class CategoryFeaturedTopic < ActiveRecord::Base belongs_to :category belongs_to :topic NEXT_CATEGORY_ID_KEY = 'category-featured-topic:next-category-id'.freeze DEFAULT_BATCH_SIZE = 100 # Populates the category featured topics. def self.feature_topics(batched: false, batch_size: nil) current = {} CategoryFeaturedTopic.select(:topic_id, :category_id).order(:rank).each do |f| (current[f.category_id] ||= []) << f.topic_id end batch_size ||= DEFAULT_BATCH_SIZE next_category_id = batched ? $redis.get(NEXT_CATEGORY_ID_KEY).to_i : 0 categories = Category.select(:id, :topic_id, :num_featured_topics) .where('id >= ?', next_category_id) .order('id ASC') .limit(batch_size) .to_a if batched if categories.length == batch_size next_id = Category.where('id > ?', categories.last.id).order('id asc').limit(1).pluck(:id)[0] next_id ? $redis.setex(NEXT_CATEGORY_ID_KEY, 1.day, next_id) : clear_batch! else clear_batch! end end categories.each do |c| CategoryFeaturedTopic.feature_topics_for(c, current[c.id] || []) end end def self.clear_batch! $redis.del(NEXT_CATEGORY_ID_KEY) end def self.feature_topics_for(c, existing = nil) return if c.blank? query_opts = { per_page: c.num_featured_topics, except_topic_ids: [c.topic_id], visible: true, no_definitions: true } # It may seem a bit odd that we are running 2 queries here, when admin # can clearly pull out all the topics needed. # We do so, so anonymous will ALWAYS get some topics # If we only fetched as admin we may have a situation where anon can see # no featured topics (all the previous 2x topics are only visible to admins) # Add topics, even if they're in secured categories or invisible query = TopicQuery.new(CategoryFeaturedTopic.fake_admin, query_opts) results = query.list_category_topic_ids(c).uniq # Add some topics that are visible to everyone: anon_query = TopicQuery.new(nil, query_opts.merge(except_topic_ids: [c.topic_id] + results)) results += anon_query.list_category_topic_ids(c).uniq return if results == existing CategoryFeaturedTopic.transaction do CategoryFeaturedTopic.where(category_id: c.id).delete_all if results results.each_with_index do |topic_id, idx| begin c.category_featured_topics.create(topic_id: topic_id, rank: idx) rescue PG::UniqueViolation # If another process features this topic, just ignore it end end end end end def self.fake_admin # fake an admin admin = User.new admin.admin = true admin.id = -1 admin end end # == Schema Information # # Table name: category_featured_topics # # category_id :integer not null # topic_id :integer not null # created_at :datetime not null # updated_at :datetime not null # rank :integer default(0), not null # id :integer not null, primary key # # Indexes # # cat_featured_threads (category_id,topic_id) UNIQUE # index_category_featured_topics_on_category_id_and_rank (category_id,rank) #