Python example of how to use Redis for caching

redis_cache.py

"""Library to use Redis for the cache.

Usage:
    from redis_cache import redis_cached

    @redis_cached
    def foo(bar, baz, misc=123):
        return bar + baz + misc
"""

import hashlib
import json
from functools import wraps

import redis


CACHE_EXPIRY = 60 * 60 * 24  # 1 day


def _get_cache_key(function_name, *args, **kwargs):
    """Returns the key to use in Redis.

    Uses {function_name}:{args_hash} format;
    args_hash is the MD5 digest of JSON-serialized arguments.
    """
    hasher = hashlib.md5()
    hasher.update(json.dumps([args, kwargs]))
    return '{function_name}:{args_hash}'.format(
        function_name=function_name,
        args_hash=hasher.hexdigest()
    )


def redis_cached(func):
    """Decorator for caching functions results in Redis."""
    cache = redis.Redis()  # TODO: your connect params here

    @wraps(func)
    def wrapper(*args, **kwargs):
        """Tries to get result from the cache, else calculates it and saves."""
        cache_key = _get_cache_key(func.__name__, *args, **kwargs)

        result = cache.get(cache_key)
        if result is not None:
            return result

        result = func(*args, **kwargs)
        cache.set(cache_key, result, ex=CACHE_EXPIRY)
        return result

    return wrapper