8000 gh-95051: ensure that timeouts scheduled with `asyncio.Timeout` that have already expired are deliverered promptly by graingert · Pull Request #95109 · python/cpython · GitHub
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gh-95051: ensure that timeouts scheduled with asyncio.Timeout that have already expired are deliverered promptly #95109

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Merged
merged 9 commits into from
Jul 24, 2022
3 changes: 3 additions & 0 deletions Doc/library/asyncio-task.rst
Original file line number Diff line number Diff line change
Expand Up @@ -625,6 +625,9 @@ Timeouts

If *when* is a float, it is set as the new deadline.

if *when* is in the past, the timeout will trigger on the next
iteration of the event loop.

.. method:: expired() -> bool

Return whether the context manager has exceeded its deadline
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8 changes: 4 additions & 4 deletions Lib/asyncio/timeouts.py
Original file line number Diff line number Diff line change
Expand Up @@ -52,10 +52,10 @@ def reschedule(self, when: Optional[float]) -> None:
self._timeout_handler = None
else:
loop = events.get_running_loop()
self._timeout_handler = loop.call_at(
when,
self._on_timeout,
)
if when <= loop.time():
self._timeout_handler = loop.call_soon(self._on_timeout)
else:
self._timeout_handler = loop.call_at(when, self._on_timeout)

def expired(self) -> bool:
"""Is timeout expired during execution?"""
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24 changes: 24 additions & 0 deletions Lib/test/test_asyncio/test_timeouts.py
Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,30 @@ async def test_timeout_zero(self):
self.assertLess(t1-t0, 2)
self.assertTrue(t0 <= cm.when() <= t1)

async def test_timeout_zero_sleep_zero(self):
loop = asyncio.get_running_loop()
t0 = loop.time()
with self.assertRaises(TimeoutError):
async with asyncio.timeout(0) as cm:
await asyncio.sleep(0)
t1 = loop.time()
self.assertTrue(cm.expired())
# 2 sec for slow CI boxes
self.assertLess(t1-t0, 2)
self.assertTrue(t0 <= cm.when() <= t1)

async def test_timeout_in_the_past_sleep_zero(self):
loop = asyncio.get_running_loop()
t0 = loop.time()
with self.assertRaises(TimeoutError):
async with asyncio.timeout(-11) as cm:
await asyncio.sleep(0)
t1 = loop.time()
self.assertTrue(cm.expired())
# 2 sec for slow CI boxes
self.assertLess(t1-t0, 2)
self.assertTrue(t0 >= cm.when() <= t1)

async def test_foreign_exception_passed(self):
with self.assertRaises(KeyError):
async with asyncio.timeout(0.01) as cm:
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Ensure that timeouts scheduled with :class:`asyncio.Timeout` that have already expired are delivered promptly.
0