141 lines
4.7 KiB
Python
141 lines
4.7 KiB
Python
"""Helper to handle a set of topics to subscribe to."""
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from __future__ import annotations
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from collections.abc import Callable, Coroutine
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from typing import Any
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import attr
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from homeassistant.core import HomeAssistant
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from . import debug_info
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from .. import mqtt
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from .const import DEFAULT_QOS
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from .models import MessageCallbackType
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@attr.s(slots=True)
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class EntitySubscription:
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"""Class to hold data about an active entity topic subscription."""
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hass: HomeAssistant = attr.ib()
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topic: str | None = attr.ib()
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message_callback: MessageCallbackType = attr.ib()
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subscribe_task: Coroutine[Any, Any, Callable[[], None]] | None = attr.ib()
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unsubscribe_callback: Callable[[], None] | None = attr.ib()
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qos: int = attr.ib(default=0)
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encoding: str = attr.ib(default="utf-8")
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def resubscribe_if_necessary(
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self, hass: HomeAssistant, other: EntitySubscription | None
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) -> None:
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"""Re-subscribe to the new topic if necessary."""
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if not self._should_resubscribe(other):
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assert other
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self.unsubscribe_callback = other.unsubscribe_callback
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return
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if other is not None and other.unsubscribe_callback is not None:
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other.unsubscribe_callback()
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# Clear debug data if it exists
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debug_info.remove_subscription(
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self.hass, other.message_callback, str(other.topic)
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)
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if self.topic is None:
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# We were asked to remove the subscription or not to create it
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return
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# Prepare debug data
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debug_info.add_subscription(self.hass, self.message_callback, self.topic)
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self.subscribe_task = mqtt.async_subscribe(
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hass, self.topic, self.message_callback, self.qos, self.encoding
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)
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async def subscribe(self) -> None:
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"""Subscribe to a topic."""
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if not self.subscribe_task:
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return
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self.unsubscribe_callback = await self.subscribe_task
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def _should_resubscribe(self, other: EntitySubscription | None) -> bool:
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"""Check if we should re-subscribe to the topic using the old state."""
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if other is None:
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return True
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return (
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self.topic,
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self.qos,
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self.encoding,
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) != (
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other.topic,
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other.qos,
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other.encoding,
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)
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def async_prepare_subscribe_topics(
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hass: HomeAssistant,
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new_state: dict[str, EntitySubscription] | None,
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topics: dict[str, Any],
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) -> dict[str, EntitySubscription]:
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"""Prepare (re)subscribe to a set of MQTT topics.
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State is kept in sub_state and a dictionary mapping from the subscription
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key to the subscription state.
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After this function has been called, async_subscribe_topics must be called to
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finalize any new subscriptions.
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Please note that the sub state must not be shared between multiple
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sets of topics. Every call to async_subscribe_topics must always
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contain _all_ the topics the subscription state should manage.
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"""
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current_subscriptions = new_state if new_state is not None else {}
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new_state = {}
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for key, value in topics.items():
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# Extract the new requested subscription
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requested = EntitySubscription(
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topic=value.get("topic", None),
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message_callback=value.get("msg_callback", None),
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unsubscribe_callback=None,
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qos=value.get("qos", DEFAULT_QOS),
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encoding=value.get("encoding", "utf-8"),
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hass=hass,
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subscribe_task=None,
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)
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# Get the current subscription state
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current = current_subscriptions.pop(key, None)
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requested.resubscribe_if_necessary(hass, current)
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new_state[key] = requested
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# Go through all remaining subscriptions and unsubscribe them
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for remaining in current_subscriptions.values():
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if remaining.unsubscribe_callback is not None:
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remaining.unsubscribe_callback()
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# Clear debug data if it exists
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debug_info.remove_subscription(
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hass, remaining.message_callback, str(remaining.topic)
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)
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return new_state
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async def async_subscribe_topics(
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hass: HomeAssistant,
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sub_state: dict[str, EntitySubscription] | None,
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) -> None:
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"""(Re)Subscribe to a set of MQTT topics."""
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if sub_state is None:
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return
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for sub in sub_state.values():
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await sub.subscribe()
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def async_unsubscribe_topics(
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hass: HomeAssistant, sub_state: dict[str, EntitySubscription] | None
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) -> dict[str, EntitySubscription]:
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"""Unsubscribe from all MQTT topics managed by async_subscribe_topics."""
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return async_prepare_subscribe_topics(hass, sub_state, {})
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