[dist] add device partition

core/distributed/device_partition.hpp

@@ -0,0 +1,92 @@
+// SPDX-FileCopyrightText: 2024 The Ginkgo authors
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+#ifndef GINKGO_PARTITION_HPP
+#define GINKGO_PARTITION_HPP
+
+#include <ginkgo/core/distributed/partition.hpp>
+
+#include "core/base/segmented_array.hpp"
+
+namespace gko {
+
+
+template <typename LocalIndexType, typename GlobalIndexType>
+struct device_partition {
+    using local_index_type = LocalIndexType;
+    using global_index_type = GlobalIndexType;
+    using comm_index_type = experimental::distributed::comm_index_type;
+
+    comm_index_type num_parts;
+    comm_index_type num_empty_parts;
+    size_type size;
+    global_index_type* offsets_begin;
+    global_index_type* offsets_end;
+    local_index_type* starting_indices_begin;
+    local_index_type* starting_indices_end;
+    local_index_type* part_sizes_begin;
+    local_index_type* part_sizes_end;
+    const comm_index_type* part_ids_begin;
+    const comm_index_type* part_ids_end;
+    device_segmented_array<const size_type> ranges_by_part;
+};
+
+
+/**
+ * Create device_segmented_array from a segmented_array.
+ */
+template <typename LocalIndexType, typename GlobalIndexType>
+constexpr device_partition<const LocalIndexType, const GlobalIndexType>
+to_device(
+    const experimental::distributed::Partition<LocalIndexType, GlobalIndexType>*
+        partition)
+{
+    auto num_ranges = partition->get_num_ranges();
+    auto num_parts = partition->get_num_parts();
+    return {num_parts,
+            partition->get_num_empty_parts(),
+            partition->get_size(),
+            partition->get_range_bounds(),
+            partition->get_range_bounds() + num_ranges + 1,
+            partition->get_range_starting_indices(),
+            partition->get_range_starting_indices() + num_ranges,
+            partition->get_part_sizes(),
+            partition->get_part_sizes() + num_parts,
+            partition->get_part_ids(),
+            partition->get_part_ids() + num_parts,
+            to_device(partition->get_ranges_by_part())};
+}
+
+/**
+ * Explicitly create a const version of device_segmented_array.
+ *
+ * This is mostly relevant for tests.
+ */
+template <typename LocalIndexType, typename GlobalIndexType>
+constexpr device_partition<const LocalIndexType, const GlobalIndexType>
+to_device_const(
+    const experimental::distributed::Partition<LocalIndexType, GlobalIndexType>*
+        partition)
+{
+    auto num_ranges = partition->get_num_ranges();
+    auto num_parts = partition->get_num_parts();
+    return {num_parts,
+            partition->get_num_empty_parts(),
+            partition->get_size(),
+            partition->get_range_bounds(),
+            partition->get_range_bounds() + num_ranges + 1,
+            partition->get_range_starting_indices(),
+            partition->get_range_starting_indices() + num_ranges,
+            partition->get_part_sizes(),
+            partition->get_part_sizes() + num_parts,
+            partition->get_part_ids(),
+            partition->get_part_ids() + num_parts,
+            to_device(partition->get_ranges_by_part())};
+}
+
+
+}  // namespace gko
+
+
+#endif  // GINKGO_PARTITION_HPP