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CPython: callback trampolines hold their callback for the call and release their arguments #35

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Merged
bdbarnett merged 1 commit into from
Oct 15, 2026
Merged

CPython: callback trampolines hold their callback for the call and release their arguments #35

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20 changes: 15 additions & 5 deletions binding/emit_cpython_native.py
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Original file line number Diff line number Diff line change
Expand Up @@ -751,9 +751,10 @@ def gen_callback_func_cpython(func, func_name=None, user_data_argument=False):
" lvpy_release_lock_for_python();\n"
" lvpy_nesting_inc();\n"
" PyObject *result = PyObject_CallObject(py_cb, py_args);\n"
" Py_DECREF(py_args);\n"
" Py_DECREF(py_cb);\n"
" lvpy_nesting_dec();\n"
" lvpy_reacquire_lock_after_python();\n"
" Py_DECREF(py_args);\n"
" if (result) Py_DECREF(result);\n"
" else PyErr_Clear();\n"
" PyGILState_Release(gstate);"
Expand All @@ -763,9 +764,10 @@ def gen_callback_func_cpython(func, func_name=None, user_data_argument=False):
" lvpy_release_lock_for_python();\n"
" lvpy_nesting_inc();\n"
" PyObject *result = PyObject_CallObject(py_cb, py_args);\n"
" Py_DECREF(py_args);\n"
" Py_DECREF(py_cb);\n"
" lvpy_nesting_dec();\n"
" lvpy_reacquire_lock_after_python();\n"
" Py_DECREF(py_args);\n"
" if (!result) { PyErr_Clear(); PyGILState_Release(gstate); return%s; }\n"
" %s _c_res = %s(result);\n"
" Py_DECREF(result);\n"
Expand All @@ -787,9 +789,13 @@ def gen_callback_func_cpython(func, func_name=None, user_data_argument=False):
if (!callbacks) {{ PyGILState_Release(gstate); return{void_default}; }}
PyObject *py_cb = PyDict_GetItemString(callbacks, "{func_name}");
if (!py_cb || !PyCallable_Check(py_cb)) {{ PyGILState_Release(gstate); return{void_default}; }}
/* Hold the callback for the whole call: it may replace or remove its
* own registration while it runs. */
Py_INCREF(py_cb);
{build_args}
PyObject *py_args = PyTuple_Pack({num_args}, {tuple_args});
if (!py_args) {{ PyGILState_Release(gstate); return{void_default}; }}
PyObject *py_args = ({args_ok}) ? PyTuple_Pack({num_args}{tuple_args}) : NULL;
{release_args}
if (!py_args) {{ PyErr_Clear(); Py_DECREF(py_cb); PyGILState_Release(gstate); return{void_default}; }}
{tail}
}}
""".format(
Expand All @@ -801,7 +807,11 @@ def gen_callback_func_cpython(func, func_name=None, user_data_argument=False):
user_data=full_user_data,
build_args="\n ".join(build_arg_lines),
num_args=len(args),
tuple_args=", ".join(tuple_items) if tuple_items else "",
tuple_args="".join(", " + item for item in tuple_items),
args_ok=" && ".join(tuple_items) if tuple_items else "1",
release_args="\n ".join(
"Py_XDECREF(%s);" % item for item in tuple_items
),
tail=tail,
void_default=void_default,
)
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