mpiguard.hh

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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
// SPDX-FileCopyrightInfo: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception

#ifndef DUNE_COMMON_PARALLEL_MPIGUARD_HH
#define DUNE_COMMON_PARALLEL_MPIGUARD_HH

#if HAVE_MPI
#include <mpi.h>
#endif

#include <dune/common/exceptions.hh>
#include <dune/common/parallel/communication.hh>
#include <dune/common/parallel/mpicommunication.hh>
#include <dune/common/parallel/mpihelper.hh>

namespace Dune
{

#ifndef DOXYGEN

  /*
     Interface class for the communication needed by MPIGuard
   */
  struct GuardCommunicator
  {
    // cleanup
    virtual ~GuardCommunicator() {};
    // all the communication methods we need
    virtual int rank() = 0;
    virtual int size() = 0;
    virtual int sum(int i) = 0;
    // create a new GuardCommunicator pointer
    template <class C>
    static GuardCommunicator * create(const Communication<C> & c);
#if HAVE_MPI
    inline
    static GuardCommunicator * create(const MPI_Comm & c);
#endif
  };

  namespace {
    /*
       templated implementation of different communication classes
     */
    // the default class will always fail, due to the missing implementation of "sum"
    template <class Imp>
    struct GenericGuardCommunicator
      : public GuardCommunicator
    {};
    // specialization for Communication
    template <class T>
    struct GenericGuardCommunicator< Communication<T> >
      : public GuardCommunicator
    {
      const Communication<T> comm;
      GenericGuardCommunicator(const Communication<T> & c) :
        comm(c) {}
      int rank() override { return comm.rank(); };
      int size() override { return comm.size(); };
      int sum(int i) override { return comm.sum(i); }
    };

#if HAVE_MPI
    // specialization for MPI_Comm
    template <>
    struct GenericGuardCommunicator<MPI_Comm>
      : public GenericGuardCommunicator< Communication<MPI_Comm> >
    {
      GenericGuardCommunicator(const MPI_Comm & c) :
        GenericGuardCommunicator< Communication<MPI_Comm> >(
          Communication<MPI_Comm>(c)) {}
    };
#endif
  }   // anonymous namespace

  template<class C>
  GuardCommunicator * GuardCommunicator::create(const Communication<C> & comm)
  {
    return new GenericGuardCommunicator< Communication<C> >(comm);
  }

#if HAVE_MPI
  GuardCommunicator * GuardCommunicator::create(const MPI_Comm & comm)
  {
    return new GenericGuardCommunicator< Communication<MPI_Comm> >(comm);
  }
#endif

#endif

  class MPIGuardError : public ParallelError {};

  class MPIGuard
  {
    GuardCommunicator * comm_;
    bool active_;

    // we don't want to copy this class
    MPIGuard (const MPIGuard &);

  public:
    MPIGuard (bool active=true) :
      comm_(GuardCommunicator::create(
              MPIHelper::getCommunication())),
      active_(active)
    {}

    MPIGuard (MPIHelper & m, bool active=true) :
      comm_(GuardCommunicator::create(
              m.getCommunication())),
      active_(active)
    {}

    template <class C>
    MPIGuard (const C & comm, bool active=true) :
      comm_(GuardCommunicator::create(comm)),
      active_(active)
    {}

#if HAVE_MPI
     MPIGuard (const MPI_Comm & comm, bool active=true) :
      comm_(GuardCommunicator::create(comm)),
      active_(active)
    {}
#endif

    ~MPIGuard()
    {
      if (active_)
      {
        active_ = false;
        finalize(false);
      }
      delete comm_;
    }

    void reactivate() {
      if (active_ == true)
        finalize();
      active_ = true;
    }

    void finalize(bool success = true)
    {
      int result = success ? 0 : 1;
      bool was_active = active_;
      active_ = false;
      result = comm_->sum(result);
      if (result>0 && was_active)
      {
        DUNE_THROW(MPIGuardError, "Terminating process "
                   << comm_->rank() << " due to "
                   << result << " remote error(s)");
      }
    }
  };

}

#endif // DUNE_COMMON_PARALLEL_MPIGUARD_HH