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SickRage/lib/shove/cache/simple.py

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# -*- coding: utf-8 -*-
'''
Single-process in-memory cache.
The shove psuedo-URL for a simple cache is:
simple://
'''
import time
import random
from shove import SimpleBase
class SimpleCache(SimpleBase):
'''Single-process in-memory cache.'''
def __init__(self, engine, **kw):
super(SimpleCache, self).__init__(engine, **kw)
# Get random seed
random.seed()
# Set maximum number of items to cull if over max
self._maxcull = kw.get('maxcull', 10)
# Set max entries
self._max_entries = kw.get('max_entries', 300)
# Set timeout
self.timeout = kw.get('timeout', 300)
def __getitem__(self, key):
exp, value = super(SimpleCache, self).__getitem__(key)
# Delete if item timed out.
if exp < time.time():
super(SimpleCache, self).__delitem__(key)
raise KeyError(key)
return value
def __setitem__(self, key, value):
# Cull values if over max # of entries
if len(self) >= self._max_entries:
self._cull()
# Set expiration time and value
exp = time.time() + self.timeout
super(SimpleCache, self).__setitem__(key, (exp, value))
def _cull(self):
'''Remove items in cache to make room.'''
num, maxcull = 0, self._maxcull
# Cull number of items allowed (set by self._maxcull)
for key in self.keys():
# Remove only maximum # of items allowed by maxcull
if num <= maxcull:
# Remove items if expired
try:
self[key]
except KeyError:
num += 1
else:
break
# Remove any additional items up to max # of items allowed by maxcull
while len(self) >= self._max_entries and num <= maxcull:
# Cull remainder of allowed quota at random
del self[random.choice(self.keys())]
num += 1
__all__ = ['SimpleCache']