def get_following_user_id_set(cls, from_user_id):
# cache set in Redis
name = FOLLOWINGS_PATTERN.format(user_id=from_user_id)
user_id_set = RedisHelper.get_all_members_from_set(name)
# cache hit, need to change b'123' -> 123
if user_id_set is not None:
user_id_set_new = set([])
for user_id in user_id_set:
if isinstance(user_id, bytes):
user_id = user_id.decode('utf-8')
user_id_set_new.add(int(user_id))
return user_id_set_new
# cache miss
if not GateKeeper.is_switch_on('switch_friendship_to_hbase'):
friendships = Friendship.objects.filter(from_user_id=from_user_id)
else:
friendships = HBaseFollowing.filter(prefix=(from_user_id, None))
user_id_set = set([
fs.to_user_id
for fs in friendships
])
# push in Redis
RedisHelper.add_id_to_set(name, user_id_set)
return user_id_set
def decr_comments_count(sender, instance, **kwargs):
from tweets.models import Tweet
from django.db.models import F
Tweet.objects.filter(id=instance.tweet_id)\
.update(comments_count=F('comments_count') - 1)
invalidate_object_cache(sender=Tweet, instance=instance.tweet)
RedisHelper.decr_count(instance.tweet, 'comments_count')
def decr_comments_count(sender, instance, **kwargs):
from tweets.models import Tweet
from django.db.models import F
# handle comment deletion
Tweet.objects.filter(id=instance.tweet_id) \
.update(comments_count=F('comments_count') - 1)
RedisHelper.decr_count(instance.tweet, 'comments_count')
def incr_comments_count(sender, instance, created, **kwargs):
from tweets.models import Tweet
from django.db.models import F
if not created:
return
Tweet.objects.filter(id=instance.tweet_id).update(comments_count=F('comments_count') + 1)
RedisHelper.incr_count(instance.tweet, 'comments_count')
def decr_comment_count(sender, instance, **kwargs):
from tweets.models import Tweet
from django.db.models import F
# atomic operations for concurrency safe
# django F translated SQL ensures concurrency safe in db level
Tweet.objects.filter(id=instance.tweet_id) \
.update(comment_count=F('comment_count') - 1)
# extra counter in cache
# the cached popular object should not be invalid frequently
RedisHelper.decr_count(instance.tweet, 'comment_count')
def decr_likes_count(sender, instance, **kwargs):
from tweets.models import Tweet
from django.db.models import F
model_class = instance.content_type.model_class()
if model_class != Tweet:
return
Tweet.objects.filter(id=instance.object_id).update(likes_count = F('likes_count') - 1)
tweet = instance.content_object
RedisHelper.decr_count(tweet, 'likes_count')
def decr_likes_count(sender, instance, **kwargs):
from tweets.models import Tweet
from django.db.models import F
model_class = instance.content_type.model_class()
if model_class != Tweet:
# TODO HOMEWORK 给 Comment 使用类似的方法进行 likes_count 的统计
return
# handle tweet likes cancel
Tweet.objects.filter(id=instance.object_id).update(likes_count=F('likes_count') - 1)
RedisHelper.decr_count(instance.content_object, 'likes_count')
def incr_comments_count(sender, instance, created, **kwargs):
from tweets.models import Tweet
from django.db.models import F
if not created:
return
# handle new comment
Tweet.objects.filter(id=instance.tweet_id)\
.update(comments_count=F('comments_count') + 1)
#invalidate_object_cache(sender=Tweet, instance=instance.tweet)
RedisHelper.incr_count(instance.tweet, 'comments_count')
def decr_likes_count(sender, instance, **kwargs):
from tweets.models import Tweet
from django.db.models import F
model_class = instance.content_type.model_class()
if model_class != Tweet:
# TODO: we can later do similar things to calculate number of likes for comments
return
Tweet.objects.filter(id=instance.object_id).update(
likes_count=F('likes_count') - 1)
tweet = instance.content_object
RedisHelper.decr_count(tweet, 'likes_count')
def decr_like_count(sender, instance, **kwargs):
from tweets.models import Tweet
model_class = instance.content_type.model_class()
if model_class != Tweet:
return
# atomic operations for concurrency safe
# django F translated SQL ensures concurrency safe in db level
Tweet.objects.filter(id=instance.object_id)\
.update(like_count=F('like_count') - 1)
# extra counter in cache
# the cached popular object should not be invalid frequently
RedisHelper.decr_count(instance.content_object, 'like_count')
def incr_likes_count(sender, instance, created, **kwargs):
from tweets.models import Tweet
from django.db.models import F
if not created:
return
model_class = instance.content_type.model_class()
if model_class != Tweet:
return
Tweet.objects.filter(id=instance.object_id).update(
likes_count=F('likes_count') + 1)
RedisHelper.incr_count(instance.content_object, 'likes_count')
def load_tweets_through_cache(cls, user_id):
# Django query is lazy loading
# it is triggered by iterations inside the load_object()
queryset = Tweet.objects.filter(
user_id=user_id).order_by('-created_at')
name = USER_TWEET_PATTERN.format(user_id=user_id)
return RedisHelper.load_objects(name, queryset)
def incr_likes_count(sender, instance, created, **kwargs):
from tweets.models import Tweet
from django.db.models import F
if not created:
return
model_class = instance.content_type.model_class()
if model_class != Tweet:
return
# can't use tweet.likes_count += 1; tweet.save() way.
# as this is not atom action, must use update db operation.
Tweet.objects.filter(id=instance.object_id).update(likes_count=F('likes_count') + 1)
tweet = instance.content_object
RedisHelper.incr_count(tweet, 'likes_count')
def incr_likes_count(sender, instance, created, **kwargs):
from tweets.models import Tweet
from django.db.models import F
if not created:
return
model_class = instance.content_type.model_class()
if model_class != Tweet:
# TODO: we can later do similar things to calculate number of likes for comments
return
# update db first and then call cache update
Tweet.objects.filter(id=instance.object_id).update(
likes_count=F('likes_count') + 1)
tweet = instance.content_object
RedisHelper.incr_count(tweet, 'likes_count')
def incr_likes_count(sender, instance, created, **kwargs):
from tweets.models import Tweet
from django.db.models import F
if not created:
return
model_class = instance.content_type.model_class()
if model_class != Tweet:
return
# 不可以使用tweet = instance.content_object; tweet.likes_count += 1; tweet.save()的方式
# 因为这个操作不是原子操作，必须使用update语句才是原子操作
# SQL query: UPDATE likes_count = likes_count + 1 from tweets_table where id = <instance.object.id>
tweet = instance.content_object
Tweet.objects.filter(id=tweet.id).update(likes_count=F('likes_count') + 1)
RedisHelper.incr_count(tweet, 'likes_count')
def incr_likes_count(sender, instance, created, **kwargs):
from tweets.models import Tweet
from django.db.models import F
if not created:
return
model_class = instance.content_type.model_class()
if model_class != Tweet:
# TODO HOMEWORK 给 Comment 使用类似的方法进行 likes_count 的统计
return
# 不可以使用 tweet.likes_count += 1; tweet.save() 的方式
# 因此这个操作不是原子操作，必须使用 update 语句才是原子操作
Tweet.objects.filter(id=instance.object_id).update(likes_count=F('likes_count') + 1)
tweet = instance.content_object
RedisHelper.incr_count(tweet, 'likes_count')
def get_cached_newsfeeds(cls, user_id):
key = USER_NEWSFEEDS_PATTERN.format(user_id=user_id)
if GateKeeper.is_switch_on('switch_newsfeed_to_hbase'):
serializer = HBaseModelSerializer
else:
serializer = DjangoModelSerializer
return RedisHelper.load_objects(key,
lazy_load_newsfeeds(user_id),
serializer=serializer)
def decr_likes_count(sender, instance, **kwargs):
from comments.models import Comment
from tweets.models import Tweet
from django.db.models import F
model_class = instance.content_type.model_class()
if model_class == Comment:
# handle comment likes canceled
Comment.objects.filter(id=instance.object_id).update(
likes_count=F('likes_count') - 1)
comment = instance.content_object
RedisHelper.decr_count(comment, 'likes_count')
else:
# handle tweet likes canceled
Tweet.objects.filter(id=instance.object_id).update(
likes_count=F('likes_count') - 1)
tweet = instance.content_object
RedisHelper.decr_count(tweet, 'likes_count')
def incr_likes_count(sender, instance, created, **kwargs):
from tweets.models import Tweet
from django.db.models import F
if not created:
return
model_class = instance.content_type.model_class()
if model_class != Tweet:
return
# Do not use tweet.likes_count += 1; tweet_save()
# because this is not a atomic operation, we have to use update
# SQL Query: UPDATE likes_count = likes_count + 1 FROM tweets_table WHERE id=<instance.object_id>
# Method 1
Tweet.objects.filter(id=instance.object_id).update(
likes_count=F('likes_count') + 1)
RedisHelper.incr_count(instance.content_object, 'likes_count')
def incr_likes_count(sender, instance, created, **kwargs):
from tweets.models import Tweet
from django.db.models import F
if not created:
return
model_class = instance.content_type.model_class()
if model_class != Tweet:
# TODO HOMEWORK 给 Comment 使用类似的方法进行 likes_count 的统计
return
# 不可以使用 tweet.likes_count += 1; tweet.save() 的方式
# tweet = instance.content_object
# tweet.likes_count += 1
# tweet.save() -- this is wrong way!
# 因这个操作不是原子操作，必须使用 update 语句才是原子操作
# SQL Query: UPDATE likes_count = likes_count + 1 FROM tweets_table WHERE id=<instance.object_id>
# Method 1
Tweet.objects.filter(id=instance.object_id).update(likes_count=F('likes_count') + 1)
RedisHelper.incr_count(instance.content_object, 'likes_count')
def incr_likes_count(sender, instance, created, **kwargs):
from comments.models import Comment
from tweets.models import Tweet
from django.db.models import F
if not created:
return
model_class = instance.content_type.model_class()
if model_class == Comment:
# handle comment likes created
Comment.objects.filter(id=instance.object_id).update(
likes_count=F('likes_count') + 1)
comment = instance.content_object
RedisHelper.incr_count(comment, 'likes_count')
else:
# handle tweet likes created
# Don't use tweet.likes_count += 1; tweet.save()
# not atomic, must use "update"
Tweet.objects.filter(id=instance.object_id).update(
likes_count=F('likes_count') + 1)
tweet = instance.content_object
RedisHelper.incr_count(tweet, 'likes_count')
def index():
form = InfoForm()
if form.validate_on_submit():
session['nick'] = form.nick.data
session['age'] = form.age.data
session['level'] = form.level.data
session['goal'] = form.goal.data
session['country'] = form.country.data
session['skype'] = form.skype.data
if not "iid" in session.keys():
session['iid'] = CommonHelper.randomString(12)
rediis.hset("sessions", session['iid'], str(dict(session)))
return redirect(url_for('index'))
sessions = RedisHelper.convert_redis_to_json(rediis, "sessions")
resp = make_response(
render_template("index.html", form=form, sessions=sessions))
resp.set_cookie("key", "value", "key2", "value2")
return resp
def push_tweet_to_cache(cls, tweet):
queryset = Tweet.objects.filter(
user_id=tweet.user_id).order_by('-created_at')
key = USER_TWEETS_PATTERN.format(user_id=tweet.user_id)
RedisHelper.push_object(key, tweet, queryset)
def get_cached_tweet(cls, user_id):
# queryset is lazy loading, here is not get data from db yet
queryset = Tweet.objects.filter(
user_id=user_id).order_by('-created_at')
key = USER_TWEETS_PATTERN.format(user_id=user_id)
return RedisHelper.load_objects(key, queryset)
def push_newsfeed_to_cache(cls, newsfeed):
queryset = NewsFeed.objects.filter(user_id=newsfeed.user_id).order_by('-created_at')
key = USER_NEWSFEEDS_PATTERN.format(user_id=newsfeed.user_id)
RedisHelper.push_object(key, newsfeed, queryset)
def get_cached_newsfeeds(cls, user_id):
queryset = NewsFeed.objects.filter(user_id=user_id).order_by('-created_at')
key = USER_NEWSFEEDS_PATTERN.format(user_id=user_id)
return RedisHelper.load_objects(key, queryset)
def get_cached_tweets(cls, user_id):
queryset = Tweet.objects.filter(
user_id=user_id).order_by('-created_at')
key = USER_TWEETS_PATTERN.format(user_id=user_id)
return RedisHelper.load_objects(key, queryset)
def get_comments_count(self, obj):
# return obj.comments_count
return RedisHelper.get_count(obj, 'comments_count')
def get_likes_count(self, obj):
# return obj.likes_count
return RedisHelper.get_count(obj, 'likes_count')
def get_comments_count(self, obj):
# Django定义的反查机制
return RedisHelper.get_count(obj, 'comments_count')