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Use `async_generator`'s `aclosing()` helper 

Take @njsmith's advice and properly close actor invoked async generators
using `async_generator.aclosing()` instead of hacking it (as previous)
with a shielded cancel scope.
asyncgen_closing_fix
Tyler Goodlet 2018-07-13 22:18:08 -04:00
parent 2b7bbf32a1
commit 1f85f71534
1 changed files with 10 additions and 14 deletions
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24
tractor/__init__.py
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@ -12,7 +12,7 @@ import traceback
import uuid import uuid
import trio import trio
from async_generator import asynccontextmanager from async_generator import asynccontextmanager, aclosing
from .ipc import Channel, _connect_chan from .ipc import Channel, _connect_chan
from .log import get_console_log, get_logger from .log import get_console_log, get_logger
@ -77,8 +77,15 @@ async def _invoke(
coro = func(**kwargs) coro = func(**kwargs)
if inspect.isasyncgen(coro): if inspect.isasyncgen(coro):
with trio.open_cancel_scope() as cs: # XXX: massive gotcha! If the containing scope
async for item in coro: # is cancelled and we execute the below line,
# any ``ActorNursery.__aexit__()`` WON'T be
# triggered in the underlying async gen! So we
# have to properly handle the closing (aclosing)
# of the async gen in order to be sure the cancel
# is propagated!
async with aclosing(coro) as agen:
async for item in agen:
# TODO: can we send values back in here? # TODO: can we send values back in here?
# it's gonna require a `while True:` and # it's gonna require a `while True:` and
# some non-blocking way to retrieve new `asend()` # some non-blocking way to retrieve new `asend()`
@ -86,24 +93,13 @@ async def _invoke(
# to_send = await chan.recv_nowait() # to_send = await chan.recv_nowait()
# if to_send is not None: # if to_send is not None:
# to_yield = await coro.asend(to_send) # to_yield = await coro.asend(to_send)
# XXX: massive gotcha! If the containing scope
# is cancelled and we execute the below line,
# any ``ActorNursery.__aexit__()`` WON'T be
# triggered in the underlying async gen! So we
# have to shield here (which shouldn't matter)
# in order to be sure the cancel is propagated!
cs.shield = True
await chan.send({'yield': item, 'cid': cid}) await chan.send({'yield': item, 'cid': cid})
cs.shield = False
log.debug(f"Finished iterating {coro}") log.debug(f"Finished iterating {coro}")
# TODO: we should really support a proper # TODO: we should really support a proper
# `StopAsyncIteration` system here for returning a final # `StopAsyncIteration` system here for returning a final
# value if desired # value if desired
cs.shield = True
await chan.send({'stop': None, 'cid': cid}) await chan.send({'stop': None, 'cid': cid})
cs.shield = False
else: else:
if treat_as_gen: if treat_as_gen:
# XXX: the async-func may spawn further tasks which push # XXX: the async-func may spawn further tasks which push