Johnny Cache is a caching framework for django applications. It works with the django caching abstraction, but was developed specifically with the use of memcached in mind. Its main feature is a patch on Django’s ORM that automatically caches all reads in a consistent manner. It works with Django 1.1, 1.2, and 1.3.
You can install johnny with pip:
pip install johnny-cache
You can fork johnny-cache from its hg repository:
hg clone http://bitbucket.org/jmoiron/johnny-cache
Please use bitbucket’s issue tracker to report bugs. Contact the authors at @jmoiron and @finder83.
A typical settings.py file configured for johnny-cache:
# add johnny's middleware
MIDDLEWARE_CLASSES = (
'johnny.middleware.LocalStoreClearMiddleware',
'johnny.middleware.QueryCacheMiddleware',
# ...
)
# some johnny settings
CACHES = {
'default' : dict(
BACKEND = 'johnny.backends.memcached.MemcachedCache',
LOCATION = ['127.0.0.1:11211'],
JOHNNY_CACHE = True,
)
}
JOHNNY_MIDDLEWARE_KEY_PREFIX='jc_myproj'
Note: The above configuration is for Django 1.3, which radically changed its cache configuration. To see a full inspection of options for earlier versions of Django please see the queryset cache docs.
The MIDDLEWARE_CLASSES setting enables two middlewares: the outer one clears a thread-local dict-like cache located at johnny.cache.local at the end of every request, and should really be the outer most middleware in your stack. The second one enables the main feature of Johnny: the queryset cache.
The CACHES configuration includes a custom backend, which allows cache times of “0” to be interpreted as “forever”, and marks the default cache backend as the one Johnny will use.
Finally, the project’s name is worked into the Johnny key prefix so that if other projects are run using the same cache pool, Johnny won’t confuse the cache for one project with the cache for another.
With these settings, all of your ORM queries are now cached. You should read the queryset cache documentation closely to see if you are doing anything that might require manual invalidation.
Johnny does not define any views, urls, or models, so we can skip adding it to INSTALLED_APPS.
The usage for johnny.cache.get_backend has changed; it now returns a QueryCacheBackend instance rather than the appropriate version of the class. Most uses of this function would have been get_backend()(), which can now be effectively replaced with get_backend().