cmd/trace: move viewer data structs into cmd/internal/traceviewer

The ViewerEvent, ViewerData and ViewerFrame structs are moved into
cmd/internal/traceviewer, and renamed Event, Data, and Frame.

The structs are the same, except for the following: A definition
for the JSON "bp" field that's defined in the trace format, but
missing in the structs has been added. Also, the Tid and Pid fields
on Event have been renamed TID and PID to better match Go style.
Finally, the footer field on ViewerData, which hasn't been used
for a while, has been removed.

This CL is in preparation for the usage of these structs by cmd/go's
tracing functionality.

Updates #38714

Change-Id: I345f23617b96d4629b876ae717f89d56a67e05a3
Reviewed-on: https://go-review.googlesource.com/c/go/+/239098
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>

3 files changed, 54 insertions, 81 deletions

diff --git a/src/cmd/trace/trace.go b/src/cmd/trace/trace.go
index b452376627..30c80f0e04 100644
--- a/src/cmd/trace/trace.go
+++ b/src/cmd/trace/trace.go
@@ -5,6 +5,7 @@
 package main
 
 import (
+	"cmd/internal/traceviewer"
 	"encoding/json"
 	"fmt"
 	"internal/trace"
@@ -325,7 +326,7 @@ func splittingTraceConsumer(max int) (*splitter, traceConsumer) {
 	}
 
 	var (
-		data = ViewerData{Frames: make(map[string]ViewerFrame)}
+		data = traceviewer.Data{Frames: make(map[string]traceviewer.Frame)}
 
 		sizes []eventSz
 		cw    countingWriter
@@ -337,7 +338,7 @@ func splittingTraceConsumer(max int) (*splitter, traceConsumer) {
 		consumeTimeUnit: func(unit string) {
 			data.TimeUnit = unit
 		},
-		consumeViewerEvent: func(v *ViewerEvent, required bool) {
+		consumeViewerEvent: func(v *traceviewer.Event, required bool) {
 			if required {
 				// Store required events inside data
 				// so flush can include them in the required
@@ -350,7 +351,7 @@ func splittingTraceConsumer(max int) (*splitter, traceConsumer) {
 			sizes = append(sizes, eventSz{v.Time, cw.size + 1}) // +1 for ",".
 			cw.size = 0
 		},
-		consumeViewerFrame: func(k string, v ViewerFrame) {
+		consumeViewerFrame: func(k string, v traceviewer.Frame) {
 			data.Frames[k] = v
 		},
 		flush: func() {
@@ -478,36 +479,6 @@ type gInfo struct {
 	markAssist *trace.Event // if non-nil, the mark assist currently running.
 }
 
-type ViewerData struct {
-	Events   []*ViewerEvent         `json:"traceEvents"`
-	Frames   map[string]ViewerFrame `json:"stackFrames"`
-	TimeUnit string                 `json:"displayTimeUnit"`
-
-	// This is where mandatory part of the trace starts (e.g. thread names)
-	footer int
-}
-
-type ViewerEvent struct {
-	Name     string      `json:"name,omitempty"`
-	Phase    string      `json:"ph"`
-	Scope    string      `json:"s,omitempty"`
-	Time     float64     `json:"ts"`
-	Dur      float64     `json:"dur,omitempty"`
-	Pid      uint64      `json:"pid"`
-	Tid      uint64      `json:"tid"`
-	ID       uint64      `json:"id,omitempty"`
-	Stack    int         `json:"sf,omitempty"`
-	EndStack int         `json:"esf,omitempty"`
-	Arg      interface{} `json:"args,omitempty"`
-	Cname    string      `json:"cname,omitempty"`
-	Category string      `json:"cat,omitempty"`
-}
-
-type ViewerFrame struct {
-	Name   string `json:"name"`
-	Parent int    `json:"parent,omitempty"`
-}
-
 type NameArg struct {
 	Name string `json:"name"`
 }
@@ -528,8 +499,8 @@ type SortIndexArg struct {
 
 type traceConsumer struct {
 	consumeTimeUnit    func(unit string)
-	consumeViewerEvent func(v *ViewerEvent, required bool)
-	consumeViewerFrame func(key string, f ViewerFrame)
+	consumeViewerEvent func(v *traceviewer.Event, required bool)
+	consumeViewerFrame func(key string, f traceviewer.Frame)
 	flush              func()
 }
 
@@ -775,23 +746,23 @@ func generateTrace(params *traceParams, consumer traceConsumer) error {
 		ctx.emitSectionFooter(procsSection, "PROCS", 2)
 	}
 
-	ctx.emitFooter(&ViewerEvent{Name: "thread_name", Phase: "M", Pid: procsSection, Tid: trace.GCP, Arg: &NameArg{"GC"}})
-	ctx.emitFooter(&ViewerEvent{Name: "thread_sort_index", Phase: "M", Pid: procsSection, Tid: trace.GCP, Arg: &SortIndexArg{-6}})
+	ctx.emitFooter(&traceviewer.Event{Name: "thread_name", Phase: "M", PID: procsSection, TID: trace.GCP, Arg: &NameArg{"GC"}})
+	ctx.emitFooter(&traceviewer.Event{Name: "thread_sort_index", Phase: "M", PID: procsSection, TID: trace.GCP, Arg: &SortIndexArg{-6}})
 
-	ctx.emitFooter(&ViewerEvent{Name: "thread_name", Phase: "M", Pid: procsSection, Tid: trace.NetpollP, Arg: &NameArg{"Network"}})
-	ctx.emitFooter(&ViewerEvent{Name: "thread_sort_index", Phase: "M", Pid: procsSection, Tid: trace.NetpollP, Arg: &SortIndexArg{-5}})
+	ctx.emitFooter(&traceviewer.Event{Name: "thread_name", Phase: "M", PID: procsSection, TID: trace.NetpollP, Arg: &NameArg{"Network"}})
+	ctx.emitFooter(&traceviewer.Event{Name: "thread_sort_index", Phase: "M", PID: procsSection, TID: trace.NetpollP, Arg: &SortIndexArg{-5}})
 
-	ctx.emitFooter(&ViewerEvent{Name: "thread_name", Phase: "M", Pid: procsSection, Tid: trace.TimerP, Arg: &NameArg{"Timers"}})
-	ctx.emitFooter(&ViewerEvent{Name: "thread_sort_index", Phase: "M", Pid: procsSection, Tid: trace.TimerP, Arg: &SortIndexArg{-4}})
+	ctx.emitFooter(&traceviewer.Event{Name: "thread_name", Phase: "M", PID: procsSection, TID: trace.TimerP, Arg: &NameArg{"Timers"}})
+	ctx.emitFooter(&traceviewer.Event{Name: "thread_sort_index", Phase: "M", PID: procsSection, TID: trace.TimerP, Arg: &SortIndexArg{-4}})
 
-	ctx.emitFooter(&ViewerEvent{Name: "thread_name", Phase: "M", Pid: procsSection, Tid: trace.SyscallP, Arg: &NameArg{"Syscalls"}})
-	ctx.emitFooter(&ViewerEvent{Name: "thread_sort_index", Phase: "M", Pid: procsSection, Tid: trace.SyscallP, Arg: &SortIndexArg{-3}})
+	ctx.emitFooter(&traceviewer.Event{Name: "thread_name", Phase: "M", PID: procsSection, TID: trace.SyscallP, Arg: &NameArg{"Syscalls"}})
+	ctx.emitFooter(&traceviewer.Event{Name: "thread_sort_index", Phase: "M", PID: procsSection, TID: trace.SyscallP, Arg: &SortIndexArg{-3}})
 
 	// Display rows for Ps if we are in the default trace view mode (not goroutine-oriented presentation)
 	if ctx.mode&modeGoroutineOriented == 0 {
 		for i := 0; i <= maxProc; i++ {
-			ctx.emitFooter(&ViewerEvent{Name: "thread_name", Phase: "M", Pid: procsSection, Tid: uint64(i), Arg: &NameArg{fmt.Sprintf("Proc %v", i)}})
-			ctx.emitFooter(&ViewerEvent{Name: "thread_sort_index", Phase: "M", Pid: procsSection, Tid: uint64(i), Arg: &SortIndexArg{i}})
+			ctx.emitFooter(&traceviewer.Event{Name: "thread_name", Phase: "M", PID: procsSection, TID: uint64(i), Arg: &NameArg{fmt.Sprintf("Proc %v", i)}})
+			ctx.emitFooter(&traceviewer.Event{Name: "thread_sort_index", Phase: "M", PID: procsSection, TID: uint64(i), Arg: &SortIndexArg{i}})
 		}
 	}
 
@@ -829,27 +800,27 @@ func generateTrace(params *traceParams, consumer traceConsumer) error {
 			if !ctx.gs[k] {
 				continue
 			}
-			ctx.emitFooter(&ViewerEvent{Name: "thread_name", Phase: "M", Pid: procsSection, Tid: k, Arg: &NameArg{v.name}})
+			ctx.emitFooter(&traceviewer.Event{Name: "thread_name", Phase: "M", PID: procsSection, TID: k, Arg: &NameArg{v.name}})
 		}
 		// Row for the main goroutine (maing)
-		ctx.emitFooter(&ViewerEvent{Name: "thread_sort_index", Phase: "M", Pid: procsSection, Tid: ctx.maing, Arg: &SortIndexArg{-2}})
+		ctx.emitFooter(&traceviewer.Event{Name: "thread_sort_index", Phase: "M", PID: procsSection, TID: ctx.maing, Arg: &SortIndexArg{-2}})
 		// Row for GC or global state (specified with G=0)
-		ctx.emitFooter(&ViewerEvent{Name: "thread_sort_index", Phase: "M", Pid: procsSection, Tid: 0, Arg: &SortIndexArg{-1}})
+		ctx.emitFooter(&traceviewer.Event{Name: "thread_sort_index", Phase: "M", PID: procsSection, TID: 0, Arg: &SortIndexArg{-1}})
 	}
 
 	return nil
 }
 
-func (ctx *traceContext) emit(e *ViewerEvent) {
+func (ctx *traceContext) emit(e *traceviewer.Event) {
 	ctx.consumer.consumeViewerEvent(e, false)
 }
 
-func (ctx *traceContext) emitFooter(e *ViewerEvent) {
+func (ctx *traceContext) emitFooter(e *traceviewer.Event) {
 	ctx.consumer.consumeViewerEvent(e, true)
 }
 func (ctx *traceContext) emitSectionFooter(sectionID uint64, name string, priority int) {
-	ctx.emitFooter(&ViewerEvent{Name: "process_name", Phase: "M", Pid: sectionID, Arg: &NameArg{name}})
-	ctx.emitFooter(&ViewerEvent{Name: "process_sort_index", Phase: "M", Pid: sectionID, Arg: &SortIndexArg{priority}})
+	ctx.emitFooter(&traceviewer.Event{Name: "process_name", Phase: "M", PID: sectionID, Arg: &NameArg{name}})
+	ctx.emitFooter(&traceviewer.Event{Name: "process_sort_index", Phase: "M", PID: sectionID, Arg: &SortIndexArg{priority}})
 }
 
 func (ctx *traceContext) time(ev *trace.Event) float64 {
@@ -880,7 +851,7 @@ func (ctx *traceContext) emitSlice(ev *trace.Event, name string) {
 	ctx.emit(ctx.makeSlice(ev, name))
 }
 
-func (ctx *traceContext) makeSlice(ev *trace.Event, name string) *ViewerEvent {
+func (ctx *traceContext) makeSlice(ev *trace.Event, name string) *traceviewer.Event {
 	// If ViewerEvent.Dur is not a positive value,
 	// trace viewer handles it as a non-terminating time interval.
 	// Avoid it by setting the field with a small value.
@@ -888,12 +859,12 @@ func (ctx *traceContext) makeSlice(ev *trace.Event, name string) *ViewerEvent {
 	if ev.Link.Ts-ev.Ts <= 0 {
 		durationUsec = 0.0001 // 0.1 nanoseconds
 	}
-	sl := &ViewerEvent{
+	sl := &traceviewer.Event{
 		Name:     name,
 		Phase:    "X",
 		Time:     ctx.time(ev),
 		Dur:      durationUsec,
-		Tid:      ctx.proc(ev),
+		TID:      ctx.proc(ev),
 		Stack:    ctx.stack(ev.Stk),
 		EndStack: ctx.stack(ev.Link.Stk),
 	}
@@ -927,16 +898,16 @@ func (ctx *traceContext) emitTask(task *taskDesc, sortIndex int) {
 	taskName := task.name
 	durationUsec := float64(task.lastTimestamp()-task.firstTimestamp()) / 1e3
 
-	ctx.emitFooter(&ViewerEvent{Name: "thread_name", Phase: "M", Pid: tasksSection, Tid: taskRow, Arg: &NameArg{fmt.Sprintf("T%d %s", task.id, taskName)}})
-	ctx.emit(&ViewerEvent{Name: "thread_sort_index", Phase: "M", Pid: tasksSection, Tid: taskRow, Arg: &SortIndexArg{sortIndex}})
+	ctx.emitFooter(&traceviewer.Event{Name: "thread_name", Phase: "M", PID: tasksSection, TID: taskRow, Arg: &NameArg{fmt.Sprintf("T%d %s", task.id, taskName)}})
+	ctx.emit(&traceviewer.Event{Name: "thread_sort_index", Phase: "M", PID: tasksSection, TID: taskRow, Arg: &SortIndexArg{sortIndex}})
 	ts := float64(task.firstTimestamp()) / 1e3
-	sl := &ViewerEvent{
+	sl := &traceviewer.Event{
 		Name:  taskName,
 		Phase: "X",
 		Time:  ts,
 		Dur:   durationUsec,
-		Pid:   tasksSection,
-		Tid:   taskRow,
+		PID:   tasksSection,
+		TID:   taskRow,
 		Cname: pickTaskColor(task.id),
 	}
 	targ := TaskArg{ID: task.id}
@@ -953,8 +924,8 @@ func (ctx *traceContext) emitTask(task *taskDesc, sortIndex int) {
 
 	if task.create != nil && task.create.Type == trace.EvUserTaskCreate && task.create.Args[1] != 0 {
 		ctx.arrowSeq++
-		ctx.emit(&ViewerEvent{Name: "newTask", Phase: "s", Tid: task.create.Args[1], ID: ctx.arrowSeq, Time: ts, Pid: tasksSection})
-		ctx.emit(&ViewerEvent{Name: "newTask", Phase: "t", Tid: taskRow, ID: ctx.arrowSeq, Time: ts, Pid: tasksSection})
+		ctx.emit(&traceviewer.Event{Name: "newTask", Phase: "s", TID: task.create.Args[1], ID: ctx.arrowSeq, Time: ts, PID: tasksSection})
+		ctx.emit(&traceviewer.Event{Name: "newTask", Phase: "t", TID: taskRow, ID: ctx.arrowSeq, Time: ts, PID: tasksSection})
 	}
 }
 
@@ -975,12 +946,12 @@ func (ctx *traceContext) emitRegion(s regionDesc) {
 	scopeID := fmt.Sprintf("%x", id)
 	name := s.Name
 
-	sl0 := &ViewerEvent{
+	sl0 := &traceviewer.Event{
 		Category: "Region",
 		Name:     name,
 		Phase:    "b",
 		Time:     float64(s.firstTimestamp()) / 1e3,
-		Tid:      s.G, // only in goroutine-oriented view
+		TID:      s.G, // only in goroutine-oriented view
 		ID:       uint64(regionID),
 		Scope:    scopeID,
 		Cname:    pickTaskColor(s.TaskID),
@@ -990,12 +961,12 @@ func (ctx *traceContext) emitRegion(s regionDesc) {
 	}
 	ctx.emit(sl0)
 
-	sl1 := &ViewerEvent{
+	sl1 := &traceviewer.Event{
 		Category: "Region",
 		Name:     name,
 		Phase:    "e",
 		Time:     float64(s.lastTimestamp()) / 1e3,
-		Tid:      s.G,
+		TID:      s.G,
 		ID:       uint64(regionID),
 		Scope:    scopeID,
 		Cname:    pickTaskColor(s.TaskID),
@@ -1021,7 +992,7 @@ func (ctx *traceContext) emitHeapCounters(ev *trace.Event) {
 		diff = ctx.heapStats.nextGC - ctx.heapStats.heapAlloc
 	}
 	if tsWithinRange(ev.Ts, ctx.startTime, ctx.endTime) {
-		ctx.emit(&ViewerEvent{Name: "Heap", Phase: "C", Time: ctx.time(ev), Pid: 1, Arg: &heapCountersArg{ctx.heapStats.heapAlloc, diff}})
+		ctx.emit(&traceviewer.Event{Name: "Heap", Phase: "C", Time: ctx.time(ev), PID: 1, Arg: &heapCountersArg{ctx.heapStats.heapAlloc, diff}})
 	}
 	ctx.prevHeapStats = ctx.heapStats
 }
@@ -1037,7 +1008,7 @@ func (ctx *traceContext) emitGoroutineCounters(ev *trace.Event) {
 		return
 	}
 	if tsWithinRange(ev.Ts, ctx.startTime, ctx.endTime) {
-		ctx.emit(&ViewerEvent{Name: "Goroutines", Phase: "C", Time: ctx.time(ev), Pid: 1, Arg: &goroutineCountersArg{uint64(ctx.gstates[gRunning]), uint64(ctx.gstates[gRunnable]), uint64(ctx.gstates[gWaitingGC])}})
+		ctx.emit(&traceviewer.Event{Name: "Goroutines", Phase: "C", Time: ctx.time(ev), PID: 1, Arg: &goroutineCountersArg{uint64(ctx.gstates[gRunning]), uint64(ctx.gstates[gRunnable]), uint64(ctx.gstates[gWaitingGC])}})
 	}
 	ctx.prevGstates = ctx.gstates
 }
@@ -1052,7 +1023,7 @@ func (ctx *traceContext) emitThreadCounters(ev *trace.Event) {
 		return
 	}
 	if tsWithinRange(ev.Ts, ctx.startTime, ctx.endTime) {
-		ctx.emit(&ViewerEvent{Name: "Threads", Phase: "C", Time: ctx.time(ev), Pid: 1, Arg: &threadCountersArg{
+		ctx.emit(&traceviewer.Event{Name: "Threads", Phase: "C", Time: ctx.time(ev), PID: 1, Arg: &threadCountersArg{
 			Running:   ctx.threadStats.prunning,
 			InSyscall: ctx.threadStats.insyscall}})
 	}
@@ -1090,13 +1061,13 @@ func (ctx *traceContext) emitInstant(ev *trace.Event, name, category string) {
 		}
 		arg = &Arg{ev.Args[0]}
 	}
-	ctx.emit(&ViewerEvent{
+	ctx.emit(&traceviewer.Event{
 		Name:     name,
 		Category: category,
 		Phase:    "I",
 		Scope:    "t",
 		Time:     ctx.time(ev),
-		Tid:      ctx.proc(ev),
+		TID:      ctx.proc(ev),
 		Stack:    ctx.stack(ev.Stk),
 		Cname:    cname,
 		Arg:      arg})
@@ -1134,8 +1105,8 @@ func (ctx *traceContext) emitArrow(ev *trace.Event, name string) {
 	}
 
 	ctx.arrowSeq++
-	ctx.emit(&ViewerEvent{Name: name, Phase: "s", Tid: ctx.proc(ev), ID: ctx.arrowSeq, Time: ctx.time(ev), Stack: ctx.stack(ev.Stk), Cname: color})
-	ctx.emit(&ViewerEvent{Name: name, Phase: "t", Tid: ctx.proc(ev.Link), ID: ctx.arrowSeq, Time: ctx.time(ev.Link), Cname: color})
+	ctx.emit(&traceviewer.Event{Name: name, Phase: "s", TID: ctx.proc(ev), ID: ctx.arrowSeq, Time: ctx.time(ev), Stack: ctx.stack(ev.Stk), Cname: color})
+	ctx.emit(&traceviewer.Event{Name: name, Phase: "t", TID: ctx.proc(ev.Link), ID: ctx.arrowSeq, Time: ctx.time(ev.Link), Cname: color})
 }
 
 func (ctx *traceContext) stack(stk []*trace.Frame) int {
@@ -1157,7 +1128,7 @@ func (ctx *traceContext) buildBranch(parent frameNode, stk []*trace.Frame) int {
 		node.id = ctx.frameSeq
 		node.children = make(map[uint64]frameNode)
 		parent.children[frame.PC] = node
-		ctx.consumer.consumeViewerFrame(strconv.Itoa(node.id), ViewerFrame{fmt.Sprintf("%v:%v", frame.Fn, frame.Line), parent.id})
+		ctx.consumer.consumeViewerFrame(strconv.Itoa(node.id), traceviewer.Frame{Name: fmt.Sprintf("%v:%v", frame.Fn, frame.Line), Parent: parent.id})
 	}
 	return ctx.buildBranch(node, stk)
 }
@@ -1192,7 +1163,7 @@ type jsonWriter struct {
 }
 
 func viewerDataTraceConsumer(w io.Writer, start, end int64) traceConsumer {
-	frames := make(map[string]ViewerFrame)
+	frames := make(map[string]traceviewer.Frame)
 	enc := json.NewEncoder(w)
 	written := 0
 	index := int64(-1)
@@ -1204,7 +1175,7 @@ func viewerDataTraceConsumer(w io.Writer, start, end int64) traceConsumer {
 			enc.Encode(unit)
 			io.WriteString(w, ",")
 		},
-		consumeViewerEvent: func(v *ViewerEvent, required bool) {
+		consumeViewerEvent: func(v *traceviewer.Event, required bool) {
 			index++
 			if !required && (index < start || index > end) {
 				// not in the range. Skip!
@@ -1221,7 +1192,7 @@ func viewerDataTraceConsumer(w io.Writer, start, end int64) traceConsumer {
 			// Same should be applied to splittingTraceConsumer.
 			written++
 		},
-		consumeViewerFrame: func(k string, v ViewerFrame) {
+		consumeViewerFrame: func(k string, v traceviewer.Frame) {
 			frames[k] = v
 		},
 		flush: func() {
diff --git a/src/cmd/trace/trace_test.go b/src/cmd/trace/trace_test.go
index ef2d06c961..dd12e8cd20 100644
--- a/src/cmd/trace/trace_test.go
+++ b/src/cmd/trace/trace_test.go
@@ -7,6 +7,7 @@
 package main
 
 import (
+	"cmd/internal/traceviewer"
 	"context"
 	"internal/trace"
 	"io/ioutil"
@@ -78,7 +79,7 @@ func TestGoroutineCount(t *testing.T) {
 	// Use the default viewerDataTraceConsumer but replace
 	// consumeViewerEvent to intercept the ViewerEvents for testing.
 	c := viewerDataTraceConsumer(ioutil.Discard, 0, 1<<63-1)
-	c.consumeViewerEvent = func(ev *ViewerEvent, _ bool) {
+	c.consumeViewerEvent = func(ev *traceviewer.Event, _ bool) {
 		if ev.Name == "Goroutines" {
 			cnt := ev.Arg.(*goroutineCountersArg)
 			if cnt.Runnable+cnt.Running > 2 {
@@ -165,7 +166,7 @@ func TestPreemptedMarkAssist(t *testing.T) {
 	c := viewerDataTraceConsumer(ioutil.Discard, 0, 1<<63-1)
 
 	marks := 0
-	c.consumeViewerEvent = func(ev *ViewerEvent, _ bool) {
+	c.consumeViewerEvent = func(ev *traceviewer.Event, _ bool) {
 		if strings.Contains(ev.Name, "MARK ASSIST") {
 			marks++
 		}
@@ -216,7 +217,7 @@ func TestFoo(t *testing.T) {
 	c := viewerDataTraceConsumer(ioutil.Discard, 0, 1<<63-1)
 
 	var logBeforeTaskEnd, logAfterTaskEnd bool
-	c.consumeViewerEvent = func(ev *ViewerEvent, _ bool) {
+	c.consumeViewerEvent = func(ev *traceviewer.Event, _ bool) {
 		if ev.Name == "log before task ends" {
 			logBeforeTaskEnd = true
 		}
diff --git a/src/cmd/trace/trace_unix_test.go b/src/cmd/trace/trace_unix_test.go
index fec060e121..645978e0f8 100644
--- a/src/cmd/trace/trace_unix_test.go
+++ b/src/cmd/trace/trace_unix_test.go
@@ -8,6 +8,7 @@ package main
 
 import (
 	"bytes"
+	"cmd/internal/traceviewer"
 	traceparser "internal/trace"
 	"io/ioutil"
 	"runtime"
@@ -83,7 +84,7 @@ func TestGoroutineInSyscall(t *testing.T) {
 	// Check only one thread for the pipe read goroutine is
 	// considered in-syscall.
 	c := viewerDataTraceConsumer(ioutil.Discard, 0, 1<<63-1)
-	c.consumeViewerEvent = func(ev *ViewerEvent, _ bool) {
+	c.consumeViewerEvent = func(ev *traceviewer.Event, _ bool) {
 		if ev.Name == "Threads" {
 			arg := ev.Arg.(*threadCountersArg)
 			if arg.InSyscall > 1 {