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gh-100227: Make the Global PyModuleDef Cache Safe for Isolated Interpreters #103084

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Merged
ericsnowcurrently merged 14 commits into from
Mar 29, 2023
Merged

gh-100227: Make the Global PyModuleDef Cache Safe for Isolated Interpreters #103084

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ff4eb36
Make _PyRuntime.imports.extensions a struct.
ericsnowcurrently Mar 27, 2023
e558d76
Factor out add_threadstate().
ericsnowcurrently Mar 21, 2023
acf5269
Add _PyThreadState_InitDetached().
ericsnowcurrently Mar 21, 2023
181106e
Add _PyThreadState_ClearDetached().
ericsnowcurrently Mar 21, 2023
b8ffbba
Add extensions_lock_acquire() and extensions_lock_release().
ericsnowcurrently Mar 27, 2023
a86aea5
Add _PyRuntime.imports.extensions.main_tstate.
ericsnowcurrently Mar 27, 2023
d79afe5
Add _PyThreadState_BindDetached() and _PyThreadState_UnbindDetached().
ericsnowcurrently Mar 28, 2023
5182186
Share the extensions dict safely.
ericsnowcurrently Mar 28, 2023
f6db0a2
Intern the name and filename in the main interpreter.
ericsnowcurrently Mar 28, 2023
dac9c23
Fix the asserts in _PyThreadState_BindDetached() and _PyThreadState_U…
ericsnowcurrently Mar 28, 2023
8d442e2
Swap back when done using main_tstate.
ericsnowcurrently Mar 28, 2023
ee70a96
Disable a prematurely-restrictive assert.
ericsnowcurrently Mar 28, 2023
e9c37fe
Fix a copy-and-paste bug.
ericsnowcurrently Mar 28, 2023
8e005bf
Decref name & filename if copied.
ericsnowcurrently Mar 29, 2023
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Share the extensions dict safely.
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@ericsnowcurrently
ericsnowcurrently committed Mar 28, 2023
commit 51821860affc43f26478f6faddd9007424200132
88 changes: 71 additions & 17 deletions Python/import.c
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Original file line number Diff line number Diff line change
Expand Up @@ -905,18 +905,19 @@ _extensions_cache_get(PyObject *filename, PyObject *name)
PyModuleDef *def = NULL;
extensions_lock_acquire();

PyObject *extensions = EXTENSIONS.dict;
if (extensions == NULL) {
goto finally;
}
PyObject *key = PyTuple_Pack(2, filename, name);
if (key == NULL) {
goto finally;
}

PyObject *extensions = EXTENSIONS.dict;
if (extensions == NULL) {
goto finally;
}
def = (PyModuleDef *)PyDict_GetItemWithError(extensions, key);
Py_DECREF(key);

finally:
Py_XDECREF(key);
extensions_lock_release();
return def;
}
Expand All @@ -925,30 +926,60 @@ static int
_extensions_cache_set(PyObject *filename, PyObject *name, PyModuleDef *def)
{
int res = -1;
PyThreadState *oldts = NULL;
extensions_lock_acquire();

/* Swap to the main interpreter, if necessary. This matters if
the dict hasn't been created yet or if the item isn't in the
dict yet. In both cases we must ensure the relevant objects
are created using the main interpreter. */
PyThreadState *main_tstate = &EXTENSIONS.main_tstate;
PyInterpreterState *interp = _PyInterpreterState_GET();
if (!_Py_IsMainInterpreter(interp)) {
_PyThreadState_BindDetached(main_tstate);
oldts = _PyThreadState_Swap(interp->runtime, main_tstate);
assert(!_Py_IsMainInterpreter(oldts->interp));
}

PyObject *key = PyTuple_Pack(2, filename, name);
if (key == NULL) {
goto finally;
}

PyObject *extensions = EXTENSIONS.dict;
if (extensions == NULL) {
extensions = PyDict_New();
if (extensions == NULL) {
goto finally;
}
extensions_lock_acquire();
EXTENSIONS.dict = extensions;
}
PyObject *key = PyTuple_Pack(2, filename, name);
if (key == NULL) {

PyModuleDef *actual = (PyModuleDef *)PyDict_GetItemWithError(extensions, key);
if (PyErr_Occurred()) {
goto finally;
}
else if (actual != NULL) {
/* We expect it to be static, so it must be the same pointer. */
assert(def == actual);
res = 0;
goto finally;
}

/* This might trigger a resize, which is why we must switch
to the main interpreter. */
res = PyDict_SetItem(extensions, key, (PyObject *)def);
Py_DECREF(key);
if (res < 0) {
res = -1;
goto finally;
}
res = 0;

finally:
if (oldts != NULL) {
_PyThreadState_UnbindDetached(main_tstate);
}
Py_XDECREF(key);
extensions_lock_release();
return res;
}
Expand All @@ -957,28 +988,51 @@ static int
_extensions_cache_delete(PyObject *filename, PyObject *name)
{
int res = -1;
PyThreadState *oldts = NULL;
extensions_lock_acquire();

PyObject *key = PyTuple_Pack(2, filename, name);
if (key == NULL) {
goto finally;
}

_PyThreadState_BindDetached(&EXTENSIONS.main_tstate);

PyObject *extensions = EXTENSIONS.dict;
if (extensions == NULL) {
res = 0;
goto finally;
}
PyObject *key = PyTuple_Pack(2, filename, name);
if (key == NULL) {

PyModuleDef *actual = (PyModuleDef *)PyDict_GetItemWithError(extensions, key);
if (PyErr_Occurred()) {
goto finally;
}
else if (actual == NULL) {
/* It was already removed or never added. */
res = 0;
goto finally;
}

/* Swap to the main interpreter, if necessary. */
PyThreadState *main_tstate = &EXTENSIONS.main_tstate;
PyInterpreterState *interp = _PyInterpreterState_GET();
if (!_Py_IsMainInterpreter(interp)) {
_PyThreadState_BindDetached(main_tstate);
oldts = _PyThreadState_Swap(interp->runtime, main_tstate);
assert(!_Py_IsMainInterpreter(oldts->interp));
}

if (PyDict_DelItem(extensions, key) < 0) {
if (!PyErr_ExceptionMatches(PyExc_KeyError)) {
Py_DECREF(key);
goto finally;
}
PyErr_Clear();
goto finally;
}
Py_DECREF(key);
res = 0;

finally:
if (oldts != NULL) {
_PyThreadState_UnbindDetached(main_tstate);
}
Py_XDECREF(key);
extensions_lock_release();
return res;
}
Expand Down