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mastodon/app/models/trends/statuses.rb

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# frozen_string_literal: true
class Trends::Statuses < Trends::Base
PREFIX = 'trending_statuses'
BATCH_SIZE = 100
self.default_options = {
threshold: 5,
review_threshold: 3,
score_halflife: 1.hour.freeze,
decay_threshold: 0.3,
}
class Query < Trends::Query
def to_arel
scope = Status.joins(:trend).reorder(score: :desc)
scope = scope.reorder(language_order_clause.desc, score: :desc) if preferred_languages.present?
scope = scope.merge(StatusTrend.allowed) if @allowed
scope = scope.not_excluded_by_account(@account).not_domain_blocked_by_account(@account) if @account.present?
scope = scope.offset(@offset) if @offset.present?
scope = scope.limit(@limit) if @limit.present?
scope
end
private
def language_order_clause
Arel::Nodes::Case.new.when(StatusTrend.arel_table[:language].in(preferred_languages)).then(1).else(0)
end
end
def register(status, at_time = Time.now.utc)
add(status.proper, status.account_id, at_time) if eligible?(status.proper)
end
def add(status, _account_id, at_time = Time.now.utc)
record_used_id(status.id, at_time)
end
def query
Query.new(key_prefix, klass)
end
def refresh(at_time = Time.now.utc)
# First, recalculate scores for statuses that were trending previously. We split the queries
# to avoid having to load all of the IDs into Ruby just to send them back into Postgres
Status.where(id: StatusTrend.select(:status_id)).includes(:status_stat, :account).reorder(nil).find_in_batches(batch_size: BATCH_SIZE) do |statuses|
calculate_scores(statuses, at_time)
end
# Then, calculate scores for statuses that were used today. There are potentially some
# duplicate items here that we might process one more time, but that should be fine
Status.where(id: recently_used_ids(at_time)).includes(:status_stat, :account).reorder(nil).find_in_batches(batch_size: BATCH_SIZE) do |statuses|
calculate_scores(statuses, at_time)
end
# Now that all trends have up-to-date scores, and all the ones below the threshold have
# been removed, we can recalculate their positions
StatusTrend.recalculate_ordered_rank
end
def request_review
StatusTrend.locales.flat_map do |language|
score_at_threshold = StatusTrend.where(language: language, allowed: true).by_rank.ranked_below(options[:review_threshold]).first&.score || 0
status_trends = StatusTrend.where(language: language, allowed: false).joins(:status).includes(status: :account)
status_trends.filter_map do |trend|
status = trend.status
if trend.score > score_at_threshold && !status.trendable? && status.requires_review_notification?
status.account.touch(:requested_review_at)
status
end
end
end
end
protected
def key_prefix
PREFIX
end
def klass
Status
end
private
def eligible?(status)
status.created_at.past? && status.public_visibility? && status.account.discoverable? && !status.account.silenced? && !status.account.sensitized? && status.spoiler_text.blank? && !status.sensitive? && !status.reply? && valid_locale?(status.language)
end
def calculate_scores(statuses, at_time)
items = statuses.map do |status|
expected = 1.0
observed = (status.reblogs_count + status.favourites_count).to_f
score = if expected > observed || observed < options[:threshold]
0
else
((observed - expected)**2) / expected
end
decaying_score = if score.zero? || !eligible?(status)
0
else
score * (0.5**((at_time.to_f - status.created_at.to_f) / options[:score_halflife].to_f))
end
[decaying_score, status]
end
to_insert = items.filter { |(score, _)| score >= options[:decay_threshold] }
to_delete = items.filter { |(score, _)| score < options[:decay_threshold] }
StatusTrend.upsert_all(to_insert.map { |(score, status)| { status_id: status.id, account_id: status.account_id, score: score, language: status.language, allowed: status.trendable? || false } }, unique_by: :status_id) if to_insert.any?
StatusTrend.where(status_id: to_delete.map { |(_, status)| status.id }).delete_all if to_delete.any?
end
end