CTest: use std::chrono::steady_clock for time keeping

It was reported in issue #17345 that CTest does not use monotonic time
to report test duration. Monotonic clocks are not affected by large NTP
adjustments or things like daylight savings time.

As CMake 3.10 requires C++11, which introduced std::chrono, this commit
moves the time keeping in CTest from cmSystemTools::GetTime() to
std::chrono::steady_clock.

Fixes: #17345

1 files changed, 25 insertions, 17 deletions

diff --git a/Source/CTest/cmCTestScriptHandler.cxx b/Source/CTest/cmCTestScriptHandler.cxx
index 198f6e576d..3bf27a0b16 100644
--- a/Source/CTest/cmCTestScriptHandler.cxx
+++ b/Source/CTest/cmCTestScriptHandler.cxx
@@ -5,10 +5,12 @@
 #include "cmsys/Directory.hxx"
 #include "cmsys/Process.h"
 #include <map>
+#include <ratio>
 #include <sstream>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <type_traits>
 #include <utility>
 
 #include "cmCTest.h"
@@ -79,7 +81,7 @@ cmCTestScriptHandler::cmCTestScriptHandler()
   this->CMake = nullptr;
   this->GlobalGenerator = nullptr;
 
-  this->ScriptStartTime = 0;
+  this->ScriptStartTime = std::chrono::steady_clock::time_point();
 
   // the *60 is because the settings are in minutes but GetTime is seconds
   this->MinimumInterval = 30 * 60;
@@ -111,7 +113,7 @@ void cmCTestScriptHandler::Initialize()
   this->ContinuousDuration = -1;
 
   // what time in seconds did this script start running
-  this->ScriptStartTime = 0;
+  this->ScriptStartTime = std::chrono::steady_clock::time_point();
 
   delete this->Makefile;
   this->Makefile = nullptr;
@@ -158,11 +160,10 @@ void cmCTestScriptHandler::UpdateElapsedTime()
 {
   if (this->Makefile) {
     // set the current elapsed time
-    char timeString[20];
-    int itime = static_cast<unsigned int>(cmSystemTools::GetTime() -
-                                          this->ScriptStartTime);
-    sprintf(timeString, "%i", itime);
-    this->Makefile->AddDefinition("CTEST_ELAPSED_TIME", timeString);
+    auto itime = std::chrono::duration_cast<std::chrono::seconds>(
+      std::chrono::steady_clock::now() - this->ScriptStartTime);
+    auto timeString = std::to_string(itime.count());
+    this->Makefile->AddDefinition("CTEST_ELAPSED_TIME", timeString.c_str());
   }
 }
 
@@ -507,7 +508,7 @@ int cmCTestScriptHandler::RunConfigurationScript(
 
   int result;
 
-  this->ScriptStartTime = cmSystemTools::GetTime();
+  this->ScriptStartTime = std::chrono::steady_clock::now();
 
   // read in the script
   if (pscope) {
@@ -558,22 +559,27 @@ int cmCTestScriptHandler::RunCurrentScript()
   // for a continuous, do we ned to run it more than once?
   if (this->ContinuousDuration >= 0) {
     this->UpdateElapsedTime();
-    double ending_time = cmSystemTools::GetTime() + this->ContinuousDuration;
+    auto ending_time = std::chrono::steady_clock::now() +
+      std::chrono::duration<double>(this->ContinuousDuration);
     if (this->EmptyBinDirOnce) {
       this->EmptyBinDir = true;
     }
     do {
-      double interval = cmSystemTools::GetTime();
+      auto startOfInterval = std::chrono::steady_clock::now();
       result = this->RunConfigurationDashboard();
-      interval = cmSystemTools::GetTime() - interval;
-      if (interval < this->MinimumInterval) {
-        this->SleepInSeconds(
-          static_cast<unsigned int>(this->MinimumInterval - interval));
+      auto interval = std::chrono::steady_clock::now() - startOfInterval;
+      auto minimumInterval =
+        std::chrono::duration<double>(this->MinimumInterval);
+      if (interval < minimumInterval) {
+        auto sleepTime = std::chrono::duration_cast<std::chrono::seconds>(
+                           minimumInterval - interval)
+                           .count();
+        this->SleepInSeconds(static_cast<unsigned int>(sleepTime));
       }
       if (this->EmptyBinDirOnce) {
         this->EmptyBinDir = false;
       }
-    } while (cmSystemTools::GetTime() < ending_time);
+    } while (std::chrono::steady_clock::now() < ending_time);
   }
   // otherwise just run it once
   else {
@@ -967,7 +973,9 @@ double cmCTestScriptHandler::GetRemainingTimeAllowed()
     return 1.0e7;
   }
 
-  double timelimit = atof(timelimitS);
+  auto timelimit = std::chrono::duration<double>(atof(timelimitS));
 
-  return timelimit - cmSystemTools::GetTime() + this->ScriptStartTime;
+  auto duration = std::chrono::duration_cast<std::chrono::duration<double>>(
+    std::chrono::steady_clock::now() - this->ScriptStartTime);
+  return (timelimit - duration).count();
 }