added: utility to broadcast multiple variables in one operation

CMakeLists.txt

@@ -342,6 +342,18 @@ opm_add_test(test_parallelwellinfo_mpi
   NO_COMPILE
     )
 
+opm_add_test(test_broadcast
+  DEPENDS "opmsimulators"
+  LIBRARIES opmsimulators ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY}
+  SOURCES
+    tests/test_broadcast.cpp
+  CONDITION
+    MPI_FOUND AND Boost_UNIT_TEST_FRAMEWORK_FOUND
+  DRIVER_ARGS
+    -n 4
+    -b ${PROJECT_BINARY_DIR}
+)
+
 include(OpmBashCompletion)
 
 if (NOT BUILD_FLOW)

opm/simulators/utils/ParallelRestart.hpp

@@ -361,6 +361,53 @@ ADD_PACK_PROTOTYPES(RestartValue)
 ADD_PACK_PROTOTYPES(std::string)
 ADD_PACK_PROTOTYPES(time_point)
 
+template<typename T, typename... Args>
+void variadic_packsize(size_t& size, Parallel::Communication comm, T& first, Args&&... args)
+{
+  size += packSize(first, comm);
+  if constexpr (sizeof...(args) > 0)
+      variadic_packsize(size, comm, std::forward<Args>(args)...);
+}
+
+template<typename T, typename... Args>
+void variadic_pack(int& pos, std::vector<char>& buffer, Parallel::Communication comm, T& first, Args&&... args)
+{
+  pack(first, buffer, pos, comm);
+  if constexpr (sizeof...(args) > 0)
+      variadic_pack(pos, buffer, comm, std::forward<Args>(args)...);
+}
+
+template<typename T, typename... Args>
+void variadic_unpack(int& pos, std::vector<char>& buffer, Parallel::Communication comm, T& first, Args&&... args)
+{
+  unpack(first, buffer, pos, comm);
+  if constexpr (sizeof...(args) > 0)
+      variadic_unpack(pos, buffer, comm, std::forward<Args>(args)...);
+}
+
+template<typename... Args>
+void broadcast(Parallel::Communication comm, int root, Args&&... args)
+{
+  if (comm.size() == 1)
+      return;
+
+  size_t size = 0;
+  if (comm.rank() == root)
+      variadic_packsize(size, comm, std::forward<Args>(args)...);
+
+  comm.broadcast(&size, 1, root);
+  std::vector<char> buffer(size);
+  if (comm.rank() == root) {
+      int pos = 0;
+      variadic_pack(pos, buffer, comm, std::forward<Args>(args)...);
+  }
+  comm.broadcast(buffer.data(), size, root);
+  if (comm.rank() != root) {
+      int pos = 0;
+      variadic_unpack(pos, buffer, comm, std::forward<Args>(args)...);
+  }
+}
+
 } // end namespace Mpi
 
 RestartValue loadParallelRestart(const EclipseIO* eclIO, Action::State& actionState, SummaryState& summaryState,

tests/test_broadcast.cpp

@@ -0,0 +1,94 @@
+/*
+  Copyright 2018 SINTEF Digital, Mathematics and Cybernetics.
+  Copyright 2018 Equinor.
+
+  This file is part of the Open Porous Media project (OPM).
+
+  OPM is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  OPM is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <config.h>
+
+#define BOOST_TEST_MODULE TestBroadCast
+#define BOOST_TEST_NO_MAIN
+
+#include <boost/test/unit_test.hpp>
+
+#include <opm/simulators/utils/ParallelRestart.hpp>
+#include <dune/common/parallel/mpihelper.hh>
+
+#include <numeric>
+
+#if HAVE_MPI
+struct MPIError
+{
+    MPIError(std::string s, int e) : errorstring(std::move(s)), errorcode(e){}
+    std::string errorstring;
+    int errorcode;
+};
+
+void MPI_err_handler(MPI_Comm*, int* err_code, ...)
+{
+    std::vector<char> err_string(MPI_MAX_ERROR_STRING);
+    int err_length;
+    MPI_Error_string(*err_code, err_string.data(), &err_length);
+    std::string s(err_string.data(), err_length);
+    std::cerr << "An MPI Error ocurred:" << std::endl << s << std::endl;
+    throw MPIError(s, *err_code);
+}
+#endif
+
+bool
+init_unit_test_func()
+{
+    return true;
+}
+
+BOOST_AUTO_TEST_CASE(BroadCast)
+{
+    auto cc = Dune::MPIHelper::getCollectiveCommunication();
+
+    std::vector<double> d(3);
+    if (cc.rank() == 0)
+        std::iota(d.begin(), d.end(), 1.0);
+
+    std::vector<int> i(3);
+    if (cc.rank() == 0)
+        std::iota(i.begin(), i.end(), 4);
+
+    double d1 = cc.rank() == 0 ? 7.0 : 0.0;
+    size_t i1 = cc.rank() == 0 ? 8 : 0;
+
+    Opm::Mpi::broadcast(cc, 0, d, i, d1, i1);
+
+    for (size_t c = 0; c < 3; ++c) {
+        BOOST_CHECK_EQUAL(d[c], 1.0+c);
+        BOOST_CHECK_EQUAL(i[c], 4+c);
+    }
+    BOOST_CHECK_EQUAL(d1, 7.0);
+    BOOST_CHECK_EQUAL(i1, 8);
+}
+
+int main(int argc, char** argv)
+{
+    Dune::MPIHelper::instance(argc, argv);
+#if HAVE_MPI
+    // register a throwing error handler to allow for
+    // debugging with "catch throw" in gdb
+    MPI_Errhandler handler;
+    MPI_Comm_create_errhandler(MPI_err_handler, &handler);
+    MPI_Comm_set_errhandler(MPI_COMM_WORLD, handler);
+#endif
+    return boost::unit_test::unit_test_main(&init_unit_test_func, argc, argv);
+}