Initial Windows Support

.github/workflows/ci.yml

@@ -177,8 +177,75 @@ jobs:
           cpp-coveralls -i src -i include -e src/external --exclude-pattern "/usr/*" --dump cpp_cov.json
           coveralls --merge=cpp_cov.json --service=github
 
+  win:
+    runs-on: windows-latest
+    strategy:
+      matrix:
+        python-version: ["3.11"]
+        omp: [n, y]
+
+        include:
+          - python-version: "3.11"
+            omp: n
+          - python-version: "3.11"
+            omp: y
+    name: "Windows Python ${{ matrix.python-version }} (omp=${{ matrix.omp }})"
+
+    env:
+      OMP: ${{ matrix.omp }}
+      EVENT: ${{ matrix.event }}
+      NPY_DISABLE_CPU_FEATURES: "AVX512F AVX512_SKX"
+      OPENBLAS_NUM_THREADS: 1
+      # libfabric complains about fork() as a result of using Python multiprocessing.
+      # We can work around it with RDMAV_FORK_SAFE=1 in libfabric < 1.13 and with
+      # FI_EFA_FORK_SAFE=1 in more recent versions.
+      RDMAV_FORK_SAFE: 1
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Environment Variables
+        shell: pwsh
+        run: |
+          [Environment]::SetEnvironmentVariable("OPENMC_CROSS_SECTIONS", "$Env:GITHUB_WORKSPACE\nndc_hdf5\cross_sections.xml", 'Machine')
+          [Environment]::SetEnvironmentVariable("OPENMC_ENDF_DATA", "$Env:GITHUB_WORKSPACE\endf-b-vii.1", 'Machine')
+
+      - name: Cache XS
+        uses: actions/cache@v4
+        with:
+          path: |
+            ${{github.workspace}}\nndc_hdf5
+            ${{github.workspace}}\endf-b-vii.1
+          key: ${{ runner.os }}-build-xs-cache
+
+      - name: Install
+        shell: pwsh
+        run: |
+          ${{github.workspace}}\tools\ci\gha-install.ps1
+
+      - name: Before
+        shell: pwsh
+        run: ${{github.workspace}}\tools\ci\download-xs.ps1
+
+      - name: Test
+        shell: pwsh
+        run: |
+          ctest --output-on-failure -C Release ${{ github.workspace }}\build\
+          ${{github.workspace}}\tools\ci\gha-script.ps1
+
+      - name: Setup tmate debug session
+        continue-on-error: true
+        if: ${{ contains(env.COMMIT_MESSAGE, '[gha-debug]') }}
+        uses: mxschmitt/action-tmate@v3
+        timeout-minutes: 10
+
   finish:
-    needs: main
+    needs: [win, main]
     runs-on: ubuntu-latest
     steps:
       - name: Coveralls Finished

CMakeLists.txt

@@ -95,6 +95,11 @@ endif()
 
 if(OPENMC_USE_OPENMP)
   find_package(OpenMP REQUIRED)
+
+  if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
+    # Special flag to get OpenMP to work on Windows with MSVC
+    list(APPEND cxxflags /openmp:llvm)
+  endif()
 endif()
 
 #===============================================================================
@@ -167,6 +172,12 @@ if(NOT DEFINED HDF5_PREFER_PARALLEL)
   endif()
 endif()
 
+if (MSVC)
+  # To avoid problems with loading DLLs on Windows in the Python API,
+  # we should try to link libhdf5 statically.
+  set(HDF5_USE_STATIC_LIBRARIES TRUE)
+endif()
+
 find_package(HDF5 REQUIRED COMPONENTS C HL)
 
 # Remove HDF5 transitive dependencies that are system libraries
@@ -211,24 +222,22 @@ endif()
 
 # Skip for Visual Studio which has its own configurations through GUI
 if(NOT MSVC)
+  set(CMAKE_POSITION_INDEPENDENT_CODE ON)
 
-set(CMAKE_POSITION_INDEPENDENT_CODE ON)
-
-if(OPENMC_ENABLE_PROFILE)
-  list(APPEND cxxflags -g -fno-omit-frame-pointer)
-endif()
+  if(OPENMC_ENABLE_PROFILE)
+    list(APPEND cxxflags -g -fno-omit-frame-pointer)
+  endif()
 
-if(OPENMC_ENABLE_COVERAGE)
-  list(APPEND cxxflags --coverage)
-  list(APPEND ldflags --coverage)
+  if(OPENMC_ENABLE_COVERAGE)
+    list(APPEND cxxflags --coverage)
+    list(APPEND ldflags --coverage)
+  endif()
 endif()
 
 # Show flags being used
 message(STATUS "OpenMC C++ flags: ${cxxflags}")
 message(STATUS "OpenMC Linker flags: ${ldflags}")
 
-endif()
-
 #===============================================================================
 # Update git submodules as needed
 #===============================================================================
@@ -446,20 +455,31 @@ list(APPEND libopenmc_SOURCES
   src/external/quartic_solver.cpp
   src/external/Faddeeva.cc)
 
-# For Visual Studio compilers
+#===============================================================================
+# openmc library
+#===============================================================================
+add_library(libopenmc SHARED ${libopenmc_SOURCES})
+add_library(OpenMC::libopenmc ALIAS libopenmc)
+
+# For compilers on Windows
 if(MSVC)
-  # Use static library (otherwise explicit symbol portings are needed)
-  add_library(libopenmc STATIC ${libopenmc_SOURCES})
+  # This ensures that all function/class method symbols are exported, without
+  # needing to add the export macros in the source.
+  set_target_properties(libopenmc PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS ON)
+
+  # This compile definition is needed to make sure that the correct macros
+  # are used for exporting symbols in the dll. While the
+  # WINDOWS_EXPORT_ALL_SYMBOLS exports all function/class symbols, it
+  # unfortunately does not work on global variables, which still need the macro.
+  target_compile_definitions(libopenmc PRIVATE -DOPENMC_DLL_EXPORTS)
 
   # To use the shared HDF5 libraries on Windows, the H5_BUILT_AS_DYNAMIC_LIB
   # compile definition must be specified.
-  target_compile_definitions(libopenmc PRIVATE -DH5_BUILT_AS_DYNAMIC_LIB)
-else()
-  add_library(libopenmc SHARED ${libopenmc_SOURCES})
+  if (NOT HDF5_USE_STATIC_LIBRARIES)
+    target_compile_definitions(libopenmc PRIVATE -DH5_BUILT_AS_DYNAMIC_LIB)
+  endif()
 endif()
 
-add_library(OpenMC::libopenmc ALIAS libopenmc)
-
 # Avoid vs error lnk1149 :output filename matches input filename
 if(NOT MSVC)
   set_target_properties(libopenmc PROPERTIES OUTPUT_NAME openmc)

include/openmc/capi.h

@@ -284,8 +284,17 @@ extern int OPENMC_E_DATA;
 extern int OPENMC_E_PHYSICS;
 extern int OPENMC_E_WARNING;
 
+// Macro to ensure global variables are exported in Windows DLLs
+#if defined(_WIN32) && defined(OPENMC_DLL_EXPORTS)
+#define OPENMC_API __declspec(dllexport)
+#elif defined(_WIN32)
+#define OPENMC_API __declspec(dllimport)
+#else
+#define OPENMC_API
+#endif
+
 // Global variables
-extern char openmc_err_msg[256];
+extern char OPENMC_API openmc_err_msg[256];
 
 #ifdef __cplusplus
 }

include/openmc/constants.h

@@ -365,6 +365,19 @@ enum class GeometryType { CSG, DAG };
 // representations. This value represents no surface.
 constexpr int32_t SURFACE_NONE {0};
 
+//==============================================================================
+// Shared Libraries on Windows need the functions/classes/variables to be
+// exposed to be declared with this special keyword "__declspec(dllexport)".
+// We use a macro for this, so that it is only exported on Windows.
+
+#if defined(_WIN32) && defined(OPENMC_DLL_EXPORTS)
+#define OPENMC_API __declspec(dllexport)
+#elif defined(_WIN32)
+#define OPENMC_API __declspec(dllimport)
+#else
+#define OPENMC_API
+#endif
+
 } // namespace openmc
 
 #endif // OPENMC_CONSTANTS_H

include/openmc/dagmc.h

@@ -1,9 +1,11 @@
 #ifndef OPENMC_DAGMC_H
 #define OPENMC_DAGMC_H
 
+#include "openmc/constants.h" // Needed for OPENMC_API
+
 namespace openmc {
-extern "C" const bool DAGMC_ENABLED;
-extern "C" const bool UWUW_ENABLED;
+extern "C" const bool OPENMC_API DAGMC_ENABLED;
+extern "C" const bool OPENMC_API UWUW_ENABLED;
 } // namespace openmc
 
 // always include the XML interface header

include/openmc/event.h

@@ -7,6 +7,8 @@
 #include "openmc/particle.h"
 #include "openmc/shared_array.h"
 
+#include <tuple>
+
 namespace openmc {
 
 //==============================================================================

include/openmc/geometry.h

@@ -10,7 +10,7 @@
 
 namespace openmc {
 
-class BoundaryInfo;
+struct BoundaryInfo;
 class GeometryState;
 
 //==============================================================================

include/openmc/mcpl_interface.h

@@ -1,6 +1,7 @@
 #ifndef OPENMC_MCPL_INTERFACE_H
 #define OPENMC_MCPL_INTERFACE_H
 
+#include "openmc/constants.h"
 #include "openmc/particle_data.h"
 #include "openmc/span.h"
 #include "openmc/vector.h"
@@ -13,7 +14,7 @@ namespace openmc {
 // Constants
 //==============================================================================
 
-extern "C" const bool MCPL_ENABLED;
+extern "C" const bool OPENMC_API MCPL_ENABLED;
 
 //==============================================================================
 // Functions

include/openmc/mesh.h

@@ -11,6 +11,7 @@
 #include "xtensor/xtensor.hpp"
 
 #include "openmc/bounding_box.h"
+#include "openmc/constants.h" // for OPENMC_API
 #include "openmc/error.h"
 #include "openmc/memory.h" // for unique_ptr
 #include "openmc/particle.h"
@@ -50,7 +51,7 @@ enum class ElementType { UNSUPPORTED = -1, LINEAR_TET, LINEAR_HEX };
 // Global variables
 //==============================================================================
 
-extern "C" const bool LIBMESH_ENABLED;
+extern "C" const bool OPENMC_API LIBMESH_ENABLED;
 
 class Mesh;
 
@@ -578,7 +579,7 @@ class CylindricalMesh : public PeriodicStructuredMesh {
 
   inline int sanitize_angular_index(int idx, bool full, int N) const
   {
-    if ((idx > 0) and (idx <= N)) {
+    if ((idx > 0) && (idx <= N)) {
       return idx;
     } else if (full) {
       return (idx + N - 1) % N + 1;
@@ -640,7 +641,7 @@ class SphericalMesh : public PeriodicStructuredMesh {
 
   inline int sanitize_angular_index(int idx, bool full, int N) const
   {
-    if ((idx > 0) and (idx <= N)) {
+    if ((idx > 0) && (idx <= N)) {
       return idx;
     } else if (full) {
       return (idx + N - 1) % N + 1;

include/openmc/message_passing.h

@@ -7,14 +7,15 @@
 #include <mpi.h>
 #endif
 
+#include "openmc/constants.h"
 #include "openmc/vector.h"
 
 namespace openmc {
 namespace mpi {
 
 extern int rank;
 extern int n_procs;
-extern bool master;
+extern bool OPENMC_API master;
 
 #ifdef OPENMC_MPI
 extern MPI_Datatype source_site;

include/openmc/settings.h

@@ -136,9 +136,10 @@ extern ResScatMethod res_scat_method; //!< resonance upscattering method
 extern double res_scat_energy_min; //!< Min energy in [eV] for res. upscattering
 extern double res_scat_energy_max; //!< Max energy in [eV] for res. upscattering
 extern vector<std::string>
-  res_scat_nuclides;           //!< Nuclides using res. upscattering treatment
-extern RunMode run_mode;       //!< Run mode (eigenvalue, fixed src, etc.)
-extern SolverType solver_type; //!< Solver Type (Monte Carlo or Random Ray)
+  res_scat_nuclides; //!< Nuclides using res. upscattering treatment
+extern RunMode OPENMC_API run_mode; //!< Run mode (eigenvalue, fixed src, etc.)
+extern SolverType OPENMC_API
+  solver_type; //!< Solver Type (Monte Carlo or Random Ray)
 extern std::unordered_set<int>
   sourcepoint_batch; //!< Batches when source should be written
 extern std::unordered_set<int>

include/openmc/shared_array.h

@@ -72,13 +72,23 @@ class SharedArray {
   {
     // Atomically capture the index we want to write to
     int64_t idx;
+#if _WIN32 && !__INTEL_COMPILER
+#pragma omp atomic capture
+    idx = size_++;
+#else
 #pragma omp atomic capture seq_cst
     idx = size_++;
+#endif
 
     // Check that we haven't written off the end of the array
     if (idx >= capacity_) {
+#if _WIN32 && !__INTEL_COMPILER
+#pragma omp atomic write
+      size_ = capacity_;
+#else
 #pragma omp atomic write seq_cst
       size_ = capacity_;
+#endif
       return -1;
     }
 

include/openmc/tallies/filter.h

@@ -150,7 +150,7 @@ class Filter {
 
 namespace model {
 extern "C" int32_t n_filters;
-extern std::unordered_map<int, int> filter_map;
+extern std::unordered_map<int, int> OPENMC_API filter_map;
 extern vector<unique_ptr<Filter>> tally_filters;
 } // namespace model
 

openmc/deplete/pool.py

@@ -10,10 +10,17 @@
 
 from openmc.mpi import comm
 
+import sys
+
 # Configurable switch that enables / disables the use of
 # multiprocessing routines during depletion
 USE_MULTIPROCESSING = True
 
+# Not sure why, but using multiprocessing on Windows leads to many transport
+# simulations being run over eachother and leads to catastrophe.
+if sys.platform == 'win32':
+    USE_MULTIPROCESSING = False
+
 # Allow user to override the number of worker processes to use for depletion
 # calculations
 NUM_PROCESSES = None