Python initialization code tidy up

I've moved the initialization of statics a little earlier on - a little
safer as it is hard to follow exactly when some of these were being
used, such as SWIG_Py_None which sometimes replaces Py_None.

CHANGES.current

@@ -7,6 +7,11 @@ the issue number to the end of the URL: https://github.com/swig/swig/issues/
 Version 4.0.0 (in progress)
 ===========================
 
+2018-06-30: petrmitrichev
+            [Python] #1275 #1279 Remove function-local statics that call Python code
+            in order to avoid deadlocks with multi-threaded usage. These are now
+            file scope static variables and are initialized during module initialization.
+
 2018-06-15: wsfulton
             [Python] Fix seg fault using Python 2 when passing a Python string, containing
             invalid utf-8 content, to a wstring or wchar * parameter. A TypeError is thrown instead, eg:

Lib/python/pyinit.swg

@@ -379,6 +379,14 @@ SWIG_init(void) {
   assert(metatype);
 #endif
 
+#ifdef SWIG_PYTHON_BUILD_NONE
+  SWIG_Py_None_global = Py_BuildValue("");
+  Py_DECREF(SWIG_Py_None_global);
+#endif
+
+  SWIG_This_global = SWIG_Python_str_FromChar("this");
+  SWIG_Python_TypeCache_global = PyDict_New();
+
   /* Fix SwigMethods to carry the callback ptrs when needed */
   SWIG_Python_FixMethods(SwigMethods, swig_const_table, swig_types, swig_type_initial);
 
@@ -429,13 +437,11 @@ SWIG_init(void) {
     SwigPyBuiltin_AddPublicSymbol(public_interface, SwigMethods[i].ml_name);
   for (i = 0; swig_const_table[i].name != 0; ++i)
     SwigPyBuiltin_AddPublicSymbol(public_interface, swig_const_table[i].name);
+#else
+  SwigPyObject_type_global = SwigPyObject_TypeOnce();
 #endif
 
-  SWIG_Py_None_global_Init();
+  SwigPyPacked_type_global = SwigPyPacked_TypeOnce();
-  SwigPyObject_type_global_Init();
-  SwigPyPacked_type_global_Init();
-  SWIG_Python_TypeCache_global_Init();
-
   SWIG_InstallConstants(d,swig_const_table);
 %}
 

Lib/python/pyrun.swg

@@ -241,42 +241,20 @@ extern "C" {
 #   undef Py_None
 #   define Py_None SWIG_Py_None()
 #  endif
-SWIGRUNTIMEINLINE PyObject * 
-_SWIG_Py_None(void)
-{
-  PyObject *none = Py_BuildValue("");
-  Py_DECREF(none);
-  return none;
-}
 
-/* This used to be a function-local static variable, but accessing Python
- * C API from inside a function-local static initializer can lead to deadlocks.
- * https://github.com/swig/swig/issues/1275 */
 static PyObject *SWIG_Py_None_global = 0;
 
-SWIGRUNTIME void SWIG_Py_None_global_Init(void) {
-  SWIG_Py_None_global = _SWIG_Py_None();
-}
-
 SWIGRUNTIME PyObject *
-SWIG_Py_None(void)
+SWIG_Py_None(void) {
-{
   assert(SWIG_Py_None_global);
   return SWIG_Py_None_global;
 }
-
-#else
-SWIGRUNTIME void SWIG_Py_None_global_Init(void)
-{
-  // Do nothing
-}
 #endif
 
 /* The python void return value */
 
 SWIGRUNTIMEINLINE PyObject * 
-SWIG_Py_Void(void)
+SWIG_Py_Void(void) {
-{
   PyObject *none = Py_None;
   Py_INCREF(none);
   return none;
@@ -485,6 +463,7 @@ SWIGRUNTIME PyTypeObject* SwigPyObject_TypeOnce(void);
 
 #ifdef SWIGPYTHON_BUILTIN
 static swig_type_info *SwigPyObject_stype = 0;
+
 SWIGRUNTIME PyTypeObject*
 SwigPyObject_type(void) {
     SwigPyClientData *cd;
@@ -494,20 +473,9 @@ SwigPyObject_type(void) {
     assert(cd->pytype);
     return cd->pytype;
 }
-
-SWIGRUNTIME void SwigPyObject_type_global_Init(void) {
-  // Do nothing
-}
 #else
-/* This used to be a function-local static variable, but accessing Python
- * C API from inside a function-local static initializer can lead to deadlocks.
- * https://github.com/swig/swig/issues/1275 */
 static PyTypeObject *SwigPyObject_type_global = 0;
 
-SWIGRUNTIME void SwigPyObject_type_global_Init(void) {
-  SwigPyObject_type_global = SwigPyObject_TypeOnce();
-}
-
 SWIGRUNTIME PyTypeObject*
 SwigPyObject_type(void) {
   assert(SwigPyObject_type_global);
@@ -855,15 +823,8 @@ SwigPyPacked_compare(SwigPyPacked *v, SwigPyPacked *w)
 
 SWIGRUNTIME PyTypeObject* SwigPyPacked_TypeOnce(void);
 
-/* This used to be a function-local static variable, but accessing Python
- * C API from inside a function-local static initializer can lead to deadlocks.
- * https://github.com/swig/swig/issues/1275 */
 static PyTypeObject* SwigPyPacked_type_global = 0;
 
-SWIGRUNTIME void SwigPyPacked_type_global_Init(void) {
-  SwigPyPacked_type_global = SwigPyPacked_TypeOnce();
-}
-
 SWIGRUNTIME PyTypeObject*
 SwigPyPacked_type(void) {
   assert(SwigPyPacked_type_global);
@@ -1004,20 +965,12 @@ SwigPyPacked_UnpackData(PyObject *obj, void *ptr, size_t size)
  * pointers/data manipulation
  * ----------------------------------------------------------------------------- */
 
-SWIGRUNTIMEINLINE PyObject *
+static PyObject *SWIG_This_global = NULL;
-_SWIG_This(void)
-{
-    return SWIG_Python_str_FromChar("this");
-}
-
-static PyObject *swig_this = NULL;
 
 SWIGRUNTIME PyObject *
-SWIG_This(void)
+SWIG_This(void) {
-{
+  assert(SWIG_This_global);
-  if (swig_this == NULL)
+  return SWIG_This_global;
-    swig_this = _SWIG_This();
-  return swig_this;
 }
 
 /* #define SWIG_PYTHON_SLOW_GETSET_THIS */
@@ -1446,7 +1399,7 @@ SWIG_Python_DestroyModule(PyObject *obj)
     }
   }
   Py_DECREF(SWIG_This());
-  swig_this = NULL;
+  SWIG_This_global = NULL;
 }
 
 SWIGRUNTIME void
@@ -1466,15 +1419,8 @@ SWIG_Python_SetModule(swig_module_info *swig_module) {
   }
 }
 
-/* This used to be a function-local static variable, but accessing Python
- * C API from inside a function-local static initializer can lead to deadlocks.
- * https://github.com/swig/swig/issues/1275 */
 static PyObject *SWIG_Python_TypeCache_global = 0;
 
-SWIGRUNTIME void SWIG_Python_TypeCache_global_Init(void) {
-  SWIG_Python_TypeCache_global = PyDict_New();
-}
-
 /* The python cached type query */
 SWIGRUNTIME PyObject *
 SWIG_Python_TypeCache(void) {