Sync variable progress.

include/mpi/all.hpp

@@ -71,6 +71,7 @@
 
 #include <mpi/extensions/detach.hpp>
 #include <mpi/extensions/future.hpp>
+#include <mpi/extensions/sync_variable.hpp>
 
 #include <mpi/io/enums/access_mode.hpp>
 #include <mpi/io/enums/seek_mode.hpp>

include/mpi/extensions/sync_variable.hpp

@@ -0,0 +1,51 @@
+#pragma once
+
+#include <cstdint>
+
+#include <mpi/core/utility/container_adapter.hpp>
+
+namespace mpi
+{
+// The type must satisfy compliant.
+template <typename type>
+class sync_variable
+{
+public:
+  explicit sync_variable  (const communicator& communicator, const std::int32_t root = 0)
+  : communicator_(communicator), window_(communicator, sizeof type), root_(root)
+  {
+
+  }
+  sync_variable           (const sync_variable&  that) = delete ;
+  sync_variable           (      sync_variable&& temp) = default;
+  virtual ~sync_variable  ()                           = default;
+  sync_variable& operator=(const sync_variable&  that) = delete ;
+  sync_variable& operator=(      sync_variable&& temp) = default;
+
+  void put(const type& value)
+  {
+    window_.lock  (root_, false);
+    window_.put   (value , root_, 0, 1, container_adapter<type>::data_type());
+    window_.unlock(root_);
+  }                
+  [[nodiscard]]    
+  type get() const 
+  {               
+    type result;
+    window_.lock  (root_, false);
+    window_.get   (result, root_, 0, 1, container_adapter<type>::data_type());
+    window_.unlock(root_);
+    return result;
+  }
+
+  void synchronize() const
+  {
+    window_.fence();
+  }
+
+protected:
+  const communicator& communicator_;
+  window              window_      ;
+  std::int32_t        root_        ;
+};
+}

tests/future_test.cpp

@@ -1,5 +1,3 @@
-#include <iostream>
-
 #include "internal/doctest.h"
 
 #define MPI_USE_EXCEPTIONS

tests/sync_variable_test.cpp

@@ -0,0 +1,40 @@
+#include "internal/doctest.h"
+
+#define MPI_USE_EXCEPTIONS
+
+#include <mpi/all.hpp>
+
+TEST_CASE("Sync Variable Test")
+{
+  mpi::environment environment  ;
+  const auto&      communicator = mpi::world_communicator;
+
+  for (auto i = 0; i < 1000; ++i)
+  {
+    mpi::sync_variable<std::int32_t> variable(communicator);
+    if (communicator.rank() == 0)
+      variable.put(i);
+
+    variable.synchronize(); // Why is this necessary :(
+
+    if (communicator.rank() != 0)
+      REQUIRE(variable.get() == i);
+  }
+
+  for (auto i = 0; i < 1000; ++i)
+  {
+    mpi::sync_variable<std::array<std::int32_t, 3>> variable(communicator);
+    if (communicator.rank() == 0)
+      variable.put({i, i + 1, i + 2});
+
+    variable.synchronize(); // Why is this necessary :(
+
+    if (communicator.rank() != 0)
+    {
+      auto value = variable.get();
+      REQUIRE(value[0] == i    );
+      REQUIRE(value[1] == i + 1);
+      REQUIRE(value[2] == i + 2);
+    }
+  }
+}