Add strong interpreter reference functions.

Author: ZeroIntensity

Include/cpython/pystate.h

@@ -277,23 +277,36 @@ PyAPI_FUNC(void) _PyInterpreterState_SetEvalFrameFunc(
     PyInterpreterState *interp,
     _PyFrameEvalFunction eval_frame);
 
-/* Similar to PyInterpreterState_Get(), but returns the interpreter with an
- * incremented reference count. PyInterpreterState_Delete() won't delete the
- * full interpreter structure until the reference is released by
- * PyThreadState_Ensure() or PyInterpreterState_Release(). */
-PyAPI_FUNC(PyInterpreterState *) PyInterpreterState_Hold(void);
+/* Strong interpreter references */
 
-PyAPI_FUNC(PyInterpreterState *) PyInterpreterState_Lookup(int64_t interp_id);
+typedef uintptr_t PyInterpreterRef;
 
-/* Release a reference to an interpreter incremented by PyInterpreterState_Hold() */
-PyAPI_FUNC(void) PyInterpreterState_Release(PyInterpreterState *interp);
+PyAPI_FUNC(PyInterpreterRef) PyInterpreterRef_Get(void);
+PyAPI_FUNC(PyInterpreterRef) PyInterpreterRef_Dup(PyInterpreterRef ref);
+PyAPI_FUNC(PyInterpreterRef) PyInterpreterState_AsStrong(PyInterpreterState *interp);
+PyAPI_FUNC(void) PyInterpreterRef_Close(PyInterpreterRef ref);
+
+#define PyInterpreterRef_Close(ref) do {    \
+    PyInterpreterRef_Close(ref);            \
+    ref = 0;                                \
+} while (0);                                \
+
+/* Weak interpreter references */
+
+typedef struct _interpreter_weakref {
+    int64_t id;
+    Py_ssize_t refcount;
+} PyInterpreterWeakRef;
+
+PyAPI_FUNC(PyInterpreterWeakRef) PyInterpreterWeakRef_Get(void);
+PyAPI_FUNC(PyInterpreterWeakRef) PyInterpreterWeakRef_Dup(PyInterpreterWeakRef wref);
+PyAPI_FUNC(PyInterpreterRef) PyInterpreterWeakRef_AsStrong(PyInterpreterWeakRef wref);
+PyAPI_FUNC(void) PyInterpreterWeakRef_Close(PyInterpreterWeakRef wref);
 
 // Exports for '_testcapi' shared extension
 PyAPI_FUNC(Py_ssize_t) _PyInterpreterState_Refcount(PyInterpreterState *interp);
 PyAPI_FUNC(void) _PyInterpreterState_Incref(PyInterpreterState *interp);
 
-PyAPI_FUNC(int) PyThreadState_SetDaemon(int daemon);
-
 PyAPI_FUNC(int) PyThreadState_Ensure(PyInterpreterState *interp);
 
 PyAPI_FUNC(void) PyThreadState_Release(void);

Python/pystate.c

@@ -3229,12 +3229,38 @@ _PyInterpreterState_Incref(PyInterpreterState *interp)
     _Py_atomic_add_ssize(&interp->threads.finalizing.countdown, 1);
 }
 
-PyInterpreterState *
-PyInterpreterState_Hold(void)
+static PyInterpreterState *
+ref_as_interp(PyInterpreterRef ref)
+{
+    PyInterpreterState *interp = (PyInterpreterState *)ref;
+    if (interp == NULL) {
+        Py_FatalError("Got a null interpreter reference, likely due to use after close.");
+    }
+
+    return interp;
+}
+
+PyInterpreterRef
+PyInterpreterRef_Get(void)
 {
     PyInterpreterState *interp = PyInterpreterState_Get();
     _PyInterpreterState_Incref(interp);
-    return interp;
+    return (PyInterpreterRef)interp;
+}
+
+PyInterpreterRef
+PyInterpreterRef_Dup(PyInterpreterRef ref)
+{
+    PyInterpreterState *interp = ref_as_interp(ref);
+    _PyInterpreterState_Incref(interp);
+    return (PyInterpreterRef)interp;
+}
+
+void
+PyInterpreterRef_Close(PyInterpreterRef ref)
+{
+    PyInterpreterState *interp = ref_as_interp(ref);
+    decref_interpreter(ref);
 }
 
 PyInterpreterState *
@@ -3260,13 +3286,6 @@ PyInterpreterState_Lookup(int64_t interp_id)
     return interp;
 }
 
-void
-PyInterpreterState_Release(PyInterpreterState *interp)
-{
-    assert(interp != NULL);
-    decref_interpreter(interp);
-}
-
 int
 PyThreadState_Ensure(PyInterpreterState *interp)
 {