feat: MpiWrapper::allReduce overload for arrays.

src/coreComponents/common/CMakeLists.txt

@@ -48,6 +48,7 @@ set( common_headers
      Tensor.hpp
      TimingMacros.hpp
      TypeDispatch.hpp
+     TypesHelpers.hpp
      initializeEnvironment.hpp
      LifoStorage.hpp
      LifoStorageCommon.hpp

src/coreComponents/common/MpiWrapper.hpp

@@ -22,6 +22,7 @@
 
 #include "common/DataTypes.hpp"
 #include "common/Span.hpp"
+#include "common/TypesHelpers.hpp"
 
 #if defined(GEOS_USE_MPI)
   #include <mpi.h>
@@ -385,6 +386,17 @@ struct MpiWrapper
   template< typename T >
   static void allReduce( Span< T const > src, Span< T > dst, Reduction const op, MPI_Comm comm = MPI_COMM_GEOS );
 
+  /**
+   * @brief Convenience wrapper for the MPI_Allreduce function. Version for arrays.
+   * @tparam T type of data to reduce. Must correspond to a valid MPI_Datatype.
+   * @param src[in] The values to send to the reduction.
+   * @param dst[out] The resulting values.
+   * @param op The Reduction enum to perform.
+   * @param comm The communicator.
+   */
+  template< typename CONTAINER_TYPE >
+  static void allReduce( CONTAINER_TYPE const & src, CONTAINER_TYPE & dst, Reduction const op, MPI_Comm const comm = MPI_COMM_GEOS );
+
 
   /**
    * @brief Strongly typed wrapper around MPI_Reduce.
@@ -1073,6 +1085,15 @@ void MpiWrapper::allReduce( Span< T const > const src, Span< T > const dst, Redu
   allReduce( src.data(), dst.data(), LvArray::integerConversion< int >( src.size() ), getMpiOp( op ), comm );
 }
 
+template< typename CONTAINER_TYPE >
+void MpiWrapper::allReduce( CONTAINER_TYPE const & src, CONTAINER_TYPE & dst, Reduction const op, MPI_Comm const comm )
+{
+  static_assert( std::is_trivially_copyable< typename get_value_type< CONTAINER_TYPE >::type >::value,
+                 "The type in the container must be trivially copiable." );
+  GEOS_ASSERT_EQ( src.size(), dst.size() );
+  allReduce( src.data(), dst.data(), LvArray::integerConversion< int >( src.size() ), getMpiOp( op ), comm );
+}
+
 template< typename T >
 T MpiWrapper::sum( T const & value, MPI_Comm comm )
 {

src/coreComponents/common/TypesHelpers.hpp

@@ -0,0 +1,66 @@
+/*
+ * ------------------------------------------------------------------------------------------------------------
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ * Copyright (c) 2016-2024 Lawrence Livermore National Security LLC
+ * Copyright (c) 2018-2024 Total, S.A
+ * Copyright (c) 2018-2024 The Board of Trustees of the Leland Stanford Junior University
+ * Copyright (c) 2023-2024 Chevron
+ * Copyright (c) 2019-     GEOS/GEOSX Contributors
+ * All rights reserved
+ *
+ * See top level LICENSE, COPYRIGHT, CONTRIBUTORS, NOTICE, and ACKNOWLEDGEMENTS files for details.
+ * ------------------------------------------------------------------------------------------------------------
+ */
+
+/**
+ * @file TypeHelpers.hpp
+ *
+ */
+
+#ifndef TYPES_HELPERS_HPP
+#define TYPES_HELPERS_HPP
+
+#include <type_traits>
+
+namespace geos
+{
+
+namespace internal
+{
+
+template< typename T, typename = void >
+struct has_value_type : std::false_type {};
+
+template< typename T >
+struct has_value_type< T, std::void_t< typename T::value_type > > : std::true_type {};
+
+template< typename T, typename = void >
+struct has_ValueType : std::false_type {};
+
+template< typename T >
+struct has_ValueType< T, std::void_t< typename T::ValueType > > : std::true_type {};
+
+}   // namespace internal
+
+template< typename T, typename Enable = void >
+struct get_value_type
+{
+  static_assert( sizeof(T) == 0, "CONTAINER_TYPE must define either value_type or ValueType." );
+};
+
+template< typename T >
+struct get_value_type< T, std::enable_if_t< internal::has_value_type< T >::value > >
+{
+  using type = typename T::value_type;
+};
+
+template< typename T >
+struct get_value_type< T, std::enable_if_t< !internal::has_value_type< T >::value && internal::has_ValueType< T >::value > >
+{
+  using type = typename T::ValueType;
+};
+
+} // namespace geos
+
+#endif /* TYPES_HELPERS_HPP */

src/coreComponents/physicsSolvers/PhysicsSolverBaseKernels.hpp

@@ -309,16 +309,17 @@ class L2ResidualNormHelper
   {
     array1d< real64 > sumLocalResidualNorm( localResidualNorm.size() );
     array1d< real64 > sumLocalResidualNormalizer( localResidualNormalizer.size() );
-    MpiWrapper::allReduce( localResidualNorm.data(),
-                           sumLocalResidualNorm.data(),
-                           localResidualNorm.size(),
-                           MpiWrapper::getMpiOp( MpiWrapper::Reduction::Sum ),
+
+    MpiWrapper::allReduce( localResidualNorm,
+                           sumLocalResidualNorm,
+                           MpiWrapper::Reduction::Sum,
                            MPI_COMM_GEOS );
+
     MpiWrapper::allReduce( localResidualNormalizer.data(),
                            sumLocalResidualNormalizer.data(),
-                           localResidualNormalizer.size(),
-                           MpiWrapper::getMpiOp( MpiWrapper::Reduction::Sum ),
+                           MpiWrapper::Reduction::Sum,
                            MPI_COMM_GEOS );
+
     for( integer i = 0; i < localResidualNorm.size(); ++i )
     {
       globalResidualNorm[i] = sqrt( sumLocalResidualNorm[i] ) / sqrt( sumLocalResidualNormalizer[i] );