core/homeassistant/helpers/singleton.py

122 lines
3.3 KiB
Python

"""Helper to help coordinating calls."""
from __future__ import annotations
import asyncio
from collections.abc import Callable, Coroutine
import functools
from typing import Any, Literal, assert_type, cast, overload
from homeassistant.core import HomeAssistant
from homeassistant.loader import bind_hass
from homeassistant.util.hass_dict import HassKey
type _FuncType[_T] = Callable[[HomeAssistant], _T]
type _Coro[_T] = Coroutine[Any, Any, _T]
@overload
def singleton[_T](
data_key: HassKey[_T], *, async_: Literal[True]
) -> Callable[[_FuncType[_Coro[_T]]], _FuncType[_Coro[_T]]]: ...
@overload
def singleton[_T](
data_key: HassKey[_T],
) -> Callable[[_FuncType[_T]], _FuncType[_T]]: ...
@overload
def singleton[_T](data_key: str) -> Callable[[_FuncType[_T]], _FuncType[_T]]: ...
def singleton[_S, _T, _U](
data_key: Any, *, async_: bool = False
) -> Callable[[_FuncType[_S]], _FuncType[_S]]:
"""Decorate a function that should be called once per instance.
Result will be cached and simultaneous calls will be handled.
"""
@overload
def wrapper(func: _FuncType[_Coro[_T]]) -> _FuncType[_Coro[_T]]: ...
@overload
def wrapper(func: _FuncType[_U]) -> _FuncType[_U]: ...
def wrapper(func: _FuncType[_Coro[_T] | _U]) -> _FuncType[_Coro[_T] | _U]:
"""Wrap a function with caching logic."""
if not asyncio.iscoroutinefunction(func):
@functools.lru_cache(maxsize=1)
@bind_hass
@functools.wraps(func)
def wrapped(hass: HomeAssistant) -> _U:
if data_key not in hass.data:
hass.data[data_key] = func(hass)
return cast(_U, hass.data[data_key])
return wrapped
@bind_hass
@functools.wraps(func)
async def async_wrapped(hass: HomeAssistant) -> _T:
if data_key not in hass.data:
evt = hass.data[data_key] = asyncio.Event()
result = await func(hass)
hass.data[data_key] = result
evt.set()
return cast(_T, result)
obj_or_evt = hass.data[data_key]
if isinstance(obj_or_evt, asyncio.Event):
await obj_or_evt.wait()
return cast(_T, hass.data[data_key])
return cast(_T, obj_or_evt)
return async_wrapped
return wrapper
async def _test_singleton_typing(hass: HomeAssistant) -> None:
"""Test singleton overloads work as intended.
This is tested during the mypy run. Do not move it to 'tests'!
"""
# Test HassKey
key = HassKey[int]("key")
@singleton(key)
def func(hass: HomeAssistant) -> int:
return 2
@singleton(key, async_=True)
async def async_func(hass: HomeAssistant) -> int:
return 2
assert_type(func(hass), int)
assert_type(await async_func(hass), int)
# Test invalid use of 'async_' with sync function
@singleton(key, async_=True) # type: ignore[arg-type]
def func_error(hass: HomeAssistant) -> int:
return 2
# Test string key
other_key = "key"
@singleton(other_key)
def func2(hass: HomeAssistant) -> str:
return ""
@singleton(other_key)
async def async_func2(hass: HomeAssistant) -> str:
return ""
assert_type(func2(hass), str)
assert_type(await async_func2(hass), str)