47 lines
1.2 KiB
Python
47 lines
1.2 KiB
Python
"""Helper to help coordinating calls."""
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import asyncio
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import functools
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from typing import Awaitable, Callable, TypeVar, cast
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from homeassistant.core import HomeAssistant
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from homeassistant.loader import bind_hass
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T = TypeVar("T")
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FUNC = Callable[[HomeAssistant], Awaitable[T]]
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def singleton(data_key: str) -> Callable[[FUNC], FUNC]:
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"""Decorate a function that should be called once per instance.
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Result will be cached and simultaneous calls will be handled.
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"""
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def wrapper(func: FUNC) -> FUNC:
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"""Wrap a function with caching logic."""
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@bind_hass
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@functools.wraps(func)
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async def wrapped(hass: HomeAssistant) -> T:
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obj_or_evt = hass.data.get(data_key)
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if not obj_or_evt:
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evt = hass.data[data_key] = asyncio.Event()
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result = await func(hass)
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hass.data[data_key] = result
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evt.set()
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return cast(T, result)
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if isinstance(obj_or_evt, asyncio.Event):
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evt = obj_or_evt
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await evt.wait()
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return cast(T, hass.data.get(data_key))
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return cast(T, obj_or_evt)
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return wrapped
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return wrapper
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