Calculate trends in temporary sets to avoid having to manage items that go below the decay threshold while not having any moments where a half-processed set is accessible to end-users
99 lines
2.4 KiB
Ruby
99 lines
2.4 KiB
Ruby
# frozen_string_literal: true
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class Trends::Tags < Trends::Base
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PREFIX = 'trending_tags'
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self.default_options = {
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threshold: 5,
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review_threshold: 3,
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max_score_cooldown: 2.days.freeze,
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max_score_halflife: 4.hours.freeze,
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decay_threshold: 1,
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}
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def register(status, at_time = Time.now.utc)
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return unless !status.reblog? && status.public_visibility? && !status.account.silenced?
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status.tags.each do |tag|
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add(tag, status.account_id, at_time) if tag.usable?
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end
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end
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def add(tag, account_id, at_time = Time.now.utc)
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tag.history.add(account_id, at_time)
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record_used_id(tag.id, at_time)
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end
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def refresh(at_time = Time.now.utc)
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tags = Tag.where(id: (recently_used_ids(at_time) + currently_trending_ids(false, -1)).uniq)
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calculate_scores(tags, at_time)
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end
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def request_review
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tags = Tag.where(id: currently_trending_ids(false, -1))
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tags.filter_map do |tag|
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next unless would_be_trending?(tag.id) && !tag.trendable? && tag.requires_review_notification?
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tag.touch(:requested_review_at)
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tag
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end
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end
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protected
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def key_prefix
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PREFIX
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end
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def klass
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Tag
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end
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private
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def calculate_scores(tags, at_time)
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items = []
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tags.each do |tag|
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expected = tag.history.get(at_time - 1.day).accounts.to_f
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expected = 1.0 if expected.zero?
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observed = tag.history.get(at_time).accounts.to_f
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max_time = tag.max_score_at
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max_score = tag.max_score
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max_score = 0 if max_time.nil? || max_time < (at_time - options[:max_score_cooldown])
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score = begin
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if expected > observed || observed < options[:threshold]
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0
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else
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((observed - expected)**2) / expected
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end
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end
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if score > max_score
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max_score = score
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max_time = at_time
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# Not interested in triggering any callbacks for this
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tag.update_columns(max_score: max_score, max_score_at: max_time)
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end
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decaying_score = max_score * (0.5**((at_time.to_f - max_time.to_f) / options[:max_score_halflife].to_f))
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next unless decaying_score >= options[:decay_threshold]
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items << { score: decaying_score, item: tag }
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end
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replace_items('', items)
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end
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def filter_for_allowed_items(items)
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items.select { |item| item[:item].trendable? }
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end
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def would_be_trending?(id)
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score(id) > score_at_rank(options[:review_threshold] - 1)
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end
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end
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