One more super subtle cancellation fix
See python-trio/trio#455 for the deats...asyncgen_closing_fix
Tyler Goodlet
parent
c326a90484
commit
2b7bbf32a1
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@ -77,21 +77,33 @@ async def _invoke(
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coro = func(**kwargs)
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if inspect.isasyncgen(coro):
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async for item in coro:
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# TODO: can we send values back in here?
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# it's gonna require a `while True:` and
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# some non-blocking way to retrieve new `asend()`
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# values from the channel:
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# to_send = await chan.recv_nowait()
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# if to_send is not None:
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# to_yield = await coro.asend(to_send)
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await chan.send({'yield': item, 'cid': cid})
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with trio.open_cancel_scope() as cs:
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async for item in coro:
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# TODO: can we send values back in here?
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# it's gonna require a `while True:` and
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# some non-blocking way to retrieve new `asend()`
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# values from the channel:
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# to_send = await chan.recv_nowait()
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# if to_send is not None:
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# to_yield = await coro.asend(to_send)
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log.debug(f"Finished iterating {coro}")
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# TODO: we should really support a proper
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# `StopAsyncIteration` system here for returning a final
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# value if desired
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await chan.send({'stop': None, 'cid': cid})
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# XXX: massive gotcha! If the containing scope
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# is cancelled and we execute the below line,
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# any ``ActorNursery.__aexit__()`` WON'T be
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# triggered in the underlying async gen! So we
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# have to shield here (which shouldn't matter)
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# in order to be sure the cancel is propagated!
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cs.shield = True
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await chan.send({'yield': item, 'cid': cid})
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cs.shield = False
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log.debug(f"Finished iterating {coro}")
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# TODO: we should really support a proper
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# `StopAsyncIteration` system here for returning a final
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# value if desired
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cs.shield = True
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await chan.send({'stop': None, 'cid': cid})
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cs.shield = False
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else:
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if treat_as_gen:
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# XXX: the async-func may spawn further tasks which push
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@ -102,14 +114,15 @@ async def _invoke(
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else:
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await chan.send({'return': await coro, 'cid': cid})
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task_status.started()
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except Exception:
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log.exception("Actor errored:")
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if not raise_errs:
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await chan.send({'error': traceback.format_exc(), 'cid': cid})
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log.exception("Actor errored:")
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else:
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raise
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task_status.started()
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async def result_from_q(q, chan):
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"""Process a msg from a remote actor.
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@ -444,33 +457,36 @@ class Actor:
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self._process_messages, self._parent_chan)
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if self.main:
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with trio.open_cancel_scope() as main_scope:
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self._main_scope = main_scope
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try:
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if self._parent_chan:
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try:
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if self._parent_chan:
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async with trio.open_nursery() as n:
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self._main_scope = n.cancel_scope
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log.debug(f"Starting main task `{self.main}`")
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# spawned subactor so deliver "main"
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# task result(s) back to parent
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await nursery.start(
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await n.start(
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_invoke, 'main',
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self._parent_chan, self.main, {},
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# treat_as_gen, raise_errs params
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False, True
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)
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else:
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# run directly - we are an "unspawned actor"
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else:
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with trio.open_cancel_scope() as main_scope:
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self._main_scope = main_scope
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# run directly we are an "unspawned actor"
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log.debug(f"Running `{self.main}` directly")
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result = await self.main()
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finally:
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self._main_complete.set()
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# tear down channel server in order to ensure
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# we exit normally when the main task is done
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if not self._outlive_main:
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log.debug(f"Shutting down channel server")
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self.cancel_server()
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log.debug(f"Shutting down root nursery")
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nursery.cancel_scope.cancel()
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if main_scope.cancelled_caught:
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finally:
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# tear down channel server in order to ensure
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# we exit normally when the main task is done
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if not self._outlive_main:
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log.debug(f"Shutting down channel server")
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self.cancel_server()
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log.debug(f"Shutting down root nursery")
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nursery.cancel_scope.cancel()
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self._main_complete.set()
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if self._main_scope.cancelled_caught:
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log.debug("Main task was cancelled sucessfully")
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log.debug("Waiting on root nursery to complete")
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# blocks here as expected if no nursery was provided until
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@ -659,6 +675,7 @@ class Portal:
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log.debug(
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f"Cancelling async gen call {cid} to "
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f"{self.channel.uid}")
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raise
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return yield_from_q()
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@ -874,14 +891,19 @@ class ActorNursery:
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"""Wait on all subactor's main routines to complete.
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"""
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if etype is not None:
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# XXX: hypothetically an error could be raised and then
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# a cancel signal shows up slightly after in which case the
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# else block here might not complete? Should both be shielded?
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if etype is trio.Cancelled:
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log.warn(f"{current_actor().uid} was cancelled with {etype}, "
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"cancelling actor nursery")
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with trio.open_cancel_scope(shield=True):
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log.warn(
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f"{current_actor().uid} was cancelled with {etype}"
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", cancelling actor nursery")
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await self.cancel()
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else:
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log.exception(f"{current_actor().uid} errored with {etype}, "
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"cancelling actor nursery")
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log.exception(
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f"{current_actor().uid} errored with {etype}, "
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"cancelling actor nursery")
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await self.cancel()
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else:
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# XXX: this is effectively the lone cancellation/supervisor
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