Make the adios2 python module compatible for both mpi and nompi (#14)

bindings/CMakeLists.txt

 if(ADIOS_USE_Python)
-  if(NOT BUILD_SHARED_LIBS)
-    message(ERROR "Python bindings are only supported for shared libraries")
-  endif()
   add_subdirectory(python)
 endif()

bindings/python/ADIOSPy.cpp

@@ -20,7 +20,11 @@ ADIOSPy::ADIOSPy(MPI_Comm mpiComm, const bool debug)
 {
 }
 
-ADIOSPy::ADIOSPy(const bool debug) : ADIOSPy(MPI_COMM_SELF, debug) {}
+ADIOSPy::ADIOSPy(const bool debug)
+: m_DebugMode(debug), m_ADIOS(debug)
+{
+}
+
 
 IOPy ADIOSPy::DeclareIO(const std::string name)
 {

bindings/python/ADIOSPy.h

@@ -15,6 +15,8 @@
 #include <string>
 /// \endcond
 
+#include <adios2.h>
+
 #include "IOPy.h"
 
 namespace adios

bindings/python/CMakeLists.txt

-find_package(PythonInterp REQUIRED)
-find_package(PythonModule REQUIRED COMPONENTS mpi4py mpi4py/mpi4py.h)
+if(NOT BUILD_SHARED_LIBS)
+  message(ERROR "Python bindings are only supported for shared libraries")
+endif()
 
 pybind11_add_module(adios2py MODULE
   ADIOSPy.h
@@ -16,12 +17,18 @@ pybind11_add_module(adios2py MODULE
   VariablePy.h
   VariablePy.cpp
 )
-target_link_libraries(adios2py PUBLIC adios2 PythonModule::mpi4py)
+target_link_libraries(adios2py PRIVATE adios2)
+if(ADIOS_USE_MPI)
+  find_package(PythonModule REQUIRED COMPONENTS mpi4py mpi4py/mpi4py.h)
+  target_link_libraries(adios2py PRIVATE PythonModule::mpi4py)
+endif()
 
+find_package(PythonInterp REQUIRED)
 set(python_package_dir ${CMAKE_INSTALL_LIBDIR}/python${PYTHON_VERSION_MAJOR}${PYTHON_VERSION_MINOR}/site-packages)
 set_target_properties(adios2py PROPERTIES
-  PREFIX ""
   OUTPUT_NAME adios2
+  PREFIX "${PYTHON_MODULE_PREFIX}"
+  SUFFIX "${PYTHON_MODULE_EXTENSION}"
   LIBRARY_OUTPUT_DIRECTORY ${ADIOS_BINARY_DIR}/${python_package_dir}
   RUNTIME_OUTPUT_DIRECTORY ${ADIOS_BINARY_DIR}/${python_package_dir}
 )

bindings/python/gluePyBind11.cpp

@@ -11,9 +11,12 @@
 #include <stdexcept>
 
 #include <adios2.h>
-#include <mpi4py/mpi4py.h>
 #include <pybind11/pybind11.h>
 
+#ifdef ADIOS2_HAVE_MPI
+#include <mpi4py/mpi4py.h>
+#endif
+
 #include "ADIOSPy.h"
 #include "EnginePy.h"
 #include "IOPy.h"
@@ -21,6 +24,7 @@
 #include "adiosPyFunctions.h"
 #include "adiosPyTypes.h"
 
+#ifdef ADIOS2_HAVE_MPI
 adios::ADIOSPy ADIOSPyInit(adios::pyObject &object, const bool debugMode)
 {
     MPI_Comm *mpiCommPtr = PyMPIComm_Get(object.ptr());
@@ -39,14 +43,22 @@ adios::ADIOSPy ADIOSPyInit(adios::pyObject &object, const bool debugMode)
     }
     return adios::ADIOSPy(*mpiCommPtr, debugMode);
 }
+#else
+adios::ADIOSPy ADIOSPyInit(const bool debugMode)
+{
+    return adios::ADIOSPy(debugMode);
+}
+#endif
 
 PYBIND11_PLUGIN(adios2)
 {
+#ifdef ADIOS2_HAVE_MPI  
     if (import_mpi4py() < 0)
     {
         throw std::runtime_error(
             "ERROR: mpi4py not loaded correctly\n"); /* Python 2.X */
     }
+#endif
 
     pybind11::module m("adios2", "ADIOS2 Python bindings using pybind11");
     m.attr("DebugON") = true;
@@ -73,10 +85,6 @@ PYBIND11_PLUGIN(adios2)
              pybind11::arg("isConstantDims") = false)
         .def("GetVariable", &adios::IOPy::GetVariable,
              pybind11::return_value_policy::reference_internal)
-        //        .def("Open", (adios::EnginePy (adios::IOPy::*)(
-        //                         const std::string &, const int,
-        //                         adios::pyObject &)) &
-        //                         adios::IOPy::Open)   doesn't work
         .def("Open", (adios::EnginePy (adios::IOPy::*)(const std::string &,
                                                        const int)) &
                          adios::IOPy::Open);

bindings/python/gluePyBind11_nompi.cpp

-/*
- * Distributed under the OSI-approved Apache License, Version 2.0.  See
- * accompanying file Copyright.txt for details.
- *
- * gluePyBind11_nompi.cpp
- *
- *  Created on: Jun 12, 2017
- *      Author: William F Godoy godoywf@ornl.gov
- */
-
-#include <stdexcept>
-
-#include <adios2.h>
-#include <pybind11/pybind11.h>
-
-#include "ADIOSPy.h"
-#include "EnginePy.h"
-#include "IOPy.h"
-#include "VariablePy.h"
-#include "adiosPyFunctions.h"
-#include "adiosPyTypes.h"
-
-adios::ADIOSPy ADIOSPyInit(const bool debugMode)
-{
-    return adios::ADIOSPy(debugMode);
-}
-
-PYBIND11_PLUGIN(adios2)
-{
-    pybind11::module m("adios2", "ADIOS2 Python bindings using pybind11");
-    m.attr("DebugON") = true;
-    m.attr("DebugOFF") = false;
-    m.attr("ConstantDims") = true;
-    m.attr("OpenModeWrite") = static_cast<int>(adios::OpenMode::Write);
-    m.attr("OpenModeRead") = static_cast<int>(adios::OpenMode::Read);
-    m.attr("OpenModeAppend") = static_cast<int>(adios::OpenMode::Append);
-    m.attr("OpenModeReadWrite") = static_cast<int>(adios::OpenMode::ReadWrite);
-    m.def("ADIOS", &ADIOSPyInit, "Function that creates an ADIOS class object");
-
-    pybind11::class_<adios::ADIOSPy>(m, "ADIOSPy")
-        .def("DeclareIO", &adios::ADIOSPy::DeclareIO);
-
-    pybind11::class_<adios::IOPy>(m, "IOPy")
-        .def("SetEngine", &adios::IOPy::SetEngine)
-        .def("SetParameters", &adios::IOPy::SetParameters)
-        .def("AddTransport", &adios::IOPy::AddTransport)
-        .def("DefineVariable", &adios::IOPy::DefineVariable,
-             pybind11::return_value_policy::reference_internal,
-             pybind11::arg("name"), pybind11::arg("shape") = adios::pyList(),
-             pybind11::arg("start") = adios::pyList(),
-             pybind11::arg("count") = adios::pyList(),
-             pybind11::arg("isConstantDims") = false)
-        .def("GetVariable", &adios::IOPy::GetVariable,
-             pybind11::return_value_policy::reference_internal)
-        .def("Open", (adios::EnginePy (adios::IOPy::*)(const std::string &,
-                                                       const int)) &
-                         adios::IOPy::Open);
-
-    pybind11::class_<adios::VariablePy>(m, "VariablePy")
-        .def("SetDimensions", &adios::VariablePy::SetDimensions);
-
-    pybind11::class_<adios::EnginePy>(m, "EnginePy")
-        .def("Write", &adios::EnginePy::Write)
-        .def("Advance", &adios::EnginePy::Advance,
-             pybind11::arg("timeoutSeconds") = 0.)
-        .def("Close", &adios::EnginePy::Close,
-             pybind11::arg("transportIndex") = -1);
-
-    return m.ptr();
-}