534 lines
14 KiB
Python
534 lines
14 KiB
Python
"""
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Bidirectional streaming and context API.
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"""
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import platform
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import pytest
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import trio
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import tractor
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from conftest import tractor_test
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# the general stream semantics are
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# - normal termination: far end relays a stop message which
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# terminates an ongoing ``MsgStream`` iteration
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# - cancel termination: context is cancelled on either side cancelling
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# the "linked" inter-actor task context
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_state: bool = False
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@tractor.context
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async def simple_setup_teardown(
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ctx: tractor.Context,
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data: int,
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block_forever: bool = False,
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) -> None:
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# startup phase
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global _state
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_state = True
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# signal to parent that we're up
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await ctx.started(data + 1)
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try:
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if block_forever:
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# block until cancelled
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await trio.sleep_forever()
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else:
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return 'yo'
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finally:
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_state = False
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async def assert_state(value: bool):
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global _state
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assert _state == value
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@pytest.mark.parametrize(
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'error_parent',
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[False, ValueError, KeyboardInterrupt],
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)
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@pytest.mark.parametrize(
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'callee_blocks_forever',
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[False, True],
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ids=lambda item: f'callee_blocks_forever={item}'
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)
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@pytest.mark.parametrize(
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'pointlessly_open_stream',
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[False, True],
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ids=lambda item: f'open_stream={item}'
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)
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def test_simple_context(
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error_parent,
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callee_blocks_forever,
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pointlessly_open_stream,
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):
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timeout = 1.5 if not platform.system() == 'Windows' else 3
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async def main():
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with trio.fail_after(timeout):
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async with tractor.open_nursery() as nursery:
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portal = await nursery.start_actor(
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'simple_context',
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enable_modules=[__name__],
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)
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try:
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async with portal.open_context(
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simple_setup_teardown,
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data=10,
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block_forever=callee_blocks_forever,
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) as (ctx, sent):
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assert sent == 11
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if callee_blocks_forever:
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await portal.run(assert_state, value=True)
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else:
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assert await ctx.result() == 'yo'
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if not error_parent:
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await ctx.cancel()
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if pointlessly_open_stream:
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async with ctx.open_stream():
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if error_parent:
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raise error_parent
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if callee_blocks_forever:
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await ctx.cancel()
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else:
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# in this case the stream will send a
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# 'stop' msg to the far end which needs
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# to be ignored
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pass
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else:
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if error_parent:
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raise error_parent
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finally:
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# after cancellation
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if not error_parent:
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await portal.run(assert_state, value=False)
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# shut down daemon
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await portal.cancel_actor()
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if error_parent:
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try:
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trio.run(main)
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except error_parent:
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pass
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except trio.MultiError as me:
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# XXX: on windows it seems we may have to expect the group error
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from tractor._exceptions import is_multi_cancelled
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assert is_multi_cancelled(me)
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else:
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trio.run(main)
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# basic stream terminations:
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# - callee context closes without using stream
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# - caller context closes without using stream
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# - caller context calls `Context.cancel()` while streaming
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# is ongoing resulting in callee being cancelled
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# - callee calls `Context.cancel()` while streaming and caller
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# sees stream terminated in `RemoteActorError`
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# TODO: future possible features
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# - restart request: far end raises `ContextRestart`
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@tractor.context
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async def close_ctx_immediately(
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ctx: tractor.Context,
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) -> None:
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await ctx.started()
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global _state
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async with ctx.open_stream():
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pass
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@tractor_test
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async def test_callee_closes_ctx_after_stream_open():
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'callee context closes without using stream'
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async with tractor.open_nursery() as n:
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portal = await n.start_actor(
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'fast_stream_closer',
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enable_modules=[__name__],
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)
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async with portal.open_context(
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close_ctx_immediately,
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# flag to avoid waiting the final result
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# cancel_on_exit=True,
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) as (ctx, sent):
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assert sent is None
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with trio.fail_after(0.5):
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async with ctx.open_stream() as stream:
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# should fall through since ``StopAsyncIteration``
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# should be raised through translation of
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# a ``trio.EndOfChannel`` by
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# ``trio.abc.ReceiveChannel.__anext__()``
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async for _ in stream:
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assert 0
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else:
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# verify stream is now closed
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try:
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await stream.receive()
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except trio.EndOfChannel:
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pass
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# TODO: should be just raise the closed resource err
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# directly here to enforce not allowing a re-open
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# of a stream to the context (at least until a time of
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# if/when we decide that's a good idea?)
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try:
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async with ctx.open_stream() as stream:
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pass
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except trio.ClosedResourceError:
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pass
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await portal.cancel_actor()
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@tractor.context
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async def expect_cancelled(
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ctx: tractor.Context,
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) -> None:
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global _state
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_state = True
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await ctx.started()
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try:
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async with ctx.open_stream() as stream:
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async for msg in stream:
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await stream.send(msg) # echo server
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except trio.Cancelled:
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# expected case
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_state = False
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raise
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else:
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assert 0, "Wasn't cancelled!?"
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@pytest.mark.parametrize(
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'use_ctx_cancel_method',
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[False, True],
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)
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@tractor_test
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async def test_caller_closes_ctx_after_callee_opens_stream(
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use_ctx_cancel_method: bool,
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):
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'caller context closes without using stream'
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async with tractor.open_nursery() as n:
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portal = await n.start_actor(
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'ctx_cancelled',
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enable_modules=[__name__],
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)
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async with portal.open_context(
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expect_cancelled,
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) as (ctx, sent):
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await portal.run(assert_state, value=True)
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assert sent is None
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# call cancel explicitly
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if use_ctx_cancel_method:
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await ctx.cancel()
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try:
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async with ctx.open_stream() as stream:
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async for msg in stream:
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pass
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except tractor.ContextCancelled:
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raise # XXX: must be propagated to __aexit__
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else:
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assert 0, "Should have context cancelled?"
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# channel should still be up
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assert portal.channel.connected()
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# ctx is closed here
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await portal.run(assert_state, value=False)
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else:
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try:
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with trio.fail_after(0.2):
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await ctx.result()
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assert 0, "Callee should have blocked!?"
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except trio.TooSlowError:
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await ctx.cancel()
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try:
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async with ctx.open_stream() as stream:
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async for msg in stream:
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pass
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except tractor.ContextCancelled:
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pass
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else:
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assert 0, "Should have received closed resource error?"
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# ctx is closed here
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await portal.run(assert_state, value=False)
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# channel should not have been destroyed yet, only the
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# inter-actor-task context
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assert portal.channel.connected()
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# teardown the actor
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await portal.cancel_actor()
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@tractor_test
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async def test_multitask_caller_cancels_from_nonroot_task():
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async with tractor.open_nursery() as n:
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portal = await n.start_actor(
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'ctx_cancelled',
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enable_modules=[__name__],
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)
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async with portal.open_context(
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expect_cancelled,
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) as (ctx, sent):
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await portal.run(assert_state, value=True)
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assert sent is None
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async with ctx.open_stream() as stream:
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async def send_msg_then_cancel():
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await stream.send('yo')
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await portal.run(assert_state, value=True)
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await ctx.cancel()
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await portal.run(assert_state, value=False)
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async with trio.open_nursery() as n:
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n.start_soon(send_msg_then_cancel)
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try:
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async for msg in stream:
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assert msg == 'yo'
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except tractor.ContextCancelled:
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raise # XXX: must be propagated to __aexit__
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# channel should still be up
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assert portal.channel.connected()
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# ctx is closed here
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await portal.run(assert_state, value=False)
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# channel should not have been destroyed yet, only the
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# inter-actor-task context
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assert portal.channel.connected()
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# teardown the actor
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await portal.cancel_actor()
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@tractor.context
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async def cancel_self(
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ctx: tractor.Context,
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) -> None:
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global _state
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_state = True
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await ctx.cancel()
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try:
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with trio.fail_after(0.1):
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await trio.sleep_forever()
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except trio.Cancelled:
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raise
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except trio.TooSlowError:
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# should never get here
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assert 0
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@tractor_test
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async def test_callee_cancels_before_started():
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'''callee calls `Context.cancel()` while streaming and caller
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sees stream terminated in `ContextCancelled`.
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'''
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async with tractor.open_nursery() as n:
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portal = await n.start_actor(
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'cancels_self',
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enable_modules=[__name__],
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)
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try:
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async with portal.open_context(
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cancel_self,
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) as (ctx, sent):
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async with ctx.open_stream():
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await trio.sleep_forever()
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# raises a special cancel signal
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except tractor.ContextCancelled as ce:
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ce.type == trio.Cancelled
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# teardown the actor
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await portal.cancel_actor()
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@tractor.context
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async def simple_rpc(
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ctx: tractor.Context,
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data: int,
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) -> None:
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"""Test a small ping-pong server.
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"""
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# signal to parent that we're up
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await ctx.started(data + 1)
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print('opening stream in callee')
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async with ctx.open_stream() as stream:
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count = 0
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while True:
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try:
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await stream.receive() == 'ping'
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except trio.EndOfChannel:
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assert count == 10
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break
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else:
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print('pong')
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await stream.send('pong')
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count += 1
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@tractor.context
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async def simple_rpc_with_forloop(
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ctx: tractor.Context,
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data: int,
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) -> None:
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"""Same as previous test but using ``async for`` syntax/api.
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"""
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# signal to parent that we're up
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await ctx.started(data + 1)
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print('opening stream in callee')
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async with ctx.open_stream() as stream:
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count = 0
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async for msg in stream:
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assert msg == 'ping'
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print('pong')
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await stream.send('pong')
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count += 1
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else:
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assert count == 10
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@pytest.mark.parametrize(
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'use_async_for',
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[True, False],
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)
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@pytest.mark.parametrize(
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'server_func',
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[simple_rpc, simple_rpc_with_forloop],
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)
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def test_simple_rpc(server_func, use_async_for):
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"""The simplest request response pattern.
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"""
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async def main():
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async with tractor.open_nursery() as n:
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portal = await n.start_actor(
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'rpc_server',
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enable_modules=[__name__],
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)
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async with portal.open_context(
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server_func, # taken from pytest parameterization
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data=10,
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) as (ctx, sent):
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assert sent == 11
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async with ctx.open_stream() as stream:
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if use_async_for:
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count = 0
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# receive msgs using async for style
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print('ping')
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await stream.send('ping')
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async for msg in stream:
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assert msg == 'pong'
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print('ping')
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await stream.send('ping')
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count += 1
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if count >= 9:
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break
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else:
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# classic send/receive style
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for _ in range(10):
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print('ping')
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await stream.send('ping')
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assert await stream.receive() == 'pong'
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# stream should terminate here
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# final context result(s) should be consumed here in __aexit__()
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await portal.cancel_actor()
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trio.run(main)
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