globals.hpp

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// Copyright (c) 2010, Lawrence Livermore National Security, LLC. Produced at
// the Lawrence Livermore National Laboratory. LLNL-CODE-443211. All Rights
// reserved. See file COPYRIGHT for details.
//
// This file is part of the MFEM library. For more information and source code
// availability see http://mfem.org.
//
// MFEM is free software; you can redistribute it and/or modify it under the
// terms of the GNU Lesser General Public License (as published by the Free
// Software Foundation) version 2.1 dated February 1999.

#ifndef MFEM_GLOBALS_HPP
#define MFEM_GLOBALS_HPP

#include "../config/config.hpp"
#include <iostream>

#ifdef MFEM_USE_MPI
#include <mpi.h>
#endif

namespace mfem
{

/// Simple extension of std::ostream.
/** This class adds the ability to enable and disable the stream. The associated
    std::streambuf and tied std::ostream can be replaced with that of any
    std::ostream. */
class OutStream : public std::ostream
{
protected:
   // Pointer that stores the associated streambuf when output is disabled.
   std::streambuf *m_rdbuf;
   // Pointer that stores the tied ostream when output is disabled.
   std::ostream *m_tie;

public:
   /** @brief Construct an OutStream from the given stream @a out, by using its
       `rdbuf()`. */
   OutStream(std::ostream &out) : std::ostream(NULL) { SetStream(out); }

   /** @brief Replace the `rdbuf()` and `tie()` of the OutStream with that of
       @a out, enabling output. */
   void SetStream(std::ostream &out)
   {
      rdbuf(m_rdbuf = out.rdbuf()); tie(m_tie = out.tie());
   }

   /// Enable output.
   void Enable() { if (!IsEnabled()) { rdbuf(m_rdbuf); tie(m_tie); } }
   /// Disable output.
   void Disable()
   {
      if (IsEnabled()) { m_rdbuf = rdbuf(NULL); m_tie = tie(NULL); }
   }
   /// Check if output is enabled.
   bool IsEnabled() const { return (rdbuf() != NULL); }
};


/** @brief Global stream used by the library for standard output. Initially it
    uses the same std::streambuf as std::cout, however that can be changed.
    @sa OutStream. */
extern OutStream out;
/** @brief Global stream used by the library for standard error output.
    Initially it uses the same std::streambuf as std::cerr, however that can be
    changed.
    @sa OutStream. */
extern OutStream err;


/** @brief Construct a string of the form "<prefix><myid><suffix>" where the
    integer @a myid is padded with leading zeros to be at least @a width digits
    long. */
/** This is a convenience function, e.g. to redirect mfem::out to individual
    files for each rank, one can use:
    \code
       std::ofstream out_file(MakeParFilename("app_out.", myid).c_str());
       mfem::out.SetStream(out_file);
    \endcode
*/
std::string MakeParFilename(const std::string &prefix, const int myid,
                            const std::string suffix = "", const int width = 6);


#ifdef MFEM_USE_MPI

/** @name MFEM "global" communicator functions.

    Functions for getting and setting the MPI communicator used by the library
    as the "global" communicator.

    Currently, the MFEM "global" communicator is used only by the function
    mfem_error(), invoked when an error is detected - the "global" communicator
    is used as a parameter to MPI_Abort() to terminate all "global" tasks. */
///@{

/// Get MFEM's "global" MPI communicator.
MPI_Comm GetGlobalMPI_Comm();

/// Set MFEM's "global" MPI communicator.
void SetGlobalMPI_Comm(MPI_Comm comm);

///@}

#endif

} // namespace mfem

#endif