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, 9 deletions

diff --git a/Source/CTest/cmCTestBuildAndTestHandler.cxx b/Source/CTest/cmCTestBuildAndTestHandler.cxx
index a0d68a0..b603758 100644
--- a/Source/CTest/cmCTestBuildAndTestHandler.cxx
+++ b/Source/CTest/cmCTestBuildAndTestHandler.cxx
@@ -10,6 +10,7 @@
 #include "cmake.h"
 
 #include "cmsys/Process.h"
+#include <chrono>
 #include <stdlib.h>
 
 cmCTestBuildAndTestHandler::cmCTestBuildAndTestHandler()
@@ -192,7 +193,7 @@ int cmCTestBuildAndTestHandler::RunCMakeAndTest(std::string* outstring)
 
   // we need to honor the timeout specified, the timeout include cmake, build
   // and test time
-  double clock_start = cmSystemTools::GetTime();
+  auto clock_start = std::chrono::steady_clock::now();
 
   // make sure the binary dir is there
   out << "Internal cmake changing into directory: " << this->BinaryDir
@@ -222,10 +223,12 @@ int cmCTestBuildAndTestHandler::RunCMakeAndTest(std::string* outstring)
     this->BuildTargets.push_back("");
   }
   for (std::string const& tar : this->BuildTargets) {
-    double remainingTime = 0;
+    std::chrono::duration<double> remainingTime = std::chrono::seconds(0);
     if (this->Timeout > 0) {
-      remainingTime = this->Timeout - cmSystemTools::GetTime() + clock_start;
-      if (remainingTime <= 0) {
+      remainingTime = std::chrono::duration<double>(this->Timeout) -
+        std::chrono::duration_cast<std::chrono::seconds>(
+                        std::chrono::steady_clock::now() - clock_start);
+      if (remainingTime <= std::chrono::seconds(0)) {
         if (outstring) {
           *outstring = "--build-and-test timeout exceeded. ";
         }
@@ -248,7 +251,7 @@ int cmCTestBuildAndTestHandler::RunCMakeAndTest(std::string* outstring)
     int retVal = cm.GetGlobalGenerator()->Build(
       this->SourceDir, this->BinaryDir, this->BuildProject, tar, output,
       this->BuildMakeProgram, config, !this->BuildNoClean, false, false,
-      remainingTime);
+      remainingTime.count());
     out << output;
     // if the build failed then return
     if (retVal) {
@@ -320,10 +323,12 @@ int cmCTestBuildAndTestHandler::RunCMakeAndTest(std::string* outstring)
   out << "\n";
 
   // how much time is remaining
-  double remainingTime = 0;
+  std::chrono::duration<double> remainingTime = std::chrono::seconds(0);
   if (this->Timeout > 0) {
-    remainingTime = this->Timeout - cmSystemTools::GetTime() + clock_start;
-    if (remainingTime <= 0) {
+    remainingTime = std::chrono::duration<double>(this->Timeout) -
+      std::chrono::duration_cast<std::chrono::seconds>(
+                      std::chrono::steady_clock::now() - clock_start);
+    if (remainingTime <= std::chrono::seconds(0)) {
       if (outstring) {
         *outstring = "--build-and-test timeout exceeded. ";
       }
@@ -332,7 +337,7 @@ int cmCTestBuildAndTestHandler::RunCMakeAndTest(std::string* outstring)
   }
 
   int runTestRes = this->CTest->RunTest(testCommand, &outs, &retval, nullptr,
-                                        remainingTime, nullptr);
+                                        remainingTime.count(), nullptr);
 
   if (runTestRes != cmsysProcess_State_Exited || retval != 0) {
     out << "Test command failed: " << testCommand[0] << "\n";