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gh-128384: Add thread-safe context manager to "warnings" module #128300

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gh-128384: Add thread-safe context manager to "warnings" module #128300

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deb659d
Add locking to warnings.py.
nascheme Dec 27, 2024
902df7c
Add 'context' parameter to Thread.
nascheme Dec 21, 2024
e61b40e
Make _contextvars a builtin module.
nascheme Dec 28, 2024
3bac8d1
wip: warnings local_context
nascheme Dec 27, 2024
c7287ad
Rename function, add locking to _filters_mutated().
nascheme Jan 1, 2025
1521276
Use re-entrant lock for warnings module.
nascheme Jan 1, 2025
e5c128a
Make _warnings use _warnings_context.
nascheme Jan 1, 2025
948a9e9
Add unit tests for warnings.Context
nascheme Jan 2, 2025
fc20826
Improve Context.resetwarnings().
nascheme Jan 2, 2025
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Use re-entrant lock for warnings module.
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@nascheme
nascheme committed Jan 1, 2025
commit 152127603b0ba7012cb0bb7767a45d7b39b7ec39
2 changes: 1 addition & 1 deletion Include/internal/pycore_warnings.h
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Expand Up @@ -14,7 +14,7 @@ struct _warnings_runtime_state {
PyObject *filters; /* List */
PyObject *once_registry; /* Dict */
PyObject *default_action; /* String */
PyMutex mutex;
_PyRecursiveMutex lock;
long filters_version;
};

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5 changes: 1 addition & 4 deletions Lib/warnings.py
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Expand Up @@ -905,10 +905,7 @@ def __exit__(self, *args):

import _thread

# Note that this is a non-reentrant lock, matching what's used by
# _acquire_lock() and _release_lock(). Care must be taken to
# not deadlock.
_lock = _thread.LockType()
_lock = _thread.RLock()

_filters_version = 1

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32 changes: 16 additions & 16 deletions Python/_warnings.c
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Expand Up @@ -249,7 +249,7 @@ warnings_acquire_lock_impl(PyObject *module)
WarningsState *st = warnings_get_state(interp);
assert(st != NULL);

_PyMutex_Lock(&st->mutex);
_PyRecursiveMutex_Lock(&st->lock);
Py_RETURN_NONE;
}

Expand All @@ -270,7 +270,7 @@ warnings_release_lock_impl(PyObject *module)
WarningsState *st = warnings_get_state(interp);
assert(st != NULL);

_PyMutex_Unlock(&st->mutex);
_PyRecursiveMutex_Unlock(&st->lock);
Py_RETURN_NONE;
}

Expand All @@ -280,7 +280,7 @@ get_once_registry(PyInterpreterState *interp)
WarningsState *st = warnings_get_state(interp);
assert(st != NULL);

_Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(&st->mutex);
assert(PyMutex_IsLocked(&st->lock.mutex));

PyObject *registry = GET_WARNINGS_ATTR(interp, onceregistry, 0);
if (registry == NULL) {
Expand Down Expand Up @@ -308,7 +308,7 @@ get_default_action(PyInterpreterState *interp)
WarningsState *st = warnings_get_state(interp);
assert(st != NULL);

_Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(&st->mutex);
assert(PyMutex_IsLocked(&st->lock.mutex));

PyObject *default_action = GET_WARNINGS_ATTR(interp, defaultaction, 0);
if (default_action == NULL) {
Expand Down Expand Up @@ -340,7 +340,7 @@ get_filter(PyInterpreterState *interp, PyObject *category,
WarningsState *st = warnings_get_state(interp);
assert(st != NULL);

_Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(&st->mutex);
assert(PyMutex_IsLocked(&st->lock.mutex));

PyObject *warnings_filters = GET_WARNINGS_ATTR(interp, filters, 0);
if (warnings_filters == NULL) {
Expand Down Expand Up @@ -440,7 +440,7 @@ already_warned(PyInterpreterState *interp, PyObject *registry, PyObject *key,

WarningsState *st = warnings_get_state(interp);
assert(st != NULL);
_Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(&st->mutex);
assert(PyMutex_IsLocked(&st->lock.mutex));

PyObject *version_obj;
if (PyDict_GetItemRef(registry, &_Py_ID(version), &version_obj) < 0) {
Expand Down Expand Up @@ -1040,10 +1040,10 @@ do_warn(PyObject *message, PyObject *category, Py_ssize_t stack_level,
assert(st != NULL);
#endif

Py_BEGIN_CRITICAL_SECTION_MUT(&st->mutex);
_PyRecursiveMutex_Lock(&st->lock);
res = warn_explicit(tstate, category, message, filename, lineno, module, registry,
NULL, source);
Py_END_CRITICAL_SECTION();
_PyRecursiveMutex_Unlock(&st->lock);
Py_DECREF(filename);
Py_DECREF(registry);
Py_DECREF(module);
Expand Down Expand Up @@ -1197,10 +1197,10 @@ warnings_warn_explicit_impl(PyObject *module, PyObject *message,
assert(st != NULL);
#endif

Py_BEGIN_CRITICAL_SECTION_MUT(&st->mutex);
_PyRecursiveMutex_Lock(&st->lock);
returned = warn_explicit(tstate, category, message, filename, lineno,
mod, registry, source_line, sourceobj);
Py_END_CRITICAL_SECTION();
_PyRecursiveMutex_Unlock(&st->lock);
Py_XDECREF(source_line);
return returned;
}
Expand All @@ -1223,8 +1223,8 @@ warnings_filters_mutated_lock_held_impl(PyObject *module)
assert(st != NULL);

// Note that the lock must be held by the caller.
if (!PyMutex_IsLocked(&st->mutex)) {
PyErr_SetString(PyExc_RuntimeError, "warnings mutex is not held");
if (!PyMutex_IsLocked(&st->lock.mutex)) {
PyErr_SetString(PyExc_RuntimeError, "warnings lock is not held");
return NULL;
}

Expand Down Expand Up @@ -1352,10 +1352,10 @@ PyErr_WarnExplicitObject(PyObject *category, PyObject *message,
assert(st != NULL);
#endif

Py_BEGIN_CRITICAL_SECTION_MUT(&st->mutex);
_PyRecursiveMutex_Lock(&st->lock);
res = warn_explicit(tstate, category, message, filename, lineno,
module, registry, NULL, NULL);
Py_END_CRITICAL_SECTION();
_PyRecursiveMutex_Unlock(&st->lock);
if (res == NULL)
return -1;
Py_DECREF(res);
Expand Down Expand Up @@ -1425,10 +1425,10 @@ PyErr_WarnExplicitFormat(PyObject *category,
assert(st != NULL);
#endif

Py_BEGIN_CRITICAL_SECTION_MUT(&st->mutex);
_PyRecursiveMutex_Lock(&st->lock);
res = warn_explicit(tstate, category, message, filename, lineno,
module, registry, NULL, NULL);
Py_END_CRITICAL_SECTION();
_PyRecursiveMutex_Unlock(&st->lock);
Py_DECREF(message);
if (res != NULL) {
Py_DECREF(res);
Expand Down