Support building free-threaded interrogate wheel

For interrogatedb, we just wrap all calls with a mutex for now

Author: rdb

cmake/macros/Python.cmake

@@ -60,7 +60,7 @@ function(add_python_target target)
     add_library(${target} ${MODULE_TYPE} ${sources})
     target_link_libraries(${target} PKG::PYTHON)
   else()
-    if(MODULE_TYPE STREQUAL "MODULE")
+    if(MODULE_TYPE STREQUAL "MODULE" AND NOT PYTHON_FREETHREADED)
       Python_add_library(${target} MODULE USE_SABI 3.3 ${sources})
     else()
       Python_add_library(${target} ${MODULE_TYPE} ${sources})

src/Config.cmake

@@ -83,6 +83,15 @@ if(Python_FOUND)
   set(PYTHON_INCLUDE_DIRS ${Python_INCLUDE_DIRS})
   set(PYTHON_LIBRARY_DIRS ${Python_LIBRARY_DIRS})
   set(PYTHON_VERSION_STRING ${Python_VERSION})
+
+  execute_process(COMMAND ${Python_EXECUTABLE}
+    -c "import sysconfig;print(sysconfig.get_config_var('Py_GIL_DISABLED') or 0)"
+    OUTPUT_VARIABLE PYTHON_FREETHREADED
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  if(PYTHON_FREETHREADED)
+    # The free-threaded build has no stable ABI (yet).
+    set(_IMPORTED_AS Python::Module)
+  endif()
 endif()
 
 if(CMAKE_VERSION VERSION_LESS "3.15")
@@ -162,7 +171,15 @@ if(HAVE_PYTHON)
 
   endif()
 
-  if(CYGWIN)
+  if(PYTHON_FREETHREADED)
+    if(CYGWIN)
+      set(_EXT_SUFFIX ".${Python_SOABI}.dll")
+    elseif(WIN32)
+      set(_EXT_SUFFIX ".${Python_SOABI}.pyd")
+    else()
+      set(_EXT_SUFFIX ".${Python_SOABI}.so")
+    endif()
+  elseif(CYGWIN)
     set(_EXT_SUFFIX ".dll")
   elseif(WIN32)
     set(_EXT_SUFFIX ".pyd")

src/interrogate/interfaceMakerPythonSimple.cxx

@@ -48,10 +48,13 @@ InterfaceMakerPythonSimple::
  */
 void InterfaceMakerPythonSimple::
 write_includes(std::ostream &out) {
-  out << "#if PY_VERSION_HEX >= 0x30300000\n";
+  out << "#if PY_VERSION_HEX >= 0x30300000 && !defined(Py_GIL_DISABLED)\n";
   out << "#define Py_LIMITED_API 0x30300000\n";
   out << "#endif\n\n";
   InterfaceMakerPython::write_includes(out);
+  out << "\n#ifdef Py_GIL_DISABLED\n";
+  out << "static PyMutex mutex;\n";
+  out << "#endif\n\n";
 }
 
 /**
@@ -132,7 +135,11 @@ write_module(ostream &out,ostream *out_h, InterrogateModuleDef *def) {
 
       << "INIT_FUNC() {\n"
       << "#if PY_MAJOR_VERSION >= 3\n"
-      << "  return PyModule_Create(&python_simple_module);\n"
+      << "  PyObject *module = PyModule_Create(&python_simple_module);\n"
+      << "#ifdef Py_GIL_DISABLED\n"
+      << "  PyUnstable_Module_SetGIL(module, Py_MOD_GIL_NOT_USED);\n"
+      << "#endif\n"
+      << "  return module;\n"
       << "#else\n"
       << "  Py_InitModule(\"" << def->library_name << "\", python_simple_funcs);\n"
       << "#endif\n"
@@ -380,6 +387,9 @@ void InterfaceMakerPythonSimple::write_function_instance(ostream &out, Interface
         << "    }\n";
   }
 
+  out << "#ifdef Py_GIL_DISABLED\n";
+  out << "    PyMutex_Lock(&mutex);\n";
+  out << "#endif\n";
   if (track_interpreter) {
     out << "    in_interpreter = 0;\n";
   }
@@ -397,6 +407,9 @@ void InterfaceMakerPythonSimple::write_function_instance(ostream &out, Interface
     if (track_interpreter) {
       out << "    in_interpreter = 1;\n";
     }
+    out << "#ifdef Py_GIL_DISABLED\n";
+    out << "    PyMutex_Unlock(&mutex);\n";
+    out << "#endif\n";
     if (!extra_cleanup.empty()) {
       out << "   " << extra_cleanup << "\n";
     }
@@ -411,6 +424,9 @@ void InterfaceMakerPythonSimple::write_function_instance(ostream &out, Interface
       if (track_interpreter) {
         out << "    in_interpreter = 1;\n";
       }
+      out << "#ifdef Py_GIL_DISABLED\n";
+      out << "    PyMutex_Unlock(&mutex);\n";
+      out << "#endif\n";
       if (!extra_cleanup.empty()) {
         out << "   " << extra_cleanup << "\n";
       }
@@ -425,6 +441,9 @@ void InterfaceMakerPythonSimple::write_function_instance(ostream &out, Interface
       if (track_interpreter) {
         out << "    in_interpreter = 1;\n";
       }
+      out << "#ifdef Py_GIL_DISABLED\n";
+      out << "    PyMutex_Unlock(&mutex);\n";
+      out << "#endif\n";
       if (!extra_cleanup.empty()) {
         out << "   " << extra_cleanup << "\n";
       }