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# frozen_string_literal: true
class TrendingTags
KEY = 'trending_tags'
HALF_LIFE = 1.day.to_i
MAX_ITEMS = 500
EXPIRE_HISTORY_AFTER = 7.days.seconds
class << self
def record_use!(tag, account, at_time = Time.now.utc)
return if disallowed_hashtags.include?(tag.name) || account.silenced?
increment_vote!(tag.id, at_time)
increment_historical_use!(tag.id, at_time)
increment_unique_use!(tag.id, account.id, at_time)
end
def get(limit)
tag_ids = redis.zrevrange(KEY, 0, limit).map(&:to_i)
tags = Tag.where(id: tag_ids).to_a.map { |tag| [tag.id, tag] }.to_h
tag_ids.map { |tag_id| tags[tag_id] }.compact
end
private
def increment_vote!(tag_id, at_time)
redis.zincrby(KEY, (2**((at_time.to_i - epoch) / HALF_LIFE)).to_f, tag_id.to_s)
redis.zremrangebyrank(KEY, 0, -MAX_ITEMS) if rand < (2.to_f / MAX_ITEMS)
end
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
# The epoch needs to be 2.5 years in the future if the half-life is one day
# While dynamic, it will always be the same within one year
def epoch
@epoch ||= Date.new(Date.current.year + 2.5, 10, 1).to_datetime.to_i
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
def redis
Redis.current
end
end
end
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