- # frozen_string_literal: true
-
- class TrendingTags
- KEY = 'trending_tags'
- EXPIRE_HISTORY_AFTER = 7.days.seconds
- EXPIRE_TRENDS_AFTER = 1.day.seconds
- THRESHOLD = 5
-
- class << self
- include Redisable
-
- def record_use!(tag, account, at_time = Time.now.utc)
- return if disallowed_hashtags.include?(tag.name) || account.silenced? || account.bot?
-
- increment_historical_use!(tag.id, at_time)
- increment_unique_use!(tag.id, account.id, at_time)
- increment_vote!(tag.id, at_time)
- end
-
- def get(limit)
- key = "#{KEY}:#{Time.now.utc.beginning_of_day.to_i}"
- tag_ids = redis.zrevrange(key, 0, limit - 1).map(&:to_i)
- tags = Tag.where(id: tag_ids).to_a.each_with_object({}) { |tag, h| h[tag.id] = tag }
- tag_ids.map { |tag_id| tags[tag_id] }.compact
- end
-
- private
-
- def increment_historical_use!(tag_id, at_time)
- key = "activity:tags:#{tag_id}:#{at_time.beginning_of_day.to_i}"
- redis.incrby(key, 1)
- redis.expire(key, EXPIRE_HISTORY_AFTER)
- end
-
- def increment_unique_use!(tag_id, account_id, at_time)
- key = "activity:tags:#{tag_id}:#{at_time.beginning_of_day.to_i}:accounts"
- redis.pfadd(key, account_id)
- redis.expire(key, EXPIRE_HISTORY_AFTER)
- end
-
- def increment_vote!(tag_id, at_time)
- key = "#{KEY}:#{at_time.beginning_of_day.to_i}"
- expected = redis.pfcount("activity:tags:#{tag_id}:#{(at_time - 1.day).beginning_of_day.to_i}:accounts").to_f
- expected = 1.0 if expected.zero?
- observed = redis.pfcount("activity:tags:#{tag_id}:#{at_time.beginning_of_day.to_i}:accounts").to_f
-
- if expected > observed || observed < THRESHOLD
- redis.zrem(key, tag_id.to_s)
- else
- score = ((observed - expected)**2) / expected
- redis.zadd(key, score, tag_id.to_s)
- end
-
- redis.expire(key, EXPIRE_TRENDS_AFTER)
- end
-
- def disallowed_hashtags
- return @disallowed_hashtags if defined?(@disallowed_hashtags)
-
- @disallowed_hashtags = Setting.disallowed_hashtags.nil? ? [] : Setting.disallowed_hashtags
- @disallowed_hashtags = @disallowed_hashtags.split(' ') if @disallowed_hashtags.is_a? String
- @disallowed_hashtags = @disallowed_hashtags.map(&:downcase)
- end
- end
- end
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