tractor/tests/test_context_stream_semanti...

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'''
``async with ():`` inlined context-stream cancellation testing.
Verify the we raise errors when streams are opened prior to sync-opening
a ``tractor.Context`` beforehand.
'''
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from itertools import count
import platform
from typing import Optional
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import pytest
import trio
import tractor
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from tractor._exceptions import StreamOverrun
from conftest import tractor_test
# ``Context`` semantics are as follows,
# ------------------------------------
# - standard setup/teardown:
# ``Portal.open_context()`` starts a new
# remote task context in another actor. The target actor's task must
# call ``Context.started()`` to unblock this entry on the caller side.
# the callee task executes until complete and returns a final value
# which is delivered to the caller side and retreived via
# ``Context.result()``.
# - cancel termination:
# context can be cancelled on either side where either end's task can
# call ``Context.cancel()`` which raises a local ``trio.Cancelled``
# and sends a task cancel request to the remote task which in turn
# raises a ``trio.Cancelled`` in that scope, catches it, and re-raises
# as ``ContextCancelled``. This is then caught by
# ``Portal.open_context()``'s exit and we get a graceful termination
# of the linked tasks.
# - error termination:
# error is caught after all context-cancel-scope tasks are cancelled
# via regular ``trio`` cancel scope semantics, error is sent to other
# side and unpacked as a `RemoteActorError`.
# ``Context.open_stream() as stream: MsgStream:`` msg semantics are:
# -----------------------------------------------------------------
# - either side can ``.send()`` which emits a 'yield' msgs and delivers
# a value to the a ``MsgStream.receive()`` call.
# - stream closure: one end relays a 'stop' message which terminates an
# ongoing ``MsgStream`` iteration.
# - cancel/error termination: as per the context semantics above but
# with implicit stream closure on the cancelling end.
_state: bool = False
@tractor.context
async def error_before_started(
ctx: tractor.Context,
) -> None:
# send an unserializable type
await ctx.started(object())
def test_error_before_started():
async def main():
async with tractor.open_nursery() as n:
portal = await n.start_actor(
'errorer',
enable_modules=[__name__],
)
async with portal.open_context(
error_before_started
) as (ctx, sent):
await trio.sleep(1)
with pytest.raises(tractor.RemoteActorError) as excinfo:
trio.run(main)
assert excinfo.value.type == TypeError
@tractor.context
async def too_many_starteds(
ctx: tractor.Context,
) -> None:
'''
Call ``Context.started()`` more then once (an error).
'''
await ctx.started()
try:
await ctx.started()
except RuntimeError:
raise
@tractor.context
async def not_started_but_stream_opened(
ctx: tractor.Context,
) -> None:
'''
Enter ``Context.open_stream()`` without calling ``.started()``.
'''
try:
async with ctx.open_stream():
assert 0
except RuntimeError:
raise
@pytest.mark.parametrize(
'target',
[too_many_starteds, not_started_but_stream_opened],
ids='misuse_type={}'.format,
)
def test_started_misuse(target):
async def main():
async with tractor.open_nursery() as n:
portal = await n.start_actor(
target.__name__,
enable_modules=[__name__],
)
async with portal.open_context(target) as (ctx, sent):
await trio.sleep(1)
with pytest.raises(tractor.RemoteActorError):
trio.run(main)
@tractor.context
async def simple_setup_teardown(
ctx: tractor.Context,
data: int,
block_forever: bool = False,
) -> None:
# startup phase
global _state
_state = True
# signal to parent that we're up
await ctx.started(data + 1)
try:
if block_forever:
# block until cancelled
await trio.sleep_forever()
else:
return 'yo'
finally:
_state = False
async def assert_state(value: bool):
global _state
assert _state == value
@pytest.mark.parametrize(
'error_parent',
[False, ValueError, KeyboardInterrupt],
)
@pytest.mark.parametrize(
'callee_blocks_forever',
[False, True],
ids=lambda item: f'callee_blocks_forever={item}'
)
@pytest.mark.parametrize(
'pointlessly_open_stream',
[False, True],
ids=lambda item: f'open_stream={item}'
)
def test_simple_context(
error_parent,
callee_blocks_forever,
pointlessly_open_stream,
):
timeout = 1.5 if not platform.system() == 'Windows' else 4
async def main():
with trio.fail_after(timeout):
async with tractor.open_nursery() as nursery:
portal = await nursery.start_actor(
'simple_context',
enable_modules=[__name__],
)
try:
async with portal.open_context(
simple_setup_teardown,
data=10,
block_forever=callee_blocks_forever,
) as (ctx, sent):
assert sent == 11
if callee_blocks_forever:
await portal.run(assert_state, value=True)
else:
assert await ctx.result() == 'yo'
if not error_parent:
await ctx.cancel()
if pointlessly_open_stream:
async with ctx.open_stream():
if error_parent:
raise error_parent
if callee_blocks_forever:
await ctx.cancel()
else:
# in this case the stream will send a
# 'stop' msg to the far end which needs
# to be ignored
pass
else:
if error_parent:
raise error_parent
finally:
# after cancellation
if not error_parent:
await portal.run(assert_state, value=False)
# shut down daemon
await portal.cancel_actor()
if error_parent:
try:
trio.run(main)
except error_parent:
pass
except trio.MultiError as me:
# XXX: on windows it seems we may have to expect the group error
from tractor._exceptions import is_multi_cancelled
assert is_multi_cancelled(me)
else:
trio.run(main)
# basic stream terminations:
# - callee context closes without using stream
# - caller context closes without using stream
# - caller context calls `Context.cancel()` while streaming
# is ongoing resulting in callee being cancelled
# - callee calls `Context.cancel()` while streaming and caller
# sees stream terminated in `RemoteActorError`
# TODO: future possible features
# - restart request: far end raises `ContextRestart`
@tractor.context
async def close_ctx_immediately(
ctx: tractor.Context,
) -> None:
await ctx.started()
global _state
async with ctx.open_stream():
pass
@tractor_test
async def test_callee_closes_ctx_after_stream_open():
'callee context closes without using stream'
async with tractor.open_nursery() as n:
portal = await n.start_actor(
'fast_stream_closer',
enable_modules=[__name__],
)
async with portal.open_context(
close_ctx_immediately,
# flag to avoid waiting the final result
# cancel_on_exit=True,
) as (ctx, sent):
assert sent is None
with trio.fail_after(0.5):
async with ctx.open_stream() as stream:
# should fall through since ``StopAsyncIteration``
# should be raised through translation of
# a ``trio.EndOfChannel`` by
# ``trio.abc.ReceiveChannel.__anext__()``
async for _ in stream:
assert 0
else:
# verify stream is now closed
try:
await stream.receive()
except trio.EndOfChannel:
pass
# TODO: should be just raise the closed resource err
# directly here to enforce not allowing a re-open
# of a stream to the context (at least until a time of
# if/when we decide that's a good idea?)
try:
async with ctx.open_stream() as stream:
pass
except trio.ClosedResourceError:
pass
await portal.cancel_actor()
@tractor.context
async def expect_cancelled(
ctx: tractor.Context,
) -> None:
global _state
_state = True
await ctx.started()
try:
async with ctx.open_stream() as stream:
async for msg in stream:
await stream.send(msg) # echo server
except trio.Cancelled:
# expected case
_state = False
raise
else:
assert 0, "Wasn't cancelled!?"
@pytest.mark.parametrize(
'use_ctx_cancel_method',
[False, True],
)
@tractor_test
async def test_caller_closes_ctx_after_callee_opens_stream(
use_ctx_cancel_method: bool,
):
'caller context closes without using stream'
async with tractor.open_nursery() as n:
portal = await n.start_actor(
'ctx_cancelled',
enable_modules=[__name__],
)
async with portal.open_context(
expect_cancelled,
) as (ctx, sent):
await portal.run(assert_state, value=True)
assert sent is None
# call cancel explicitly
if use_ctx_cancel_method:
await ctx.cancel()
try:
async with ctx.open_stream() as stream:
async for msg in stream:
pass
except tractor.ContextCancelled:
raise # XXX: must be propagated to __aexit__
else:
assert 0, "Should have context cancelled?"
# channel should still be up
assert portal.channel.connected()
# ctx is closed here
await portal.run(assert_state, value=False)
else:
try:
with trio.fail_after(0.2):
await ctx.result()
assert 0, "Callee should have blocked!?"
except trio.TooSlowError:
await ctx.cancel()
try:
async with ctx.open_stream() as stream:
async for msg in stream:
pass
except tractor.ContextCancelled:
pass
else:
assert 0, "Should have received closed resource error?"
# ctx is closed here
await portal.run(assert_state, value=False)
# channel should not have been destroyed yet, only the
# inter-actor-task context
assert portal.channel.connected()
# teardown the actor
await portal.cancel_actor()
@tractor_test
async def test_multitask_caller_cancels_from_nonroot_task():
async with tractor.open_nursery() as n:
portal = await n.start_actor(
'ctx_cancelled',
enable_modules=[__name__],
)
async with portal.open_context(
expect_cancelled,
) as (ctx, sent):
await portal.run(assert_state, value=True)
assert sent is None
async with ctx.open_stream() as stream:
async def send_msg_then_cancel():
await stream.send('yo')
await portal.run(assert_state, value=True)
await ctx.cancel()
await portal.run(assert_state, value=False)
async with trio.open_nursery() as n:
n.start_soon(send_msg_then_cancel)
try:
async for msg in stream:
assert msg == 'yo'
except tractor.ContextCancelled:
raise # XXX: must be propagated to __aexit__
# channel should still be up
assert portal.channel.connected()
# ctx is closed here
await portal.run(assert_state, value=False)
# channel should not have been destroyed yet, only the
# inter-actor-task context
assert portal.channel.connected()
# teardown the actor
await portal.cancel_actor()
@tractor.context
async def cancel_self(
ctx: tractor.Context,
) -> None:
global _state
_state = True
await ctx.cancel()
# should inline raise immediately
try:
async with ctx.open_stream():
pass
except tractor.ContextCancelled:
pass
# check a real ``trio.Cancelled`` is raised on a checkpoint
try:
with trio.fail_after(0.1):
await trio.sleep_forever()
except trio.Cancelled:
raise
except trio.TooSlowError:
# should never get here
assert 0
@tractor_test
async def test_callee_cancels_before_started():
'''
Callee calls `Context.cancel()` while streaming and caller
sees stream terminated in `ContextCancelled`.
'''
async with tractor.open_nursery() as n:
portal = await n.start_actor(
'cancels_self',
enable_modules=[__name__],
)
try:
async with portal.open_context(
cancel_self,
) as (ctx, sent):
async with ctx.open_stream():
await trio.sleep_forever()
# raises a special cancel signal
except tractor.ContextCancelled as ce:
ce.type == trio.Cancelled
# teardown the actor
await portal.cancel_actor()
@tractor.context
async def never_open_stream(
ctx: tractor.Context,
) -> None:
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'''
Context which never opens a stream and blocks.
'''
await ctx.started()
await trio.sleep_forever()
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@tractor.context
async def keep_sending_from_callee(
ctx: tractor.Context,
msg_buffer_size: Optional[int] = None,
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) -> None:
'''
Send endlessly on the calleee stream.
'''
await ctx.started()
async with ctx.open_stream(
msg_buffer_size=msg_buffer_size,
) as stream:
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for msg in count():
print(f'callee sending {msg}')
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await stream.send(msg)
await trio.sleep(0.01)
@pytest.mark.parametrize(
'overrun_by',
[
('caller', 1, never_open_stream),
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('cancel_caller_during_overrun', 1, never_open_stream),
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('callee', 0, keep_sending_from_callee),
],
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ids='overrun_condition={}'.format,
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)
def test_one_end_stream_not_opened(overrun_by):
'''
This should exemplify the bug from:
https://github.com/goodboy/tractor/issues/265
'''
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overrunner, buf_size_increase, entrypoint = overrun_by
from tractor._actor import Actor
buf_size = buf_size_increase + Actor.msg_buffer_size
async def main():
async with tractor.open_nursery() as n:
portal = await n.start_actor(
entrypoint.__name__,
enable_modules=[__name__],
)
async with portal.open_context(
entrypoint,
) as (ctx, sent):
assert sent is None
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if 'caller' in overrunner:
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async with ctx.open_stream() as stream:
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for i in range(buf_size):
print(f'sending {i}')
await stream.send(i)
if 'cancel' in overrunner:
# without this we block waiting on the child side
await ctx.cancel()
else:
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# expect overrun error to be relayed back
# and this sleep interrupted
await trio.sleep_forever()
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else:
# callee overruns caller case so we do nothing here
await trio.sleep_forever()
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await portal.cancel_actor()
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# 2 overrun cases and the no overrun case (which pushes right up to
# the msg limit)
if overrunner == 'caller':
with pytest.raises(tractor.RemoteActorError) as excinfo:
trio.run(main)
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assert excinfo.value.type == StreamOverrun
elif 'cancel' in overrunner:
with pytest.raises(trio.MultiError) as excinfo:
trio.run(main)
multierr = excinfo.value
for exc in multierr.exceptions:
etype = type(exc)
if etype == tractor.RemoteActorError:
assert exc.type == StreamOverrun
else:
assert etype == tractor.ContextCancelled
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elif overrunner == 'callee':
with pytest.raises(tractor.RemoteActorError) as excinfo:
trio.run(main)
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# TODO: embedded remote errors so that we can verify the source
# error?
# the callee delivers an error which is an overrun wrapped
# in a remote actor error.
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assert excinfo.value.type == tractor.RemoteActorError
else:
trio.run(main)
@tractor.context
async def echo_back_sequence(
ctx: tractor.Context,
seq: list[int],
msg_buffer_size: Optional[int] = None,
) -> None:
'''
Send endlessly on the calleee stream.
'''
await ctx.started()
async with ctx.open_stream(
msg_buffer_size=msg_buffer_size,
) as stream:
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seq = list(seq) # bleh, `msgpack`...
count = 0
while count < 3:
batch = []
async for msg in stream:
batch.append(msg)
if batch == seq:
break
for msg in batch:
print(f'callee sending {msg}')
await stream.send(msg)
count += 1
return 'yo'
def test_stream_backpressure():
'''
Demonstrate small overruns of each task back and forth
on a stream not raising any errors by default.
'''
async def main():
async with tractor.open_nursery() as n:
portal = await n.start_actor(
'callee_sends_forever',
enable_modules=[__name__],
)
seq = list(range(3))
async with portal.open_context(
echo_back_sequence,
seq=seq,
msg_buffer_size=1,
) as (ctx, sent):
assert sent is None
async with ctx.open_stream(msg_buffer_size=1) as stream:
count = 0
while count < 3:
for msg in seq:
print(f'caller sending {msg}')
await stream.send(msg)
await trio.sleep(0.1)
batch = []
async for msg in stream:
batch.append(msg)
if batch == seq:
break
count += 1
# here the context should return
assert await ctx.result() == 'yo'
# cancel the daemon
await portal.cancel_actor()
trio.run(main)