mpi: workaround uninitialized MPI_Status

Some MPI implementations (i.e. MPICH) do not initialize the members of
the `MPI_Status` struct/object. This may lead to undefined behaviour in
our error-checking and logging.

Signed-off-by: Torbjörn Klatt <[email protected]>

Author: torbjoernk

include/pfasst/mpi_communicator.hpp

@@ -11,6 +11,29 @@ using namespace std;
 #include "pfasst/logging.hpp"
 
 
+/**
+ * creates and initializes a new _empty_ `MPI_Status` object
+ *
+ * An _empty_ `MPI_Status` is defined as an `MPI_Status` object with `MPI_ERROR` as `MPI_SUCCESS`,
+ * `MPI_SOURCE` as `MPI_ANY_SOURCE` and `MPI_TAG` as `MPI_ANY_TAG`
+ * (cf. MPI Standard v3; section 3.7.3).
+ *
+ * rationale: some MPI implementations don't initialize the members of `MPI_Status` correctly
+ *
+ * @returns _empty_ `MPI_Status` object
+ *
+ * @ingroup Utilities
+ */
+inline static MPI_Status MPI_Status_factory()
+{
+  MPI_Status stat;
+  stat.MPI_ERROR = MPI_SUCCESS;
+  stat.MPI_SOURCE = MPI_ANY_SOURCE;
+  stat.MPI_TAG = MPI_ANY_TAG;
+  return stat;
+}
+
+
 namespace pfasst
 {
   namespace mpi

src/pfasst/encap/vector_impl.hpp

@@ -207,7 +207,7 @@ namespace pfasst
       if (mpi.size() == 1) { return; }
       if (mpi.rank() == 0) { return; }
 
-      MPI_Status stat;
+      MPI_Status stat = MPI_Status_factory();
       int err = MPI_SUCCESS;
 
       if (blocking) {
@@ -231,7 +231,7 @@ namespace pfasst
       if (mpi.size() == 1) { return; }
       if (mpi.rank() == mpi.size() - 1) { return; }
 
-      MPI_Status stat;
+      MPI_Status stat = MPI_Status_factory();
       int err = MPI_SUCCESS;
       int dest = (mpi.rank() + 1) % mpi.size();