VTK tests: check all VTK files with one python invocation

This merge request replaces the checkVTKFile function with a VTKChecker class which allows to queue up files and then check all of them within a single python invocation. As importing the vtk Python module has a significant overhead, this reduces the time to run the tests noticeably:

Test	Old	New
vtktest	384 sec	21 sec
vtktest-mpi-2	945 sec	17 sec
subsamplingvtktest	198 sec	22 sec

for one of multiple parallel builds on the CI system.

Note that in the case of the parallel test using MPI, the second rank just busy-waits. If the test runs much quicker, the second process will only run a shorter time as well, removing CPU contention between parallel builds. This should explain the much larger effect of this change for the parallel case.

Closes: #67 (closed)

dune/grid/io/file/test/checkvtkfile.hh

@@ -8,12 +8,18 @@
 #include <ios>
 #include <iostream>
 #include <ostream>
+#include <set>
 #include <sstream>
 #include <string>
 
 #include <sys/wait.h>
 
 #include <dune/common/exceptions.hh>
+#include <dune/common/test/testsuite.hh>
+
+namespace Dune {
+
+namespace Impl {
 
 // quote so the result can be used inside '...' in python
 // quotes not included in the result
@@ -83,9 +89,9 @@ inline bool is_suffix(const std::string &s, const std::string &suffix)
     s.compare(s.size() - suffix.size(), suffix.size(), suffix) == 0;
 }
 
-inline int checkVTKFile(const std::string &name)
+inline bool havePythonVTK()
 {
-  static const bool havePythonVTK = [] {
+  static const bool result = [] {
     // This check is invoked only once, even in a multithreading environment,
     // since it is invoked in the initializer of a static variable.
     if(runPython("from vtk import *") == 0)
@@ -95,32 +101,78 @@ inline int checkVTKFile(const std::string &name)
               << "vtk can read the files we wrote." << std::endl;
     return false;
   } ();
-  if(!havePythonVTK)
-  {
-    std::cerr << "skip: " << name << std::endl;
-    return 77;
-  }
 
-  std::string reader;
-  if     (is_suffix(name, ".vtu"))  reader = "vtkXMLUnstructuredGridReader";
-  else if(is_suffix(name, ".pvtu")) reader = "vtkXMLPUnstructuredGridReader";
-  else if(is_suffix(name, ".vtp"))  reader = "vtkXMLPolyDataReader";
-  else if(is_suffix(name, ".pvtp")) reader = "vtkXMLPPolyDataReader";
-  else DUNE_THROW(Dune::NotImplemented,
-                  "Unknown vtk file extension: " << name);
-
-  std::cout << "Loading " << name << " using python vtk" << std::endl;
-  std::string pycode =
-    "from vtk import *;"
-    "import sys;"
-    "reader = "+reader+"();"
-    "reader.SetFileName('"+pyq(name)+"');"
-    "reader.Update();"
-    // check that the number of of cells is > 0
-    "sys.exit(not (reader.GetOutput().GetNumberOfCells() > 0));";
-  int result = runPython(pycode);
-  std::cout << (result == 0 ? "pass: " : "fail: ") << name << std::endl;
   return result;
 }
 
+inline std::string pythonVTKReader(const std::string& filename)
+{
+  if     (is_suffix(filename, ".vtu"))  return "vtkXMLUnstructuredGridReader";
+  else if(is_suffix(filename, ".pvtu")) return "vtkXMLPUnstructuredGridReader";
+  else if(is_suffix(filename, ".vtp"))  return "vtkXMLPolyDataReader";
+  else if(is_suffix(filename, ".pvtp")) return "vtkXMLPPolyDataReader";
+  else DUNE_THROW(Dune::NotImplemented,
+                  "Unknown vtk file extension: " << filename);
+}
+
+} /* namespace Impl */
+
+class VTKChecker
+{
+public:
+  void push(const std::string& file)
+    {
+      auto res = files_.insert(file);
+      if (not res.second) {
+        testSuite_.check(false, "VTKChecker")
+          << "'" << file << "' was added multiple times";
+      }
+    }
+
+  int check()
+    {
+      if (not Impl::havePythonVTK()) {
+        return 77;
+      }
+      else if (not files_.empty()) {
+        const int result = Impl::runPython(generatePythonCode());
+        testSuite_.check(result == 0);
+      }
+      return testSuite_.exit();
+    }
+
+  const TestSuite& testSuite() const
+    {
+      return testSuite_;
+    }
+
+private:
+  std::string generatePythonCode() const
+    {
+      std::stringstream code;
+
+      code << "from vtk import *\n"
+           << "import sys\n"
+           << "passed = True\n";
+
+      for (const auto& file : files_) {
+        code << "reader = " << Impl::pythonVTKReader(file) << "()\n"
+             << "reader.SetFileName('" << Impl::pyq(file) << "')\n"
+             << "reader.Update()\n"
+             << "if (not (reader.GetOutput().GetNumberOfCells() > 0)):\n"
+             << "    print('ERROR in {}'.format('" << Impl::pyq(file) << "'))\n"
+             << "    passed = False\n";
+      }
+
+      code << "sys.exit(0 if passed else 1)\n";
+
+      return code.str();
+    }
+
+  std::set< std::string > files_;
+  TestSuite testSuite_;
+};
+
+} /* namespace Dune */
+
 #endif // DUNE_GRID_IO_FILE_TEST_CHECKVTKFILE_HH