django-cache-utils is a Django app that provides some utilities to make cache-related work easier:
* django memcached cache backend with group O(1) invalidation ability, dog-pile effect prevention using MintCache algorythm and project version support to allow gracefull updates and multiple django projects on same memcached instance. Long keys (>250) are truncated and appended with md5 hash.
* cached decorator. Can be applied to function, method or classmethod. Supports bulk O(1) cache invalidation and meaningful cache keys. Takes function's arguments and full name into account while constructing cache key.
Installation
pip install django-cache-utils
and then:
# settings.py
CACHE_BACKEND = 'cache_utils.group_backend://localhost:11211/'
Usage
from django.db import models
from cache_utils.decorators import cached
class CityManager(models.Manager):
# cache a method result. 'self' parameter is ignored
@cached(60*60*24, 'cities')
def default(self):
return self.active()[0]
# cache a method result. 'self' parameter is ignored, args and
# kwargs are used to construct cache key
@cached(60*60*24, 'cities')
def get(self, *args, **kwargs):
return super(CityManager, self).get(*args, **kwargs)
class City(models.Model):
# ... field declarations
objects = CityManager()
# an example how to cache django model methods by instance id
def has_offers(self):
@cached(30)
def offer_count(pk):
return self.offer_set.count()
return history_count(self.pk) > 0
# cache the function result based on passed parameter
@cached(60*60*24, 'cities')
def get_cities(slug)
return City.objects.get(slug=slug)
# cache for 'cities' group can be invalidated at once
def invalidate_city(sender, **kwargs):
cache.invalidate_group('cities')
pre_delete.connect(invalidate_city, City)
post_save.connect(invalidate_city, City)
Notes
django-cache-utils use 2 reads from memcached to get a value if 'group' argument is passed to 'cached' decorator:
@cached(60)
def my_func(param)
return ..
@cached(60, 'my_group')
def my_func2(param)
return ..
# 1 read from memcached
value1 = my_func(1)
# 2 reads from memcached + ability to invalidate all values at once
value2 = my_func2(2)
Running tests
Add 'cache_utils' to INSTALLED_APPS and run ./manage test cache_utils.
Requirements:
· Python
· Django
