goodboy
GitHub
commit
3f1bc37143
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@ -0,0 +1,12 @@
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Add `tokio-style broadcast channels
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<https://docs.rs/tokio/1.11.0/tokio/sync/broadcast/index.html>`_ as
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a solution for `#204 <https://github.com/goodboy/tractor/pull/204>`_ and
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discussed thoroughly in `trio/#987
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<https://github.com/python-trio/trio/issues/987>`_.
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This gives us local task broadcast functionality using a new
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``BroadcastReceiver`` type which can wrap ``trio.ReceiveChannel`` and
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provide fan-out copies of a stream of data to every subscribed consumer.
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We use this new machinery to provide a ``ReceiveMsgStream.subscribe()``
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async context manager which can be used by actor-local concumers tasks
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to easily pull from a shared and dynamic IPC stream.
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@ -0,0 +1,459 @@
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"""
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Broadcast channels for fan-out to local tasks.
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"""
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from contextlib import asynccontextmanager
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from functools import partial
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from itertools import cycle
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import time
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from typing import Optional, List, Tuple
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import pytest
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import trio
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from trio.lowlevel import current_task
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import tractor
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from tractor._broadcast import broadcast_receiver, Lagged
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@tractor.context
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async def echo_sequences(
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ctx: tractor.Context,
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) -> None:
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'''Bidir streaming endpoint which will stream
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back any sequence it is sent item-wise.
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'''
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await ctx.started()
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async with ctx.open_stream() as stream:
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async for sequence in stream:
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seq = list(sequence)
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for value in seq:
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await stream.send(value)
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print(f'producer sent {value}')
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async def ensure_sequence(
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stream: tractor.ReceiveMsgStream,
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sequence: list,
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delay: Optional[float] = None,
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) -> None:
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name = current_task().name
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async with stream.subscribe() as bcaster:
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assert not isinstance(bcaster, type(stream))
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async for value in bcaster:
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print(f'{name} rx: {value}')
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assert value == sequence[0]
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sequence.remove(value)
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if delay:
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await trio.sleep(delay)
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if not sequence:
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# fully consumed
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break
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@asynccontextmanager
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async def open_sequence_streamer(
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sequence: List[int],
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arb_addr: Tuple[str, int],
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start_method: str,
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) -> tractor.MsgStream:
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async with tractor.open_nursery(
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arbiter_addr=arb_addr,
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start_method=start_method,
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) as tn:
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portal = await tn.start_actor(
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'sequence_echoer',
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enable_modules=[__name__],
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)
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async with portal.open_context(
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echo_sequences,
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) as (ctx, first):
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assert first is None
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async with ctx.open_stream() as stream:
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yield stream
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await portal.cancel_actor()
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def test_stream_fan_out_to_local_subscriptions(
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arb_addr,
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start_method,
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):
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sequence = list(range(1000))
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async def main():
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async with open_sequence_streamer(
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sequence,
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arb_addr,
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start_method,
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) as stream:
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async with trio.open_nursery() as n:
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for i in range(10):
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n.start_soon(
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ensure_sequence,
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stream,
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sequence.copy(),
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name=f'consumer_{i}',
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)
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await stream.send(tuple(sequence))
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async for value in stream:
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print(f'source stream rx: {value}')
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assert value == sequence[0]
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sequence.remove(value)
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if not sequence:
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# fully consumed
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break
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trio.run(main)
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@pytest.mark.parametrize(
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'task_delays',
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[
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(0.01, 0.001),
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(0.001, 0.01),
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]
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)
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def test_consumer_and_parent_maybe_lag(
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arb_addr,
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start_method,
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task_delays,
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):
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async def main():
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sequence = list(range(300))
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parent_delay, sub_delay = task_delays
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async with open_sequence_streamer(
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sequence,
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arb_addr,
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start_method,
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) as stream:
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try:
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async with trio.open_nursery() as n:
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n.start_soon(
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ensure_sequence,
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stream,
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sequence.copy(),
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sub_delay,
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name='consumer_task',
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)
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await stream.send(tuple(sequence))
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# async for value in stream:
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lagged = False
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lag_count = 0
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while True:
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try:
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value = await stream.receive()
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print(f'source stream rx: {value}')
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if lagged:
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# re set the sequence starting at our last
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# value
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sequence = sequence[sequence.index(value) + 1:]
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else:
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assert value == sequence[0]
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sequence.remove(value)
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lagged = False
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except Lagged:
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lagged = True
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print(f'source stream lagged after {value}')
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lag_count += 1
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continue
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# lag the parent
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await trio.sleep(parent_delay)
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if not sequence:
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# fully consumed
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break
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print(f'parent + source stream lagged: {lag_count}')
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if parent_delay > sub_delay:
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assert lag_count > 0
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except Lagged:
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# child was lagged
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assert parent_delay < sub_delay
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trio.run(main)
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def test_faster_task_to_recv_is_cancelled_by_slower(
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arb_addr,
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start_method,
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):
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'''Ensure that if a faster task consuming from a stream is cancelled
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the slower task can continue to receive all expected values.
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'''
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async def main():
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sequence = list(range(1000))
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async with open_sequence_streamer(
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sequence,
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arb_addr,
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start_method,
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) as stream:
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async with trio.open_nursery() as n:
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n.start_soon(
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ensure_sequence,
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stream,
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sequence.copy(),
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0,
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name='consumer_task',
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)
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await stream.send(tuple(sequence))
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# pull 3 values, cancel the subtask, then
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# expect to be able to pull all values still
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for i in range(20):
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try:
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value = await stream.receive()
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print(f'source stream rx: {value}')
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await trio.sleep(0.01)
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except Lagged:
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print(f'parent overrun after {value}')
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continue
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print('cancelling faster subtask')
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n.cancel_scope.cancel()
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try:
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value = await stream.receive()
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print(f'source stream after cancel: {value}')
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except Lagged:
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print(f'parent overrun after {value}')
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# expect to see all remaining values
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with trio.fail_after(0.5):
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async for value in stream:
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assert stream._broadcaster._state.recv_ready is None
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print(f'source stream rx: {value}')
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if value == 999:
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# fully consumed and we missed no values once
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# the faster subtask was cancelled
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break
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# await tractor.breakpoint()
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# await stream.receive()
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print(f'final value: {value}')
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trio.run(main)
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def test_subscribe_errors_after_close():
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async def main():
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size = 1
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tx, rx = trio.open_memory_channel(size)
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async with broadcast_receiver(rx, size) as brx:
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pass
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try:
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# open and close
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async with brx.subscribe():
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pass
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except trio.ClosedResourceError:
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assert brx.key not in brx._state.subs
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else:
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assert 0
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trio.run(main)
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def test_ensure_slow_consumers_lag_out(
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arb_addr,
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start_method,
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):
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'''This is a pure local task test; no tractor
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machinery is really required.
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'''
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async def main():
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# make sure it all works within the runtime
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async with tractor.open_root_actor():
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num_laggers = 4
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laggers: dict[str, int] = {}
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retries = 3
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size = 100
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tx, rx = trio.open_memory_channel(size)
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brx = broadcast_receiver(rx, size)
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async def sub_and_print(
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delay: float,
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) -> None:
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task = current_task()
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start = time.time()
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async with brx.subscribe() as lbrx:
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while True:
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print(f'{task.name}: starting consume loop')
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try:
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async for value in lbrx:
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print(f'{task.name}: {value}')
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await trio.sleep(delay)
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if task.name == 'sub_1':
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# the non-lagger got
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# a ``trio.EndOfChannel``
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# because the ``tx`` below was closed
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assert len(lbrx._state.subs) == 1
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await lbrx.aclose()
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assert len(lbrx._state.subs) == 0
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except trio.ClosedResourceError:
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# only the fast sub will try to re-enter
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# iteration on the now closed bcaster
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assert task.name == 'sub_1'
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return
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except Lagged:
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lag_time = time.time() - start
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lags = laggers[task.name]
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print(
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f'restarting slow task {task.name} '
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f'that bailed out on {lags}:{value} '
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f'after {lag_time:.3f}')
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if lags <= retries:
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laggers[task.name] += 1
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continue
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else:
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print(
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f'{task.name} was too slow and terminated '
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f'on {lags}:{value}')
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return
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async with trio.open_nursery() as nursery:
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for i in range(1, num_laggers):
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task_name = f'sub_{i}'
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laggers[task_name] = 0
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nursery.start_soon(
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partial(
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sub_and_print,
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delay=i*0.001,
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),
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name=task_name,
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)
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# allow subs to sched
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await trio.sleep(0.1)
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async with tx:
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for i in cycle(range(size)):
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await tx.send(i)
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if len(brx._state.subs) == 2:
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# only one, the non lagger, sub is left
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break
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# the non-lagger
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assert laggers.pop('sub_1') == 0
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for n, v in laggers.items():
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assert v == 4
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assert tx._closed
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assert not tx._state.open_send_channels
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# check that "first" bcaster that we created
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# above, never wass iterated and is thus overrun
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try:
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await brx.receive()
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except Lagged:
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# expect tokio style index truncation
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seq = brx._state.subs[brx.key]
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assert seq == len(brx._state.queue) - 1
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# all backpressured entries in the underlying
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# channel should have been copied into the caster
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# queue trailing-window
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async for i in rx:
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print(f'bped: {i}')
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assert i in brx._state.queue
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# should be noop
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await brx.aclose()
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trio.run(main)
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def test_first_recver_is_cancelled():
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async def main():
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# make sure it all works within the runtime
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async with tractor.open_root_actor():
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tx, rx = trio.open_memory_channel(1)
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brx = broadcast_receiver(rx, 1)
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cs = trio.CancelScope()
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sequence = list(range(3))
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async def sub_and_recv():
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with cs:
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async with brx.subscribe() as bc:
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async for value in bc:
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print(value)
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async def cancel_and_send():
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await trio.sleep(0.2)
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cs.cancel()
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await tx.send(1)
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async with trio.open_nursery() as n:
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n.start_soon(sub_and_recv)
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await trio.sleep(0.1)
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assert brx._state.recv_ready
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n.start_soon(cancel_and_send)
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# ensure that we don't hang because no-task is now
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# waiting on the underlying receive..
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with trio.fail_after(0.5):
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value = await brx.receive()
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print(f'parent: {value}')
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assert value == 1
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trio.run(main)
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|
@ -567,7 +567,7 @@ class Actor:
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try:
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send_chan, recv_chan = self._cids2qs[(actorid, cid)]
|
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except KeyError:
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send_chan, recv_chan = trio.open_memory_channel(1000)
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send_chan, recv_chan = trio.open_memory_channel(2**6)
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send_chan.cid = cid # type: ignore
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recv_chan.cid = cid # type: ignore
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self._cids2qs[(actorid, cid)] = send_chan, recv_chan
|
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|
|
|
|||
|
|
@ -0,0 +1,315 @@
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|||
'''
|
||||
``tokio`` style broadcast channel.
|
||||
https://docs.rs/tokio/1.11.0/tokio/sync/broadcast/index.html
|
||||
|
||||
'''
|
||||
from __future__ import annotations
|
||||
from abc import abstractmethod
|
||||
from collections import deque
|
||||
from contextlib import asynccontextmanager
|
||||
from dataclasses import dataclass
|
||||
from functools import partial
|
||||
from operator import ne
|
||||
from typing import Optional, Callable, Awaitable, Any, AsyncIterator, Protocol
|
||||
from typing import Generic, TypeVar
|
||||
|
||||
import trio
|
||||
from trio._core._run import Task
|
||||
from trio.abc import ReceiveChannel
|
||||
from trio.lowlevel import current_task
|
||||
|
||||
|
||||
# A regular invariant generic type
|
||||
T = TypeVar("T")
|
||||
|
||||
# covariant because AsyncReceiver[Derived] can be passed to someone
|
||||
# expecting AsyncReceiver[Base])
|
||||
ReceiveType = TypeVar("ReceiveType", covariant=True)
|
||||
|
||||
|
||||
class AsyncReceiver(
|
||||
Protocol,
|
||||
Generic[ReceiveType],
|
||||
):
|
||||
'''An async receivable duck-type that quacks much like trio's
|
||||
``trio.abc.ReceieveChannel``.
|
||||
|
||||
'''
|
||||
@abstractmethod
|
||||
async def receive(self) -> ReceiveType:
|
||||
...
|
||||
|
||||
@abstractmethod
|
||||
def __aiter__(self) -> AsyncIterator[ReceiveType]:
|
||||
...
|
||||
|
||||
@abstractmethod
|
||||
async def __anext__(self) -> ReceiveType:
|
||||
...
|
||||
|
||||
# ``trio.abc.AsyncResource`` methods
|
||||
@abstractmethod
|
||||
async def aclose(self):
|
||||
...
|
||||
|
||||
@abstractmethod
|
||||
async def __aenter__(self) -> AsyncReceiver[ReceiveType]:
|
||||
...
|
||||
|
||||
@abstractmethod
|
||||
async def __aexit__(self, *args) -> None:
|
||||
...
|
||||
|
||||
|
||||
class Lagged(trio.TooSlowError):
|
||||
'''Subscribed consumer task was too slow and was overrun
|
||||
by the fastest consumer-producer pair.
|
||||
|
||||
'''
|
||||
|
||||
|
||||
@dataclass
|
||||
class BroadcastState:
|
||||
'''Common state to all receivers of a broadcast.
|
||||
|
||||
'''
|
||||
queue: deque
|
||||
maxlen: int
|
||||
|
||||
# map of underlying instance id keys to receiver instances which
|
||||
# must be provided as a singleton per broadcaster set.
|
||||
subs: dict[int, int]
|
||||
|
||||
# broadcast event to wake up all sleeping consumer tasks
|
||||
# on a newly produced value from the sender.
|
||||
recv_ready: Optional[tuple[int, trio.Event]] = None
|
||||
|
||||
|
||||
class BroadcastReceiver(ReceiveChannel):
|
||||
'''A memory receive channel broadcaster which is non-lossy for the
|
||||
fastest consumer.
|
||||
|
||||
Additional consumer tasks can receive all produced values by registering
|
||||
with ``.subscribe()`` and receiving from the new instance it delivers.
|
||||
|
||||
'''
|
||||
def __init__(
|
||||
self,
|
||||
|
||||
rx_chan: AsyncReceiver,
|
||||
state: BroadcastState,
|
||||
receive_afunc: Optional[Callable[[], Awaitable[Any]]] = None,
|
||||
|
||||
) -> None:
|
||||
|
||||
# register the original underlying (clone)
|
||||
self.key = id(self)
|
||||
self._state = state
|
||||
state.subs[self.key] = -1
|
||||
|
||||
# underlying for this receiver
|
||||
self._rx = rx_chan
|
||||
self._recv = receive_afunc or rx_chan.receive
|
||||
self._closed: bool = False
|
||||
|
||||
async def receive(self) -> ReceiveType:
|
||||
|
||||
key = self.key
|
||||
state = self._state
|
||||
|
||||
# TODO: ideally we can make some way to "lock out" the
|
||||
# underlying receive channel in some way such that if some task
|
||||
# tries to pull from it directly (i.e. one we're unaware of)
|
||||
# then it errors out.
|
||||
|
||||
# only tasks which have entered ``.subscribe()`` can
|
||||
# receive on this broadcaster.
|
||||
try:
|
||||
seq = state.subs[key]
|
||||
except KeyError:
|
||||
if self._closed:
|
||||
raise trio.ClosedResourceError
|
||||
|
||||
raise RuntimeError(
|
||||
f'{self} is not registerd as subscriber')
|
||||
|
||||
# check that task does not already have a value it can receive
|
||||
# immediately and/or that it has lagged.
|
||||
if seq > -1:
|
||||
# get the oldest value we haven't received immediately
|
||||
try:
|
||||
value = state.queue[seq]
|
||||
except IndexError:
|
||||
|
||||
# adhere to ``tokio`` style "lagging":
|
||||
# "Once RecvError::Lagged is returned, the lagging
|
||||
# receiver's position is updated to the oldest value
|
||||
# contained by the channel. The next call to recv will
|
||||
# return this value."
|
||||
# https://docs.rs/tokio/1.11.0/tokio/sync/broadcast/index.html#lagging
|
||||
|
||||
# decrement to the last value and expect
|
||||
# consumer to either handle the ``Lagged`` and come back
|
||||
# or bail out on its own (thus un-subscribing)
|
||||
state.subs[key] = state.maxlen - 1
|
||||
|
||||
# this task was overrun by the producer side
|
||||
task: Task = current_task()
|
||||
raise Lagged(f'Task {task.name} was overrun')
|
||||
|
||||
state.subs[key] -= 1
|
||||
return value
|
||||
|
||||
# current task already has the latest value **and** is the
|
||||
# first task to begin waiting for a new one
|
||||
if state.recv_ready is None:
|
||||
|
||||
if self._closed:
|
||||
raise trio.ClosedResourceError
|
||||
|
||||
event = trio.Event()
|
||||
state.recv_ready = key, event
|
||||
|
||||
# if we're cancelled here it should be
|
||||
# fine to bail without affecting any other consumers
|
||||
# right?
|
||||
try:
|
||||
value = await self._recv()
|
||||
|
||||
# items with lower indices are "newer"
|
||||
# NOTE: ``collections.deque`` implicitly takes care of
|
||||
# trucating values outside our ``state.maxlen``. In the
|
||||
# alt-backend-array-case we'll need to make sure this is
|
||||
# implemented in similar ringer-buffer-ish style.
|
||||
state.queue.appendleft(value)
|
||||
|
||||
# broadcast new value to all subscribers by increasing
|
||||
# all sequence numbers that will point in the queue to
|
||||
# their latest available value.
|
||||
|
||||
# don't decrement the sequence for this task since we
|
||||
# already retreived the last value
|
||||
|
||||
# XXX: which of these impls is fastest?
|
||||
|
||||
# subs = state.subs.copy()
|
||||
# subs.pop(key)
|
||||
|
||||
for sub_key in filter(
|
||||
# lambda k: k != key, state.subs,
|
||||
partial(ne, key), state.subs,
|
||||
):
|
||||
state.subs[sub_key] += 1
|
||||
|
||||
# NOTE: this should ONLY be set if the above task was *NOT*
|
||||
# cancelled on the `._recv()` call.
|
||||
event.set()
|
||||
return value
|
||||
|
||||
except trio.Cancelled:
|
||||
# handle cancelled specially otherwise sibling
|
||||
# consumers will be awoken with a sequence of -1
|
||||
# state.recv_ready = trio.Cancelled
|
||||
if event.statistics().tasks_waiting:
|
||||
event.set()
|
||||
raise
|
||||
|
||||
finally:
|
||||
|
||||
# Reset receiver waiter task event for next blocking condition.
|
||||
# this MUST be reset even if the above ``.recv()`` call
|
||||
# was cancelled to avoid the next consumer from blocking on
|
||||
# an event that won't be set!
|
||||
state.recv_ready = None
|
||||
|
||||
# This task is all caught up and ready to receive the latest
|
||||
# value, so queue sched it on the internal event.
|
||||
else:
|
||||
seq = state.subs[key]
|
||||
assert seq == -1 # sanity
|
||||
_, ev = state.recv_ready
|
||||
await ev.wait()
|
||||
|
||||
# NOTE: if we ever would like the behaviour where if the
|
||||
# first task to recv on the underlying is cancelled but it
|
||||
# still DOES trigger the ``.recv_ready``, event we'll likely need
|
||||
# this logic:
|
||||
|
||||
if seq > -1:
|
||||
# stuff from above..
|
||||
seq = state.subs[key]
|
||||
|
||||
value = state.queue[seq]
|
||||
state.subs[key] -= 1
|
||||
return value
|
||||
|
||||
elif seq == -1:
|
||||
# XXX: In the case where the first task to allocate the
|
||||
# ``.recv_ready`` event is cancelled we will be woken with
|
||||
# a non-incremented sequence number and thus will read the
|
||||
# oldest value if we use that. Instead we need to detect if
|
||||
# we have not been incremented and then receive again.
|
||||
return await self.receive()
|
||||
|
||||
else:
|
||||
raise ValueError(f'Invalid sequence {seq}!?')
|
||||
|
||||
@asynccontextmanager
|
||||
async def subscribe(
|
||||
self,
|
||||
) -> AsyncIterator[BroadcastReceiver]:
|
||||
'''Subscribe for values from this broadcast receiver.
|
||||
|
||||
Returns a new ``BroadCastReceiver`` which is registered for and
|
||||
pulls data from a clone of the original ``trio.abc.ReceiveChannel``
|
||||
provided at creation.
|
||||
|
||||
'''
|
||||
if self._closed:
|
||||
raise trio.ClosedResourceError
|
||||
|
||||
state = self._state
|
||||
br = BroadcastReceiver(
|
||||
rx_chan=self._rx,
|
||||
state=state,
|
||||
receive_afunc=self._recv,
|
||||
)
|
||||
# assert clone in state.subs
|
||||
assert br.key in state.subs
|
||||
|
||||
try:
|
||||
yield br
|
||||
finally:
|
||||
await br.aclose()
|
||||
|
||||
async def aclose(
|
||||
self,
|
||||
) -> None:
|
||||
|
||||
if self._closed:
|
||||
return
|
||||
|
||||
# XXX: leaving it like this consumers can still get values
|
||||
# up to the last received that still reside in the queue.
|
||||
self._state.subs.pop(self.key)
|
||||
|
||||
self._closed = True
|
||||
|
||||
|
||||
def broadcast_receiver(
|
||||
|
||||
recv_chan: AsyncReceiver,
|
||||
max_buffer_size: int,
|
||||
**kwargs,
|
||||
|
||||
) -> BroadcastReceiver:
|
||||
|
||||
return BroadcastReceiver(
|
||||
recv_chan,
|
||||
state=BroadcastState(
|
||||
queue=deque(maxlen=max_buffer_size),
|
||||
maxlen=max_buffer_size,
|
||||
subs={},
|
||||
),
|
||||
**kwargs,
|
||||
)
|
||||
|
|
@ -294,6 +294,7 @@ class Portal:
|
|||
async def open_stream_from(
|
||||
self,
|
||||
async_gen_func: Callable, # typing: ignore
|
||||
shield: bool = False,
|
||||
**kwargs,
|
||||
|
||||
) -> AsyncGenerator[ReceiveMsgStream, None]:
|
||||
|
|
@ -320,7 +321,9 @@ class Portal:
|
|||
ctx = Context(self.channel, cid, _portal=self)
|
||||
try:
|
||||
# deliver receive only stream
|
||||
async with ReceiveMsgStream(ctx, recv_chan) as rchan:
|
||||
async with ReceiveMsgStream(
|
||||
ctx, recv_chan, shield=shield
|
||||
) as rchan:
|
||||
self._streams.add(rchan)
|
||||
yield rchan
|
||||
|
||||
|
|
|
|||
|
|
@ -2,12 +2,14 @@
|
|||
Message stream types and APIs.
|
||||
|
||||
"""
|
||||
from __future__ import annotations
|
||||
import inspect
|
||||
from contextlib import contextmanager, asynccontextmanager
|
||||
from dataclasses import dataclass
|
||||
from typing import (
|
||||
Any, Iterator, Optional, Callable,
|
||||
AsyncGenerator, Dict,
|
||||
AsyncIterator
|
||||
)
|
||||
|
||||
import warnings
|
||||
|
|
@ -17,6 +19,7 @@ import trio
|
|||
from ._ipc import Channel
|
||||
from ._exceptions import unpack_error, ContextCancelled
|
||||
from ._state import current_actor
|
||||
from ._broadcast import broadcast_receiver, BroadcastReceiver
|
||||
from .log import get_logger
|
||||
|
||||
|
||||
|
|
@ -47,11 +50,14 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
|
|||
def __init__(
|
||||
self,
|
||||
ctx: 'Context', # typing: ignore # noqa
|
||||
rx_chan: trio.abc.ReceiveChannel,
|
||||
rx_chan: trio.MemoryReceiveChannel,
|
||||
shield: bool = False,
|
||||
_broadcaster: Optional[BroadcastReceiver] = None,
|
||||
|
||||
) -> None:
|
||||
self._ctx = ctx
|
||||
self._rx_chan = rx_chan
|
||||
self._broadcaster = _broadcaster
|
||||
|
||||
# flag to denote end of stream
|
||||
self._eoc: bool = False
|
||||
|
|
@ -231,6 +237,50 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
|
|||
# still need to consume msgs that are "in transit" from the far
|
||||
# end (eg. for ``Context.result()``).
|
||||
|
||||
@asynccontextmanager
|
||||
async def subscribe(
|
||||
self,
|
||||
|
||||
) -> AsyncIterator[BroadcastReceiver]:
|
||||
'''Allocate and return a ``BroadcastReceiver`` which delegates
|
||||
to this message stream.
|
||||
|
||||
This allows multiple local tasks to receive each their own copy
|
||||
of this message stream.
|
||||
|
||||
This operation is indempotent and and mutates this stream's
|
||||
receive machinery to copy and window-length-store each received
|
||||
value from the far end via the internally created broudcast
|
||||
receiver wrapper.
|
||||
|
||||
'''
|
||||
# NOTE: This operation is indempotent and non-reversible, so be
|
||||
# sure you can deal with any (theoretical) overhead of the the
|
||||
# allocated ``BroadcastReceiver`` before calling this method for
|
||||
# the first time.
|
||||
if self._broadcaster is None:
|
||||
|
||||
bcast = self._broadcaster = broadcast_receiver(
|
||||
self,
|
||||
# use memory channel size by default
|
||||
self._rx_chan._state.max_buffer_size, # type: ignore
|
||||
receive_afunc=self.receive,
|
||||
)
|
||||
|
||||
# NOTE: we override the original stream instance's receive
|
||||
# method to now delegate to the broadcaster's ``.receive()``
|
||||
# such that new subscribers will be copied received values
|
||||
# and this stream doesn't have to expect it's original
|
||||
# consumer(s) to get a new broadcast rx handle.
|
||||
self.receive = bcast.receive # type: ignore
|
||||
# seems there's no graceful way to type this with ``mypy``?
|
||||
# https://github.com/python/mypy/issues/708
|
||||
|
||||
async with self._broadcaster.subscribe() as bstream:
|
||||
assert bstream.key != self._broadcaster.key
|
||||
assert bstream._recv == self._broadcaster._recv
|
||||
yield bstream
|
||||
|
||||
|
||||
class MsgStream(ReceiveMsgStream, trio.abc.Channel):
|
||||
"""
|
||||
|
|
@ -247,17 +297,6 @@ class MsgStream(ReceiveMsgStream, trio.abc.Channel):
|
|||
'''
|
||||
await self._ctx.chan.send({'yield': data, 'cid': self._ctx.cid})
|
||||
|
||||
# TODO: but make it broadcasting to consumers
|
||||
def clone(self):
|
||||
"""Clone this receive channel allowing for multi-task
|
||||
consumption from the same channel.
|
||||
|
||||
"""
|
||||
return MsgStream(
|
||||
self._ctx,
|
||||
self._rx_chan.clone(),
|
||||
)
|
||||
|
||||
|
||||
@dataclass
|
||||
class Context:
|
||||
|
|
|
|||
Loading…
Reference in New Issue