tractor/tests/test_cancellation.py

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"""
Cancellation and error propagation
"""
from itertools import repeat
import pytest
import trio
import tractor
from conftest import tractor_test
async def assert_err():
assert 0
def test_remote_error(arb_addr):
"""Verify an error raises in a subactor is propagated to the parent.
"""
async def main():
async with tractor.open_nursery() as nursery:
portal = await nursery.run_in_actor('errorer', assert_err)
# get result(s) from main task
try:
return await portal.result()
except tractor.RemoteActorError:
print("Look Maa that actor failed hard, hehh")
raise
except Exception:
pass
assert 0, "Remote error was not raised?"
with pytest.raises(tractor.RemoteActorError):
# also raises
tractor.run(main, arbiter_addr=arb_addr)
def do_nothing():
pass
def test_cancel_single_subactor(arb_addr):
async def main():
async with tractor.open_nursery() as nursery:
portal = await nursery.start_actor(
'nothin', rpc_module_paths=[__name__],
)
assert (await portal.run(__name__, 'do_nothing')) is None
# would hang otherwise
await nursery.cancel()
tractor.run(main, arbiter_addr=arb_addr)
async def stream_forever():
for i in repeat("I can see these little future bubble things"):
# each yielded value is sent over the ``Channel`` to the
# parent actor
yield i
await trio.sleep(0.01)
@tractor_test
async def test_cancel_infinite_streamer():
# stream for at most 1 seconds
with trio.move_on_after(1) as cancel_scope:
async with tractor.open_nursery() as n:
portal = await n.start_actor(
f'donny',
rpc_module_paths=[__name__],
)
# this async for loop streams values from the above
# async generator running in a separate process
async for letter in await portal.run(__name__, 'stream_forever'):
print(letter)
# we support trio's cancellation system
assert cancel_scope.cancelled_caught
assert n.cancelled
@tractor_test
async def test_one_cancels_all():
"""Verify one failed actor causes all others in the nursery
to be cancelled just like in trio.
This is the first and only supervisory strategy at the moment.
"""
try:
async with tractor.open_nursery() as n:
real_actors = []
for i in range(3):
real_actors.append(await n.start_actor(
f'actor_{i}',
rpc_module_paths=[__name__],
))
# start one actor that will fail immediately
await n.run_in_actor('extra', assert_err)
# should error here with a ``RemoteActorError`` containing
# an ``AssertionError`
except tractor.RemoteActorError:
assert n.cancelled is True
assert not n._children
else:
pytest.fail("Should have gotten a remote assertion error?")