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, 14 insertions, 11 deletions

diff --git a/Source/CTest/cmCTestCoverageHandler.cxx b/Source/CTest/cmCTestCoverageHandler.cxx
index 56eeceb..85f6ce9 100644
--- a/Source/CTest/cmCTestCoverageHandler.cxx
+++ b/Source/CTest/cmCTestCoverageHandler.cxx
@@ -21,11 +21,13 @@
 #include "cmsys/Process.h"
 #include "cmsys/RegularExpression.hxx"
 #include <algorithm>
+#include <chrono>
 #include <iomanip>
 #include <iterator>
 #include <sstream>
 #include <stdio.h>
 #include <stdlib.h>
+#include <type_traits>
 #include <utility>
 
 class cmMakefile;
@@ -290,13 +292,14 @@ int cmCTestCoverageHandler::ProcessHandler()
   this->LoadLabels();
 
   cmGeneratedFileStream ofs;
-  double elapsed_time_start = cmSystemTools::GetTime();
+  auto elapsed_time_start = std::chrono::steady_clock::now();
   if (!this->StartLogFile("Coverage", ofs)) {
     cmCTestLog(this->CTest, ERROR_MESSAGE,
                "Cannot create LastCoverage.log file" << std::endl);
   }
 
-  ofs << "Performing coverage: " << elapsed_time_start << std::endl;
+  ofs << "Performing coverage: "
+      << elapsed_time_start.time_since_epoch().count() << std::endl;
   this->CleanCoverageLogFiles(ofs);
 
   cmSystemTools::ConvertToUnixSlashes(sourceDir);
@@ -621,10 +624,10 @@ int cmCTestCoverageHandler::ProcessHandler()
   covSumXML.Element("EndDateTime", end_time);
   covSumXML.Element("EndTime",
                     static_cast<unsigned int>(cmSystemTools::GetTime()));
-  covSumXML.Element(
-    "ElapsedMinutes",
-    static_cast<int>((cmSystemTools::GetTime() - elapsed_time_start) / 6) /
-      10.0);
+  covSumXML.Element("ElapsedMinutes",
+                    std::chrono::duration_cast<std::chrono::minutes>(
+                      std::chrono::steady_clock::now() - elapsed_time_start)
+                      .count());
   covSumXML.EndElement(); // Coverage
   this->CTest->EndXML(covSumXML);
 
@@ -1963,7 +1966,7 @@ int cmCTestCoverageHandler::RunBullseyeSourceSummary(
     return 0;
   }
   this->CTest->StartXML(xml, this->AppendXML);
-  double elapsed_time_start = cmSystemTools::GetTime();
+  auto elapsed_time_start = std::chrono::steady_clock::now();
   std::string coverage_start_time = this->CTest->CurrentTime();
   xml.StartElement("Coverage");
   xml.Element("StartDateTime", coverage_start_time);
@@ -2090,10 +2093,10 @@ int cmCTestCoverageHandler::RunBullseyeSourceSummary(
   xml.Element("PercentCoverage", SAFEDIV(percent_coverage, number_files));
   xml.Element("EndDateTime", end_time);
   xml.Element("EndTime", static_cast<unsigned int>(cmSystemTools::GetTime()));
-  xml.Element(
-    "ElapsedMinutes",
-    static_cast<int>((cmSystemTools::GetTime() - elapsed_time_start) / 6) /
-      10.0);
+  xml.Element("ElapsedMinutes",
+              std::chrono::duration_cast<std::chrono::minutes>(
+                std::chrono::steady_clock::now() - elapsed_time_start)
+                .count());
   xml.EndElement(); // Coverage
   this->CTest->EndXML(xml);