Add an exchange function which allows to send/recv Array lists

This function is by now only valid for integer Array vector (send array lists
constant values)

src/utils/Messenger.cpp

@@ -113,3 +113,49 @@ _broadcast(Array<int>& array, int root_rank) const
 #endif // PASTIS_HAS_MPI
   return array;
 }
+
+
+void Messenger::
+_exchange(const std::vector<Array<const int>>& sent_array_list,
+          std::vector<Array<int>>& recv_array_list) const
+{
+#ifdef PASTIS_HAS_MPI
+  std::vector<MPI_Request> request_list;
+
+  for (size_t i_send=0; i_send<sent_array_list.size(); ++i_send) {
+    const Array<const int> sent_array = sent_array_list[i_send];
+    if (sent_array.size()>0) {
+      MPI_Request request;
+      MPI_Isend(&(sent_array[0]), sent_array.size(), MPI_INT, i_send, 0, MPI_COMM_WORLD, &request);
+      request_list.push_back(request);
+    }
+  }
+
+  for (size_t i_recv=0; i_recv<recv_array_list.size(); ++i_recv) {
+    Array<int> recv_array = recv_array_list[i_recv];
+    if (recv_array.size()>0) {
+      MPI_Request request;
+      MPI_Irecv(&(recv_array[0]), recv_array.size(), MPI_INT, i_recv, 0, MPI_COMM_WORLD, &request);
+      request_list.push_back(request);
+    }
+  }
+
+  std::vector<MPI_Status> status_list(request_list.size());
+  if (MPI_SUCCESS != MPI_Waitall(request_list.size(), &(request_list[0]), &(status_list[0]))) {
+    std::cerr << "Communication error!\n";
+    std::exit(1);
+  }
+
+#else // PASTIS_HAS_MPI
+  std::cerr << "NIY\n";
+  std::exit(1);
+#endif // PASTIS_HAS_MPI
+}
+
+void Messenger::
+_exchange(const std::vector<Array<int>>& sent_array_list,
+          std::vector<Array<int>>& recv_array_list) const
+{
+  std::cerr << "NIY\n";
+  std::exit(1);
+}

src/utils/Messenger.hpp

@@ -21,6 +21,10 @@ class Messenger
   Array<int> _broadcast(Array<int>& array, int root_rank) const;
   Array<int> _allToAll(const Array<int>& sent_array, Array<int>& recv_array) const;
 
+  void _exchange(const std::vector<Array<const int>>& sent_array_list,
+                 std::vector<Array<int>>& recv_array_list) const;
+  void _exchange(const std::vector<Array<int>>& sent_array_list,
+                 std::vector<Array<int>>& recv_array_list) const;
  public:
   static void create(int& argc, char* argv[]);
   static void destroy();
@@ -95,6 +99,24 @@ class Messenger
     }
   }
 
+  template <typename SendDataType,
+            typename RecvDataType>
+  PASTIS_INLINE
+  void exchange(const std::vector<Array<SendDataType>>& sent_array_list,
+                std::vector<Array<RecvDataType>>& recv_array_list) const
+  {
+    static_assert(std::is_same_v<std::remove_const_t<SendDataType>,RecvDataType>,
+                  "send and receive data type do not match");
+    static_assert(not std::is_const_v<RecvDataType>,
+                  "receive data type cannot be const");
+
+    if constexpr(std::is_same<RecvDataType, int>()) {
+      _exchange(sent_array_list, recv_array_list);
+    } else {
+      static_assert(std::is_same<RecvDataType, int>(), "unexpected type of data");
+    }
+  }
+
   Messenger(const Messenger&) = delete;
   ~Messenger();
 };
@@ -153,4 +175,18 @@ Array<DataType> broadcast(const Array<DataType>& array, int root_rank)
   return messenger().broadcast(array, root_rank);
 }
 
+template <typename SendDataType,
+          typename RecvDataType>
+PASTIS_INLINE
+void exchange(const std::vector<Array<SendDataType>>& sent_array_list,
+              std::vector<Array<RecvDataType>>& recv_array_list)
+{
+  static_assert(std::is_same_v<std::remove_const_t<SendDataType>,RecvDataType>,
+                "send and receive data type do not match");
+  static_assert(not std::is_const_v<RecvDataType>,
+                "receive data type cannot be const");
+
+  messenger().exchange(sent_array_list, recv_array_list);
+}
+
 #endif // MESSENGER_HPP