terminal: add ability to print goroutine labels (#1879)

Documentation/cli/README.md

@@ -274,7 +274,8 @@ Print out info for every goroutine. The flag controls what information is shown
 	-r	displays location of topmost stackframe (including frames inside private runtime functions)
 	-g	displays location of go instruction that created the goroutine
 	-s	displays location of the start function
-	-t	displays stack trace of goroutine
+	-t	displays goroutine's stacktrace
+	-l	displays goroutine's labels
 
 If no flag is specified the default is -u.
 

pkg/terminal/command.go

@@ -189,7 +189,8 @@ Print out info for every goroutine. The flag controls what information is shown
 	-r	displays location of topmost stackframe (including frames inside private runtime functions)
 	-g	displays location of go instruction that created the goroutine
 	-s	displays location of the start function
-	-t	displays stack trace of goroutine
+	-t	displays goroutine's stacktrace
+	-l	displays goroutine's labels
 
 If no flag is specified the default is -u.`},
 		{aliases: []string{"goroutine", "gr"}, allowedPrefixes: onPrefix, cmdFn: c.goroutine, helpMsg: `Shows or changes current goroutine
@@ -612,14 +613,24 @@ func (a byGoroutineID) Less(i, j int) bool { return a[i].ID < a[j].ID }
 // The number of goroutines we're going to request on each RPC call
 const goroutineBatchSize = 10000
 
-func printGoroutines(t *Term, gs []*api.Goroutine, fgl formatGoroutineLoc, bPrintStack bool, state *api.DebuggerState) error {
+type printGoroutinesFlags uint8
+
+const (
+	printGoroutinesStack printGoroutinesFlags = 1 << iota
+	printGoroutinesLabels
+)
+
+func printGoroutines(t *Term, gs []*api.Goroutine, fgl formatGoroutineLoc, flags printGoroutinesFlags, state *api.DebuggerState) error {
 	for _, g := range gs {
 		prefix := "  "
 		if state.SelectedGoroutine != nil && g.ID == state.SelectedGoroutine.ID {
 			prefix = "* "
 		}
 		fmt.Printf("%sGoroutine %s\n", prefix, formatGoroutine(g, fgl))
-		if bPrintStack {
+		if flags&printGoroutinesLabels != 0 {
+			writeGoroutineLabels(os.Stdout, g, "\t")
+		}
+		if flags&printGoroutinesStack != 0 {
 			stack, err := t.client.Stacktrace(g.ID, 10, 0, nil)
 			if err != nil {
 				return err
@@ -633,7 +644,7 @@ func printGoroutines(t *Term, gs []*api.Goroutine, fgl formatGoroutineLoc, bPrin
 func goroutines(t *Term, ctx callContext, argstr string) error {
 	args := strings.Split(argstr, " ")
 	var fgl = fglUserCurrent
-	bPrintStack := false
+	var flags printGoroutinesFlags
 
 	switch len(args) {
 	case 0:
@@ -650,7 +661,9 @@ func goroutines(t *Term, ctx callContext, argstr string) error {
 			case "-s":
 				fgl = fglStart
 			case "-t":
-				bPrintStack = true
+				flags |= printGoroutinesStack
+			case "-l":
+				flags |= printGoroutinesLabels
 			case "":
 				// nothing to do
 			default:
@@ -675,7 +688,7 @@ func goroutines(t *Term, ctx callContext, argstr string) error {
 			return err
 		}
 		sort.Sort(byGoroutineID(gs))
-		err = printGoroutines(t, gs, fgl, bPrintStack, state)
+		err = printGoroutines(t, gs, fgl, flags, state)
 		if err != nil {
 			return err
 		}
@@ -877,6 +890,36 @@ func writeGoroutineLong(w io.Writer, g *api.Goroutine, prefix string) {
 		prefix, formatLocation(g.UserCurrentLoc),
 		prefix, formatLocation(g.GoStatementLoc),
 		prefix, formatLocation(g.StartLoc))
+	writeGoroutineLabels(w, g, prefix+"\t")
+}
+
+func writeGoroutineLabels(w io.Writer, g *api.Goroutine, prefix string) {
+	const maxNumberOfGoroutineLabels = 5
+
+	if len(g.Labels) <= 0 {
+		return
+	}
+
+	keys := make([]string, 0, len(g.Labels))
+	for k := range g.Labels {
+		keys = append(keys, k)
+	}
+	sort.Strings(keys)
+	more := false
+	if len(keys) > maxNumberOfGoroutineLabels {
+		more = true
+		keys = keys[:maxNumberOfGoroutineLabels]
+	}
+	fmt.Fprintf(w, "%sLabels: ", prefix)
+	for i, k := range keys {
+		fmt.Fprintf(w, "%q:%q", k, g.Labels[k])
+		if i != len(keys)-1 {
+			fmt.Fprintf(w, ", ")
+		} else if more {
+			fmt.Fprintf(w, "... (%d more)", len(g.Labels)-maxNumberOfGoroutineLabels)
+		}
+	}
+	fmt.Fprintf(w, "\n")
 }
 
 func restart(t *Term, ctx callContext, args string) error {