98 lines
3.3 KiB
Python
98 lines
3.3 KiB
Python
"""Helper to handle a set of topics to subscribe to."""
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import logging
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from typing import Any, Callable, Dict, Optional
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import attr
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from homeassistant.components import mqtt
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from homeassistant.helpers.typing import HomeAssistantType
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from homeassistant.loader import bind_hass
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from .const import DEFAULT_QOS
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from .models import MessageCallbackType
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_LOGGER = logging.getLogger(__name__)
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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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topic = attr.ib(type=str)
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message_callback = attr.ib(type=MessageCallbackType)
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unsubscribe_callback = attr.ib(type=Optional[Callable[[], None]])
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qos = attr.ib(type=int, default=0)
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encoding = attr.ib(type=str, default="utf-8")
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async def resubscribe_if_necessary(self, hass, other):
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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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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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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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self.unsubscribe_callback = await 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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def _should_resubscribe(self, other):
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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 (self.topic, self.qos, self.encoding) != (
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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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@bind_hass
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async def async_subscribe_topics(
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hass: HomeAssistantType,
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new_state: Optional[Dict[str, EntitySubscription]],
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topics: Dict[str, Any],
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):
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"""(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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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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)
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# Get the current subscription state
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current = current_subscriptions.pop(key, None)
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await 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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return new_state
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@bind_hass
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async def async_unsubscribe_topics(hass: HomeAssistantType, sub_state: dict):
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"""Unsubscribe from all MQTT topics managed by async_subscribe_topics."""
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return await async_subscribe_topics(hass, sub_state, {})
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