cmd/trace: task-oriented view includes child tasks

R=go1.11

Change-Id: Ibb09e309c745eba811a0b53000c063bc10a055e1
Reviewed-on: https://go-review.googlesource.com/90218
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Peter Weinberger <pjw@google.com>

src/cmd/trace/annotations.go

@@ -20,12 +20,13 @@ func init() {
 
 // httpUserTasks reports all tasks found in the trace.
 func httpUserTasks(w http.ResponseWriter, r *http.Request) {
-	tasks, err := analyzeAnnotations()
+	res, err := analyzeAnnotations()
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
 
+	tasks := res.tasks
 	summary := make(map[string]taskStats)
 	for _, task := range tasks {
 		stats, ok := summary[task.name]
@@ -62,11 +63,12 @@ func httpUserTask(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	tasks, err := analyzeAnnotations()
+	res, err := analyzeAnnotations()
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
+	tasks := res.tasks
 
 	type event struct {
 		WhenString string
@@ -139,21 +141,27 @@ func httpUserTask(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+type annotationAnalysisResult struct {
+	tasks    map[uint64]*taskDesc // tasks
+	gcEvents []*trace.Event       // GCStartevents, sorted
+}
+
 // analyzeAnnotations analyzes user annotation events and
 // returns the task descriptors keyed by internal task id.
-func analyzeAnnotations() (map[uint64]*taskDesc, error) {
+func analyzeAnnotations() (annotationAnalysisResult, error) {
 	res, err := parseTrace()
 	if err != nil {
-		return nil, fmt.Errorf("failed to parse trace: %v", err)
+		return annotationAnalysisResult{}, fmt.Errorf("failed to parse trace: %v", err)
 	}
 
 	events := res.Events
 	if len(events) == 0 {
-		return nil, fmt.Errorf("empty trace")
+		return annotationAnalysisResult{}, fmt.Errorf("empty trace")
 	}
 
 	tasks := allTasks{}
 	activeSpans := map[uint64][]*trace.Event{} // goid to active span start events
+	var gcEvents []*trace.Event
 
 	for _, ev := range events {
 		goid := ev.G
@@ -164,6 +172,17 @@ func analyzeAnnotations() (map[uint64]*taskDesc, error) {
 			task := tasks.task(taskid)
 			task.addEvent(ev)
 
+			// retrieve parent task information
+			if typ == trace.EvUserTaskCreate {
+				if parentID := ev.Args[1]; parentID != 0 {
+					parentTask := tasks.task(parentID)
+					task.parent = parentTask
+					if parentTask != nil {
+						parentTask.children = append(parentTask.children, task)
+					}
+				}
+			}
+
 			if typ == trace.EvUserSpan {
 				mode := ev.Args[1]
 				spans := activeSpans[goid]
@@ -191,9 +210,12 @@ func analyzeAnnotations() (map[uint64]*taskDesc, error) {
 			taskid := spans[len(spans)-1].Args[0]
 			task := tasks.task(taskid)
 			task.addEvent(ev)
+
+		case trace.EvGCStart:
+			gcEvents = append(gcEvents, ev)
 		}
 	}
-	return tasks, nil
+	return annotationAnalysisResult{tasks: tasks, gcEvents: gcEvents}, nil
 }
 
 // taskDesc represents a task.
@@ -206,6 +228,16 @@ type taskDesc struct {
 
 	create *trace.Event // Task create event
 	end    *trace.Event // Task end event
+
+	parent   *taskDesc
+	children []*taskDesc
+}
+
+func newTaskDesc(id uint64) *taskDesc {
+	return &taskDesc{
+		id:         id,
+		goroutines: make(map[uint64][]*trace.Event),
+	}
 }
 
 func (task *taskDesc) String() string {
@@ -220,6 +252,14 @@ func (task *taskDesc) String() string {
 	for _, s := range task.spans {
 		fmt.Fprintf(wb, "\t\t%s(goid=%d)\n", s.name, s.goid)
 	}
+	if task.parent != nil {
+		fmt.Fprintf(wb, "\tparent: %s\n", task.parent.name)
+	}
+	fmt.Fprintf(wb, "\t%d children:\n", len(task.children))
+	for _, c := range task.children {
+		fmt.Fprintf(wb, "\t\t%s\n", c.name)
+	}
+
 	return wb.String()
 }
 
@@ -297,6 +337,21 @@ func (task *taskDesc) complete() bool {
 	return task.create != nil && task.end != nil
 }
 
+// descendents returns all the task nodes in the subtree rooted from this task.
+func (task *taskDesc) decendents() []*taskDesc {
+	if task == nil {
+		return nil
+	}
+	res := []*taskDesc{task}
+	for i := 0; len(res[i:]) > 0; i++ {
+		t := res[i]
+		for _, c := range t.children {
+			res = append(res, c)
+		}
+	}
+	return res
+}
+
 // firstTimestamp returns the first timestamp of this task found in
 // this trace. If the trace does not contain the task creation event,
 // the first timestamp of the trace will be returned.
@@ -701,7 +756,11 @@ func describeEvent(ev *trace.Event) string {
 	case trace.EvGoEnd, trace.EvGoStop:
 		return "goroutine stopped"
 	case trace.EvUserLog:
-		return fmt.Sprintf("%v=%v", ev.SArgs[0], ev.SArgs[1])
+		if k, v := ev.SArgs[0], ev.SArgs[1]; k == "" {
+			return v
+		} else {
+			return fmt.Sprintf("%v=%v", k, v)
+		}
 	case trace.EvUserSpan:
 		if ev.Args[1] == 0 {
 			duration := "unknown"

src/cmd/trace/annotations_test.go

@@ -63,10 +63,12 @@ func TestAnalyzeAnnotations(t *testing.T) {
 	// Run prog0 and capture the execution trace.
 	traceProgram(prog0, "TestAnalyzeAnnotations")
 
-	tasks, err := analyzeAnnotations()
+	res, err := analyzeAnnotations()
 	if err != nil {
 		t.Fatalf("failed to analyzeAnnotations: %v", err)
 	}
+	tasks := res.tasks
+
 	// For prog0, we expect
 	//   - task with name = "task0", with three spans.
 	//   - task with name = "task1", with no span.
@@ -103,6 +105,78 @@ func TestAnalyzeAnnotations(t *testing.T) {
 	}
 }
 
+// prog1 creates a task hierarchy consisting of three tasks.
+func prog1() {
+	ctx := context.Background()
+	ctx1, done1 := trace.NewContext(ctx, "task1")
+	defer done1()
+	trace.WithSpan(ctx1, "task1.span", func(ctx context.Context) {
+		ctx2, done2 := trace.NewContext(ctx, "task2")
+		defer done2()
+		trace.WithSpan(ctx2, "task2.span", func(ctx context.Context) {
+			ctx3, done3 := trace.NewContext(ctx, "task3")
+			defer done3()
+			trace.WithSpan(ctx3, "task3.span", func(ctx context.Context) {
+			})
+		})
+	})
+}
+
+func TestAnalyzeAnnotationTaskTree(t *testing.T) {
+	// Run prog1 and capture the execution trace.
+	traceProgram(prog1, "TestAnalyzeAnnotationTaskTree")
+
+	res, err := analyzeAnnotations()
+	if err != nil {
+		t.Fatalf("failed to analyzeAnnotation: %v", err)
+	}
+	tasks := res.tasks
+
+	// For prog0, we expect
+	//   - task with name = "", with taskless.span in spans.
+	//   - task with name = "task0", with three spans.
+	wantTasks := map[string]struct {
+		parent   string
+		children []string
+		spans    []string
+	}{
+		"task1": {
+			parent:   "",
+			children: []string{"task2"},
+			spans:    []string{"task1.span"},
+		},
+		"task2": {
+			parent:   "task1",
+			children: []string{"task3"},
+			spans:    []string{"task2.span"},
+		},
+		"task3": {
+			parent:   "task2",
+			children: nil,
+			spans:    []string{"task3.span"},
+		},
+	}
+
+	for _, task := range tasks {
+		want, ok := wantTasks[task.name]
+		if !ok {
+			t.Errorf("unexpected task: %s", task)
+			continue
+		}
+		delete(wantTasks, task.name)
+
+		if parentName(task) != want.parent ||
+			!reflect.DeepEqual(childrenNames(task), want.children) ||
+			!reflect.DeepEqual(spanNames(task), want.spans) {
+			t.Errorf("got %v; want %+v", task, want)
+		}
+	}
+
+	if len(wantTasks) > 0 {
+		t.Errorf("no more tasks; want %+v", wantTasks)
+	}
+}
+
 // traceProgram runs the provided function while tracing is enabled,
 // parses the captured trace, and sets the global trace loader to
 // point to the parsed trace.
@@ -133,6 +207,20 @@ func spanNames(task *taskDesc) (ret []string) {
 	return ret
 }
 
+func parentName(task *taskDesc) string {
+	if task.parent != nil {
+		return task.parent.name
+	}
+	return ""
+}
+
+func childrenNames(task *taskDesc) (ret []string) {
+	for _, s := range task.children {
+		ret = append(ret, s.name)
+	}
+	return ret
+}
+
 func swapLoaderData(res traceparser.ParseResult, err error) {
 	// swap loader's data.
 	parseTrace() // fool loader.once.

src/cmd/trace/trace.go

@@ -195,8 +195,8 @@ func httpJsonTrace(w http.ResponseWriter, r *http.Request) {
 			log.Printf("failed to parse taskid parameter %q: %v", taskids, err)
 			return
 		}
-		tasks, _ := analyzeAnnotations()
-		task, ok := tasks[taskid]
+		annotRes, _ := analyzeAnnotations()
+		task, ok := annotRes.tasks[taskid]
 		if !ok {
 			log.Printf("failed to find task with id %d", taskid)
 			return
@@ -206,8 +206,15 @@ func httpJsonTrace(w http.ResponseWriter, r *http.Request) {
 		params.startTime = task.firstTimestamp() - 1
 		params.endTime = task.lastTimestamp() + 1
 		params.maing = goid
-		params.gs = task.RelatedGoroutines(res.Events, 0) // find only directly involved goroutines
-		params.showTask = task
+		params.tasks = task.decendents()
+		gs := map[uint64]bool{}
+		for _, t := range params.tasks {
+			// find only directly involved goroutines
+			for k, v := range t.RelatedGoroutines(res.Events, 0) {
+				gs[k] = v
+			}
+		}
+		params.gs = gs
 	}
 
 	data, err := generateTrace(params)
@@ -296,7 +303,7 @@ type traceParams struct {
 	endTime   int64
 	maing     uint64          // for goroutine-oriented view, place this goroutine on the top row
 	gs        map[uint64]bool // Goroutines to be displayed for goroutine-oriented or task-oriented view
-	showTask  *taskDesc       // Task to be displayed
+	tasks     []*taskDesc     // Tasks to be displayed. tasks[0] is the top-most task
 }
 
 type traceviewMode int
@@ -627,6 +634,7 @@ func generateTrace(params *traceParams) (ViewerData, error) {
 	ctx.emit(&ViewerEvent{Name: "thread_name", Phase: "M", Pid: 0, Tid: trace.SyscallP, Arg: &NameArg{"Syscalls"}})
 	ctx.emit(&ViewerEvent{Name: "thread_sort_index", Phase: "M", Pid: 0, Tid: trace.SyscallP, Arg: &SortIndexArg{-3}})
 
+	// Display rows for Ps if we are in the default trace view mode.
 	if ctx.mode == defaultTraceview {
 		for i := 0; i <= maxProc; i++ {
 			ctx.emit(&ViewerEvent{Name: "thread_name", Phase: "M", Pid: 0, Tid: uint64(i), Arg: &NameArg{fmt.Sprintf("Proc %v", i)}})
@@ -634,9 +642,10 @@ func generateTrace(params *traceParams) (ViewerData, error) {
 		}
 	}
 
-	// Display task and its spans
+	// Display task and its spans if we are in the taskTrace view mode.
+	if ctx.mode == taskTraceview {
 		taskRow := uint64(trace.GCP + 1)
-	if task := ctx.showTask; task != nil {
+		for _, task := range ctx.tasks {
 			taskName := fmt.Sprintf("Task %s(%d)", task.name, task.id)
 			ctx.emit(&ViewerEvent{Name: "thread_name", Phase: "M", Pid: 0, Tid: taskRow, Arg: &NameArg{"Tasks"}})
 			ctx.emit(&ViewerEvent{Name: "thread_sort_index", Phase: "M", Pid: 0, Tid: taskRow, Arg: &SortIndexArg{-3}})
@@ -647,7 +656,9 @@ func generateTrace(params *traceParams) (ViewerData, error) {
 				ctx.emitSpan(s)
 			}
 		}
+	}
 
+	// Display goroutine rows if we are either in gtrace or taskTrace view mode.
 	if ctx.mode != defaultTraceview && ctx.gs != nil {
 		for k, v := range ginfos {
 			if !ctx.gs[k] {