From 32b4470ea37f1e27b32947788a914a8161818ad3 Mon Sep 17 00:00:00 2001
From: Tobias Christiansen <tobyase@serenityos.org>
Date: Mon, 23 Aug 2021 23:30:36 +0200
Subject: [PATCH] Shell: Use new Statistics tool in 'time -n' command

The new Statistics utility is now used when calling 'time -n' to get
some more information of the timings. For now only the standard
deviation is given in addition to the average.

This commit completely undos #9645 because everything that touched moved
into AK::Statistics.
---
 Userland/Shell/Builtin.cpp | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/Userland/Shell/Builtin.cpp b/Userland/Shell/Builtin.cpp
index 414e378eee7..1dbfa41af2e 100644
--- a/Userland/Shell/Builtin.cpp
+++ b/Userland/Shell/Builtin.cpp
@@ -9,6 +9,7 @@
 #include "Shell/Formatter.h"
 #include <AK/LexicalPath.h>
 #include <AK/ScopeGuard.h>
+#include <AK/Statistics.h>
 #include <AK/String.h>
 #include <LibCore/ArgsParser.h>
 #include <LibCore/EventLoop.h>
@@ -898,8 +899,7 @@ int Shell::builtin_time(int argc, const char** argv)
 
     auto commands = expand_aliases({ move(command) });
 
-    Vector<int> iteration_times;
-    iteration_times.ensure_capacity(number_of_iterations);
+    AK::Statistics iteration_times;
 
     int exit_code = 1;
     for (int i = 0; i < number_of_iterations; ++i) {
@@ -909,25 +909,21 @@ int Shell::builtin_time(int argc, const char** argv)
             block_on_job(job);
             exit_code = job.exit_code();
         }
-        iteration_times.unchecked_append(timer.elapsed());
+        iteration_times.add(timer.elapsed());
     }
 
     if (number_of_iterations == 1) {
-        warnln("Time: {} ms", iteration_times.first());
+        warnln("Time: {} ms", iteration_times.values().first());
     } else {
-        float total_time = 0;
-        for (auto time : iteration_times)
-            total_time += static_cast<float>(time);
-        float average = total_time / number_of_iterations;
-
-        float total_time_excluding_first = total_time - static_cast<float>(iteration_times.first());
-        float average_excluding_first = total_time_excluding_first / (number_of_iterations - 1);
+        AK::Statistics iteration_times_excluding_first;
+        for (size_t i = 1; i < iteration_times.size(); i++)
+            iteration_times_excluding_first.add(iteration_times.values()[i]);
 
         warnln("Timing report:");
         warnln("==============");
         warnln("Command:         {}", String::join(' ', args));
-        warnln("Average time:    {} ms", average);
-        warnln("Excluding first: {} ms", average_excluding_first);
+        warnln("Average time:    {:.2} ms (median: {}, stddev: {:.2})", iteration_times.average(), iteration_times.median(), iteration_times.standard_deviation());
+        warnln("Excluding first: {:.2} ms (median: {}, stddev: {:.2})", iteration_times_excluding_first.average(), iteration_times_excluding_first.median(), iteration_times_excluding_first.standard_deviation());
     }
 
     return exit_code;