v: add a TOTAL line, to the output of -show-timings, to minimise the need for external tools on windows (#21847)

cmd/v/v.v

@@ -61,14 +61,19 @@ fn main() {
 	$if time_v ? {
 		timers_should_print = true
 	}
-	mut timers := util.new_timers(should_print: timers_should_print, label: 'main')
-	timers.start('v total')
-	defer {
-		timers.show('v total')
+	if '-show-timings' in os.args {
+		timers_should_print = true
+		unbuffer_stdout()
 	}
+	mut timers := util.new_timers(should_print: timers_should_print, label: 'main')
 	timers.start('v start')
 	timers.show('v start')
-	timers.start('parse_CLI_args')
+	timers.start('TOTAL')
+	// use at_exit here, instead of defer, since some code paths later do early exit(0) or exit(1), for showing errors, or after `v run`
+	at_exit(fn [mut timers] () {
+		timers.show('TOTAL')
+	})!
+	timers.start('v parsing CLI args')
 	args := os.args[1..]
 
 	if args.len == 0 || args[0] in ['-', 'repl'] {
@@ -90,7 +95,7 @@ fn main() {
 		eprintln('-usecache is currently disabled on windows')
 		exit(1)
 	}
-	timers.show('parse_CLI_args')
+	timers.show('v parsing CLI args')
 	// Start calling the correct functions/external tools
 	// Note for future contributors: Please add new subcommands in the `match` block below.
 	if command in external_tools {

vlib/v/util/timers.v

@@ -71,7 +71,10 @@ pub fn (mut t Timers) measure(name string) i64 {
 		eprintln('>   Available timers:')
 		eprintln('>   ${timer_keys}')
 	}
-	ms := t.swatches[name].elapsed().microseconds()
+	mut sw := t.swatches[name]
+	ms := sw.elapsed().microseconds()
+	sw.pause()
+	t.swatches[name] = sw
 	return ms
 }
 
@@ -112,8 +115,8 @@ pub fn (mut t Timers) message(name string) string {
 }
 
 pub fn (mut t Timers) show(label string) {
-	formatted_message := t.message(label)
 	if t.should_print {
+		formatted_message := t.message(label)
 		println(formatted_message)
 	}
 	t.already_shown << label