ISTLSolverRuntimeOptionProxy.hpp

/*
  Copyright 2025 Equinor ASA

  This file is part of the Open Porous Media project (OPM).
  OPM is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  OPM is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  You should have received a copy of the GNU General Public License
  along with OPM.  If not, see <http://www.gnu.org/licenses/>.
*/

#ifndef OPM_ISTLSOLVERRUNTIMEOPTIONPROXY_HEADER_INCLUDED
#define OPM_ISTLSOLVERRUNTIMEOPTIONPROXY_HEADER_INCLUDED

#include "opm/simulators/linalg/FlowLinearSolverParameters.hpp"
#include <opm/simulators/linalg/setupPropertyTree.hpp>
#include <opm/simulators/linalg/AbstractISTLSolver.hpp>
#include <opm/simulators/linalg/ISTLSolver.hpp>
#include <opm/models/utils/propertysystem.hh>
#if COMPILE_GPU_BRIDGE
#include <opm/simulators/linalg/ISTLSolverGpuBridge.hpp>
#endif

#if USE_HIP
#include <opm/simulators/linalg/gpuistl_hip/ISTLSolverGPUISTL.hpp>
#elif HAVE_CUDA
#include <opm/simulators/linalg/gpuistl/ISTLSolverGPUISTL.hpp>
#endif

#include <opm/simulators/linalg/system/ISTLSolverSystem.hpp>

#include <filesystem>
#include <fmt/format.h>

namespace Opm
{

template <class TypeTag>
class ISTLSolverRuntimeOptionProxy : public AbstractISTLSolver<GetPropType<TypeTag, Properties::SparseMatrixAdapter>,
                                                               GetPropType<TypeTag, Properties::GlobalEqVector>>
{
public:
    using SparseMatrixAdapter = GetPropType<TypeTag, Properties::SparseMatrixAdapter>;
    using Vector = GetPropType<TypeTag, Properties::GlobalEqVector>;
    using Simulator = GetPropType<TypeTag, Properties::Simulator>;
    using Matrix = typename SparseMatrixAdapter::IstlMatrix;

#if HAVE_MPI
    using CommunicationType = Dune::OwnerOverlapCopyCommunication<int, int>;
#else
    using CommunicationType = Dune::Communication<int>;
#endif


    static void registerParameters()
    {
        FlowLinearSolverParameters::registerParameters();
    }

    ISTLSolverRuntimeOptionProxy(const Simulator& simulator,
                                 const FlowLinearSolverParameters& parameters,
                                 bool forceSerial = false)
    {
        createSolver(simulator, parameters, forceSerial);
    }

    explicit ISTLSolverRuntimeOptionProxy(const Simulator& simulator)
    {
        createSolver(simulator);
    }


    void eraseMatrix() override
    {
        istlSolver_->eraseMatrix();
    }

    void setActiveSolver(int num) override
    {
        istlSolver_->setActiveSolver(num);
    }

    int numAvailableSolvers() const override
    {
        return istlSolver_->numAvailableSolvers();
    }

    void prepare(const SparseMatrixAdapter& M, Vector& b) override
    {
        istlSolver_->prepare(M, b);
    }

    void prepare(const Matrix& M, Vector& b) override
    {
        istlSolver_->prepare(M, b);
    }

    void setResidual(Vector& b) override
    {
        istlSolver_->setResidual(b);
    }

    void getResidual(Vector& b) const override
    {
        istlSolver_->getResidual(b);
    }

    void setMatrix(const SparseMatrixAdapter& M) override
    {
        istlSolver_->setMatrix(M);
    }

    bool solve(Vector& x) override
    {
        return istlSolver_->solve(x);
    }

    int iterations() const override
    {
        return istlSolver_->iterations();
    }

    const CommunicationType* comm() const override
    {
        return istlSolver_->comm();
    }

    int getSolveCount() const override
    {
        return istlSolver_->getSolveCount();
    }

private:
    std::unique_ptr<AbstractISTLSolver<SparseMatrixAdapter, Vector>> istlSolver_;


    template <class... Args>
    void createSolver(const Simulator& simulator, Args&&... args)
    {
        auto linSolverConf = Parameters::Get<Parameters::LinearSolver>();
        bool useSystemCpr = (linSolverConf == "system_cpr");
        if (!useSystemCpr && linSolverConf.size() > 5
            && linSolverConf.ends_with(".json")
            && std::filesystem::exists(linSolverConf)) {
            try {
                PropertyTree prm(linSolverConf);
                useSystemCpr = (prm.get<std::string>("preconditioner.type", "") == "system_cpr");
            } catch (...) {}
        }
        if (useSystemCpr) {
            using Indices = GetPropType<TypeTag, Properties::Indices>;
            const auto backend = Parameters::linearSolverAcceleratorTypeFromCLI();
            if (backend != Parameters::LinearSolverAcceleratorType::CPU) {
                OPM_THROW(std::invalid_argument,
                          "The system_cpr preconditioner currently only "
                          "supports --linear-solver-accelerator=cpu");
            }
            // System solver types are hardcoded for 3-equation blackoil (see SystemTypes.hpp).
            if constexpr (Indices::numEq == 3) {
                istlSolver_ = std::make_unique<ISTLSolverSystem<TypeTag>>(
                    simulator, std::forward<Args>(args)...);
            } else {
                OPM_THROW(std::invalid_argument,
                          "The system_cpr preconditioner is only supported for "
                          "standard 3-phase blackoil (3 equations). This model has " +
                              std::to_string(Indices::numEq) + " equations.");
            }
            checkSystemCPRMatrixAddWell(Parameters::Get<Parameters::MatrixAddWellContributions>());
            return;
        }

        const auto backend = Parameters::linearSolverAcceleratorTypeFromCLI();
        if (backend == Parameters::LinearSolverAcceleratorType::CPU) {
        // Note that for now we keep the old behavior of using the bridge solver if it is available.
#if COMPILE_GPU_BRIDGE
            istlSolver_ = std::make_unique<ISTLSolverGpuBridge<TypeTag>>(simulator, std::forward<Args>(args)...);
#else
            istlSolver_ = std::make_unique<ISTLSolver<TypeTag>>(simulator, std::forward<Args>(args)...);
#endif
        }
#if HAVE_CUDA
        else if (backend == Parameters::LinearSolverAcceleratorType::GPU) {
            istlSolver_ = std::make_unique<gpuistl::ISTLSolverGPUISTL<TypeTag>>(simulator, std::forward<Args>(args)...);
        }
#endif
        else {
            // If we reach here, it means the backend is not supported. This could be because we have added a third backend
            // that we need to handle. A user error would be handled in the linearSolverAcceleratorTypeFromString function called above.
            OPM_THROW(std::invalid_argument, fmt::format(fmt::runtime("Unknown backend: {}"), Parameters::toString(backend)));
        }
    }
};
} // namespace Opm

#endif