def create_connections(N, M, K1=None, K2=None):
"""Create connections from users 1 - N.
Users with uid less equal than M will be considered as celebrities
having many followers.
Parameters
----------
N: int
The number of users.
M: int
The number of celebrities.
K1: int
The average number of followers for celebrities. Default: 0.05 * N.
K2: int
The average number of followers for normal users. Default: 0.001 * N.
"""
assert N >= M
if K1 is None:
K1 = int(N * 0.05)
if K2 is None:
K2 = int(N * 0.001)
for uid in range(1, M + 1):
pipe = conn.pipeline(False)
s = random.randint(1, N - K1)
for follower_uid in range(s, s + K1):
follow(follower_uid, uid, pipe)
pipe.execute()
for uid in range(M + 1, N + 1):
pipe = conn.pipeline(False)
s = random.randint(1, N - K2)
for follower_uid in range(s, s + K2):
follow(follower_uid, uid, pipe)
pipe.execute()
def unfollow(follower, followee):
"""Remove a connection between follower and followee."""
follow_ts = conn.zscore(utils.get_followers_key(followee), follower)
_tweets = tweets.get_tweets_since(followee, follow_ts, {'tid', 'uid'})
pipe = conn.pipeline()
pipe.zrem(utils.get_followers_key(followee), follower)
pipe.zrem(utils.get_followees_key(follower), followee)
tweets.delete_tweets(_tweets, pipe)
pipe.execute()
def get_tweets(tids, fields=None):
"""Return tweets with specified tids."""
pipe = conn.pipeline(False)
for tid in tids:
if fields is None:
pipe.hgetall(utils.get_tweet_key(tid))
else:
pipe.hmget(utils.get_tweet_key(tid), *fields)
tweets = [Tweet.load_dict(d) for d in pipe.execute()]
return tweets
def create_tweets(N, M, K1=200, K2=80):
"""Create tweets from users 1 - N.
Users with uid less equal than M will be considered as celebrities
having many followers.
"""
assert N >= M
pipe = conn.pipeline(False)
for uid in range(1, M + 1):
pipe = conn.pipeline(False)
for _ in range(K1):
post_tweet(uid, pipe, body=fake_tweet_body(),
location=fake_location())
pipe.execute()
for uid in range(M + 1, N + 1):
pipe = conn.pipeline(False)
for _ in range(K2):
post_tweet(uid, pipe, body=fake_tweet_body(),
location=fake_location())
pipe.execute()
def delete_tweets(tweets, pipe=None):
"""Delete tweets with specified tids."""
execute = True
if pipe is None:
pipe = conn.pipeline(False)
execute = True
else:
execute = False
for tweet in tweets:
delete_tweet(tweet, pipe)
if execute:
pipe.execute()
def follow(follower, followee, pipe=None):
"""Create a connection between follower and followee."""
if pipe is None:
pipe = conn.pipeline()
execute = True
else:
execute = False
pipe.zadd(utils.get_followers_key(followee),
follower, utils.get_timestamp())
pipe.zadd(utils.get_followees_key(follower),
followee, utils.get_timestamp())
if execute:
pipe.execute()
def delete_tweet(tweet, pipe=None):
"""Delete a tweet."""
followers = users.get_followers(tweet.uid)
if pipe is None:
pipe = conn.pipeline(False)
execute = True
else:
execute = False
pipe.zrem(utils.get_user_tweets_key(tweet.uid), tweet.tid)
pipe.zrem(utils.get_timeline_key(tweet.uid), tweet.tid)
for follower_uid in followers:
pipe.zrem(utils.get_timeline_key(follower_uid), tweet.tid)
pipe.delete(utils.get_tweet_key(tweet.tid))
if execute:
pipe.execute()
def refresh_timeline(uid):
"""Refresh user's timeline.
Fetch all delayed tweets from his/her followees.
"""
last_tid = conn.zrevrange(utils.get_timeline_key(uid), 0, 0)
last_tweet = tweets.get_tweet(last_tid)
if not last_tweet:
return
followees = get_followees(uid)
pipe = conn.pipeline(False)
for followee in followees:
_tweets = tweets.get_tweets_since(followee, last_tweet.ts,
{'tid', 'datetime'})
for tweet in _tweets:
pipe.zadd(utils.get_timeline_key(uid), tweet.tid, tweet.ts)
pipe.execute()
def post_tweet(uid, pipe=None, **tweet_info):
"""Create a new tweet with basic infomation.
Parameters
----------
uid: str
User ID.
pipe: Pipeline object
A Redis pipeline object, if given, need to execute manually outside
this function.
body: str
The body of the tweet.
location: str
The location when posting this tweet.
original: bool
Whether this tweet is an original tweet or just a retweet.
"""
tweet_info['uid'] = uid
tweet_info['tid'] = uuid4().hex
tweet_info['datetime'] = datetime.now()
tweet_info.setdefault('original', True)
tweet = Tweet.load_dict(tweet_info)
if pipe is None:
pipe = conn.pipeline(False)
execute = True
else:
execute = False
pipe.hmset(utils.get_tweet_key(tweet.tid), tweet.dump_dict())
pipe.zadd(utils.get_user_tweets_key(uid), tweet.tid, tweet.ts)
pipe.zadd(utils.get_timeline_key(uid), tweet.tid, tweet.ts)
if users.get_followers_count(uid) < config.DIRECT_INSERT_THRES:
# Perform direct insertion
followers = users.get_followers(uid)
for follower_uid in followers:
pipe.zadd(utils.get_timeline_key(follower_uid), tweet.tid,
tweet.ts)
if execute:
pipe.execute()