add collective communication to generic vanguard

opm/simulators/flow/Main.hpp

@@ -98,11 +98,6 @@ namespace Opm {
     // with incorrect locale settings.
     resetLocale();
 
-# if HAVE_DUNE_FEM
-    Dune::Fem::MPIManager::initialize(argc, argv);
-# else
-    Dune::MPIHelper::instance(argc, argv);
-# endif
     FlowMainEbos<TypeTag> mainfunc(argc, argv, outputCout, outputFiles);
     return mainfunc.execute();
   }
@@ -152,6 +147,14 @@ namespace Opm
         {
         }
 
+        ~Main()
+        {
+#if HAVE_MPI && !HAVE_DUNE_FEM
+            EclGenericVanguard::setCommunication(nullptr);
+            MPI_Finalize();
+#endif
+        }
+
         int runDynamic()
         {
             int exitCode = EXIT_SUCCESS;
@@ -361,12 +364,11 @@ namespace Opm
             Dune::Fem::MPIManager::initialize(argc_, argv_);
             int mpiRank = Dune::Fem::MPIManager::rank();
 #else
-            // the design of the plain dune MPIHelper class is quite flawed: there is no way to
-            // get the instance without having the argc and argv parameters available and it is
-            // not possible to determine the MPI rank and size without an instance. (IOW: the
-            // rank() and size() methods are supposed to be static.)
-            const auto& mpiHelper = Dune::MPIHelper::instance(argc_, argv_);
-            int mpiRank = mpiHelper.rank();
+#if HAVE_MPI
+            MPI_Init(&argc_, &argv_);
+#endif
+            EclGenericVanguard::setCommunication(std::make_unique<EclGenericVanguard::CommunicationType>());
+            int mpiRank = EclGenericVanguard::comm().rank();
 #endif
 
             // we always want to use the default locale, and thus spare us the trouble