minor refactoring before adding the optimiezd version

src/field/DistributedField.cpp

@@ -143,7 +143,20 @@ namespace gmshfem::field
       local.push_back({dof->numType(), dof->entity(), rank});
     }
 
+    
+    // MPI type for key/rank
+    int blocklengths[3] = {1, 1, 1};
+    MPI_Datatype types[3] = {MPI_UNSIGNED_LONG, MPI_UNSIGNED_LONG, MPI_INT};
+    MPI_Datatype mpi_struct_type;
+    MPI_Aint offsets[3];
+    offsets[0] = offsetof(ShareDofInfo, type);
+    offsets[1] = offsetof(ShareDofInfo, entity);
+    offsets[2] = offsetof(ShareDofInfo, this_rank);
+    MPI_Type_create_struct(3, blocklengths, offsets, types, &mpi_struct_type);
+    MPI_Type_commit(&mpi_struct_type);
+
     // Get the sizes and offset of the global array
+    if(!neighboringRanks) {
       int total_size = 0;
       std::vector< int > sizes(commSize), displs(commSize);
       int loc_size = local.size();
@@ -154,23 +167,19 @@ namespace gmshfem::field
         total_size += sizes[i];
       }
 
-    // Create temporary MPI Type for the struct
-    const int nitems = 3;
-    int blocklengths[3] = {1, 1, 1};
-    MPI_Datatype types[3] = {MPI_UNSIGNED_LONG, MPI_UNSIGNED_LONG, MPI_INT};
-    MPI_Datatype mpi_struct_type;
-    MPI_Aint offsets[3];
-    offsets[0] = offsetof(ShareDofInfo, type);
-    offsets[1] = offsetof(ShareDofInfo, entity);
-    offsets[2] = offsetof(ShareDofInfo, this_rank);
-    MPI_Type_create_struct(nitems, blocklengths, offsets, types, &mpi_struct_type);
-    MPI_Type_commit(&mpi_struct_type);
       // Synchronize the full array
       global.resize(total_size);
 
+      if(rank == 0)
+        msg::info << "Synchronizing Interface Ownership with a total of " << global.size() << " interface DOFs exchanged." << msg::endl;
+
       MPI_Allgatherv(local.data(), local.size(), mpi_struct_type,
                      global.data(), sizes.data(), displs.data(), mpi_struct_type,
                      MPI_COMM_WORLD);
+    }
+    else {
+      // TODO
+    }
 
     // Free the type
     MPI_Type_free(&mpi_struct_type);