0]))
	conditions = append(conditions, func(_ parsedTrace, task trace.UserTaskSummary) bool {
	return task.Name == typ[0]
	})
	}
	if complete := r.FormValue("complete"); complete == "1" {
	name = append(name, "complete")
	conditions = append(conditions, func(_ parsedTrace, task trace.UserTaskSummary) bool {
	return task.Complete()
	})
	} else if complete == "0" {
	name = append(name, "incomplete")
	conditions = append(conditions, func(_ parsedTrace, task trace.UserTaskSummary) bool {
	return !task.Complete()
	})
	}
	if lat, err := time.ParseDuration(r.FormValue("latmin")); err == nil {
	name = append(name, fmt.Sprintf("latency >= %s", lat))
	conditions = append(conditions, func(t parsedTrace, task trace.UserTaskSummary) bool {
	return task.Complete() && taskInterval(t, task).duration() >= lat
	})
	}
	if lat, err := time.ParseDuration(r.FormValue("latmax")); err == nil {
	name = append(name, fmt.Sprintf("latency <= %s", lat))
	conditions = append(conditions, func(t parsedTrace, task trace.UserTaskSummary) bool {
	return task.Complete() && taskInterval(t, task).duration() <= lat
	})
	}
	if text := r.FormValue("logtext"); text != "" {
	name = append(name, fmt.Sprintf("log contains %q", text))
	conditions = append(conditions, func(_ parsedTrace, task trace.UserTaskSummary) bool {
	return taskMatches(task, text)
	})
	}

	return &taskFilter{name: strings.Join(name, ","), cond: conditions}, nil
	}

	func taskInterval(t parsedTrace, s trace.UserTaskSummary) interval {
	var i interval
	if s.Start != nil {
	i.start = s.Start.Time()
	} else {
	i.start = t.startTime()
	}
	if s.End != nil {
	i.end = s.End.Time()
	} else {
	i.end = t.endTime()
	}
	return i
	}

	func taskMatches(t *trace.UserTaskSummary, text string) bool {
	matches := func(s string) bool {
	return strings.Contains(s, text)
	}
	if matches(t.Name) {
	return true
	}
	for _, r := range t.Regions {
	if matches(r.Name) {
	return true
	}
	}
	for _, ev := range t.Logs {
	log := ev.Log()
	if matches(log.Category) {
	return true
	}
	if matches(log.Message) {
	return true
	}
	}
	return false
	}

	func describeEvent(ev *tracev2.Event) string {
	switch ev.Kind() {
	case tracev2.EventStateTransition:
	st := ev.StateTransition()
	if st.Resource.Kind != tracev2.ResourceGoroutine {
	return ""
	}
	old, new := st.Goroutine()
	return fmt.Sprintf("%s -> %s", old, new)
	case tracev2.EventRegionBegin:
	return fmt.Sprintf("region %q begin", ev.Region().Type)
	case tracev2.EventRegionEnd:
	return fmt.Sprintf("region %q end", ev.Region().Type)
	case tracev2.EventTaskBegin:
	t := ev.Task()
	return fmt.Sprintf("task %q (D %d, parent %d) begin", t.Type, t.ID, t.Parent)
	case tracev2.EventTaskEnd:
	return "task end"
	case tracev2.EventLog:
	log := ev.Log()
	if log.Category != "" {
	return fmt.Sprintf("log %q", log.Message)
	}
	return fmt.Sprintf("log (category: %s): %q", log.Category, log.Message)
	}
	return ""
	}

	func primaryGoroutine(ev *tracev2.Event) tracev2.GoID {
	if ev.Kind() != tracev2.EventStateTransition {
	return ev.Goroutine()
	}
	st := ev.StateTransition()
	if st.Resource.Kind != tracev2.ResourceGoroutine {
	return tracev2.NoGoroutine
	}
	return st.Resource.Goroutine()
	}

	func elapsed(d time.Duration) string {
	b := fmt.Appendf(nil, "%.9f", d.Seconds())

	// For subsecond durations, blank all zeros before decimal point,
	// and all zeros between the decimal point and the first non-zero digit.
	if d < time.Second {
	dot := bytes.IndexByte(b, '.')
	for i := 0; i < dot; i++ {
	b[i] = ' '
	}
	for i := dot + 1; i < len(b); i++ {
	if b[i] == '0' {
	b[i] = ' '
	} else {
	break
	}
	}
	}
	return string(b)
	}

	func asMillisecond(d time.Duration) float64 {
	return float64(d.Nanoseconds()) / float64(time.Millisecond)
	}