[Python-checkins] cpython (merge 3.4 -> 3.5): asyncio: Error if awaiting in parallel on the same coroutine

Wed Nov 18 12:40:51 EST 2015

https://hg.python.org/cpython/rev/6875b0bd3cd0
changeset: 99202:6875b0bd3cd0
branch: 3.5
parent: 99198:d64bb25cf797
parent: 99201:89d66f912671
user: Yury Selivanov <yselivanov at sprymix.com>
date: Wed Nov 18 12:40:26 2015 -0500
summary:
 asyncio: Error if awaiting in parallel on the same coroutine
See https://github.com/python/asyncio/pull/293 for details.
files:
 Lib/asyncio/coroutines.py | 8 +++++-
 Lib/test/test_asyncio/test_pep492.py | 20 ++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletions(-)

diff --git a/Lib/asyncio/coroutines.py b/Lib/asyncio/coroutines.py
--- a/Lib/asyncio/coroutines.py
+++ b/Lib/asyncio/coroutines.py
@@ -140,7 +140,13 @@
 
 if compat.PY35:
 
- __await__ = __iter__ # make compatible with 'await' expression
+ def __await__(self):
+ cr_await = getattr(self.gen, 'cr_await', None)
+ if cr_await is not None:
+ raise RuntimeError(
+ "Cannot await on coroutine {!r} while it's "
+ "awaiting for {!r}".format(self.gen, cr_await))
+ return self
 
 @property
 def gi_yieldfrom(self):
diff --git a/Lib/test/test_asyncio/test_pep492.py b/Lib/test/test_asyncio/test_pep492.py
--- a/Lib/test/test_asyncio/test_pep492.py
+++ b/Lib/test/test_asyncio/test_pep492.py
@@ -203,6 +203,26 @@
 
 self.loop.run_until_complete(runner())
 
+ def test_double_await(self):
+ async def afunc():
+ await asyncio.sleep(0.1, loop=self.loop)
+
+ async def runner():
+ coro = afunc()
+ t = asyncio.Task(coro, loop=self.loop)
+ try:
+ await asyncio.sleep(0, loop=self.loop)
+ await coro
+ finally:
+ t.cancel()
+
+ self.loop.set_debug(True)
+ with self.assertRaisesRegex(
+ RuntimeError,
+ r'Cannot await.*test_double_await.*\bafunc\b.*while.*\bsleep\b'):
+
+ self.loop.run_until_complete(runner())
+
 
 if __name__ == '__main__':
 unittest.main()
-- 
Repository URL: https://hg.python.org/cpython
