diff --git a/Doc/c-api/contextvars.rst b/Doc/c-api/contextvars.rst
index 8eba54a80dc80d..b7c6550ff34aac 100644
--- a/Doc/c-api/contextvars.rst
+++ b/Doc/c-api/contextvars.rst
@@ -123,16 +123,10 @@ Context object management functions:
Enumeration of possible context object watcher events:
- - ``Py_CONTEXT_EVENT_ENTER``: A context has been entered, causing the
- :term:`current context` to switch to it. The object passed to the watch
- callback is the now-current :class:`contextvars.Context` object. Each
- enter event will eventually have a corresponding exit event for the same
- context object after any subsequently entered contexts have themselves been
- exited.
- - ``Py_CONTEXT_EVENT_EXIT``: A context is about to be exited, which will
- cause the :term:`current context` to switch back to what it was before the
- context was entered. The object passed to the watch callback is the
- still-current :class:`contextvars.Context` object.
+ - ``Py_CONTEXT_SWITCHED``: The :term:`current context` has switched to a
+ different context. The object passed to the watch callback is the
+ now-current :class:`contextvars.Context` object, or None if no context is
+ current.
.. versionadded:: 3.14
diff --git a/Include/cpython/context.h b/Include/cpython/context.h
index 3c9be7873b9399..3a7a4b459c09ad 100644
--- a/Include/cpython/context.h
+++ b/Include/cpython/context.h
@@ -29,20 +29,11 @@ PyAPI_FUNC(int) PyContext_Exit(PyObject *);
typedef enum {
/*
- * A context has been entered, causing the "current context" to switch to
- * it. The object passed to the watch callback is the now-current
- * contextvars.Context object. Each enter event will eventually have a
- * corresponding exit event for the same context object after any
- * subsequently entered contexts have themselves been exited.
+ * The current context has switched to a different context. The object
+ * passed to the watch callback is the now-current contextvars.Context
+ * object, or None if no context is current.
*/
- Py_CONTEXT_EVENT_ENTER,
- /*
- * A context is about to be exited, which will cause the "current context"
- * to switch back to what it was before the context was entered. The
- * object passed to the watch callback is the still-current
- * contextvars.Context object.
- */
- Py_CONTEXT_EVENT_EXIT,
+ Py_CONTEXT_SWITCHED = 1,
} PyContextEvent;
/*
diff --git a/Lib/test/test_capi/test_watchers.py b/Lib/test/test_capi/test_watchers.py
index f21d2627c6094b..4680d6765de122 100644
--- a/Lib/test/test_capi/test_watchers.py
+++ b/Lib/test/test_capi/test_watchers.py
@@ -577,68 +577,62 @@ class TestContextObjectWatchers(unittest.TestCase):
def context_watcher(self, which_watcher):
wid = _testcapi.add_context_watcher(which_watcher)
try:
- yield wid
+ switches = _testcapi.get_context_switches(which_watcher)
+ except ValueError:
+ switches = None
+ try:
+ yield switches
finally:
_testcapi.clear_context_watcher(wid)
- def assert_event_counts(self, exp_enter_0, exp_exit_0,
- exp_enter_1, exp_exit_1):
- self.assertEqual(
- exp_enter_0, _testcapi.get_context_watcher_num_enter_events(0))
- self.assertEqual(
- exp_exit_0, _testcapi.get_context_watcher_num_exit_events(0))
- self.assertEqual(
- exp_enter_1, _testcapi.get_context_watcher_num_enter_events(1))
- self.assertEqual(
- exp_exit_1, _testcapi.get_context_watcher_num_exit_events(1))
+ def assert_event_counts(self, want_0, want_1):
+ self.assertEqual(len(_testcapi.get_context_switches(0)), want_0)
+ self.assertEqual(len(_testcapi.get_context_switches(1)), want_1)
def test_context_object_events_dispatched(self):
# verify that all counts are zero before any watchers are registered
- self.assert_event_counts(0, 0, 0, 0)
+ self.assert_event_counts(0, 0)
# verify that all counts remain zero when a context object is
# entered and exited with no watchers registered
ctx = contextvars.copy_context()
- ctx.run(self.assert_event_counts, 0, 0, 0, 0)
- self.assert_event_counts(0, 0, 0, 0)
+ ctx.run(self.assert_event_counts, 0, 0)
+ self.assert_event_counts(0, 0)
# verify counts are as expected when first watcher is registered
with self.context_watcher(0):
- self.assert_event_counts(0, 0, 0, 0)
- ctx.run(self.assert_event_counts, 1, 0, 0, 0)
- self.assert_event_counts(1, 1, 0, 0)
+ self.assert_event_counts(0, 0)
+ ctx.run(self.assert_event_counts, 1, 0)
+ self.assert_event_counts(2, 0)
# again with second watcher registered
with self.context_watcher(1):
- self.assert_event_counts(1, 1, 0, 0)
- ctx.run(self.assert_event_counts, 2, 1, 1, 0)
- self.assert_event_counts(2, 2, 1, 1)
+ self.assert_event_counts(2, 0)
+ ctx.run(self.assert_event_counts, 3, 1)
+ self.assert_event_counts(4, 2)
# verify counts are reset and don't change after both watchers are cleared
- ctx.run(self.assert_event_counts, 0, 0, 0, 0)
- self.assert_event_counts(0, 0, 0, 0)
-
- def test_enter_error(self):
- with self.context_watcher(2):
- with catch_unraisable_exception() as cm:
- ctx = contextvars.copy_context()
- ctx.run(int, 0)
- self.assertEqual(
- cm.unraisable.err_msg,
- "Exception ignored in "
- f"Py_CONTEXT_EVENT_EXIT watcher callback for {ctx!r}"
- )
- self.assertEqual(str(cm.unraisable.exc_value), "boom!")
-
- def test_exit_error(self):
- ctx = contextvars.copy_context()
- def _in_context(stack):
- stack.enter_context(self.context_watcher(2))
-
- with catch_unraisable_exception() as cm:
- with ExitStack() as stack:
- ctx.run(_in_context, stack)
- self.assertEqual(str(cm.unraisable.exc_value), "boom!")
+ ctx.run(self.assert_event_counts, 0, 0)
+ self.assert_event_counts(0, 0)
+
+ def test_callback_error(self):
+ ctx_outer = contextvars.copy_context()
+ ctx_inner = contextvars.copy_context()
+ unraisables = []
+
+ def _in_outer():
+ with self.context_watcher(2):
+ with catch_unraisable_exception() as cm:
+ ctx_inner.run(lambda: unraisables.append(cm.unraisable))
+ unraisables.append(cm.unraisable)
+
+ ctx_outer.run(_in_outer)
+ self.assertEqual([x.err_msg for x in unraisables],
+ ["Exception ignored in Py_CONTEXT_SWITCHED "
+ f"watcher callback for {ctx!r}"
+ for ctx in [ctx_inner, ctx_outer]])
+ self.assertEqual([str(x.exc_value) for x in unraisables],
+ ["boom!", "boom!"])
def test_clear_out_of_range_watcher_id(self):
with self.assertRaisesRegex(ValueError, r"Invalid context watcher ID -1"):
@@ -654,5 +648,12 @@ def test_allocate_too_many_watchers(self):
with self.assertRaisesRegex(RuntimeError, r"no more context watcher IDs available"):
_testcapi.allocate_too_many_context_watchers()
+ def test_exit_base_context(self):
+ ctx = contextvars.Context()
+ _testcapi.clear_context_stack()
+ with self.context_watcher(0) as switches:
+ ctx.run(lambda: None)
+ self.assertEqual(switches, [ctx, None])
+
if __name__ == "__main__":
unittest.main()
diff --git a/Modules/_testcapi/watchers.c b/Modules/_testcapi/watchers.c
index b4233d07134aea..321d3aeffb6ad1 100644
--- a/Modules/_testcapi/watchers.c
+++ b/Modules/_testcapi/watchers.c
@@ -626,16 +626,12 @@ allocate_too_many_func_watchers(PyObject *self, PyObject *args)
// Test contexct object watchers
#define NUM_CONTEXT_WATCHERS 2
static int context_watcher_ids[NUM_CONTEXT_WATCHERS] = {-1, -1};
-static int num_context_object_enter_events[NUM_CONTEXT_WATCHERS] = {0, 0};
-static int num_context_object_exit_events[NUM_CONTEXT_WATCHERS] = {0, 0};
+static PyObject *context_switches[NUM_CONTEXT_WATCHERS];
static int
handle_context_watcher_event(int which_watcher, PyContextEvent event, PyObject *ctx) {
- if (event == Py_CONTEXT_EVENT_ENTER) {
- num_context_object_enter_events[which_watcher]++;
- }
- else if (event == Py_CONTEXT_EVENT_EXIT) {
- num_context_object_exit_events[which_watcher]++;
+ if (event == Py_CONTEXT_SWITCHED) {
+ PyList_Append(context_switches[which_watcher], ctx);
}
else {
return -1;
@@ -667,31 +663,28 @@ error_context_event_handler(PyContextEvent event, PyObject *ctx) {
static PyObject *
add_context_watcher(PyObject *self, PyObject *which_watcher)
{
- int watcher_id;
+ static const PyContext_WatchCallback callbacks[] = {
+ &first_context_watcher_callback,
+ &second_context_watcher_callback,
+ &error_context_event_handler,
+ };
assert(PyLong_Check(which_watcher));
long which_l = PyLong_AsLong(which_watcher);
- if (which_l == 0) {
- watcher_id = PyContext_AddWatcher(first_context_watcher_callback);
- context_watcher_ids[0] = watcher_id;
- num_context_object_enter_events[0] = 0;
- num_context_object_exit_events[0] = 0;
- }
- else if (which_l == 1) {
- watcher_id = PyContext_AddWatcher(second_context_watcher_callback);
- context_watcher_ids[1] = watcher_id;
- num_context_object_enter_events[1] = 0;
- num_context_object_exit_events[1] = 0;
- }
- else if (which_l == 2) {
- watcher_id = PyContext_AddWatcher(error_context_event_handler);
- }
- else {
+ if (which_l < 0 || which_l >= (long)Py_ARRAY_LENGTH(callbacks)) {
PyErr_Format(PyExc_ValueError, "invalid watcher %d", which_l);
return NULL;
}
+ int watcher_id = PyContext_AddWatcher(callbacks[which_l]);
if (watcher_id < 0) {
return NULL;
}
+ if (which_l >= 0 && which_l < NUM_CONTEXT_WATCHERS) {
+ context_watcher_ids[which_l] = watcher_id;
+ Py_XSETREF(context_switches[which_l], PyList_New(0));
+ if (context_switches[which_l] == NULL) {
+ return NULL;
+ }
+ }
return PyLong_FromLong(watcher_id);
}
@@ -708,8 +701,7 @@ clear_context_watcher(PyObject *self, PyObject *watcher_id)
for (int i = 0; i < NUM_CONTEXT_WATCHERS; i++) {
if (watcher_id_l == context_watcher_ids[i]) {
context_watcher_ids[i] = -1;
- num_context_object_enter_events[i] = 0;
- num_context_object_exit_events[i] = 0;
+ Py_CLEAR(context_switches[i]);
}
}
}
@@ -717,21 +709,34 @@ clear_context_watcher(PyObject *self, PyObject *watcher_id)
}
static PyObject *
-get_context_watcher_num_enter_events(PyObject *self, PyObject *watcher_id)
+clear_context_stack(PyObject *Py_UNUSED(self), PyObject *Py_UNUSED(args))
{
- assert(PyLong_Check(watcher_id));
- long watcher_id_l = PyLong_AsLong(watcher_id);
- assert(watcher_id_l >= 0 && watcher_id_l < NUM_CONTEXT_WATCHERS);
- return PyLong_FromLong(num_context_object_enter_events[watcher_id_l]);
+ PyThreadState *tstate = PyThreadState_Get();
+ if (tstate->context == NULL) {
+ Py_RETURN_NONE;
+ }
+ if (((PyContext *)tstate->context)->ctx_prev != NULL) {
+ PyErr_SetString(PyExc_RuntimeError,
+ "must first exit all non-base contexts");
+ return NULL;
+ }
+ Py_CLEAR(tstate->context);
+ Py_RETURN_NONE;
}
static PyObject *
-get_context_watcher_num_exit_events(PyObject *self, PyObject *watcher_id)
+get_context_switches(PyObject *Py_UNUSED(self), PyObject *watcher_id)
{
assert(PyLong_Check(watcher_id));
long watcher_id_l = PyLong_AsLong(watcher_id);
- assert(watcher_id_l >= 0 && watcher_id_l < NUM_CONTEXT_WATCHERS);
- return PyLong_FromLong(num_context_object_exit_events[watcher_id_l]);
+ if (watcher_id_l < 0 || watcher_id_l >= NUM_CONTEXT_WATCHERS) {
+ PyErr_Format(PyExc_ValueError, "invalid watcher %ld", watcher_id_l);
+ return NULL;
+ }
+ if (context_switches[watcher_id_l] == NULL) {
+ return PyList_New(0);
+ }
+ return Py_NewRef(context_switches[watcher_id_l]);
}
static PyObject *
@@ -835,10 +840,8 @@ static PyMethodDef test_methods[] = {
// Code object watchers.
{"add_context_watcher", add_context_watcher, METH_O, NULL},
{"clear_context_watcher", clear_context_watcher, METH_O, NULL},
- {"get_context_watcher_num_enter_events",
- get_context_watcher_num_enter_events, METH_O, NULL},
- {"get_context_watcher_num_exit_events",
- get_context_watcher_num_exit_events, METH_O, NULL},
+ {"clear_context_stack", clear_context_stack, METH_NOARGS, NULL},
+ {"get_context_switches", get_context_switches, METH_O, NULL},
{"allocate_too_many_context_watchers",
(PyCFunction) allocate_too_many_context_watchers, METH_NOARGS, NULL},
{NULL},
diff --git a/Python/context.c b/Python/context.c
index 8bc487a33c890b..95aa82206270f9 100644
--- a/Python/context.c
+++ b/Python/context.c
@@ -102,10 +102,8 @@ PyContext_CopyCurrent(void)
static const char *
context_event_name(PyContextEvent event) {
switch (event) {
- case Py_CONTEXT_EVENT_ENTER:
- return "Py_CONTEXT_EVENT_ENTER";
- case Py_CONTEXT_EVENT_EXIT:
- return "Py_CONTEXT_EVENT_EXIT";
+ case Py_CONTEXT_SWITCHED:
+ return "Py_CONTEXT_SWITCHED";
default:
return "?";
}
@@ -115,6 +113,13 @@ context_event_name(PyContextEvent event) {
static void
notify_context_watchers(PyThreadState *ts, PyContextEvent event, PyObject *ctx)
{
+ if (ctx == NULL) {
+ // This will happen after exiting the last context in the stack, which
+ // can occur if context_get was never called before entering a context
+ // (e.g., called `contextvars.Context().run()` on a fresh thread, as
+ // PyContext_Enter doesn't call context_get).
+ ctx = Py_None;
+ }
assert(Py_REFCNT(ctx) > 0);
PyInterpreterState *interp = ts->interp;
assert(interp->_initialized);
@@ -175,6 +180,16 @@ PyContext_ClearWatcher(int watcher_id)
}
+static inline void
+context_switched(PyThreadState *ts)
+{
+ ts->context_ver++;
+ // ts->context is used instead of context_get() because context_get() might
+ // throw if ts->context is NULL.
+ notify_context_watchers(ts, Py_CONTEXT_SWITCHED, ts->context);
+}
+
+
static int
_PyContext_Enter(PyThreadState *ts, PyObject *octx)
{
@@ -191,9 +206,7 @@ _PyContext_Enter(PyThreadState *ts, PyObject *octx)
ctx->ctx_entered = 1;
ts->context = Py_NewRef(ctx);
- ts->context_ver++;
-
- notify_context_watchers(ts, Py_CONTEXT_EVENT_ENTER, octx);
+ context_switched(ts);
return 0;
}
@@ -227,13 +240,11 @@ _PyContext_Exit(PyThreadState *ts, PyObject *octx)
return -1;
}
- notify_context_watchers(ts, Py_CONTEXT_EVENT_EXIT, octx);
Py_SETREF(ts->context, (PyObject *)ctx->ctx_prev);
- ts->context_ver++;
ctx->ctx_prev = NULL;
ctx->ctx_entered = 0;
-
+ context_switched(ts);
return 0;
}
diff --git a/Tools/c-analyzer/cpython/ignored.tsv b/Tools/c-analyzer/cpython/ignored.tsv
index e6c599a2ac4a46..2605825d3d0078 100644
--- a/Tools/c-analyzer/cpython/ignored.tsv
+++ b/Tools/c-analyzer/cpython/ignored.tsv
@@ -455,8 +455,8 @@ Modules/_testcapi/watchers.c - pyfunc_watchers -
Modules/_testcapi/watchers.c - func_watcher_ids -
Modules/_testcapi/watchers.c - func_watcher_callbacks -
Modules/_testcapi/watchers.c - context_watcher_ids -
-Modules/_testcapi/watchers.c - num_context_object_enter_events -
-Modules/_testcapi/watchers.c - num_context_object_exit_events -
+Modules/_testcapi/watchers.c - context_switches -
+Modules/_testcapi/watchers.c add_context_watcher callbacks -
Modules/_testcapimodule.c - BasicStaticTypes -
Modules/_testcapimodule.c - num_basic_static_types_used -
Modules/_testcapimodule.c - ContainerNoGC_members -