tractor/tests/test_context_stream_semantics.py

'''
``async with ():`` inlined context-stream cancellation testing.

Verify the we raise errors when streams are opened prior to sync-opening
a ``tractor.Context`` beforehand.

'''
from itertools import count
from typing import Optional

import pytest
import trio
import tractor
from tractor._exceptions import StreamOverrun


@tractor.context
async def really_started(
    ctx: tractor.Context,
) -> None:
    await ctx.started()
    try:
        await ctx.started()
    except RuntimeError:
        raise


def test_started_called_more_then_once():

    async def main():
        async with tractor.open_nursery() as n:
            portal = await n.start_actor(
                'too_much_starteds',
                enable_modules=[__name__],
            )

            async with portal.open_context(really_started) as (ctx, sent):
                await trio.sleep(1)
                # pass

    with pytest.raises(tractor.RemoteActorError):
        trio.run(main)


@tractor.context
async def never_open_stream(

    ctx:  tractor.Context,

) -> None:
    '''
    Context which never opens a stream and blocks.

    '''
    await ctx.started()
    await trio.sleep_forever()


@tractor.context
async def keep_sending_from_callee(

    ctx:  tractor.Context,
    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:
        for msg in count():
            print(f'callee sending {msg}')
            await stream.send(msg)
            await trio.sleep(0.01)


@pytest.mark.parametrize(
    'overrun_by',
    [
        ('caller', 1, never_open_stream),
        ('cancel_caller_during_overrun', 1, never_open_stream),
        ('callee', 0, keep_sending_from_callee),
    ],
    ids='overrun_condition={}'.format,
)
def test_one_end_stream_not_opened(overrun_by):
    '''
    This should exemplify the bug from:
    https://github.com/goodboy/tractor/issues/265

    '''
    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

                if 'caller' in overrunner:

                    async with ctx.open_stream() as stream:
                        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:
                            # expect overrun error to be relayed back
                            # and this sleep interrupted
                            await trio.sleep_forever()

                else:
                    # callee overruns caller case so we do nothing here
                    await trio.sleep_forever()

            await portal.cancel_actor()

    # 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)

        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

    elif overrunner == 'callee':
        with pytest.raises(tractor.RemoteActorError) as excinfo:
            trio.run(main)

        # 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.
        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:

        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)