dogpile_invalidate_keys.py

from dogpile.cache import make_region

# key dictionary
keys = dict()


def my_key_generator(namespace, fn, **kwargs):
    fname = fn.__name__

    def generate_key(*arg):
        # generate a key template,
        # basically just concatenate all the args with the functionname
        if namespace:
            prefix = namespace + "__" + fname
        else:
            prefix = fname
        out = str()
        for a in arg[1:]:
            out += "_" + str(a)
        key_template = prefix + "|" + out[1:]
        fruit_type = arg[1]  # fruit_type must be first parameter in all cached functions
        # store the key in the appropriate set for the fruit type
        try:
            keys[fruit_type].add(key_template)
        except KeyError:  # if it's the first one..
            keys[fruit_type] = set()
            keys[fruit_type].add(key_template)

        # return cache key
        return key_template

    return generate_key


def invalidate_fruit_cache(region, fruit_type):
    # Delete all cached data for the specified fruit type
    try:
        for key in keys[fruit_type]:
            region.delete(key)
    except KeyError:
        pass  # Probably wasn't instantiated yet.
    finally:
        keys[fruit_type] = set()


region = make_region(
    function_key_generator=my_key_generator
).configure(
    "dogpile.cache.memory"
)

# I couldn't be bothered to shop for a real gift..
# or
# much friendlier than a basket with lotion.
class FruitBasket(object):
    fruit = dict()

    def __init__(self):
        apples = self.fruit['apples'] = list()
        apples.append('Braeburn')
        apples.append('Granny Smith')
        apples.append('Delicious')
        apples.append('Fuji')
        citrus = self.fruit['citrus'] = list()
        citrus.append('Grapefruit')
        citrus.append('Limes')
        citrus.append('Oranges')
        citrus.append('Mandarins')


    @region.cache_on_arguments(expiration_time=1000)
    def get_fruit(self, fruit_type, json):
        if json:
            import json

            s = self.fruit[fruit_type]
            return "json: %s" % str(json.dumps(s))
        else:
            return "text: %s" % str(self.fruit[fruit_type])

    def fuji_to_honeycrisp(self):
        apples = self.fruit['apples']
        apples.remove('Fuji')
        apples.append('Honeycrisp')


basket = FruitBasket()

# Load up the cache
print basket.get_fruit('citrus', False)
print basket.get_fruit('apples', False)
print basket.get_fruit('apples', True)
print "Should have honeycrisp now: "

# But we won't because we've cached everything..
basket.fuji_to_honeycrisp()
print basket.get_fruit('apples', True)

# Check out the cache, remove apples. Citrus stay intact.
print region.backend._cache
print "keys: %s: " % str(keys)
print "Removing any bad apples"
invalidate_fruit_cache(region, "apples")
print region.backend._cache
print "keys: %s: " % str(keys)

# Honeycrisp Heaven
print basket.get_fruit('apples', False)
print basket.get_fruit('apples', True)