cachelper
##########
.. image:: https://travis-ci.org/suzaku/cachelper.svg?branch=master
:target: https://travis-ci.org/suzaku/cachelper
.. image:: https://img.shields.io/pypi/v/cachelper.svg
:target: https://pypi.python.org/pypi/cachelper
Useful cache helpers in one package!
.. image:: https://app.codesponsor.io/embed/MY7qFCdB7bDgiBqdjtV9ASYi/suzaku/cachelper.svg
:width: 888px
:height: 68px
:alt: Sponsor
:target: https://app.codesponsor.io/link/MY7qFCdB7bDgiBqdjtV9ASYi/suzaku/cachelper
Install
*******
.. code-block:: bash
pip install cachelper
Helpers
*******
In memory cache
===============
memoize
---------------
Caching function return values in memory.
.. code-block:: python
import cachelper
@cachelper.memoize()
def fibo(n):
if n in (0, 1):
return 1
return fibo(n - 1) + fibo(n - 2)
fibo(10)
Cache with Redis/Memcached
==============================
Using the HelperMixin
---------------------
``HelperMixin`` can be used with any cache client classes that implement the following methods:
- ``def get(self, key)``
- ``def set(self, key, value, timeout=None)``
- ``def delete(self, key)``
- ``def get_many(self, keys)``
- ``def set_many(self, mapping, timeout=None)``
For example, `RedisCache` from `werkzeug` is one such class:
.. code-block:: python
from redis import StrictRedis
from werkzeug.contrib.cache import RedisCache as _RedisCache
from cachelper import HelperMixin
class RedisCache(_RedisCache, HelperMixin):
'''werkzeug.contrib.cache.RedisCache mixed with HelperMixin'''
def get_many(self, keys):
return super().get_many(*keys)
rds = StrictRedis()
cache = RedisCache(rds)
This mixin defines these methods: ``call``, ``map``, ``__call__``.
If your class already defines methods of the same name, the mixin methods may not work correctly.
cache decorator
---------------
Add cache by decorating a function or method.
.. code-block:: python
@cache("key-{user_id}", timeout=300)
def get_name(user_id):
# Fetch user name from database
...
The cache key template can also be a function which acts as a key factory:
.. code-block:: python
def name_key(user_id):
return "key-%s" % user_id
@cache(name_key, timeout=300)
def get_name(user_id):
# Fetch user name from database
...
Just make sure the key factory function accepts the same parameters as the cached
function and returns the key.
cached function calls
------------------------------
Sometimes we don't want to cache all calls to a specific function.
So the decorator is not suitable, we may cache the call instead the function in this case:
.. code-block:: python
def get_name(user_id):
# Fetch user name from database
...
user_id = 42
key = "key-{user_id}".format(user_id=user_id)
cache.call(lambda: get_name(user_id), key, timeout=300)
cached multiple calls
------------------------------
For most cache backends, it's much faster to get or set caches in bulk.
.. code-block:: python
def get_name(user_id):
# Fetch user name from database
...
user_ids = [1, 2, 42, 1984]
names = cache.map("key-{user_id}", get_name, user_ids, timeout=300)
