set capi-struct pointer to interp state

Include/datetime.h

@@ -155,7 +155,7 @@ typedef struct
 
 
 /* Define structure for C API. */
-typedef struct {
+typedef struct _pydatetime_capi {
     /* type objects */
     PyTypeObject *DateType;
     PyTypeObject *DateTimeType;
@@ -182,7 +182,8 @@ typedef struct {
     PyObject *(*DateTime_FromDateAndTimeAndFold)(int, int, int, int, int, int, int,
         PyObject*, int, PyTypeObject*);
     PyObject *(*Time_FromTimeAndFold)(int, int, int, int, PyObject*, int, PyTypeObject*);
-
+    struct _pydatetime_capi *(*_get_capi_by_interp)(void);
+    void (*_set_capi_by_interp)(struct _pydatetime_capi *);
 } PyDateTime_CAPI;
 
 #define PyDateTime_CAPSULE_NAME "datetime.datetime_CAPI"
@@ -194,10 +195,22 @@ typedef struct {
  * */
 #ifndef _PY_DATETIME_IMPL
 /* Define global variable for the C API and a macro for setting it. */
-static PyDateTime_CAPI *PyDateTimeAPI = NULL;
-
-#define PyDateTime_IMPORT \
-    PyDateTimeAPI = (PyDateTime_CAPI *)PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)
+static PyDateTime_CAPI *
+_get_pydatetime_capi_dummy(void)
+{
+    return NULL;
+}
+static PyDateTime_CAPI *(*_get_pydatetime_capi)(void) = _get_pydatetime_capi_dummy;
+#define PyDateTimeAPI _get_pydatetime_capi()
+
+static inline void pydatetime_import(void) {
+    PyDateTime_CAPI *capi = PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0);
+    if (capi) {
+        capi->_set_capi_by_interp(capi);
+        _get_pydatetime_capi = capi->_get_capi_by_interp;
+    }
+}
+#define PyDateTime_IMPORT pydatetime_import()
 
 /* Macro for access to the UTC singleton */
 #define PyDateTime_TimeZone_UTC PyDateTimeAPI->TimeZone_UTC

Include/internal/pycore_interp.h

@@ -236,6 +236,7 @@ struct _is {
     // more comments.
     struct _obmalloc_state *obmalloc;
 
+    void *datetime_capi;
     PyObject *audit_hooks;
     PyType_WatchCallback type_watchers[TYPE_MAX_WATCHERS];
     PyCode_WatchCallback code_watchers[CODE_MAX_WATCHERS];

Lib/test/test_capi/test_misc.py

@@ -2282,6 +2282,22 @@ def test_module_state_shared_in_global(self):
         subinterp_attr_id = os.read(r, 100)
         self.assertEqual(main_attr_id, subinterp_attr_id)
 
+    @unittest.skipIf(_testmultiphase is None, "test requires _testmultiphase module")
+    def test_datetime_capi_client(self):
+        script = textwrap.dedent("""
+            import importlib.machinery
+            import importlib.util
+            fullname = '_test_datetime_capi_client'
+            origin = importlib.util.find_spec('_testmultiphase').origin
+            loader = importlib.machinery.ExtensionFileLoader(fullname, origin)
+            spec = importlib.util.spec_from_loader(fullname, loader)
+            module = importlib.util.module_from_spec(spec)
+            spec.loader.exec_module(module)
+        """)
+        exec(script)
+        ret = support.run_in_subinterp(script)
+        self.assertEqual(ret, 0)
+
 
 @requires_subinterpreters
 class InterpreterConfigTests(unittest.TestCase):

Modules/_datetimemodule.c

@@ -63,6 +63,18 @@ static datetime_state _datetime_global_state;
 
 #define STATIC_STATE() (&_datetime_global_state)
 
+void
+set_datetime_capi_by_interp(PyDateTime_CAPI *capi)
+{
+    _PyInterpreterState_GET()->datetime_capi = capi;
+}
+
+PyDateTime_CAPI *
+get_datetime_capi_by_interp(void)
+{
+    return (PyDateTime_CAPI *)_PyInterpreterState_GET()->datetime_capi;
+}
+
 /* We require that C int be at least 32 bits, and use int virtually
  * everywhere.  In just a few cases we use a temp long, where a Python
  * API returns a C long.  In such cases, we have to ensure that the
@@ -6736,12 +6748,15 @@ get_datetime_capi(void)
     datetime_state *st = STATIC_STATE();
     assert(st->utc != NULL);
     capi->TimeZone_UTC = st->utc; // borrowed ref
+    capi->_set_capi_by_interp = set_datetime_capi_by_interp;
+    capi->_get_capi_by_interp = get_datetime_capi_by_interp;
     return capi;
 }
 
 static void
 datetime_destructor(PyObject *op)
 {
+    set_datetime_capi_by_interp(NULL);
     void *ptr = PyCapsule_GetPointer(op, PyDateTime_CAPSULE_NAME);
     PyMem_Free(ptr);
 }

Modules/_testmultiphase.c

@@ -952,3 +952,38 @@ PyInit__test_shared_gil_only(void)
 {
     return PyModuleDef_Init(&shared_gil_only_def);
 }
+
+
+#include "datetime.h"
+
+static int
+datetime_capi_client_exec(PyObject *m)
+{
+    _get_pydatetime_capi = _get_pydatetime_capi_dummy;
+    if (PyDateTimeAPI != NULL) {
+        return -1;
+    }
+    PyDateTime_IMPORT;
+    if (PyDateTimeAPI == NULL) {
+        return -1;
+    }
+    if (PyDateTimeAPI != PyCapsule_Import(PyDateTime_CAPSULE_NAME, 0)) {
+        return -1;
+    }
+    return 0;
+}
+
+static PyModuleDef_Slot datetime_capi_client_slots[] = {
+    {Py_mod_exec, datetime_capi_client_exec},
+    {Py_mod_multiple_interpreters, Py_MOD_PER_INTERPRETER_GIL_SUPPORTED},
+    {0, NULL},
+};
+
+static PyModuleDef datetime_capi_client_def = TEST_MODULE_DEF(
+    "_testmultiphase_datetime_capi_client", datetime_capi_client_slots, NULL);
+
+PyMODINIT_FUNC
+PyInit__test_datetime_capi_client(void)
+{
+    return PyModuleDef_Init(&datetime_capi_client_def);
+}