Memcache mixin

memcache_mixin.py

class DBCacheMixin(object):
    """ mixin for datastore objects with cache/key lookups, inheriting classes must define:
    MCBASE, (optionally NAMESPACE -- though handled internally) """
    NAMESPACE = None
    MCBASE = "NONE_"

    @classmethod
    def get_cache(cls, key, base=None, group=None):
        base = (base or cls.MCBASE) + (group or cls.GROUP)
        r = memcache.get(key=base + str(key), namespace=cls.NAMESPACE)
        if r:
            age, obj = r
            try:
                obj.age = age
            except AttributeError:
                # means not an object
                pass
            return obj
        else:
            return None

    @classmethod
    def set_cache(cls, key, value, base=None, group=None):
        base = (base or cls.MCBASE) + (group or cls.GROUP)
        value = (time.time(), value)
        return memcache.set(key=base + str(key),value=value, namespace=cls.NAMESPACE)

    @classmethod
    def delete_cache(cls, key, base=None, group=None):
        base = (base or cls.MCBASE) + (group or cls.GROUP)
        return memcache.delete(key=base + str(key), namespace=cls.NAMESPACE)

    @webapp2.cached_property
    def uid(self):
        return self.key().id() or self.key().name()

    def cache(self, group=None):
        return self.set_cache(key=self.uid, value=self, group=group)