Class: RandomTopicSelector
- Inherits:
-
Object
- Object
- RandomTopicSelector
- Defined in:
- app/services/random_topic_selector.rb
Constant Summary collapse
- BACKFILL_SIZE =
3000
- BACKFILL_LOW_WATER_MARK =
500
Class Method Summary collapse
- .backfill(category = nil) ⇒ Object
- .cache_key(category = nil) ⇒ Object
- .next(count, category = nil) ⇒ Object
Class Method Details
.backfill(category = nil) ⇒ Object
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# File 'app/services/random_topic_selector.rb', line 7 def self.backfill(category = nil) exclude = category&.topic_id = { per_page: category ? category.num_featured_topics : 3, visible: true, no_definitions: true, } [:except_topic_ids] = [category.topic_id] if exclude if category [:category] = category.id # NOTE: at the moment this site setting scopes tightly to a category (excluding subcats) # this is done so we don't populate a junk cache [:no_subcategories] = true if SiteSetting.limit_suggested_to_category # don't leak private categories into the "everything" group [:guardian] = Guardian.new(Discourse.system_user) end query = TopicQuery.new(nil, ) results = query .latest_results .order("RANDOM()") .where(closed: false, archived: false) .where("topics.created_at > ?", SiteSetting.suggested_topics_max_days_old.days.ago) .limit(BACKFILL_SIZE) .reorder("RANDOM()") .pluck(:id) key = cache_key(category) if results.present? Discourse.redis.multi do |transaction| transaction.rpush(key, results) transaction.expire(key, 2.days) end end results end |
.cache_key(category = nil) ⇒ Object
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# File 'app/services/random_topic_selector.rb', line 91 def self.cache_key(category = nil) "random_topic_cache_#{category&.id}" end |
.next(count, category = nil) ⇒ Object
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# File 'app/services/random_topic_selector.rb', line 52 def self.next(count, category = nil) key = cache_key(category) results = [] return results if count < 1 results = Discourse.redis.multi do |transaction| transaction.lrange(key, 0, count - 1) transaction.ltrim(key, count, -1) end if !results.is_a?(Array) # Redis is in readonly mode results = Discourse.redis.lrange(key, 0, count - 1) else results = results[0] end results.map!(&:to_i) left = count - results.length backfilled = false if left > 0 ids = backfill(category) backfilled = true results += ids[0...count] results.uniq! results = results[0...count] end if !backfilled && Discourse.redis.llen(key) < BACKFILL_LOW_WATER_MARK Scheduler::Defer.later("backfill") { backfill(category) } end results end |