Invalidating a path from the Django cache recursively

Question

I am deleting a single path from the Django cache like this:

from models                   import Graph
from django.http              import HttpRequest
from         


        

Answer 1

Another option is to use a cache that supports tagging keys and evicting keys by tag. Django's built-in cache API does not have support for this approach. But at least one cache backend (not part of Django proper) does have support.

DiskCache* is an Apache2 licensed disk and file backed cache library, written in pure-Python, and compatible with Django. To use DiskCache in your project simply install it and configure your CACHES setting.

Installation is easy with pip:

$ pip install diskcache

Then configure your CACHES setting:

CACHES = {
    'default': {
        'BACKEND': 'diskcache.DjangoCache',
        'LOCATION': '/tmp/path/to/directory/',
    }
}

The cache set method is extended by an optional tag keyword argument like so:

from django.core.cache import cache

cache.set('/graph/123', value, tag='/graph/123')
cache.set('/graph/123/2009-08-01/2009-10-21', other_value, tag='/graph/123')

diskcache.DjangoCache uses a diskcache.FanoutCache internally. The corresponding FanoutCache is accessible through the _cache attribute and exposes an evict method. To evict all keys tagged with /graph/123 simply:

cache._cache.evict('/graph/123')

Though it may feel awkward to access an underscore-prefixed attribute, the DiskCache project is stable and unlikely to make significant changes to the DjangoCache implementation.

The Django cache benchmarks page has a discussion of alternative cache backends.

• Disclaimer: I am the original author of the DiskCache project.