trace: add timestamp to the output (#3358)

Fix #3356

Documentation/usage/dlv_trace.md

@@ -28,6 +28,7 @@ dlv trace [package] regexp [flags]
   -p, --pid int         Pid to attach to.
   -s, --stack int       Show stack trace with given depth. (Ignored with --ebpf)
   -t, --test            Trace a test binary.
+      --timestamp       Show timestamp in the output
 ```
 
 ### Options inherited from parent commands

cmd/dlv/cmds/commands.go

@@ -14,6 +14,7 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+	"time"
 
 	"github.com/go-delve/delve/pkg/config"
 	"github.com/go-delve/delve/pkg/gobuild"
@@ -78,11 +79,12 @@ var (
 	// rootCommand is the root of the command tree.
 	rootCommand *cobra.Command
 
-	traceAttachPid  int
-	traceExecFile   string
-	traceTestBinary bool
-	traceStackDepth int
-	traceUseEBPF    bool
+	traceAttachPid     int
+	traceExecFile      string
+	traceTestBinary    bool
+	traceStackDepth    int
+	traceUseEBPF       bool
+	traceShowTimestamp bool
 
 	// redirect specifications for target process
 	redirects []string
@@ -307,6 +309,7 @@ only see the output of the trace operations you can redirect stdout.`,
 	traceCommand.Flags().StringVarP(&traceExecFile, "exec", "e", "", "Binary file to exec and trace.")
 	traceCommand.Flags().BoolVarP(&traceTestBinary, "test", "t", false, "Trace a test binary.")
 	traceCommand.Flags().BoolVarP(&traceUseEBPF, "ebpf", "", false, "Trace using eBPF (experimental).")
+	traceCommand.Flags().BoolVarP(&traceShowTimestamp, "timestamp", "", false, "Show timestamp in the output")
 	traceCommand.Flags().IntVarP(&traceStackDepth, "stack", "s", 0, "Show stack trace with given depth. (Ignored with --ebpf)")
 	traceCommand.Flags().String("output", "debug", "Output path for the binary.")
 	rootCommand.AddCommand(traceCommand)
@@ -694,7 +697,10 @@ func traceCmd(cmd *cobra.Command, args []string) {
 			return 1
 		}
 		cmds := terminal.DebugCommands(client)
-		t := terminal.New(client, nil)
+		cfg := &config.Config{
+			TraceShowTimestamp: traceShowTimestamp,
+		}
+		t := terminal.New(client, cfg)
 		t.SetTraceNonInteractive()
 		t.RedirectTo(os.Stderr)
 		defer t.Close()
@@ -723,6 +729,11 @@ func traceCmd(cmd *cobra.Command, args []string) {
 									params.WriteString(p.Value)
 								}
 							}
+
+							if traceShowTimestamp {
+								fmt.Fprintf(os.Stderr, "%s ", time.Now().Format(time.RFC3339Nano))
+							}
+
 							if t.IsRet {
 								for _, p := range t.ReturnParams {
 									fmt.Fprintf(os.Stderr, "=> %#v\n", p.Value)

pkg/config/config.go

@@ -102,6 +102,10 @@ type Config struct {
 	// This can be used to shorten the tabstop (e.g. "  ") or to print a more
 	// visual indent (e.g. ">__ ").
 	Tab string `yaml:"tab"`
+
+	// TraceShowTimestamp controls whether to show timestamp in the trace
+	// output.
+	TraceShowTimestamp bool `yaml:"trace-show-timestamp"`
 }
 
 func (c *Config) GetSourceListLineCount() int {

pkg/terminal/command.go

@@ -23,6 +23,7 @@ import (
 	"strconv"
 	"strings"
 	"text/tabwriter"
+	"time"
 
 	"github.com/cosiner/argv"
 	"github.com/go-delve/delve/pkg/config"
@@ -2756,6 +2757,10 @@ func printBreakpointInfo(t *Term, th *api.Thread, tracepointOnNewline bool) {
 }
 
 func printTracepoint(t *Term, th *api.Thread, bpname string, fn *api.Function, args string, hasReturnValue bool) {
+	if t.conf.TraceShowTimestamp {
+		fmt.Fprintf(t.stdout, "%s ", time.Now().Format(time.RFC3339Nano))
+	}
+
 	if th.Breakpoint.Tracepoint {
 		fmt.Fprintf(t.stdout, "> goroutine(%d): %s%s(%s)\n", th.GoroutineID, bpname, fn.Name(), args)
 		printBreakpointInfo(t, th, !hasReturnValue)