peopledoc / python-pussycache

Cache Backend system for python objects

Python pussy cache

Python pussy cache is a Cache system for python objects.

Cache backends can be in-memory or redis/ You can even use the django cache framework with Python-pussy-cache.

Given a one of the cache backends and any Python class you have define, Python-pussy-cache will cache the results of methods you have define and will also manage the cache invalidation by timestamp or with methods you have defined.

Here is an example to make the thing clearer

import time
from pussycache.proxy import BaseProxy
from pussycache.cache import BaseCacheBackend
# Here is a simple class where some methods need to be cached

class MyClass(object):

      def a_long_task(self, delta):
          time.sleep(delta)
          return delta

      def forget_about_time(self):
          return None

# We set an in memory cache backend with a TTL of 30 seconds.

cache = BaseCacheBackend(30)

cache_proxy = BaseProxy(MyClass(), cache=cache,
             cached_methods=["a_long_task"],
             invalidate_methods={"forget_about_time": ["a_long_task"]})

cachedinstance = cache_proxy
# your cachedinstance is now
# ready to use. It will just work like a regular MyClass object

print cachedinstance.a_long_task(10)
# 10 seconds later
10
# if we call the same method a second time:
print cachedinstance.a_long_task(10)
10
# result is returned immediatly because it's in the cache
# but
print cachedinstance.a_long_task(3)
3
# with different parameters, the result is not cached yet.
# if you want to invalidate the cache for this method:
print cachedinstance.forget_about_time()
print cachedinstance.a_long_task(10)
# 10 seconds later
10

Of course, If you need direct access to the cache backend, you can call it directly. Let's say you need to invalidate ALL the cache :

cachedinstance._cache.clear()

The same apply if you need to call directly the cache:

cachedinstance.\_cache.set("mykey", "my value", 10)
cachedinstance.\_cache.get("mykey")
"my value"
#and 10 seconds later:
cachedinstance.\_cache.get("mykey")
#the value is gone from the cache

Tests

To run test, just install tox with pip install tox and run

tox