#!/usr/bin/env python # -*- coding: utf-8 -*- # # Copyright 2011 Yesudeep Mangalapilly # Copyright 2012 Google, Inc. # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. """ Utility collections or "bricks". :module: watchdog.utils.bricks :author: yesudeep@google.com (Yesudeep Mangalapilly) :author: lalinsky@gmail.com (Lukáš Lalinský) :author: python@rcn.com (Raymond Hettinger) Classes ======= .. autoclass:: OrderedSetQueue :members: :show-inheritance: :inherited-members: .. autoclass:: OrderedSet """ import sys import collections from .compat import queue class SkipRepeatsQueue(queue.Queue): """Thread-safe implementation of an special queue where a put of the last-item put'd will be dropped. The implementation leverages locking already implemented in the base class redefining only the primitives. Queued items must be immutable and hashable so that they can be used as dictionary keys. You must implement **only read-only properties** and the :meth:`Item.__hash__()`, :meth:`Item.__eq__()`, and :meth:`Item.__ne__()` methods for items to be hashable. An example implementation follows:: class Item(object): def __init__(self, a, b): self._a = a self._b = b @property def a(self): return self._a @property def b(self): return self._b def _key(self): return (self._a, self._b) def __eq__(self, item): return self._key() == item._key() def __ne__(self, item): return self._key() != item._key() def __hash__(self): return hash(self._key()) based on the OrderedSetQueue below """ def _init(self, maxsize): queue.Queue._init(self, maxsize) self._last_item = None def _put(self, item): if item != self._last_item: queue.Queue._put(self, item) self._last_item = item else: # `put` increments `unfinished_tasks` even if we did not put # anything into the queue here self.unfinished_tasks -= 1 def _get(self): item = queue.Queue._get(self) if item is self._last_item: self._last_item = None return item class OrderedSetQueue(queue.Queue): """Thread-safe implementation of an ordered set queue. Disallows adding a duplicate item while maintaining the order of items in the queue. The implementation leverages locking already implemented in the base class redefining only the primitives. Since the internal queue is not replaced, the order is maintained. The set is used merely to check for the existence of an item. Queued items must be immutable and hashable so that they can be used as dictionary keys. You must implement **only read-only properties** and the :meth:`Item.__hash__()`, :meth:`Item.__eq__()`, and :meth:`Item.__ne__()` methods for items to be hashable. An example implementation follows:: class Item(object): def __init__(self, a, b): self._a = a self._b = b @property def a(self): return self._a @property def b(self): return self._b def _key(self): return (self._a, self._b) def __eq__(self, item): return self._key() == item._key() def __ne__(self, item): return self._key() != item._key() def __hash__(self): return hash(self._key()) :author: lalinsky@gmail.com (Lukáš Lalinský) :url: http://stackoverflow.com/questions/1581895/how-check-if-a-task-is-already-in-python-queue """ def _init(self, maxsize): queue.Queue._init(self, maxsize) self._set_of_items = set() def _put(self, item): if item not in self._set_of_items: queue.Queue._put(self, item) self._set_of_items.add(item) else: # `put` increments `unfinished_tasks` even if we did not put # anything into the queue here self.unfinished_tasks -= 1 def _get(self): item = queue.Queue._get(self) self._set_of_items.remove(item) return item if sys.version_info >= (2, 6, 0): KEY, PREV, NEXT = list(range(3)) class OrderedSet(collections.MutableSet): """ Implementation based on a doubly-linked link and an internal dictionary. This design gives :class:`OrderedSet` the same big-Oh running times as regular sets including O(1) adds, removes, and lookups as well as O(n) iteration. .. ADMONITION:: Implementation notes Runs on Python 2.6 or later (and runs on Python 3.0 or later without any modifications). :author: python@rcn.com (Raymond Hettinger) :url: http://code.activestate.com/recipes/576694/ """ def __init__(self, iterable=None): self.end = end = [] end += [None, end, end] # sentinel node for doubly linked list self.map = {} # key --> [key, prev, next] if iterable is not None: self |= iterable def __len__(self): return len(self.map) def __contains__(self, key): return key in self.map def add(self, key): if key not in self.map: end = self.end curr = end[PREV] curr[NEXT] = end[PREV] = self.map[key] = [key, curr, end] def discard(self, key): if key in self.map: key, prev, _next = self.map.pop(key) prev[NEXT] = _next _next[PREV] = prev def __iter__(self): end = self.end curr = end[NEXT] while curr is not end: yield curr[KEY] curr = curr[NEXT] def __reversed__(self): end = self.end curr = end[PREV] while curr is not end: yield curr[KEY] curr = curr[PREV] def pop(self, last=True): if not self: raise KeyError('set is empty') key = next(reversed(self)) if last else next(iter(self)) self.discard(key) return key def __repr__(self): if not self: return '%s()' % (self.__class__.__name__,) return '%s(%r)' % (self.__class__.__name__, list(self)) def __eq__(self, other): if isinstance(other, OrderedSet): return len(self) == len(other) and list(self) == list(other) return set(self) == set(other) def __del__(self): self.clear() # remove circular references