86 lines
3.0 KiB
Python
86 lines
3.0 KiB
Python
# Copyright 2014 Thomas Amland <thomas.amland@gmail.com>
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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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, Deque, Generic, Optional, Tuple, TypeVar
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T = TypeVar("T")
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class DelayedQueue(Generic[T]):
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def __init__(self, delay):
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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):
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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) -> Optional[T]:
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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]) -> Optional[T]:
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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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with self._lock:
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for i, (elem, t, delay) 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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