Implement Xios handler as a singleton

.github/workflows/test_suite.yml

@@ -4,7 +4,6 @@ on:
   push:
     branches: [ main, develop ]
   pull_request:
-    branches: [ main, develop ]
 
 jobs:
 

core/src/ModelMetadata.cpp

@@ -1,7 +1,7 @@
 /*!
  * @file ModelMetadata.cpp
  *
- * @date 10 Dec 2024
+ * @date 02 Jan 2025
  * @author Tim Spain <timothy.spain@nersc.no>
  */
 
@@ -10,6 +10,9 @@
 #include "include/IStructure.hpp"
 #include "include/NextsimModule.hpp"
 #include "include/gridNames.hpp"
+#ifdef USE_XIOS
+#include "include/Xios.hpp"
+#endif
 
 #ifdef USE_MPI
 #include <ncDim.h>
@@ -108,10 +111,10 @@ void ModelMetadata::setTime(const TimePoint& time)
 {
     m_time = time;
 #ifdef USE_XIOS
+    Xios* xiosHandler = Xios::getInstance();
     if (!xiosHandler->isInitialized()) {
         throw std::runtime_error("ModelMetadata: Xios handler has not been initialized");
     }
-    xiosHandler->setCalendarStep(0);
     xiosHandler->setCalendarStart(time);
 #endif
 }
@@ -120,6 +123,7 @@ void ModelMetadata::incrementTime(const Duration& step)
 {
     m_time += step;
 #ifdef USE_XIOS
+    Xios* xiosHandler = Xios::getInstance();
     if (!xiosHandler->isInitialized()) {
         throw std::runtime_error("ModelMetadata: Xios handler has not been initialized");
     }

core/src/Xios.cpp

@@ -2,7 +2,7 @@
  * @file    Xios.cpp
  * @author  Tom Meltzer <tdm39@cam.ac.uk>
  * @author  Joe Wallwork <jw2423@cam.ac.uk>
- * @date    10 Dec 2024
+ * @date    02 Jan 2025
  * @brief   XIOS interface implementation
  * @details
  *
@@ -62,7 +62,14 @@ Xios::Xios(const std::string dt, const std::string contextid, const std::string
 }
 
 //! Destructor
-Xios::~Xios() { finalize(); }
+Xios::~Xios()
+{
+    finalize();
+    if (instancePtr != nullptr) {
+        delete instancePtr;
+        instancePtr = nullptr;
+    }
+}
 
 //! Close XIOS context definition once xml config has been read and calendar settings updated
 void Xios::close_context_definition()
@@ -1648,6 +1655,10 @@ void Xios::read(const std::string fieldId, ModelArray& modelarray)
         throw std::invalid_argument("Only ModelArrays of dimension 2, 3, or 4 are supported");
     }
 }
+
+// Create the singleton instance
+Xios* Xios::instancePtr = nullptr;
+
 }
 
 #endif

core/src/include/ModelMetadata.hpp

@@ -1,7 +1,7 @@
 /*!
  * @file ModelMetadata.hpp
  *
- * @date 09 Dec 2024
+ * @date 02 Jan 2025
  * @author Tim Spain <timothy.spain@nersc.no>
  */
 
@@ -12,10 +12,6 @@
 #include "include/ModelArray.hpp"
 #include "include/ModelState.hpp"
 #include "include/Time.hpp"
-#ifdef USE_XIOS
-#include "include/Xios.hpp"
-#endif
-
 #include <string>
 
 #ifdef USE_MPI
@@ -102,15 +98,6 @@ class ModelMetadata {
     int localCornerX, localCornerY, localExtentX, localExtentY, globalExtentX, globalExtentY;
 #endif
 
-#ifdef USE_XIOS
-    /*
-     * @brief Set pointer to Xios handler instance.
-     *
-     * @param xiosPtr Pointer to set
-     */
-    inline void setXiosHandler(Xios* xiosPtr) { xiosHandler = xiosPtr; }
-#endif
-
 private:
     TimePoint m_time;
     ConfigMap m_config;
@@ -129,9 +116,6 @@ class ModelMetadata {
 #ifdef USE_MPI
     const std::string bboxName = "bounding_boxes";
 #endif
-#ifdef USE_XIOS
-    Xios* xiosHandler = nullptr;
-#endif
 };
 
 } /* namespace Nextsim */

core/src/include/Xios.hpp

@@ -2,7 +2,7 @@
  * @file    Xios.hpp
  * @author  Tom Meltzer <tdm39@cam.ac.uk>
  * @author  Joe Wallwork <jw2423@cam.ac.uk>
- * @date    10 Dec 2024
+ * @date    02 Jan 2025
  * @brief   XIOS interface header
  * @details
  *
@@ -30,12 +30,37 @@ namespace Nextsim {
 void enableXios();
 
 class Xios : public Configured<Xios> {
-public:
+private:
+    static Xios* instancePtr;
+
+    // Private constructor
     Xios(const std::string dt = "P0-0T01:00:00", const std::string contextid = "nextSIM-DG",
         const std::string starttime = "1970-01-01T00:00:00Z",
         const std::string calendartype = "Gregorian");
+
+public:
+    Xios(const Xios& xiosHandler) = delete;
     ~Xios();
 
+    /*
+     * Define Xios handler Singleton
+     *
+     * NOTE: The arguments will only be used the first time this is called.
+     */
+    inline static Xios* getInstance(const std::string dt = "P0-0T01:00:00",
+        const std::string contextId = "nextSIM-DG",
+        const std::string startTime = "1970-01-01T00:00:00Z",
+        const std::string calendarType = "Gregorian")
+    {
+        if (isNull()) {
+            instancePtr = new Xios(dt, contextId, startTime, calendarType);
+        }
+        return instancePtr;
+    };
+
+    /* Utility for checking if the singleton has been created */
+    inline static bool isNull() { return (instancePtr == nullptr); }
+
     /* Initialization and finalization */
     void close_context_definition();
     void context_finalize();

core/test/CMakeLists.txt

@@ -87,13 +87,21 @@ if(ENABLE_MPI)
         )
         target_link_libraries(testXiosFile_MPI2 PRIVATE nextsimlib doctest::doctest)
 
-        add_executable(testXiosReadWrite_MPI2 "XiosReadWrite_test.cpp" "MainMPI.cpp")
-        target_compile_definitions(testXiosReadWrite_MPI2 PRIVATE USE_XIOS)
+        add_executable(testXiosRead_MPI2 "XiosRead_test.cpp" "MainMPI.cpp")
+        target_compile_definitions(testXiosRead_MPI2 PRIVATE USE_XIOS)
         target_include_directories(
-            testXiosReadWrite_MPI2
+            testXiosRead_MPI2
             PRIVATE "${MODEL_INCLUDE_DIR}" "${XIOS_INCLUDE_LIST}" "${ModulesRoot}/StructureModule"
         )
-        target_link_libraries(testXiosReadWrite_MPI2 PRIVATE nextsimlib doctest::doctest)
+        target_link_libraries(testXiosRead_MPI2 PRIVATE nextsimlib doctest::doctest)
+
+        add_executable(testXiosWrite_MPI2 "XiosWrite_test.cpp" "MainMPI.cpp")
+        target_compile_definitions(testXiosWrite_MPI2 PRIVATE USE_XIOS)
+        target_include_directories(
+            testXiosWrite_MPI2
+            PRIVATE "${MODEL_INCLUDE_DIR}" "${XIOS_INCLUDE_LIST}" "${ModulesRoot}/StructureModule"
+        )
+        target_link_libraries(testXiosWrite_MPI2 PRIVATE nextsimlib doctest::doctest)
     else()
         add_executable(testRectGrid_MPI3 "RectGrid_test.cpp" "MainMPI.cpp")
         target_compile_definitions(

core/test/ConfigOutput_test.cpp

@@ -1,7 +1,7 @@
 /*!
  * @file ConfigOutput_test.cpp
  *
- * @date 11 Dec 2024
+ * @date 02 Jan 2025
  * @author Tim Spain <timothy.spain@nersc.no>
  */
 
@@ -25,6 +25,9 @@
 #include "include/NZLevels.hpp"
 #include "include/NextsimModule.hpp"
 #include "include/gridNames.hpp"
+#ifdef USE_XIOS
+#include "include/Xios.hpp"
+#endif
 
 #include <ncDim.h>
 #include <ncFile.h>
@@ -100,10 +103,9 @@ TEST_CASE("Test periodic output")
     ModelMetadata meta;
 #ifdef USE_XIOS
     enableXios();
-    Xios xiosHandler("P0-0T01:00:00", "test1");
-    xiosHandler.setCalendarOrigin(TimePoint("1970-01-01T00:00:00Z"));
-    meta.setXiosHandler(&xiosHandler);
-    xiosHandler.close_context_definition();
+    Xios* xiosHandler = Xios::getInstance("P0-0T01:00:00", "test1");
+    xiosHandler->setCalendarOrigin(TimePoint("1970-01-01T00:00:00Z"));
+    xiosHandler->close_context_definition();
 #endif
     meta.setTime(TimePoint("2020-01-01T00:00:00Z"));
 

core/test/ParaGrid_test.cpp

@@ -1,7 +1,7 @@
 /*!
  * @file ParaGrid_test.cpp
  *
- * @date 10 Dec 2024
+ * @date 02 Jan 2025
  * @author Tim Spain <timothy.spain@nersc.no>
  */
 
@@ -23,6 +23,9 @@
 #include "include/ParaGridIO.hpp"
 #include "include/ParametricGrid.hpp"
 #include "include/gridNames.hpp"
+#ifdef USE_XIOS
+#include "include/Xios.hpp"
+#endif
 
 #include <cmath>
 #include <filesystem>
@@ -210,10 +213,9 @@ TEST_CASE("Write and read a ModelState-based ParaGrid restart file")
     ModelMetadata metadata;
 #ifdef USE_XIOS
     enableXios();
-    Xios xiosHandler("P0-0T01:00:00", "test1a");
-    xiosHandler.setCalendarOrigin(TimePoint("1970-01-01T00:00:00Z"));
-    metadata.setXiosHandler(&xiosHandler);
-    xiosHandler.close_context_definition();
+    Xios* xiosHandler = Xios::getInstance("P0-0T01:00:00");
+    xiosHandler->setCalendarOrigin(TimePoint("1970-01-01T00:00:00Z"));
+    xiosHandler->close_context_definition();
 #endif
     metadata.setTime(TimePoint("2000-01-01T00:00:00Z"));
     // The coordinates are passed through the metadata object as affix
@@ -258,9 +260,6 @@ TEST_CASE("Write and read a ModelState-based ParaGrid restart file")
 
 #ifdef USE_MPI
     ModelMetadata metadataIn(partitionFilename, test_comm);
-#ifdef USE_XIOS
-    metadataIn.setXiosHandler(&xiosHandler);
-#endif
     metadataIn.setTime(TimePoint(dateString));
     ModelState ms = gridIn.getModelState(filename, metadataIn);
 #else
@@ -413,10 +412,7 @@ TEST_CASE("Write a diagnostic ParaGrid file")
     ModelMetadata metadata;
 #ifdef USE_XIOS
     enableXios();
-    Xios xiosHandler("P0-0T01:00:00", "test2");
-    xiosHandler.setCalendarOrigin(TimePoint("1970-01-01T00:00:00Z"));
-    metadata.setXiosHandler(&xiosHandler);
-    xiosHandler.close_context_definition();
+    Xios* xiosHandler = Xios::getInstance();
 #endif
     metadata.setTime(TimePoint("2000-01-01T00:00:00Z"));
     // The coordinates are passed through the metadata object as affix
@@ -556,10 +552,7 @@ TEST_CASE("Check an exception is thrown for an invalid file name")
     ModelMetadata metadataIn(partitionFilename, test_comm);
 #ifdef USE_XIOS
     enableXios();
-    Xios xiosHandler("P0-0T01:00:00", "test4");
-    xiosHandler.setCalendarOrigin(TimePoint("1970-01-01T00:00:00Z"));
-    metadataIn.setXiosHandler(&xiosHandler);
-    xiosHandler.close_context_definition();
+    Xios* xiosHandler = Xios::getInstance();
 #endif
     metadataIn.setTime(TimePoint(dateString));
     REQUIRE_THROWS(state = gridIn.getModelState(longRandomFilename, metadataIn));
@@ -614,10 +607,7 @@ TEST_CASE("Check if a file with the old dimension names can be read")
     ModelMetadata metadata;
 #ifdef USE_XIOS
     enableXios();
-    Xios xiosHandler("P0-0T01:00:00", "test5");
-    xiosHandler.setCalendarOrigin(TimePoint("1970-01-01T00:00:00Z"));
-    metadata.setXiosHandler(&xiosHandler);
-    xiosHandler.close_context_definition();
+    Xios* xiosHandler = Xios::getInstance();
 #endif
     metadata.setMpiMetadata(test_comm);
     if (metadata.mpiMyRank == 0) {

core/test/XiosAxis_test.cpp

@@ -1,7 +1,7 @@
 /*!
  * @file    XiosAxis_test.cpp
  * @author  Joe Wallwork <jw2423@cam.ac.uk>
- * @date    03 Dec 2024
+ * @date    02 Jan 2025
  * @brief   Tests for XIOS axes
  * @details
  * This test is designed to test axis functionality of the C++ interface
@@ -29,34 +29,34 @@ MPI_TEST_CASE("TestXiosAxis", 2)
 {
     enableXios();
 
-    // Initialize an Xios instance called xios_handler
-    Xios xios_handler;
-    REQUIRE(xios_handler.isInitialized());
-    REQUIRE(xios_handler.getClientMPISize() == 2);
+    // Get the Xios singleton instance and check it's initialized
+    Xios* xiosHandler = Xios::getInstance();
+    REQUIRE(xiosHandler->isInitialized());
+    REQUIRE(xiosHandler->getClientMPISize() == 2);
 
     // --- Tests for axis API
     const std::string axisId = { "axis_A" };
-    REQUIRE_THROWS_WITH(xios_handler.getAxisSize(axisId), "Xios: Undefined axis 'axis_A'");
-    REQUIRE_THROWS_WITH(xios_handler.getAxisValues(axisId), "Xios: Undefined axis 'axis_A'");
-    xios_handler.createAxis(axisId);
-    REQUIRE_THROWS_WITH(xios_handler.createAxis(axisId), "Xios: Axis 'axis_A' already exists");
+    REQUIRE_THROWS_WITH(xiosHandler->getAxisSize(axisId), "Xios: Undefined axis 'axis_A'");
+    REQUIRE_THROWS_WITH(xiosHandler->getAxisValues(axisId), "Xios: Undefined axis 'axis_A'");
+    xiosHandler->createAxis(axisId);
+    REQUIRE_THROWS_WITH(xiosHandler->createAxis(axisId), "Xios: Axis 'axis_A' already exists");
     // Axis size
-    REQUIRE_THROWS_WITH(xios_handler.getAxisSize(axisId), "Xios: Undefined size for axis 'axis_A'");
+    REQUIRE_THROWS_WITH(xiosHandler->getAxisSize(axisId), "Xios: Undefined size for axis 'axis_A'");
     const size_t axisSize { 2 };
-    xios_handler.setAxisSize(axisId, axisSize);
-    REQUIRE(xios_handler.getAxisSize(axisId) == axisSize);
+    xiosHandler->setAxisSize(axisId, axisSize);
+    REQUIRE(xiosHandler->getAxisSize(axisId) == axisSize);
     // Axis values
     REQUIRE_THROWS_WITH(
-        xios_handler.getAxisValues(axisId), "Xios: Undefined values for axis 'axis_A'");
-    REQUIRE_THROWS_WITH(xios_handler.setAxisValues(axisId, { 0.0, 1.0, 2.0 }),
+        xiosHandler->getAxisValues(axisId), "Xios: Undefined values for axis 'axis_A'");
+    REQUIRE_THROWS_WITH(xiosHandler->setAxisValues(axisId, { 0.0, 1.0, 2.0 }),
         "Xios: Size incompatible with values for axis 'axis_A'");
     std::vector<double> axisValues { 0.0, 1.0 };
-    xios_handler.setAxisValues(axisId, axisValues);
-    std::vector<double> axis_A = xios_handler.getAxisValues(axisId);
+    xiosHandler->setAxisValues(axisId, axisValues);
+    std::vector<double> axis_A = xiosHandler->getAxisValues(axisId);
     REQUIRE(axis_A[0] == doctest::Approx(0.0));
     REQUIRE(axis_A[1] == doctest::Approx(1.0));
 
-    xios_handler.close_context_definition();
-    xios_handler.context_finalize();
+    xiosHandler->close_context_definition();
+    xiosHandler->context_finalize();
 }
 }