69 lines
2.0 KiB
Python
69 lines
2.0 KiB
Python
# -*- 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']
|