redis-simple-cache

redis-simple-cache is a pythonic interface for creating a cache over redis. It provides simple decorators that can be added to any function to cache its return values.

Requirements:

redis 2.6.2 redis-py 2.7.1 (see requirements.txt file)

Installation:

pip install redis-simple-cache

git clone git://github.com/fjsj/redis-simple-cache.git
cd redis-simple-cache
python setup.py install

Usage:

from redis_cache import cache_it

@cache_it(limit=1000, expire=60 * 60 * 24)
def fib(n):
    if n == 0:
        return 0
    elif n == 1:
        return 1
    else:
        return fib(n-1) + fib(n-2)

limit is the maximum number of keys, expire is the expire time in seconds. It is always recommended to specify a expire time, since by default redis-server will only remove keys with an expire time set in a event of full memory. But if you wish your keys to never expire, set expire to None. Note that function arguments and result must be pickleable, since cache_it uses the pickle module.

It is also possible to use redis-simple-cache as a object-oriented cache:

>> from redis_cache import SimpleCache
>> c = SimpleCache(10)  # cache that has a maximum limit of 10 keys
>> c.store("foo", "bar")
>> c.get("foo")
'bar'
>> "foo" in c  # efficient membership test, time-complexity O(1)
True
>> len(c)  # efficient cardinality calculation, time-complexity O(1)
1
>> c.keys()  # returns all keys, time-complexity O(N) with N being the cache c cardinality
set(['foo'])
>> c.flush()  # flushes the cache, time-complexity O(N) with N being the cache c cardinality
>> "foo" in c
False
>> len(c)
0

Check out more examples in the test_rediscache.py file.

Advanced:

Advanced users can customize the decorators even more by passing a SimpleCache object. For example:

my_cache = SimpleCache(limit=100, expire=60 * 60, hashkeys=True, host='localhost', port=6379, db=1)
@cache_it(cache=my_cache)
def fib(n):
    # ...

hashkeys parameter makes the SimpleCache to store keys in md5 hash. It is True by default in decorators, but False by default in a new SimpleCache object. host, port and db are the same redis config params used in StrictRedis class of redis-py.

Multisession cache:

In a case you need to keep values for many executions you only need to change how the SimpleCache gets the keys:

from redis_cache import cache_it, SimpleCache

class MultiSessionCache(SimpleCache):
    key_str = "multisession-cache"

    def make_key(self, key):
        return MultiSessionCache.key_str + "-" + str(key)

    def get_set_name(self):
        return MultiSessionCache.key_str

my_cache = MultiSessionCache(hashkeys=True)
@cache_it(cache=my_cache)
def fib(g):
    passs

The code could be changed in other to have many instances but this is the most straight form.

AUTHOR: Vivek Narayanan FORKED AND IMPROVED BY: Flávio Juvenal and Sam Zaydel LICENSE: BSD

fjsj / redis-simple-cache