Skip to content

[3.7] bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() (GH-7467) #7506

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
wants to merge 1 commit into from
Closed

[3.7] bpo-33786: Fix asynchronous generators to handle GeneratorExit in athrow() (GH-7467) #7506

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
2 changes: 1 addition & 1 deletion Lib/contextlib.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -186,7 +186,7 @@ async def __aexit__(self, typ, value, traceback):
# in this implementation
try:
await self.gen.athrow(typ, value, traceback)
raise RuntimeError("generator didn't stop after throw()")
raise RuntimeError("generator didn't stop after athrow()")
except StopAsyncIteration as exc:
return exc is not value
except RuntimeError as exc:
Expand Down
56 changes: 56 additions & 0 deletions Lib/test/test_asyncgen.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -108,6 +108,31 @@ def sync_iterate(g):
res.append(str(type(ex)))
return res

def async_iterate(g):
res = []
while True:
an = g.__anext__()
try:
while True:
try:
an.__next__()
except StopIteration as ex:
if ex.args:
res.append(ex.args[0])
break
else:
res.append('EMPTY StopIteration')
break
except StopAsyncIteration:
raise
except Exception as ex:
res.append(str(type(ex)))
break
except StopAsyncIteration:
res.append('STOP')
break
return res

def async_iterate(g):
res = []
while True:
Expand Down Expand Up @@ -297,6 +322,37 @@ async def gen():
"non-None value .* async generator"):
gen().__anext__().send(100)

def test_async_gen_exception_11(self):
def sync_gen():
yield 10
yield 20

def sync_gen_wrapper():
yield 1
sg = sync_gen()
sg.send(None)
try:
sg.throw(GeneratorExit())
except GeneratorExit:
yield 2
yield 3

async def async_gen():
yield 10
yield 20

async def async_gen_wrapper():
yield 1
asg = async_gen()
await asg.asend(None)
try:
await asg.athrow(GeneratorExit())
except GeneratorExit:
yield 2
yield 3

self.compare_generators(sync_gen_wrapper(), async_gen_wrapper())

def test_async_gen_api_01(self):
async def gen():
yield 123
Expand Down
22 changes: 22 additions & 0 deletions Lib/test/test_contextlib_async.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,28 @@ async def __aexit__(self, *args):
async with manager as context:
self.assertIs(manager, context)

@_async_test
async def test_async_gen_propagates_generator_exit(self):
# A regression test for https://bugs.python.org/issue33786.

@asynccontextmanager
async def ctx():
yield

async def gen():
async with ctx():
yield 11

ret = []
exc = ValueError(22)
with self.assertRaises(ValueError):
async with ctx():
async for val in gen():
ret.append(val)
raise exc

self.assertEqual(ret, [11])

def test_exit_is_abstract(self):
class MissingAexit(AbstractAsyncContextManager):
pass
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Core and Builtins/2018-06-06-23-24-40.bpo-33786.lBvT8z.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Fix asynchronous generators to handle GeneratorExit in athrow() correctly
15 changes: 7 additions & 8 deletions Objects/genobject.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1878,21 +1878,20 @@ async_gen_athrow_send(PyAsyncGenAThrow *o, PyObject *arg)
return NULL;

check_error:
if (PyErr_ExceptionMatches(PyExc_StopAsyncIteration)) {
if (PyErr_ExceptionMatches(PyExc_StopAsyncIteration) ||
PyErr_ExceptionMatches(PyExc_GeneratorExit))
{
o->agt_state = AWAITABLE_STATE_CLOSED;
if (o->agt_args == NULL) {
/* when aclose() is called we don't want to propagate
StopAsyncIteration; just raise StopIteration, signalling
that 'aclose()' is done. */
StopAsyncIteration or GeneratorExit; just raise
StopIteration, signalling that this 'aclose()' await
is done.
*/
PyErr_Clear();
PyErr_SetNone(PyExc_StopIteration);
}
}
else if (PyErr_ExceptionMatches(PyExc_GeneratorExit)) {
o->agt_state = AWAITABLE_STATE_CLOSED;
PyErr_Clear(); /* ignore these errors */
PyErr_SetNone(PyExc_StopIteration);
}
return NULL;
}

Expand Down