schwarz.hpp

// SPDX-FileCopyrightText: 2017 - 2025 The Ginkgo authors
//
// SPDX-License-Identifier: BSD-3-Clause
 
#ifndef GKO_PUBLIC_CORE_DISTRIBUTED_PRECONDITIONER_SCHWARZ_HPP_
#define GKO_PUBLIC_CORE_DISTRIBUTED_PRECONDITIONER_SCHWARZ_HPP_
 
 
#include <ginkgo/config.hpp>
 
 
#if GINKGO_BUILD_MPI
 
 
#include <ginkgo/core/base/abstract_factory.hpp>
#include <ginkgo/core/base/lin_op.hpp>
#include <ginkgo/core/config/config.hpp>
#include <ginkgo/core/config/registry.hpp>
#include <ginkgo/core/config/type_descriptor.hpp>
#include <ginkgo/core/distributed/matrix.hpp>
#include <ginkgo/core/distributed/vector.hpp>
#include <ginkgo/core/distributed/vector_cache.hpp>
#include <ginkgo/core/solver/solver_base.hpp>
 
 
namespace gko {
namespace experimental {
namespace distributed {
namespace preconditioner {
 
 
template <typename ValueType = default_precision,
          typename LocalIndexType = int32, typename GlobalIndexType = int64>
class Schwarz
    : public EnableLinOp<Schwarz<ValueType, LocalIndexType, GlobalIndexType>> {
    friend class EnableLinOp<Schwarz>;
    friend class EnablePolymorphicObject<Schwarz, LinOp>;
    GKO_ASSERT_SUPPORTED_VALUE_AND_DIST_INDEX_TYPE;
 
public:
    using EnableLinOp<Schwarz>::convert_to;
    using EnableLinOp<Schwarz>::move_to;
    using value_type = ValueType;
    using index_type = GlobalIndexType;
    using local_index_type = LocalIndexType;
    using global_index_type = GlobalIndexType;
 
    bool apply_uses_initial_guess() const override;
 
    GKO_CREATE_FACTORY_PARAMETERS(parameters, Factory)
    {
        std::shared_ptr<const LinOpFactory> GKO_DEFERRED_FACTORY_PARAMETER(
            local_solver);
 
        std::shared_ptr<const LinOp> GKO_FACTORY_PARAMETER_SCALAR(
            generated_local_solver, nullptr);
 
        bool GKO_FACTORY_PARAMETER_SCALAR(l1_smoother, false);
 
        ValueType GKO_FACTORY_PARAMETER_SCALAR(coarse_weight, ValueType{-1.0});
 
        std::shared_ptr<const LinOpFactory> GKO_DEFERRED_FACTORY_PARAMETER(
            coarse_level);
 
        std::shared_ptr<const LinOpFactory> GKO_DEFERRED_FACTORY_PARAMETER(
            coarse_solver);
    };
    GKO_ENABLE_LIN_OP_FACTORY(Schwarz, parameters, Factory);
    GKO_ENABLE_BUILD_METHOD(Factory);
 
    static parameters_type parse(
        const config::pnode& config, const config::registry& context,
        const config::type_descriptor& td_for_child =
            config::make_type_descriptor<ValueType, LocalIndexType,
                                         GlobalIndexType>());
 
protected:
    explicit Schwarz(std::shared_ptr<const Executor> exec)
        : EnableLinOp<Schwarz>(std::move(exec))
    {}
 
    explicit Schwarz(const Factory* factory,
                     std::shared_ptr<const LinOp> system_matrix)
        : EnableLinOp<Schwarz>(factory->get_executor(),
                               gko::transpose(system_matrix->get_size())),
          parameters_{factory->get_parameters()},
          system_matrix_{system_matrix}
    {
        this->generate(system_matrix);
    }
 
    void generate(std::shared_ptr<const LinOp> system_matrix);
 
    void apply_impl(const LinOp* b, LinOp* x) const override;
 
    template <typename VectorType>
    void apply_dense_impl(const VectorType* b, VectorType* x) const;
 
    void apply_impl(const LinOp* alpha, const LinOp* b, const LinOp* beta,
                    LinOp* x) const override;
 
private:
    void set_solver(std::shared_ptr<const LinOp> new_solver);
 
    std::shared_ptr<const LinOp> local_solver_;
    std::shared_ptr<const LinOp> system_matrix_;
 
    // Used for advanced apply
    detail::VectorCache<ValueType> cache_;
    // Used in apply for two-level method
    detail::VectorCache<ValueType> csol_cache_;
    detail::VectorCache<ValueType> crhs_cache_;
 
    std::shared_ptr<const LinOp> coarse_level_;
    std::shared_ptr<const LinOp> coarse_solver_;
    std::shared_ptr<const matrix::Dense<ValueType>> coarse_weight_;
    std::shared_ptr<const matrix::Dense<ValueType>> local_weight_;
};
 
 
}  // namespace preconditioner
}  // namespace distributed
}  // namespace experimental
}  // namespace gko
 
 
#endif  // GINKGO_BUILD_MPI
#endif  // GKO_PUBLIC_CORE_DISTRIBUTED_PRECONDITIONER_SCHWARZ_HPP_