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, 16 insertions, 9 deletions

diff --git a/Source/CTest/cmCTestTestHandler.cxx b/Source/CTest/cmCTestTestHandler.cxx
index c7ed927..b814e35 100644
--- a/Source/CTest/cmCTestTestHandler.cxx
+++ b/Source/CTest/cmCTestTestHandler.cxx
@@ -2,6 +2,7 @@
    file Copyright.txt or https://cmake.org/licensing for details.  */
 #include "cmCTestTestHandler.h"
 #include <algorithm>
+#include <chrono>
 #include <cmsys/Base64.h>
 #include <cmsys/Directory.hxx>
 #include <cmsys/RegularExpression.hxx>
@@ -15,6 +16,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
+#include <type_traits>
 
 #include "cmAlgorithms.h"
 #include "cmCTest.h"
@@ -346,7 +348,7 @@ void cmCTestTestHandler::Initialize()
 {
   this->Superclass::Initialize();
 
-  this->ElapsedTestingTime = -1;
+  this->ElapsedTestingTime = std::chrono::duration<double>();
 
   this->TestResults.clear();
 
@@ -484,12 +486,11 @@ int cmCTestTestHandler::ProcessHandler()
   int total;
 
   // start the real time clock
-  double clock_start, clock_finish;
-  clock_start = cmSystemTools::GetTime();
+  auto clock_start = std::chrono::steady_clock::now();
 
   this->ProcessDirectory(passed, failed);
 
-  clock_finish = cmSystemTools::GetTime();
+  auto clock_finish = std::chrono::steady_clock::now();
 
   total = int(passed.size()) + int(failed.size());
 
@@ -540,7 +541,10 @@ int cmCTestTestHandler::ProcessHandler()
       this->PrintLabelOrSubprojectSummary(false);
     }
     char realBuf[1024];
-    sprintf(realBuf, "%6.2f sec", clock_finish - clock_start);
+    auto durationInMs = std::chrono::duration_cast<std::chrono::milliseconds>(
+                          clock_finish - clock_start)
+                          .count();
+    sprintf(realBuf, "%6.2f sec", static_cast<double>(durationInMs) / 1000.0);
     cmCTestOptionalLog(this->CTest, HANDLER_OUTPUT,
                        "\nTotal Test time (real) = " << realBuf << "\n",
                        this->Quiet);
@@ -1201,7 +1205,7 @@ void cmCTestTestHandler::ProcessDirectory(std::vector<std::string>& passed,
   this->ComputeTestList();
   this->StartTest = this->CTest->CurrentTime();
   this->StartTestTime = static_cast<unsigned int>(cmSystemTools::GetTime());
-  double elapsed_time_start = cmSystemTools::GetTime();
+  auto elapsed_time_start = std::chrono::steady_clock::now();
 
   cmCTestMultiProcessHandler* parallel = this->CTest->GetBatchJobs()
     ? new cmCTestBatchTestHandler
@@ -1268,7 +1272,8 @@ void cmCTestTestHandler::ProcessDirectory(std::vector<std::string>& passed,
   delete parallel;
   this->EndTest = this->CTest->CurrentTime();
   this->EndTestTime = static_cast<unsigned int>(cmSystemTools::GetTime());
-  this->ElapsedTestingTime = cmSystemTools::GetTime() - elapsed_time_start;
+  this->ElapsedTestingTime =
+    std::chrono::steady_clock::now() - elapsed_time_start;
   *this->LogFile << "End testing: " << this->CTest->CurrentTime() << std::endl;
 }
 
@@ -1373,8 +1378,10 @@ void cmCTestTestHandler::GenerateDartOutput(cmXMLWriter& xml)
 
   xml.Element("EndDateTime", this->EndTest);
   xml.Element("EndTestTime", this->EndTestTime);
-  xml.Element("ElapsedMinutes",
-              static_cast<int>(this->ElapsedTestingTime / 6) / 10.0);
+  xml.Element(
+    "ElapsedMinutes",
+    std::chrono::duration_cast<std::chrono::minutes>(this->ElapsedTestingTime)
+      .count());
   xml.EndElement(); // Testing
   this->CTest->EndXML(xml);
 }