Displace some code to header file

All communication encapsulations are going to the header file to provide maximal
generality (we want to exchange more than just Array<int>).

src/utils/Messenger.cpp

 #include <Messenger.hpp>
 #include <PastisOStream.hpp>
 
-#include <pastis_config.hpp>
-
-#ifdef PASTIS_HAS_MPI
-#include <mpi.h>
-#endif // PASTIS_HAS_MPI
-
 Messenger* Messenger::m_instance = nullptr;
 
 void Messenger::create(int& argc, char* argv[])
@@ -113,62 +107,3 @@ _broadcast(Array<int>& array, int root_rank) const
 #endif // PASTIS_HAS_MPI
   return array;
 }
-
-template <typename DataType>
-void Messenger::
-_exchange(const std::vector<Array<DataType>>& sent_array_list,
-          std::vector<Array<std::remove_const_t<DataType>>>& recv_array_list) const
-{
-#ifdef PASTIS_HAS_MPI
-  std::vector<MPI_Request> request_list;
-
-  MPI_Datatype type = [&] () -> MPI_Datatype {
-                if constexpr (std::is_same_v<int,std::remove_const_t<DataType>>) {
-                  return MPI_INT;
-                } else if constexpr (std::is_same_v<CellType,std::remove_const_t<DataType>>) {
-                  return MPI_SHORT;
-                }
-              } ();
-  for (size_t i_send=0; i_send<sent_array_list.size(); ++i_send) {
-    const Array<DataType> sent_array = sent_array_list[i_send];
-    if (sent_array.size()>0) {
-      MPI_Request request;
-      MPI_Isend(&(sent_array[0]), sent_array.size(), type, 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<std::remove_const_t<DataType>> recv_array = recv_array_list[i_recv];
-    if (recv_array.size()>0) {
-      MPI_Request request;
-      MPI_Irecv(&(recv_array[0]), recv_array.size(), type, 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
-}
-
-template
-void Messenger::_exchange(const std::vector<Array<int>>& sent_array_list,
-                          std::vector<Array<int>>& recv_array_list) const;
-template
-void Messenger::_exchange(const std::vector<Array<const int>>& sent_array_list,
-                          std::vector<Array<int>>& recv_array_list) const;
-
-template
-void Messenger::_exchange(const std::vector<Array<CellType>>& sent_array_list,
-                          std::vector<Array<CellType>>& recv_array_list) const;
-template
-void Messenger::_exchange(const std::vector<Array<const CellType>>& sent_array_list,
-                          std::vector<Array<CellType>>& recv_array_list) const;

src/utils/Messenger.hpp

@@ -6,12 +6,39 @@
 
 #include <Array.hpp>
 
+#include <type_traits>
+
+#include <pastis_config.hpp>
+#ifdef PASTIS_HAS_MPI
+#include <mpi.h>
+#endif // PASTIS_HAS_MPI
+
 #warning REMOVE
 enum class CellType : unsigned short;
 
 class Messenger
 {
  private:
+#ifdef PASTIS_HAS_MPI
+  struct Helper
+  {
+    template<typename DataType>
+    static PASTIS_INLINE
+    MPI_Datatype mpiType()
+    {
+      if constexpr (std::is_const_v<DataType>) {
+        return mpiType<std::remove_const_t<DataType>>();
+      } else {
+        static_assert(std::is_arithmetic_v<DataType>,
+                      "Unexpected arithmetic type! Should not occur!");
+        static_assert(not std::is_arithmetic_v<DataType>,
+                      "MPI_Datatype are only defined for arithmetic types!");
+        return MPI_Datatype();
+      }
+    }
+  };
+#endif PASTIS_HAS_MPI
+
   static Messenger* m_instance;
   Messenger(int& argc, char* argv[]);
 
@@ -26,7 +53,51 @@ class Messenger
 
   template <typename DataType>
   void _exchange(const std::vector<Array<DataType>>& sent_array_list,
-                 std::vector<Array<std::remove_const_t<DataType>>>& recv_array_list) const;
+                 std::vector<Array<std::remove_const_t<DataType>>>& recv_array_list) const
+  {
+#ifdef PASTIS_HAS_MPI
+    std::vector<MPI_Request> request_list;
+
+#warning clean-up
+    MPI_Datatype type = [&] () -> MPI_Datatype {
+                          if constexpr (std::is_same_v<CellType,std::remove_const_t<DataType>>) {
+                            return MPI_SHORT;
+                          } else {
+                            return Messenger::Helper::mpiType<DataType>();
+                          }
+                        } ();
+
+
+    for (size_t i_send=0; i_send<sent_array_list.size(); ++i_send) {
+      const Array<DataType> sent_array = sent_array_list[i_send];
+      if (sent_array.size()>0) {
+        MPI_Request request;
+        MPI_Isend(&(sent_array[0]), sent_array.size(), type, 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<std::remove_const_t<DataType>> recv_array = recv_array_list[i_recv];
+      if (recv_array.size()>0) {
+        MPI_Request request;
+        MPI_Irecv(&(recv_array[0]), recv_array.size(), type, 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
+  }
+
 
  public:
   static void create(int& argc, char* argv[]);
@@ -113,7 +184,7 @@ class Messenger
     static_assert(not std::is_const_v<RecvDataType>,
                   "receive data type cannot be const");
 
-    if constexpr(std::is_same<RecvDataType, int>()) {
+    if constexpr(std::is_arithmetic_v<RecvDataType>) {
       _exchange(sent_array_list, recv_array_list);
     } else if constexpr(std::is_same<RecvDataType, CellType>()) {
       _exchange(sent_array_list, recv_array_list);
@@ -194,4 +265,56 @@ void exchange(const std::vector<Array<SendDataType>>& sent_array_list,
   messenger().exchange(sent_array_list, recv_array_list);
 }
 
+#ifdef PASTIS_HAS_MPI
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<char>() {return MPI_CHAR; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<int8_t>() {return MPI_INT8_T; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<int16_t>() {return MPI_INT16_T; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<int32_t>() {return MPI_INT32_T; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<int64_t>() {return MPI_INT64_T; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<uint8_t>() {return MPI_UINT8_T; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<uint16_t>() {return MPI_UINT16_T; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<uint32_t>() {return MPI_UINT32_T; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<uint64_t>() {return MPI_UINT64_T; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<signed long long int>() {return MPI_LONG_LONG_INT; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<unsigned long long int>() {return MPI_UNSIGNED_LONG_LONG; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<float>() {return MPI_FLOAT; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<double>() {return MPI_DOUBLE; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<long double>() {return MPI_LONG_DOUBLE; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<wchar_t>() {return MPI_WCHAR; }
+
+template<> PASTIS_INLINE MPI_Datatype
+Messenger::Helper::mpiType<bool>() {return MPI_CXX_BOOL; }
+
+#endif // PASTIS_HAS_MPI
+
 #endif // MESSENGER_HPP