Feature/python data sources

mapping_plugin/CMakeLists.txt

@@ -8,23 +8,66 @@
 find_package( UDA 2.7.0 REQUIRED )
 find_package( LibTokaMap REQUIRED )
 
+# Optional embedded-Python data-source support. When ON, the plugin can serve
+# data sources implemented in Python (e.g. tokamap_compass CDBDataSource) by
+# embedding CPython in uda_server. The interpreter starts lazily — only when
+# the libtokamap config declares a [python_data_sources] table — so a plugin
+# built with this ON still runs Python-free until such a source is configured.
+# When OFF the plugin has no Python dependency at all.
+option( MAPPING_PLUGIN_PYTHON "Embed CPython to serve Python data sources" OFF )
+
+set( MAPPING_PLUGIN_PYTHON_SOURCES "" )
+set( MAPPING_PLUGIN_PYTHON_INCLUDES "" )
+set( MAPPING_PLUGIN_PYTHON_DEFINITIONS "" )
+set( MAPPING_PLUGIN_PYTHON_LIBS "" )
+if( MAPPING_PLUGIN_PYTHON )
+  find_package( Python3 REQUIRED COMPONENTS Interpreter Development NumPy )
+  # Only a single dlopen-able libpython path is wanted here. Python3_LIBRARIES
+  # can be a multi-element list (and carries optimized;/debug; keywords on MSVC),
+  # which would split -DMAPPING_PLUGIN_DEFAULT_LIBPYTHON="..." across two
+  # compiler arguments and fail the compile on the unterminated quote.
+  set( MAPPING_PLUGIN_LIBPYTHON "" )
+  foreach( LIB IN LISTS Python3_LIBRARIES )
+      if( LIB MATCHES "python" AND EXISTS "${LIB}" )
+          set( MAPPING_PLUGIN_LIBPYTHON "${LIB}" )
+          break()
+      endif()
+  endforeach()
+  if( NOT MAPPING_PLUGIN_LIBPYTHON )
+      message( WARNING
+          "Could not pick a libpython path out of '${Python3_LIBRARIES}'; the plugin will need "
+          "MAPPING_PLUGIN_LIBPYTHON set in the environment to start the embedded interpreter." )
+  endif()
+  set( MAPPING_PLUGIN_PYTHON_DEFINITIONS -DMAPPING_PLUGIN_PYTHON
+      -DMAPPING_PLUGIN_DEFAULT_LIBPYTHON="${MAPPING_PLUGIN_LIBPYTHON}" )
+  set( MAPPING_PLUGIN_PYTHON_INCLUDES ${Python3_INCLUDE_DIRS} ${Python3_NumPy_INCLUDE_DIRS} )
+  set( MAPPING_PLUGIN_PYTHON_LIBS Python3::Python ${CMAKE_DL_LIBS} )
+endif()
+# Either way python_data_source.cpp is compiled: with MAPPING_PLUGIN_PYTHON it
+# carries the real implementation, otherwise a stub that only fails loudly if
+# the config actually requests Python sources.
+
 include( plugins )
 uda_plugin(
     NAME IMAS_MAP
     ENTRY_FUNC mappingPlugin
     DESCRIPTION "MAP IMAS element name to TOKAMAK data using JSON mapping files"
     EXAMPLE "IMAS_MAP::read()"
     LIBNAME mapping_plugin
-    SOURCES mapping_plugin.cpp src/uda_plugin_helpers.cpp
+    SOURCES mapping_plugin.cpp src/uda_plugin_helpers.cpp src/python_data_source.cpp
     CONFIG_FILE config/json_mapping.cfg config/libtokamap_config.toml
     EXTRA_INCLUDE_DIRS
         ${CMAKE_CURRENT_LIST_DIR}/src
         ${CMAKE_CURRENT_LIST_DIR}/ext_include
         ${UDA_CLIENT_INCLUDE_DIRS}
+        ${MAPPING_PLUGIN_PYTHON_INCLUDES}
+    EXTRA_DEFINITIONS
+        ${MAPPING_PLUGIN_PYTHON_DEFINITIONS}
     EXTRA_LINK_DIRS
         ${UDA_CLIENT_LIBRARY_DIRS}
     EXTRA_LINK_LIBS
         LibTokaMap::libtokamap
+        ${MAPPING_PLUGIN_PYTHON_LIBS}
 )
 
 # Generate scripts

mapping_plugin/mapping_plugin.cpp

@@ -31,6 +31,7 @@
 #include <server/getServerEnvironment.h>
 
 #include "uda_plugin_helpers.hpp"
+#include "python_data_source.hpp"
 
 namespace
 {
@@ -88,6 +89,7 @@ class MappingPlugin
     static int max_interface_version(IDAM_PLUGIN_INTERFACE* plugin_interface);
 
     bool m_init = false;
+    bool m_python_init = false;
     std::string m_request_function;
     libtokamap::MappingHandler m_mapping_handler;
 };
@@ -113,6 +115,20 @@ int MappingPlugin::init(IDAM_PLUGIN_INTERFACE* plugin_interface)
     const char* config_path = getenv("UDA_MAPPING_CONFIG_PATH");
     if (config_path != nullptr) {
         m_mapping_handler.init(std::filesystem::path{config_path});
+        // Register any Python data sources / custom functions declared in the
+        // MAPPING_PLUGIN_PYTHON_CONFIG file. Starts the embedded interpreter
+        // only when such a config exists; no-op otherwise (and a compile-time
+        // no-op when built without MAPPING_PLUGIN_PYTHON).
+        //
+        // Done at most once per process. reset() clears m_init, but the mapping
+        // handler keeps its registered data sources (just as it keeps its
+        // experiment register, which is why its own init() is a no-op on the
+        // second call), so re-running this would re-import the Python modules
+        // and reconnect the sources for nothing.
+        if (!m_python_init) {
+            mapping_plugin::init_python_data_sources_if_configured(m_mapping_handler);
+            m_python_init = true;
+        }
     } else {
         throw std::runtime_error{"UDA_MAPPING_CONFIG_PATH not specified"};
     }