250 lines
7.4 KiB
Python
250 lines
7.4 KiB
Python
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#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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#
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# Copyright 2011 Yesudeep Mangalapilly <yesudeep@gmail.com>
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# Copyright 2012 Google, Inc.
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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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"""
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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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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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import sys
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import collections
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from .compat import queue
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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(object):
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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):
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queue.Queue._init(self, maxsize)
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self._last_item = None
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def _put(self, item):
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if item != self._last_item:
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queue.Queue._put(self, 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):
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item = queue.Queue._get(self)
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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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class OrderedSetQueue(queue.Queue):
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"""Thread-safe implementation of an ordered set queue.
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Disallows adding a duplicate item while maintaining the
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order of items in the queue. The implementation leverages
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locking already implemented in the base class
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redefining only the primitives. Since the internal queue
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is not replaced, the order is maintained. The set is used
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merely to check for the existence of an item.
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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(object):
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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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:author: lalinsky@gmail.com (Lukáš Lalinský)
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:url: http://stackoverflow.com/questions/1581895/how-check-if-a-task-is-already-in-python-queue
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"""
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def _init(self, maxsize):
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queue.Queue._init(self, maxsize)
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self._set_of_items = set()
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def _put(self, item):
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if item not in self._set_of_items:
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queue.Queue._put(self, item)
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self._set_of_items.add(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):
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item = queue.Queue._get(self)
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self._set_of_items.remove(item)
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return item
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if sys.version_info >= (2, 6, 0):
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KEY, PREV, NEXT = list(range(3))
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class OrderedSet(collections.MutableSet):
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"""
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Implementation based on a doubly-linked link and an internal dictionary.
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This design gives :class:`OrderedSet` the same big-Oh running times as
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regular sets including O(1) adds, removes, and lookups as well as
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O(n) iteration.
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.. ADMONITION:: Implementation notes
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Runs on Python 2.6 or later (and runs on Python 3.0 or later
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without any modifications).
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:author: python@rcn.com (Raymond Hettinger)
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:url: http://code.activestate.com/recipes/576694/
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"""
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def __init__(self, iterable=None):
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self.end = end = []
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end += [None, end, end] # sentinel node for doubly linked list
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self.map = {} # key --> [key, prev, next]
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if iterable is not None:
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self |= iterable
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def __len__(self):
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return len(self.map)
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def __contains__(self, key):
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return key in self.map
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def add(self, key):
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if key not in self.map:
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end = self.end
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curr = end[PREV]
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curr[NEXT] = end[PREV] = self.map[key] = [key, curr, end]
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def discard(self, key):
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if key in self.map:
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key, prev, _next = self.map.pop(key)
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prev[NEXT] = _next
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_next[PREV] = prev
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def __iter__(self):
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end = self.end
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curr = end[NEXT]
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while curr is not end:
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yield curr[KEY]
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curr = curr[NEXT]
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def __reversed__(self):
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end = self.end
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curr = end[PREV]
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while curr is not end:
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yield curr[KEY]
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curr = curr[PREV]
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def pop(self, last=True):
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if not self:
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raise KeyError('set is empty')
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key = next(reversed(self)) if last else next(iter(self))
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self.discard(key)
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return key
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def __repr__(self):
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if not self:
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return '%s()' % (self.__class__.__name__,)
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return '%s(%r)' % (self.__class__.__name__, list(self))
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def __eq__(self, other):
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if isinstance(other, OrderedSet):
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return len(self) == len(other) and list(self) == list(other)
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return set(self) == set(other)
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def __del__(self):
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self.clear() # remove circular references
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