Merge pull request #2585 from pnorbert/doc-faq

Can I use the same library for MPI and non-MPI code?

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Short answer: No.

Short answer: Yes, since version 2.6.0. 

Long answer: This created conflicts in the past, as the MPI APIs were mocked in the sequential version.

If you need "sequential" behavior with the MPI library, use ``MPI_COMM_SELF``.

Always pass a communicator in the MPI version

Long answer: One build of ADIOS can be used by both serial and parallel applications. Use the ``-s`` and ``-m`` flags in the ``adios2-config`` command. By default, or with the ``-m`` flag, the command gives the flags for a parallel build, which add ``-DADIOS2_USE_MPI`` to the compilation flags and include extra libaries containing the MPI implementations into the linker flags. The ``-s`` flag will omit these flags. For example, if ADIOS is installed into /opt/adios2, the flags for a Fortran application will look like these:

    .. code-block:: bash

        $ /opt/adios2/bin/adios2-config --fortran-flags

        -DADIOS2_USE_MPI -I/opt/adios2/include/adios2/fortran

        $ /opt/adios2/bin/adios2-config --fortran-flags -m

        -DADIOS2_USE_MPI -I/opt/adios2/include/adios2/fortran

        $ /opt/adios2/bin/adios2-config --fortran-flags -s

        -I/opt/adios2/include/adios2/fortran

        $ /opt/adios2/bin/adios2-config --fortran-libs

        -Wl,-rpath,/opt/adios2/lib /opt/adios2/lib/libadios2_fortran_mpi.so.2.6.0 /opt/adios2/lib/libadios2_fortran.so.2.6.0 -Wl,-rpath-link,/opt/adios2/lib

        $ /opt/adios2/bin/adios2-config --fortran-libs -s

        -Wl,-rpath,/opt/adios2/lib /opt/adios2/lib/libadios2_fortran.so.2.6.0 -Wl,-rpath-link,/opt/adios2/lib

If using cmake, there are different targets to build parallel

    .. code-block:: cmake

        find_package(MPI REQUIRED)

        find_package(ADIOS2 REQUIRED)

        #...

        add_library(my_library src1.cxx src2.cxx)

        target_link_libraries(my_library PRIVATE adios2::cxx11_mpi MPI::MPI_C)

        #...

        add_library(my_f_library src1.F90 src2.F90)

        target_link_libraries(my_f_library PRIVATE adios2::fortran_mpi adios2::fortran MPI::MPI_Fortran)

and serial applications:

    .. code-block:: cmake

        find_package(ADIOS2 REQUIRED)

        #...

        add_library(my_library src1.cxx src2.cxx)

        target_link_libraries(my_library PRIVATE adios2::cxx11)

        #...

        add_library(my_f_library src1.F90 src2.F90)

        target_link_libraries(my_f_library PRIVATE adios2::fortran)

Can I use ADIOS 2 C++11 library with C++98 codes?

#!/bin/bash

set +x

set -x

echo "Setting up default XCode version"

case "$SYSTEM_JOBNAME" in

    ;;

esac

echo "Removing all existing brew package and update the formule"

brew remove --force $(brew list)

echo "Removing all existing brew package and update the formula"

brew remove --force --ignore-dependencies $(brew list --formula)

brew update

echo "Installing Kitware CMake and Ninja"

brew install cmake ninja

echo "Installing GCC"

brew install gcc

brew link --overwrite python

brew link --overwrite numpy

echo "Installing CMake and Ninja"

brew install cmake ninja

if [[ "$SYSTEM_JOBNAME" =~ .*openmpi.* ]]

then

  echo "Installing OpenMPI"