Extract Particle Communication And Update Infrastructure From PR501

src/Communicate/Archive.h

@@ -9,6 +9,9 @@
 //   that they have type char and thus contain raw bytes, unlike other typed buffers
 //   such as detail::FieldBufferData used by HaloCells.
 //
+//   On CUDA/HIP the internal buffer is allocated directly via cudaMalloc/hipMalloc
+//   so that the pointer is page-aligned (4K) and compatible with MPI IPC.
+//
 #ifndef IPPL_ARCHIVE_H
 #define IPPL_ARCHIVE_H
 
@@ -32,6 +35,7 @@ namespace ippl {
             using pointer_type = typename buffer_type::pointer_type;
 
             Archive(size_type size = 0);
+            ~Archive();
 
             /*!
              * Serialize.
@@ -40,6 +44,10 @@ namespace ippl {
             template <typename T, class... ViewArgs>
             void serialize(const Kokkos::View<T*, ViewArgs...>& view, size_type nsends);
 
+            template <typename T, class... ViewArgs, typename HashView>
+            void serialize(const Kokkos::View<T*, ViewArgs...>& view, const HashView& hash,
+                           size_type nsends);
+
             /*!
              * Serialize vector attributes
              *
@@ -52,13 +60,25 @@ namespace ippl {
             void serialize(const Kokkos::View<Vector<T, Dim>*, ViewArgs...>& view,
                            size_type nsends);
 
+            template <typename T, unsigned Dim, class... ViewArgs, typename HashView>
+            void serialize(const Kokkos::View<Vector<T, Dim>*, ViewArgs...>& view,
+                           const HashView& hash, size_type nsends);
+
             /*!
              * Deserialize.
              * @param view to put data to
              */
             template <typename T, class... ViewArgs>
             void deserialize(Kokkos::View<T*, ViewArgs...>& view, size_type nrecvs);
 
+            template <typename T, class... ViewArgs>
+            void deserialize(Kokkos::View<T*, ViewArgs...>& view, size_type offset,
+                             size_type nrecvs);
+
+            template <typename T, unsigned Dim, class... ViewArgs>
+            void deserialize(Kokkos::View<Vector<T, Dim>*, ViewArgs...>& view, size_type offset,
+                             size_type nrecvs);
+
             /*!
              * Deserialize vector attributes
              *
@@ -71,33 +91,50 @@ namespace ippl {
             void deserialize(Kokkos::View<Vector<T, Dim>*, ViewArgs...>& view, size_type nrecvs);
 
             /*!
-             * @returns a pointer to the data of the buffer
+             * @returns a pointer to the data of the buffer.
+             *          On GPU this is a page-aligned device pointer from cudaMalloc/hipMalloc.
              */
-            pointer_type getBuffer() { return buffer_m.data(); }
+            pointer_type getBuffer() { return bufferData(); }
 
             /*!
-             * @returns the size of the buffer
+             * @returns the number of bytes written so far
              */
             size_type getSize() const { return writepos_m; }
 
-            size_type getBufferSize() const { return buffer_m.size(); }
-
-            void resizeBuffer(size_type size) { Kokkos::resize(buffer_m, size); }
+            /*!
+             * @returns the total capacity of the buffer in bytes
+             */
+            size_type getBufferSize() const { return bufferSize(); }
 
-            void reallocBuffer(size_type size) { Kokkos::realloc(buffer_m, size); }
+            void resizeBuffer(size_type size);
+            void reallocBuffer(size_type size);
 
             void resetWritePos() { writepos_m = 0; }
             void resetReadPos() { readpos_m = 0; }
 
-            ~Archive() = default;
-
         private:
             //! write position for serialization
             size_type writepos_m;
             //! read position for deserialization
             size_type readpos_m;
-            //! serialized data
+
+#if defined(KOKKOS_ENABLE_CUDA) || defined(KOKKOS_ENABLE_HIP)
+            //! Raw device pointer from cudaMalloc/hipMalloc (page-aligned, IPC-safe)
+            pointer_type buffer_ptr_m = nullptr;
+            size_type buffer_size_m   = 0;
+
+            pointer_type bufferData() const { return buffer_ptr_m; }
+            size_type bufferSize() const { return buffer_size_m; }
+
+            void gpuAlloc(size_type size);
+            void gpuFree();
+#else
+            //! serialized data (standard Kokkos view on CPU)
             buffer_type buffer_m;
+
+            pointer_type bufferData() const { return buffer_m.data(); }
+            size_type bufferSize() const { return buffer_m.size(); }
+#endif
         };
     }  // namespace detail
 }  // namespace ippl