845 lines
24 KiB
Python
845 lines
24 KiB
Python
"""Extensible memoizing collections and decorators."""
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__all__ = (
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"Cache",
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"FIFOCache",
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"LFUCache",
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"LRUCache",
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"MRUCache",
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"RRCache",
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"TLRUCache",
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"TTLCache",
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"cached",
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"cachedmethod",
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)
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__version__ = "5.3.1"
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import collections
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import collections.abc
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import functools
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import heapq
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import random
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import time
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from . import keys
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class _DefaultSize:
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__slots__ = ()
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def __getitem__(self, _):
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return 1
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def __setitem__(self, _, value):
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assert value == 1
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def pop(self, _):
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return 1
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class Cache(collections.abc.MutableMapping):
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"""Mutable mapping to serve as a simple cache or cache base class."""
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__marker = object()
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__size = _DefaultSize()
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def __init__(self, maxsize, getsizeof=None):
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if getsizeof:
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self.getsizeof = getsizeof
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if self.getsizeof is not Cache.getsizeof:
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self.__size = dict()
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self.__data = dict()
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self.__currsize = 0
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self.__maxsize = maxsize
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def __repr__(self):
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return "%s(%s, maxsize=%r, currsize=%r)" % (
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self.__class__.__name__,
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repr(self.__data),
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self.__maxsize,
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self.__currsize,
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)
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def __getitem__(self, key):
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try:
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return self.__data[key]
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except KeyError:
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return self.__missing__(key)
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def __setitem__(self, key, value):
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maxsize = self.__maxsize
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size = self.getsizeof(value)
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if size > maxsize:
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raise ValueError("value too large")
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if key not in self.__data or self.__size[key] < size:
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while self.__currsize + size > maxsize:
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self.popitem()
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if key in self.__data:
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diffsize = size - self.__size[key]
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else:
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diffsize = size
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self.__data[key] = value
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self.__size[key] = size
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self.__currsize += diffsize
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def __delitem__(self, key):
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size = self.__size.pop(key)
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del self.__data[key]
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self.__currsize -= size
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def __contains__(self, key):
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return key in self.__data
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def __missing__(self, key):
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raise KeyError(key)
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def __iter__(self):
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return iter(self.__data)
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def __len__(self):
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return len(self.__data)
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def get(self, key, default=None):
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if key in self:
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return self[key]
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else:
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return default
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def pop(self, key, default=__marker):
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if key in self:
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value = self[key]
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del self[key]
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elif default is self.__marker:
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raise KeyError(key)
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else:
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value = default
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return value
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def setdefault(self, key, default=None):
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if key in self:
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value = self[key]
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else:
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self[key] = value = default
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return value
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@property
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def maxsize(self):
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"""The maximum size of the cache."""
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return self.__maxsize
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@property
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def currsize(self):
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"""The current size of the cache."""
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return self.__currsize
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@staticmethod
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def getsizeof(value):
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"""Return the size of a cache element's value."""
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return 1
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class FIFOCache(Cache):
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"""First In First Out (FIFO) cache implementation."""
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def __init__(self, maxsize, getsizeof=None):
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Cache.__init__(self, maxsize, getsizeof)
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self.__order = collections.OrderedDict()
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def __setitem__(self, key, value, cache_setitem=Cache.__setitem__):
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cache_setitem(self, key, value)
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try:
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self.__order.move_to_end(key)
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except KeyError:
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self.__order[key] = None
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def __delitem__(self, key, cache_delitem=Cache.__delitem__):
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cache_delitem(self, key)
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del self.__order[key]
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def popitem(self):
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"""Remove and return the `(key, value)` pair first inserted."""
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try:
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key = next(iter(self.__order))
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except StopIteration:
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raise KeyError("%s is empty" % type(self).__name__) from None
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else:
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return (key, self.pop(key))
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class LFUCache(Cache):
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"""Least Frequently Used (LFU) cache implementation."""
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def __init__(self, maxsize, getsizeof=None):
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Cache.__init__(self, maxsize, getsizeof)
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self.__counter = collections.Counter()
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def __getitem__(self, key, cache_getitem=Cache.__getitem__):
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value = cache_getitem(self, key)
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if key in self: # __missing__ may not store item
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self.__counter[key] -= 1
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return value
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def __setitem__(self, key, value, cache_setitem=Cache.__setitem__):
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cache_setitem(self, key, value)
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self.__counter[key] -= 1
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def __delitem__(self, key, cache_delitem=Cache.__delitem__):
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cache_delitem(self, key)
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del self.__counter[key]
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def popitem(self):
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"""Remove and return the `(key, value)` pair least frequently used."""
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try:
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((key, _),) = self.__counter.most_common(1)
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except ValueError:
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raise KeyError("%s is empty" % type(self).__name__) from None
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else:
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return (key, self.pop(key))
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class LRUCache(Cache):
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"""Least Recently Used (LRU) cache implementation."""
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def __init__(self, maxsize, getsizeof=None):
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Cache.__init__(self, maxsize, getsizeof)
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self.__order = collections.OrderedDict()
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def __getitem__(self, key, cache_getitem=Cache.__getitem__):
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value = cache_getitem(self, key)
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if key in self: # __missing__ may not store item
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self.__update(key)
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return value
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def __setitem__(self, key, value, cache_setitem=Cache.__setitem__):
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cache_setitem(self, key, value)
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self.__update(key)
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def __delitem__(self, key, cache_delitem=Cache.__delitem__):
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cache_delitem(self, key)
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del self.__order[key]
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def popitem(self):
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"""Remove and return the `(key, value)` pair least recently used."""
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try:
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key = next(iter(self.__order))
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except StopIteration:
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raise KeyError("%s is empty" % type(self).__name__) from None
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else:
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return (key, self.pop(key))
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def __update(self, key):
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try:
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self.__order.move_to_end(key)
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except KeyError:
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self.__order[key] = None
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class MRUCache(Cache):
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"""Most Recently Used (MRU) cache implementation."""
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def __init__(self, maxsize, getsizeof=None):
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Cache.__init__(self, maxsize, getsizeof)
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self.__order = collections.OrderedDict()
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def __getitem__(self, key, cache_getitem=Cache.__getitem__):
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value = cache_getitem(self, key)
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if key in self: # __missing__ may not store item
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self.__update(key)
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return value
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def __setitem__(self, key, value, cache_setitem=Cache.__setitem__):
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cache_setitem(self, key, value)
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self.__update(key)
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def __delitem__(self, key, cache_delitem=Cache.__delitem__):
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cache_delitem(self, key)
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del self.__order[key]
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def popitem(self):
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"""Remove and return the `(key, value)` pair most recently used."""
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try:
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key = next(iter(self.__order))
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except StopIteration:
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raise KeyError("%s is empty" % type(self).__name__) from None
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else:
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return (key, self.pop(key))
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def __update(self, key):
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try:
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self.__order.move_to_end(key, last=False)
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except KeyError:
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self.__order[key] = None
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class RRCache(Cache):
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"""Random Replacement (RR) cache implementation."""
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def __init__(self, maxsize, choice=random.choice, getsizeof=None):
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Cache.__init__(self, maxsize, getsizeof)
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self.__choice = choice
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@property
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def choice(self):
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"""The `choice` function used by the cache."""
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return self.__choice
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def popitem(self):
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"""Remove and return a random `(key, value)` pair."""
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try:
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key = self.__choice(list(self))
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except IndexError:
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raise KeyError("%s is empty" % type(self).__name__) from None
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else:
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return (key, self.pop(key))
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class _TimedCache(Cache):
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"""Base class for time aware cache implementations."""
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class _Timer:
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def __init__(self, timer):
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self.__timer = timer
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self.__nesting = 0
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def __call__(self):
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if self.__nesting == 0:
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return self.__timer()
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else:
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return self.__time
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def __enter__(self):
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if self.__nesting == 0:
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self.__time = time = self.__timer()
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else:
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time = self.__time
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self.__nesting += 1
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return time
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def __exit__(self, *exc):
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self.__nesting -= 1
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def __reduce__(self):
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return _TimedCache._Timer, (self.__timer,)
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def __getattr__(self, name):
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return getattr(self.__timer, name)
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def __init__(self, maxsize, timer=time.monotonic, getsizeof=None):
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Cache.__init__(self, maxsize, getsizeof)
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self.__timer = _TimedCache._Timer(timer)
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def __repr__(self, cache_repr=Cache.__repr__):
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with self.__timer as time:
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self.expire(time)
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return cache_repr(self)
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def __len__(self, cache_len=Cache.__len__):
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with self.__timer as time:
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self.expire(time)
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return cache_len(self)
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@property
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def currsize(self):
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with self.__timer as time:
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self.expire(time)
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return super().currsize
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@property
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def timer(self):
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"""The timer function used by the cache."""
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return self.__timer
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def clear(self):
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with self.__timer as time:
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self.expire(time)
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Cache.clear(self)
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def get(self, *args, **kwargs):
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with self.__timer:
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return Cache.get(self, *args, **kwargs)
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def pop(self, *args, **kwargs):
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with self.__timer:
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return Cache.pop(self, *args, **kwargs)
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def setdefault(self, *args, **kwargs):
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with self.__timer:
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return Cache.setdefault(self, *args, **kwargs)
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class TTLCache(_TimedCache):
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"""LRU Cache implementation with per-item time-to-live (TTL) value."""
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class _Link:
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__slots__ = ("key", "expires", "next", "prev")
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def __init__(self, key=None, expires=None):
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self.key = key
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self.expires = expires
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def __reduce__(self):
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return TTLCache._Link, (self.key, self.expires)
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def unlink(self):
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next = self.next
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prev = self.prev
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prev.next = next
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next.prev = prev
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def __init__(self, maxsize, ttl, timer=time.monotonic, getsizeof=None):
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_TimedCache.__init__(self, maxsize, timer, getsizeof)
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self.__root = root = TTLCache._Link()
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root.prev = root.next = root
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self.__links = collections.OrderedDict()
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self.__ttl = ttl
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def __contains__(self, key):
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try:
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link = self.__links[key] # no reordering
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except KeyError:
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return False
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else:
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return self.timer() < link.expires
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def __getitem__(self, key, cache_getitem=Cache.__getitem__):
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try:
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link = self.__getlink(key)
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except KeyError:
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expired = False
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else:
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expired = not (self.timer() < link.expires)
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if expired:
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return self.__missing__(key)
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else:
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return cache_getitem(self, key)
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def __setitem__(self, key, value, cache_setitem=Cache.__setitem__):
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with self.timer as time:
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self.expire(time)
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cache_setitem(self, key, value)
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try:
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link = self.__getlink(key)
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except KeyError:
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self.__links[key] = link = TTLCache._Link(key)
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else:
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link.unlink()
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link.expires = time + self.__ttl
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link.next = root = self.__root
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link.prev = prev = root.prev
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prev.next = root.prev = link
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def __delitem__(self, key, cache_delitem=Cache.__delitem__):
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cache_delitem(self, key)
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link = self.__links.pop(key)
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link.unlink()
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if not (self.timer() < link.expires):
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raise KeyError(key)
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def __iter__(self):
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root = self.__root
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curr = root.next
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while curr is not root:
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# "freeze" time for iterator access
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with self.timer as time:
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if time < curr.expires:
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yield curr.key
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curr = curr.next
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def __setstate__(self, state):
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self.__dict__.update(state)
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root = self.__root
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root.prev = root.next = root
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for link in sorted(self.__links.values(), key=lambda obj: obj.expires):
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link.next = root
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link.prev = prev = root.prev
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prev.next = root.prev = link
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self.expire(self.timer())
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@property
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def ttl(self):
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"""The time-to-live value of the cache's items."""
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return self.__ttl
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|
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def expire(self, time=None):
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"""Remove expired items from the cache."""
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if time is None:
|
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time = self.timer()
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root = self.__root
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curr = root.next
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links = self.__links
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cache_delitem = Cache.__delitem__
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while curr is not root and not (time < curr.expires):
|
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cache_delitem(self, curr.key)
|
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del links[curr.key]
|
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next = curr.next
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curr.unlink()
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curr = next
|
|
|
|
def popitem(self):
|
|
"""Remove and return the `(key, value)` pair least recently used that
|
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has not already expired.
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|
|
|
"""
|
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with self.timer as time:
|
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self.expire(time)
|
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try:
|
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key = next(iter(self.__links))
|
|
except StopIteration:
|
|
raise KeyError("%s is empty" % type(self).__name__) from None
|
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else:
|
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return (key, self.pop(key))
|
|
|
|
def __getlink(self, key):
|
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value = self.__links[key]
|
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self.__links.move_to_end(key)
|
|
return value
|
|
|
|
|
|
class TLRUCache(_TimedCache):
|
|
"""Time aware Least Recently Used (TLRU) cache implementation."""
|
|
|
|
@functools.total_ordering
|
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class _Item:
|
|
|
|
__slots__ = ("key", "expires", "removed")
|
|
|
|
def __init__(self, key=None, expires=None):
|
|
self.key = key
|
|
self.expires = expires
|
|
self.removed = False
|
|
|
|
def __lt__(self, other):
|
|
return self.expires < other.expires
|
|
|
|
def __init__(self, maxsize, ttu, timer=time.monotonic, getsizeof=None):
|
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_TimedCache.__init__(self, maxsize, timer, getsizeof)
|
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self.__items = collections.OrderedDict()
|
|
self.__order = []
|
|
self.__ttu = ttu
|
|
|
|
def __contains__(self, key):
|
|
try:
|
|
item = self.__items[key] # no reordering
|
|
except KeyError:
|
|
return False
|
|
else:
|
|
return self.timer() < item.expires
|
|
|
|
def __getitem__(self, key, cache_getitem=Cache.__getitem__):
|
|
try:
|
|
item = self.__getitem(key)
|
|
except KeyError:
|
|
expired = False
|
|
else:
|
|
expired = not (self.timer() < item.expires)
|
|
if expired:
|
|
return self.__missing__(key)
|
|
else:
|
|
return cache_getitem(self, key)
|
|
|
|
def __setitem__(self, key, value, cache_setitem=Cache.__setitem__):
|
|
with self.timer as time:
|
|
expires = self.__ttu(key, value, time)
|
|
if not (time < expires):
|
|
return # skip expired items
|
|
self.expire(time)
|
|
cache_setitem(self, key, value)
|
|
# removing an existing item would break the heap structure, so
|
|
# only mark it as removed for now
|
|
try:
|
|
self.__getitem(key).removed = True
|
|
except KeyError:
|
|
pass
|
|
self.__items[key] = item = TLRUCache._Item(key, expires)
|
|
heapq.heappush(self.__order, item)
|
|
|
|
def __delitem__(self, key, cache_delitem=Cache.__delitem__):
|
|
with self.timer as time:
|
|
# no self.expire() for performance reasons, e.g. self.clear() [#67]
|
|
cache_delitem(self, key)
|
|
item = self.__items.pop(key)
|
|
item.removed = True
|
|
if not (time < item.expires):
|
|
raise KeyError(key)
|
|
|
|
def __iter__(self):
|
|
for curr in self.__order:
|
|
# "freeze" time for iterator access
|
|
with self.timer as time:
|
|
if time < curr.expires and not curr.removed:
|
|
yield curr.key
|
|
|
|
@property
|
|
def ttu(self):
|
|
"""The local time-to-use function used by the cache."""
|
|
return self.__ttu
|
|
|
|
def expire(self, time=None):
|
|
"""Remove expired items from the cache."""
|
|
if time is None:
|
|
time = self.timer()
|
|
items = self.__items
|
|
order = self.__order
|
|
# clean up the heap if too many items are marked as removed
|
|
if len(order) > len(items) * 2:
|
|
self.__order = order = [item for item in order if not item.removed]
|
|
heapq.heapify(order)
|
|
cache_delitem = Cache.__delitem__
|
|
while order and (order[0].removed or not (time < order[0].expires)):
|
|
item = heapq.heappop(order)
|
|
if not item.removed:
|
|
cache_delitem(self, item.key)
|
|
del items[item.key]
|
|
|
|
def popitem(self):
|
|
"""Remove and return the `(key, value)` pair least recently used that
|
|
has not already expired.
|
|
|
|
"""
|
|
with self.timer as time:
|
|
self.expire(time)
|
|
try:
|
|
key = next(iter(self.__items))
|
|
except StopIteration:
|
|
raise KeyError("%s is empty" % self.__class__.__name__) from None
|
|
else:
|
|
return (key, self.pop(key))
|
|
|
|
def __getitem(self, key):
|
|
value = self.__items[key]
|
|
self.__items.move_to_end(key)
|
|
return value
|
|
|
|
|
|
_CacheInfo = collections.namedtuple(
|
|
"CacheInfo", ["hits", "misses", "maxsize", "currsize"]
|
|
)
|
|
|
|
|
|
def cached(cache, key=keys.hashkey, lock=None, info=False):
|
|
"""Decorator to wrap a function with a memoizing callable that saves
|
|
results in a cache.
|
|
|
|
"""
|
|
|
|
def decorator(func):
|
|
if info:
|
|
hits = misses = 0
|
|
|
|
if isinstance(cache, Cache):
|
|
|
|
def getinfo():
|
|
nonlocal hits, misses
|
|
return _CacheInfo(hits, misses, cache.maxsize, cache.currsize)
|
|
|
|
elif isinstance(cache, collections.abc.Mapping):
|
|
|
|
def getinfo():
|
|
nonlocal hits, misses
|
|
return _CacheInfo(hits, misses, None, len(cache))
|
|
|
|
else:
|
|
|
|
def getinfo():
|
|
nonlocal hits, misses
|
|
return _CacheInfo(hits, misses, 0, 0)
|
|
|
|
if cache is None:
|
|
|
|
def wrapper(*args, **kwargs):
|
|
nonlocal misses
|
|
misses += 1
|
|
return func(*args, **kwargs)
|
|
|
|
def cache_clear():
|
|
nonlocal hits, misses
|
|
hits = misses = 0
|
|
|
|
cache_info = getinfo
|
|
|
|
elif lock is None:
|
|
|
|
def wrapper(*args, **kwargs):
|
|
nonlocal hits, misses
|
|
k = key(*args, **kwargs)
|
|
try:
|
|
result = cache[k]
|
|
hits += 1
|
|
return result
|
|
except KeyError:
|
|
misses += 1
|
|
v = func(*args, **kwargs)
|
|
try:
|
|
cache[k] = v
|
|
except ValueError:
|
|
pass # value too large
|
|
return v
|
|
|
|
def cache_clear():
|
|
nonlocal hits, misses
|
|
cache.clear()
|
|
hits = misses = 0
|
|
|
|
cache_info = getinfo
|
|
|
|
else:
|
|
|
|
def wrapper(*args, **kwargs):
|
|
nonlocal hits, misses
|
|
k = key(*args, **kwargs)
|
|
try:
|
|
with lock:
|
|
result = cache[k]
|
|
hits += 1
|
|
return result
|
|
except KeyError:
|
|
with lock:
|
|
misses += 1
|
|
v = func(*args, **kwargs)
|
|
# in case of a race, prefer the item already in the cache
|
|
try:
|
|
with lock:
|
|
return cache.setdefault(k, v)
|
|
except ValueError:
|
|
return v # value too large
|
|
|
|
def cache_clear():
|
|
nonlocal hits, misses
|
|
with lock:
|
|
cache.clear()
|
|
hits = misses = 0
|
|
|
|
def cache_info():
|
|
with lock:
|
|
return getinfo()
|
|
|
|
else:
|
|
if cache is None:
|
|
|
|
def wrapper(*args, **kwargs):
|
|
return func(*args, **kwargs)
|
|
|
|
def cache_clear():
|
|
pass
|
|
|
|
elif lock is None:
|
|
|
|
def wrapper(*args, **kwargs):
|
|
k = key(*args, **kwargs)
|
|
try:
|
|
return cache[k]
|
|
except KeyError:
|
|
pass # key not found
|
|
v = func(*args, **kwargs)
|
|
try:
|
|
cache[k] = v
|
|
except ValueError:
|
|
pass # value too large
|
|
return v
|
|
|
|
def cache_clear():
|
|
cache.clear()
|
|
|
|
else:
|
|
|
|
def wrapper(*args, **kwargs):
|
|
k = key(*args, **kwargs)
|
|
try:
|
|
with lock:
|
|
return cache[k]
|
|
except KeyError:
|
|
pass # key not found
|
|
v = func(*args, **kwargs)
|
|
# in case of a race, prefer the item already in the cache
|
|
try:
|
|
with lock:
|
|
return cache.setdefault(k, v)
|
|
except ValueError:
|
|
return v # value too large
|
|
|
|
def cache_clear():
|
|
with lock:
|
|
cache.clear()
|
|
|
|
cache_info = None
|
|
|
|
wrapper.cache = cache
|
|
wrapper.cache_key = key
|
|
wrapper.cache_lock = lock
|
|
wrapper.cache_clear = cache_clear
|
|
wrapper.cache_info = cache_info
|
|
|
|
return functools.update_wrapper(wrapper, func)
|
|
|
|
return decorator
|
|
|
|
|
|
def cachedmethod(cache, key=keys.methodkey, lock=None):
|
|
"""Decorator to wrap a class or instance method with a memoizing
|
|
callable that saves results in a cache.
|
|
|
|
"""
|
|
|
|
def decorator(method):
|
|
if lock is None:
|
|
|
|
def wrapper(self, *args, **kwargs):
|
|
c = cache(self)
|
|
if c is None:
|
|
return method(self, *args, **kwargs)
|
|
k = key(self, *args, **kwargs)
|
|
try:
|
|
return c[k]
|
|
except KeyError:
|
|
pass # key not found
|
|
v = method(self, *args, **kwargs)
|
|
try:
|
|
c[k] = v
|
|
except ValueError:
|
|
pass # value too large
|
|
return v
|
|
|
|
def clear(self):
|
|
c = cache(self)
|
|
if c is not None:
|
|
c.clear()
|
|
|
|
else:
|
|
|
|
def wrapper(self, *args, **kwargs):
|
|
c = cache(self)
|
|
if c is None:
|
|
return method(self, *args, **kwargs)
|
|
k = key(self, *args, **kwargs)
|
|
try:
|
|
with lock(self):
|
|
return c[k]
|
|
except KeyError:
|
|
pass # key not found
|
|
v = method(self, *args, **kwargs)
|
|
# in case of a race, prefer the item already in the cache
|
|
try:
|
|
with lock(self):
|
|
return c.setdefault(k, v)
|
|
except ValueError:
|
|
return v # value too large
|
|
|
|
def clear(self):
|
|
c = cache(self)
|
|
if c is not None:
|
|
with lock(self):
|
|
c.clear()
|
|
|
|
wrapper.cache = cache
|
|
wrapper.cache_key = key
|
|
wrapper.cache_lock = lock
|
|
wrapper.cache_clear = clear
|
|
|
|
return functools.update_wrapper(wrapper, method)
|
|
|
|
return decorator
|