Skip to main content

Lazy Django fragment cache sweeping

Project description

Fragment cache invalidation by using a per model version token to prefix the cache keys. The version token can either be an internal memcached counter or a timestamped attribute from the model, such as updated_at.


Install with pip or with python install and add ‘cachesweeper’ to your settings.INSTALLED_APPS

post_save cache sweeper

An example setup; an article has many comments, each comment is cached, a single vote should invalidate the comment’s specific cached fragment as well as the total article’s page.

Template fragment caching

{% cachesweeper %} takes a Django ORM model as its first argument, the expiry time as its second and any following arguments are used to construct the rest of the cache key

{% load markup %}
{% load cachesweeper_tags %}
{% cachesweeper comment 500 "comment.xml" %}
    <strong>{{comment.user}}</strong> said at {{comment.created_at}}:<br/>
    <a href={% url like, %}>Like ({{comment.likes.count}})</a>
    <a href={% url dislike, %}>Dislike ({{comment.dislikes.count}})</a>
{% endcachesweeper %}

Invalidating the fragment when the model changes

On a post_save invalidate the cache for the given model. There are two options, either have Memcached keep an internal version counter for each model or using the keyword using as a means of versioning the cache.

from cachesweeper.utils import invalidate_cache_for

# using Memcached's internal counter
def invalidate_vote_cache(sender, **kwargs):
    vote = kwargs.get('instance')

post_save.connect(invalidate_vote_cache, sender=Vote)

# using a model's attribute
def invalidate_article_cache(sender, **kwargs):
    article = kwargs.get('instance')
    invalidate_cache_for(article, using='updated_at')

post_save.connect(invalidate_article_cache, sender=Article)

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for django-cache-sweeper, version 0.1.2
Filename, size File type Python version Upload date Hashes
Filename, size django_cache_sweeper-0.1.2-py2.6.egg (14.8 kB) File type Egg Python version 2.6 Upload date Hashes View
Filename, size django-cache-sweeper-0.1.2.tar.gz (6.2 kB) File type Source Python version None Upload date Hashes View

Supported by

Pingdom Pingdom Monitoring Google Google Object Storage and Download Analytics Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page