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gh-132775: Support Fallbacks in _PyObject_GetXIData() (gh-133482)

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It now supports a "full" fallback to _PyFunction_GetXIData() and then `_PyPickle_GetXIData()`.  There's also room for other fallback modes if that later makes sense.
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Eric Snow 2025-05-21 07:23:48 -06:00 • committed by GitHub
parent 0c5a8b0b55
commit 88f8102a8f
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11 changed files with 581 additions and 139 deletions
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89
Python/crossinterp.c
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@ -210,16 +210,16 @@ _Py_CallInInterpreterAndRawFree(PyInterpreterState *interp,
/* cross-interpreter data */
/**************************/
/* registry of {type -> xidatafunc} */
/* registry of {type -> _PyXIData_getdata_t} */
/* For now we use a global registry of shareable classes. An
alternative would be to add a tp_* slot for a class's
xidatafunc. It would be simpler and more efficient. */
/* For now we use a global registry of shareable classes.
An alternative would be to add a tp_* slot for a class's
_PyXIData_getdata_t. It would be simpler and more efficient. */
static void xid_lookup_init(_PyXIData_lookup_t *);
static void xid_lookup_fini(_PyXIData_lookup_t *);
struct _dlcontext;
static xidatafunc lookup_getdata(struct _dlcontext *, PyObject *);
static _PyXIData_getdata_t lookup_getdata(struct _dlcontext *, PyObject *);
#include "crossinterp_data_lookup.h"
@ -343,7 +343,7 @@ _set_xid_lookup_failure(PyThreadState *tstate, PyObject *obj, const char *msg,
set_notshareableerror(tstate, cause, 0, msg);
}
else {
msg = "%S does not support cross-interpreter data";
msg = "%R does not support cross-interpreter data";
format_notshareableerror(tstate, cause, 0, msg, obj);
}
}
@ -356,8 +356,8 @@ _PyObject_CheckXIData(PyThreadState *tstate, PyObject *obj)
if (get_lookup_context(tstate, &ctx) < 0) {
return -1;
}
xidatafunc getdata = lookup_getdata(&ctx, obj);
if (getdata == NULL) {
_PyXIData_getdata_t getdata = lookup_getdata(&ctx, obj);
if (getdata.basic == NULL && getdata.fallback == NULL) {
if (!_PyErr_Occurred(tstate)) {
_set_xid_lookup_failure(tstate, obj, NULL, NULL);
}
@ -388,9 +388,9 @@ _check_xidata(PyThreadState *tstate, _PyXIData_t *xidata)
return 0;
}
int
_PyObject_GetXIData(PyThreadState *tstate,
PyObject *obj, _PyXIData_t *xidata)
static int
_get_xidata(PyThreadState *tstate,
PyObject *obj, xidata_fallback_t fallback, _PyXIData_t *xidata)
{
PyInterpreterState *interp = tstate->interp;
@ -398,6 +398,7 @@ _PyObject_GetXIData(PyThreadState *tstate,
assert(xidata->obj == NULL);
if (xidata->data != NULL || xidata->obj != NULL) {
_PyErr_SetString(tstate, PyExc_ValueError, "xidata not cleared");
return -1;
}
// Call the "getdata" func for the object.
@ -406,8 +407,8 @@ _PyObject_GetXIData(PyThreadState *tstate,
return -1;
}
Py_INCREF(obj);
xidatafunc getdata = lookup_getdata(&ctx, obj);
if (getdata == NULL) {
_PyXIData_getdata_t getdata = lookup_getdata(&ctx, obj);
if (getdata.basic == NULL && getdata.fallback == NULL) {
if (PyErr_Occurred()) {
Py_DECREF(obj);
return -1;
@ -419,7 +420,9 @@ _PyObject_GetXIData(PyThreadState *tstate,
}
return -1;
}
int res = getdata(tstate, obj, xidata);
int res = getdata.basic != NULL
? getdata.basic(tstate, obj, xidata)
: getdata.fallback(tstate, obj, fallback, xidata);
Py_DECREF(obj);
if (res != 0) {
PyObject *cause = _PyErr_GetRaisedException(tstate);
@ -439,6 +442,51 @@ _PyObject_GetXIData(PyThreadState *tstate,
return 0;
}
int
_PyObject_GetXIDataNoFallback(PyThreadState *tstate,
PyObject *obj, _PyXIData_t *xidata)
{
return _get_xidata(tstate, obj, _PyXIDATA_XIDATA_ONLY, xidata);
}
int
_PyObject_GetXIData(PyThreadState *tstate,
PyObject *obj, xidata_fallback_t fallback,
_PyXIData_t *xidata)
{
switch (fallback) {
case _PyXIDATA_XIDATA_ONLY:
return _get_xidata(tstate, obj, fallback, xidata);
case _PyXIDATA_FULL_FALLBACK:
if (_get_xidata(tstate, obj, fallback, xidata) == 0) {
return 0;
}
PyObject *exc = _PyErr_GetRaisedException(tstate);
if (PyFunction_Check(obj)) {
if (_PyFunction_GetXIData(tstate, obj, xidata) == 0) {
Py_DECREF(exc);
return 0;
}
_PyErr_Clear(tstate);
}
// We could try _PyMarshal_GetXIData() but we won't for now.
if (_PyPickle_GetXIData(tstate, obj, xidata) == 0) {
Py_DECREF(exc);
return 0;
}
// Raise the original exception.
_PyErr_SetRaisedException(tstate, exc);
return -1;
default:
#ifdef Py_DEBUG
Py_FatalError("unsupported xidata fallback option");
#endif
_PyErr_SetString(tstate, PyExc_SystemError,
"unsupported xidata fallback option");
return -1;
}
}
/* pickle C-API */
@ -1617,14 +1665,9 @@ _PyXI_ApplyErrorCode(_PyXI_errcode code, PyInterpreterState *interp)
PyThreadState *tstate = _PyThreadState_GET();
assert(!PyErr_Occurred());
assert(code != _PyXI_ERR_NO_ERROR);
assert(code != _PyXI_ERR_UNCAUGHT_EXCEPTION);
switch (code) {
case _PyXI_ERR_NO_ERROR: _Py_FALLTHROUGH;
case _PyXI_ERR_UNCAUGHT_EXCEPTION:
// There is nothing to apply.
#ifdef Py_DEBUG
Py_UNREACHABLE();
#endif
return 0;
case _PyXI_ERR_OTHER:
// XXX msg?
PyErr_SetNone(PyExc_InterpreterError);
@ -1649,7 +1692,7 @@ _PyXI_ApplyErrorCode(_PyXI_errcode code, PyInterpreterState *interp)
break;
default:
#ifdef Py_DEBUG
Py_UNREACHABLE();
Py_FatalError("unsupported error code");
#else
PyErr_Format(PyExc_RuntimeError, "unsupported error code %d", code);
#endif
@ -1796,7 +1839,7 @@ _sharednsitem_set_value(_PyXI_namespace_item *item, PyObject *value)
return -1;
}
PyThreadState *tstate = PyThreadState_Get();
if (_PyObject_GetXIData(tstate, value, item->xidata) != 0) {
if (_PyObject_GetXIDataNoFallback(tstate, value, item->xidata) != 0) {
PyMem_RawFree(item->xidata);
item->xidata = NULL;
// The caller may want to propagate PyExc_NotShareableError