forked from goodboy/tractor
Blade runner it
Get rid of all the (requirements for) clones of the underlying receivable. We can just use a uuid generated key for each instance (thinking now this can probably just be `id(self)`). I'm fully convinced now that channel cloning is only a source of confusion and anti-patterns when we already have nurseries to define resource lifetimes. There is no benefit in particular when you allocate subscriptions using a context manager (not sure why `trio.open_memory_channel()` doesn't enforce this). Further refinements: - add a `._closed` state that will error the receiver on reuse - drop module script section; it's been moved to a real test - call the "receiver" duck-type stub a new nametokio_backup
Tyler Goodlet
parent
43820e194e
commit
e9b038e87d
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@ -9,16 +9,15 @@ from collections import deque
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from contextlib import asynccontextmanager
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from dataclasses import dataclass
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from functools import partial
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from itertools import cycle
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from operator import ne
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from typing import Optional, Callable, Awaitable, Any, AsyncIterator, Protocol
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from typing import Generic, TypeVar
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from uuid import uuid4
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import trio
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from trio._core._run import Task
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from trio.abc import ReceiveChannel
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from trio.lowlevel import current_task
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import tractor
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# A regular invariant generic type
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@ -30,14 +29,10 @@ T = TypeVar("T")
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ReceiveType = TypeVar("ReceiveType", covariant=True)
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class CloneableReceiveChannel(
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class AsyncReceiver(
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Protocol,
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Generic[ReceiveType],
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):
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@abstractmethod
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def clone(self) -> CloneableReceiveChannel[ReceiveType]:
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'''Clone this receiver usually by making a copy.'''
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@abstractmethod
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async def receive(self) -> ReceiveType:
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'''Same as in ``trio``.'''
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@ -56,7 +51,7 @@ class CloneableReceiveChannel(
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...
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@abstractmethod
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async def __aenter__(self) -> CloneableReceiveChannel[ReceiveType]:
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async def __aenter__(self) -> AsyncReceiver[ReceiveType]:
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...
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@abstractmethod
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@ -75,14 +70,13 @@ class BroadcastState:
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'''
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queue: deque
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# map of underlying clones to receiver wrappers
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# which must be provided as a singleton per broadcaster
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# clone-subscription set.
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subs: dict[CloneableReceiveChannel, int]
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# map of underlying uuid keys to receiver instances which must be
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# provided as a singleton per broadcaster set.
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subs: dict[str, int]
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# broadcast event to wakeup all sleeping consumer tasks
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# on a newly produced value from the sender.
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sender_ready: Optional[trio.Event] = None
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recv_ready: Optional[tuple[str, trio.Event]] = None
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class BroadcastReceiver(ReceiveChannel):
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@ -96,23 +90,26 @@ class BroadcastReceiver(ReceiveChannel):
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def __init__(
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self,
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rx_chan: CloneableReceiveChannel,
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key: str,
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rx_chan: AsyncReceiver,
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state: BroadcastState,
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receive_afunc: Optional[Callable[[], Awaitable[Any]]] = None,
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) -> None:
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# register the original underlying (clone)
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self.key = key
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self._state = state
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state.subs[rx_chan] = -1
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state.subs[key] = -1
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# underlying for this receiver
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self._rx = rx_chan
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self._recv = receive_afunc or rx_chan.receive
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self._closed: bool = False
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async def receive(self):
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key = self._rx
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key = self.key
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state = self._state
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# TODO: ideally we can make some way to "lock out" the
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@ -125,6 +122,9 @@ class BroadcastReceiver(ReceiveChannel):
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try:
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seq = state.subs[key]
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except KeyError:
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if self._closed:
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raise trio.ClosedResourceError
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raise RuntimeError(
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f'{self} is not registerd as subscriber')
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@ -157,9 +157,15 @@ class BroadcastReceiver(ReceiveChannel):
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# current task already has the latest value **and** is the
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# first task to begin waiting for a new one
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if state.sender_ready is None:
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if state.recv_ready is None:
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event = state.sender_ready = trio.Event()
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if self._closed:
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raise trio.ClosedResourceError
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event = trio.Event()
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state.recv_ready = key, event
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try:
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value = await self._recv()
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# items with lower indices are "newer"
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@ -183,15 +189,18 @@ class BroadcastReceiver(ReceiveChannel):
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):
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state.subs[sub_key] += 1
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return value
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finally:
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# reset receiver waiter task event for next blocking condition
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event.set()
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state.sender_ready = None
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return value
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state.recv_ready = None
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# This task is all caught up and ready to receive the latest
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# value, so queue sched it on the internal event.
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else:
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await state.sender_ready.wait()
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_, ev = state.recv_ready
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await ev.wait()
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seq = state.subs[key]
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state.subs[key] -= 1
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return state.queue[seq]
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@ -207,24 +216,22 @@ class BroadcastReceiver(ReceiveChannel):
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provided at creation.
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'''
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# if we didn't want to enforce "clone-ability" how would
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# we key arbitrary subscriptions? Use a token system?
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clone = self._rx.clone()
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# use a uuid4 for a tee-instance token
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key = str(uuid4())
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state = self._state
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br = BroadcastReceiver(
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rx_chan=clone,
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key=key,
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rx_chan=self._rx,
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state=state,
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receive_afunc=self._recv,
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)
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assert clone in state.subs
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# assert clone in state.subs
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assert key in state.subs
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try:
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yield br
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finally:
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# XXX: this is the reason this function is async: the
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# ``AsyncResource`` api.
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await clone.aclose()
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# drop from subscribers and close
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state.subs.pop(clone)
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await br.aclose()
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# TODO:
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# - should there be some ._closed flag that causes
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@ -235,22 +242,30 @@ class BroadcastReceiver(ReceiveChannel):
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async def aclose(
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self,
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) -> None:
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if self._closed:
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return
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# XXX: leaving it like this consumers can still get values
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# up to the last received that still reside in the queue.
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# Is this what we want?
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await self._rx.aclose()
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self._state.subs.pop(self._rx)
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self._state.subs.pop(self.key)
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# if not self._state.subs:
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# await self._rx.aclose()
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self._closed = True
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def broadcast_receiver(
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recv_chan: CloneableReceiveChannel,
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recv_chan: AsyncReceiver,
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max_buffer_size: int,
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**kwargs,
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) -> BroadcastReceiver:
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return BroadcastReceiver(
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str(uuid4()),
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recv_chan,
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state=BroadcastState(
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queue=deque(maxlen=max_buffer_size),
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@ -258,62 +273,3 @@ def broadcast_receiver(
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),
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**kwargs,
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)
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if __name__ == '__main__':
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async def main():
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async with tractor.open_root_actor(
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debug_mode=True,
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# loglevel='info',
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):
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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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rx = 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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lags = 0
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while True:
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async with rx.subscribe() as brx:
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try:
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async for value in brx:
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print(f'{task.name}: {value}')
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await trio.sleep(delay)
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except Lagged:
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print(
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f'restarting slow ass {task.name}'
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f'that bailed out on {lags}:{value}')
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if lags <= retries:
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lags += 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 n:
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for i in range(1, 10):
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n.start_soon(
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partial(
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sub_and_print,
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delay=i*0.01,
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),
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name=f'sub_{i}',
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)
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async with tx:
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for i in cycle(range(size)):
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print(f'sending: {i}')
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await tx.send(i)
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trio.run(main)
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