fix LRUCache
This commit is contained in:
BreakWa11
parent
8fb3cc3394
commit
0c4b00a8af
2 changed files with 240 additions and 25 deletions
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@ -22,11 +22,22 @@ import collections
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import logging
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import time
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if __name__ == '__main__':
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import os, sys, inspect
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file_path = os.path.dirname(os.path.realpath(inspect.getfile(inspect.currentframe())))
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sys.path.insert(0, os.path.join(file_path, '../'))
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try:
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from collections import OrderedDict
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print("loaded collections.OrderedDict")
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except:
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from shadowsocks.ordereddict import OrderedDict
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# this LRUCache is optimized for concurrency, not QPS
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# n: concurrency, keys stored in the cache
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# m: visits not timed out, proportional to QPS * timeout
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# get & set is O(log(n)), not O(n). thus we can support very large n
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# sweep is O((n - m)*log(n)) or O(1024*log(n)) at most,
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# get & set is O(1), not O(n). thus we can support very large n
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# sweep is O((n - m)) or O(1024) at most,
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# no metter how large the cache or timeout value is
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SWEEP_MAX_ITEMS = 1024
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@ -38,39 +49,30 @@ class LRUCache(collections.MutableMapping):
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self.timeout = timeout
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self.close_callback = close_callback
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self._store = {}
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self._time_to_keys = collections.OrderedDict()
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self._keys_to_last_time = {}
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self._visit_id = 0
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self._keys_to_last_time = OrderedDict()
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self.update(dict(*args, **kwargs)) # use the free update to set keys
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def __getitem__(self, key):
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# O(log(n))
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# O(1)
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t = time.time()
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last_t, vid = self._keys_to_last_time[key]
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self._keys_to_last_time[key] = (t, vid)
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if last_t != t:
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del self._time_to_keys[(last_t, vid)]
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self._time_to_keys[(t, vid)] = key
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last_t = self._keys_to_last_time[key]
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del self._keys_to_last_time[key]
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self._keys_to_last_time[key] = t
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return self._store[key]
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def __setitem__(self, key, value):
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# O(log(n))
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# O(1)
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t = time.time()
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if key in self._keys_to_last_time:
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last_t, vid = self._keys_to_last_time[key]
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del self._time_to_keys[(last_t, vid)]
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vid = self._visit_id
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self._visit_id += 1
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self._keys_to_last_time[key] = (t, vid)
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del self._keys_to_last_time[key]
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self._keys_to_last_time[key] = t
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self._store[key] = value
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self._time_to_keys[(t, vid)] = key
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def __delitem__(self, key):
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# O(log(n))
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last_t, vid = self._keys_to_last_time[key]
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# O(1)
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last_t = self._keys_to_last_time[key]
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del self._store[key]
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del self._keys_to_last_time[key]
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del self._time_to_keys[(last_t, vid)]
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def __iter__(self):
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return iter(self._store)
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@ -83,18 +85,17 @@ class LRUCache(collections.MutableMapping):
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now = time.time()
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c = 0
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while c < SWEEP_MAX_ITEMS:
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if len(self._time_to_keys) == 0:
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if len(self._keys_to_last_time) == 0:
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break
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last_t, vid = iter(self._time_to_keys).next()
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key = iter(self._keys_to_last_time).next()
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last_t = self._keys_to_last_time[key]
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if now - last_t <= self.timeout:
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break
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key = self._time_to_keys[(last_t, vid)]
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value = self._store[key]
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if self.close_callback is not None:
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self.close_callback(value)
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del self._store[key]
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del self._keys_to_last_time[key]
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del self._time_to_keys[(last_t, vid)]
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c += 1
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if c:
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logging.debug('%d keys swept' % c)
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214
shadowsocks/ordereddict.py
Normal file
214
shadowsocks/ordereddict.py
Normal file
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@ -0,0 +1,214 @@
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import collections
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################################################################################
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### OrderedDict
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################################################################################
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class OrderedDict(dict):
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'Dictionary that remembers insertion order'
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# An inherited dict maps keys to values.
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# The inherited dict provides __getitem__, __len__, __contains__, and get.
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# The remaining methods are order-aware.
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# Big-O running times for all methods are the same as regular dictionaries.
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# The internal self.__map dict maps keys to links in a doubly linked list.
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# The circular doubly linked list starts and ends with a sentinel element.
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# The sentinel element never gets deleted (this simplifies the algorithm).
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# Each link is stored as a list of length three: [PREV, NEXT, KEY].
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def __init__(*args, **kwds):
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'''Initialize an ordered dictionary. The signature is the same as
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regular dictionaries, but keyword arguments are not recommended because
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their insertion order is arbitrary.
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'''
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if not args:
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raise TypeError("descriptor '__init__' of 'OrderedDict' object "
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"needs an argument")
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self = args[0]
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args = args[1:]
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if len(args) > 1:
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raise TypeError('expected at most 1 arguments, got %d' % len(args))
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try:
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self.__root
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except AttributeError:
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self.__root = root = [] # sentinel node
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root[:] = [root, root, None]
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self.__map = {}
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self.__update(*args, **kwds)
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def __setitem__(self, key, value, dict_setitem=dict.__setitem__):
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'od.__setitem__(i, y) <==> od[i]=y'
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# Setting a new item creates a new link at the end of the linked list,
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# and the inherited dictionary is updated with the new key/value pair.
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if key not in self:
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root = self.__root
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last = root[0]
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last[1] = root[0] = self.__map[key] = [last, root, key]
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return dict_setitem(self, key, value)
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def __delitem__(self, key, dict_delitem=dict.__delitem__):
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'od.__delitem__(y) <==> del od[y]'
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# Deleting an existing item uses self.__map to find the link which gets
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# removed by updating the links in the predecessor and successor nodes.
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dict_delitem(self, key)
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link_prev, link_next, _ = self.__map.pop(key)
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link_prev[1] = link_next # update link_prev[NEXT]
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link_next[0] = link_prev # update link_next[PREV]
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def __iter__(self):
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'od.__iter__() <==> iter(od)'
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# Traverse the linked list in order.
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root = self.__root
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curr = root[1] # start at the first node
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while curr is not root:
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yield curr[2] # yield the curr[KEY]
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curr = curr[1] # move to next node
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def __reversed__(self):
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'od.__reversed__() <==> reversed(od)'
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# Traverse the linked list in reverse order.
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root = self.__root
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curr = root[0] # start at the last node
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while curr is not root:
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yield curr[2] # yield the curr[KEY]
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curr = curr[0] # move to previous node
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def clear(self):
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'od.clear() -> None. Remove all items from od.'
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root = self.__root
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root[:] = [root, root, None]
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self.__map.clear()
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dict.clear(self)
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# -- the following methods do not depend on the internal structure --
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def keys(self):
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'od.keys() -> list of keys in od'
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return list(self)
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def values(self):
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'od.values() -> list of values in od'
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return [self[key] for key in self]
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def items(self):
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'od.items() -> list of (key, value) pairs in od'
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return [(key, self[key]) for key in self]
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def iterkeys(self):
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'od.iterkeys() -> an iterator over the keys in od'
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return iter(self)
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def itervalues(self):
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'od.itervalues -> an iterator over the values in od'
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for k in self:
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yield self[k]
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def iteritems(self):
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'od.iteritems -> an iterator over the (key, value) pairs in od'
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for k in self:
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yield (k, self[k])
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update = collections.MutableMapping.update
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__update = update # let subclasses override update without breaking __init__
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__marker = object()
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def pop(self, key, default=__marker):
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'''od.pop(k[,d]) -> v, remove specified key and return the corresponding
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value. If key is not found, d is returned if given, otherwise KeyError
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is raised.
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'''
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if key in self:
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result = self[key]
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del self[key]
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return result
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if default is self.__marker:
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raise KeyError(key)
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return default
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def setdefault(self, key, default=None):
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'od.setdefault(k[,d]) -> od.get(k,d), also set od[k]=d if k not in od'
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if key in self:
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return self[key]
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self[key] = default
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return default
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def popitem(self, last=True):
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'''od.popitem() -> (k, v), return and remove a (key, value) pair.
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Pairs are returned in LIFO order if last is true or FIFO order if false.
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'''
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if not self:
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raise KeyError('dictionary is empty')
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key = next(reversed(self) if last else iter(self))
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value = self.pop(key)
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return key, value
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def __repr__(self, _repr_running={}):
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'od.__repr__() <==> repr(od)'
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call_key = id(self), _get_ident()
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if call_key in _repr_running:
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return '...'
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_repr_running[call_key] = 1
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try:
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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__, self.items())
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finally:
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del _repr_running[call_key]
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def __reduce__(self):
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'Return state information for pickling'
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items = [[k, self[k]] for k in self]
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inst_dict = vars(self).copy()
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for k in vars(OrderedDict()):
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inst_dict.pop(k, None)
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if inst_dict:
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return (self.__class__, (items,), inst_dict)
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return self.__class__, (items,)
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def copy(self):
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'od.copy() -> a shallow copy of od'
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return self.__class__(self)
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@classmethod
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def fromkeys(cls, iterable, value=None):
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'''OD.fromkeys(S[, v]) -> New ordered dictionary with keys from S.
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If not specified, the value defaults to None.
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'''
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self = cls()
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for key in iterable:
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self[key] = value
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return self
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def __eq__(self, other):
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'''od.__eq__(y) <==> od==y. Comparison to another OD is order-sensitive
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while comparison to a regular mapping is order-insensitive.
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'''
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if isinstance(other, OrderedDict):
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return dict.__eq__(self, other) and all(_imap(_eq, self, other))
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return dict.__eq__(self, other)
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def __ne__(self, other):
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'od.__ne__(y) <==> od!=y'
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return not self == other
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# -- the following methods support python 3.x style dictionary views --
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def viewkeys(self):
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"od.viewkeys() -> a set-like object providing a view on od's keys"
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return KeysView(self)
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def viewvalues(self):
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"od.viewvalues() -> an object providing a view on od's values"
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return ValuesView(self)
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def viewitems(self):
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"od.viewitems() -> a set-like object providing a view on od's items"
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return ItemsView(self)
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