74 lines
2.5 KiB
Python
74 lines
2.5 KiB
Python
"""Database executor helpers."""
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from __future__ import annotations
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from collections.abc import Callable
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from concurrent.futures.thread import _threads_queues, _worker
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import threading
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from typing import Any
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import weakref
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from homeassistant.util.executor import InterruptibleThreadPoolExecutor
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def _worker_with_shutdown_hook(
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shutdown_hook: Callable[[], None],
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recorder_and_worker_thread_ids: set[int],
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*args: Any,
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**kwargs: Any,
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) -> None:
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"""Create a worker that calls a function after its finished."""
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recorder_and_worker_thread_ids.add(threading.get_ident())
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_worker(*args, **kwargs)
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shutdown_hook()
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class DBInterruptibleThreadPoolExecutor(InterruptibleThreadPoolExecutor):
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"""A database instance that will not deadlock on shutdown."""
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def __init__(
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self, recorder_and_worker_thread_ids: set[int], *args: Any, **kwargs: Any
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) -> None:
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"""Init the executor with a shutdown hook support."""
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self._shutdown_hook: Callable[[], None] = kwargs.pop("shutdown_hook")
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self.recorder_and_worker_thread_ids = recorder_and_worker_thread_ids
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super().__init__(*args, **kwargs)
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def _adjust_thread_count(self) -> None:
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"""Overridden to add support for shutdown hook.
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Based on the CPython 3.10 implementation.
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"""
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# if idle threads are available, don't spin new threads
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if self._idle_semaphore.acquire( # pylint: disable=consider-using-with
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timeout=0
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):
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return
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# When the executor gets lost, the weakref callback will wake up
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# the worker threads.
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def weakref_cb( # type: ignore[no-untyped-def]
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_: Any,
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q=self._work_queue,
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) -> None:
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q.put(None)
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num_threads = len(self._threads)
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if num_threads < self._max_workers:
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thread_name = "%s_%d" % (self._thread_name_prefix or self, num_threads)
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executor_thread = threading.Thread(
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name=thread_name,
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target=_worker_with_shutdown_hook,
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args=(
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self._shutdown_hook,
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self.recorder_and_worker_thread_ids,
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weakref.ref(self, weakref_cb),
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self._work_queue,
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self._initializer,
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self._initargs,
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),
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)
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executor_thread.start()
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self._threads.add(executor_thread) # type: ignore[attr-defined]
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_threads_queues[executor_thread] = self._work_queue # type: ignore[index]
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