def __init__(self, min_cache=100, max_cache=1000):
"""initialize the cache and set min_cache / max_cache.
>>> c = Cache(123, 456)
>>> c.min_cache(), c.max_cache()
(123, 456)
"""
self.__cache = dict()
self.__cache_access = SortedSet()
self.min_cache(min_cache)
self.max_cache(max_cache)
class Cache:
""" This is a simple class to provide for easy caching of entries. You can
define a minium amount of entries and a maximum amount of entries to keep in
the cache. Once the cache size is greater then maximum amount, the cache is
shrinked down to minimum amount keeping only the entries that have been
accessed recently.
>>> c = Cache(1, 1)
>>> c.set(1, 0)
>>> c.get(1)
0
>>> c.cache_size()
1
>>> c.set(2, 1)
>>> c.get(2)
1
>>> c.get(1) == None
True
>>> c.cache_size()
1
"""
def __init__(self, min_cache=100, max_cache=1000):
"""initialize the cache and set min_cache / max_cache.
>>> c = Cache(123, 456)
>>> c.min_cache(), c.max_cache()
(123, 456)
"""
self.__cache = dict()
self.__cache_access = SortedSet()
self.min_cache(min_cache)
self.max_cache(max_cache)
def cache_size(self):
"""return the current size of the cache.
>>> c = Cache(123, 456)
>>> c.cache_size()
0
>>> for i in range(5): c.set(i, i)
>>> c.cache_size()
5
>>> c.clear()
>>> c.cache_size()
0
"""
return len(self.__cache)
def min_cache(self, min_cache=None):
"""set and return the minimum cache size.
>>> c = Cache(123, 456)
>>> c.min_cache()
123
>>> c.min_cache(321)
321
>>> c.min_cache()
321
"""
if not min_cache is None:
self.__min_cache = min_cache
return self.__min_cache
def max_cache(self, max_cache=None):
"""set and return the maximum cache size.
>>> c = Cache(123, 456)
>>> c.max_cache()
456
>>> c.max_cache(654)
654
>>> c.max_cache()
654
"""
if not max_cache is None:
self.__max_cache = max_cache
return self.__max_cache
def has_key(self, key):
"""is key cached?
>>> c = Cache()
>>> c.has_key(1)
False
>>> c.set(1, 1)
>>> c.has_key(1)
True
"""
return self.__cache.has_key(key)
def set(self, key, value):
"""store the key / value pair in the cache.
>>> c = Cache(100, 100)
>>> for i in range(0, 100):
... c.set(i, i)
>>> c.get(0)
0
>>> c.get(99)
99
"""
self.__cache[key] = value
self.__cache_access.add(datetime.now(), key)
if self.__cache_access.count() > self.__max_cache:
# remove old entries from the cache
for k in self.__cache_access.range(0,
self.__cache_access.count() - self.__min_cache):
del self.__cache[k]
self.__cache_access.remrange(0, self.__cache_access.count() -
self.__min_cache)
def get(self, key):
"""return the value for key from the cache. returns None if key is not
cached.
>>> c = Cache(100, 100)
>>> c.set(0, "zero")
>>> c.get(0)
'zero'
>>> c.get(99) == None
True
"""
if self.__cache.has_key(key):
self.__cache_access.add(datetime.now(), key)
return self.__cache[key]
return None
def clear(self):
"""remove all entries from the cache.
>>> c = Cache(100, 100)
>>> for i in range(0, 100):
... c.set(i, i)
>>> c.cache_size()
100
>>> c.clear()
>>> c.cache_size()
0
"""
self.__cache.clear()
self.__cache_access.remrange()
def __xor__(self, that):
return SortedSet(self._view ^ that)
def __sub__(self, that):
return SortedSet(self._view - that)
def __or__(self, that):
return SortedSet(self._view | that)
def __and__(self, that):
return SortedSet(self._view & that)
def keys(self):
return SortedSet(self._dict)
