Walter Oggioni
28543921c3
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added topic class
92 lines
3.0 KiB
Python
92 lines
3.0 KiB
Python
from .private import AsyncQueueIterator
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from asyncio import Queue, AbstractEventLoop, Future, CancelledError
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from typing import Callable, Optional
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from logging import getLogger
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log = getLogger(__name__)
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class Subscriber:
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_unsubscribe_callback: Callable[['Subscriber'], None]
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_event: Optional[Future]
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_loop: AbstractEventLoop
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def __init__(self, unsubscribe: Callable[['Subscriber'], None], loop: AbstractEventLoop):
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self._unsubscribe_callback = unsubscribe
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self._event: Optional[Future] = None
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self._loop = loop
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def unsubscribe(self) -> None:
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self._event.cancel()
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self._unsubscribe_callback(self)
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log.debug('Deleted subscriber %s', id(self))
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async def wait(self, tout: float) -> bool:
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self._event = self._loop.create_future()
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def callback():
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if not self._event.done():
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self._event.set_result(False)
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handle = self._loop.call_later(tout, callback)
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try:
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log.debug('Subscriber %s is waiting for an event', id(self))
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return await self._event
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except CancelledError:
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return False
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finally:
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handle.cancel()
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def notify(self) -> None:
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log.debug('Subscriber %s notified', id(self))
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if not self._event.done():
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self._event.set_result(True)
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def reset(self) -> None:
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self._event = self._loop.create_future()
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class Topic:
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_loop: AbstractEventLoop
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_queue: Queue
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_subscriptions: dict[str, set[Subscriber]]
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def __init__(self, loop: AbstractEventLoop):
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self._subscriptions: dict[str, set[Subscriber]] = dict()
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self._loop = loop
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self._queue = Queue()
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def subscribe(self, path: str) -> Subscriber:
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subscriptions = self._subscriptions
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subscriptions_per_path = subscriptions.setdefault(path, set())
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def unsubscribe_callback(subscription):
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subscriptions_per_path.remove(subscription)
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log.debug('Unsubscribed %s from topic %s', id(result), path)
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result = Subscriber(unsubscribe_callback, self._loop)
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log.debug('Created subscriber %s to topic %s', id(result), path)
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subscriptions_per_path.add(result)
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return result
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def _notify_subscriptions(self, path):
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subscriptions = self._subscriptions
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subscriptions_per_path = subscriptions.get(path, None)
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if subscriptions_per_path:
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log.debug(f"Subscribers on '{path}': {len(subscriptions_per_path)}")
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for s in subscriptions_per_path:
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s.notify()
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async def process_events(self):
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async for evt in AsyncQueueIterator(self._queue):
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log.debug(f"Processed event for path '{evt}'")
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self._notify_subscriptions(evt)
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log.debug(f"Event processor has completed")
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def post_event(self, path):
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def callback():
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self._queue.put_nowait(path)
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log.debug(f"Posted event for topic '{path}', queue size: {self._queue.qsize()}")
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self._loop.call_soon_threadsafe(callback)
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