78 lines
2.6 KiB
Python
78 lines
2.6 KiB
Python
""":module: watchdog.utils.delayed_queue
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:author: thomas.amland@gmail.com (Thomas Amland)
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:author: contact@tiger-222.fr (Mickaël Schoentgen)
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"""
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from __future__ import annotations
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import threading
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import time
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from collections import deque
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from typing import Callable, Generic, TypeVar
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T = TypeVar("T")
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class DelayedQueue(Generic[T]):
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def __init__(self, delay: float) -> None:
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self.delay_sec = delay
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self._lock = threading.Lock()
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self._not_empty = threading.Condition(self._lock)
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self._queue: deque[tuple[T, float, bool]] = deque()
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self._closed = False
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def put(self, element: T, *, delay: bool = False) -> None:
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"""Add element to queue."""
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self._lock.acquire()
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self._queue.append((element, time.time(), delay))
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self._not_empty.notify()
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self._lock.release()
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def close(self) -> None:
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"""Close queue, indicating no more items will be added."""
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self._closed = True
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# Interrupt the blocking _not_empty.wait() call in get
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self._not_empty.acquire()
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self._not_empty.notify()
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self._not_empty.release()
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def get(self) -> T | None:
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"""Remove and return an element from the queue, or this queue has been
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closed raise the Closed exception.
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"""
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while True:
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# wait for element to be added to queue
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self._not_empty.acquire()
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while len(self._queue) == 0 and not self._closed:
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self._not_empty.wait()
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if self._closed:
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self._not_empty.release()
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return None
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head, insert_time, delay = self._queue[0]
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self._not_empty.release()
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# wait for delay if required
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if delay:
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time_left = insert_time + self.delay_sec - time.time()
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while time_left > 0:
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time.sleep(time_left)
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time_left = insert_time + self.delay_sec - time.time()
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# return element if it's still in the queue
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with self._lock:
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if len(self._queue) > 0 and self._queue[0][0] is head:
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self._queue.popleft()
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return head
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def remove(self, predicate: Callable[[T], bool]) -> T | None:
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"""Remove and return the first items for which predicate is True,
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ignoring delay.
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"""
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with self._lock:
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for i, (elem, *_) in enumerate(self._queue):
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if predicate(elem):
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del self._queue[i]
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return elem
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return None
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