89 lines
2.3 KiB
Python
89 lines
2.3 KiB
Python
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"""Utility collections or "bricks".
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:module: watchdog.utils.bricks
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:author: yesudeep@google.com (Yesudeep Mangalapilly)
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:author: lalinsky@gmail.com (Lukáš Lalinský)
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:author: python@rcn.com (Raymond Hettinger)
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:author: contact@tiger-222.fr (Mickaël Schoentgen)
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Classes
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=======
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.. autoclass:: OrderedSetQueue
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:members:
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:show-inheritance:
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:inherited-members:
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.. autoclass:: OrderedSet
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"""
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from __future__ import annotations
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import queue
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from typing import TYPE_CHECKING
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if TYPE_CHECKING:
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from typing import Any
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class SkipRepeatsQueue(queue.Queue):
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"""Thread-safe implementation of an special queue where a
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put of the last-item put'd will be dropped.
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The implementation leverages locking already implemented in the base class
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redefining only the primitives.
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Queued items must be immutable and hashable so that they can be used
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as dictionary keys. You must implement **only read-only properties** and
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the :meth:`Item.__hash__()`, :meth:`Item.__eq__()`, and
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:meth:`Item.__ne__()` methods for items to be hashable.
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An example implementation follows::
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class Item:
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def __init__(self, a, b):
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self._a = a
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self._b = b
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@property
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def a(self):
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return self._a
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@property
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def b(self):
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return self._b
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def _key(self):
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return (self._a, self._b)
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def __eq__(self, item):
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return self._key() == item._key()
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def __ne__(self, item):
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return self._key() != item._key()
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def __hash__(self):
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return hash(self._key())
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based on the OrderedSetQueue below
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"""
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def _init(self, maxsize: int) -> None:
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super()._init(maxsize)
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self._last_item = None
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def _put(self, item: Any) -> None:
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if self._last_item is None or item != self._last_item:
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super()._put(item)
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self._last_item = item
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else:
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# `put` increments `unfinished_tasks` even if we did not put
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# anything into the queue here
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self.unfinished_tasks -= 1
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def _get(self) -> Any:
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item = super()._get()
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if item is self._last_item:
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self._last_item = None
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return item
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