feed.py

import config
import redis as _redis
redis = _redis.Redis(host=config.REDIS_HOST, port=int(config.REDIS_PORT))

REDIS_KEY_PATTERN           = "feed:%s:%s"
feed_key                    = lambda _type, _id: REDIS_KEY_PATTERN % (_type, _id)

DEFAULT_MAX_LENGTH          = 1000
DEFAULT_LIMIT               = 50

def add_to_feed(feed_type, feed_id, items_dict, max_length=DEFAULT_MAX_LENGTH):
    key = feed_key(feed_type, feed_id)
    resp = redis.zadd(key, **items_dict)
    trim_feed(key, max_length)
    return resp

def remove_from_feed(feed_type, feed_id, *item_ids):
    key = feed_key(feed_type, feed_id)
    resp = redis.zrem(key, *item_ids)
    return resp

def get_feed(feed_type, feed_id, limit=DEFAULT_LIMIT, page=0, with_scores=False):
    key = feed_key(feed_type, feed_id)
    min_rank = (limit * page)
    max_rank = max(min_rank + limit - 1, 1)
    return redis.zrevrange(key, min_rank, max_rank, withscores=with_scores)

def delete_feed(feed_type, feed_id):
    key = feed_key(feed_type, feed_id)
    return redis.delete(key)

def trim_feed(key, length):
    if isinstance(length, int) and length > 0:
        return redis.zremrangebyrank(key, 0, (-1 * length) - 1)
    return 0