mirror of
https://github.com/discourse/discourse.git
synced 2024-11-23 15:54:23 +08:00
99 lines
2.3 KiB
Ruby
99 lines
2.3 KiB
Ruby
# frozen_string_literal: true
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class RandomTopicSelector
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BACKFILL_SIZE = 3000
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BACKFILL_LOW_WATER_MARK = 500
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def self.backfill(category = nil)
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exclude = category&.topic_id
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options = {
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per_page: category ? category.num_featured_topics : 3,
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visible: true,
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no_definitions: true,
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}
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options[:except_topic_ids] = [category.topic_id] if exclude
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if category
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options[:category] = category.id
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# NOTE: at the moment this site setting scopes tightly to a category (excluding subcats)
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# this is done so we don't populate a junk cache
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options[:no_subcategories] = true if SiteSetting.limit_suggested_to_category
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# don't leak private categories into the "everything" group
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options[:guardian] = Guardian.new(Discourse.system_user)
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end
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query = TopicQuery.new(nil, options)
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results =
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query
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.latest_results
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.order("RANDOM()")
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.where(closed: false, archived: false)
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.where("topics.created_at > ?", SiteSetting.suggested_topics_max_days_old.days.ago)
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.limit(BACKFILL_SIZE)
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.reorder("RANDOM()")
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.pluck(:id)
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key = cache_key(category)
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if results.present?
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Discourse.redis.multi do |transaction|
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transaction.rpush(key, results)
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transaction.expire(key, 2.days)
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end
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end
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results
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end
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def self.next(count, category = nil)
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key = cache_key(category)
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results = []
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return results if count < 1
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results =
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Discourse.redis.multi do |transaction|
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transaction.lrange(key, 0, count - 1)
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transaction.ltrim(key, count, -1)
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end
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if !results.is_a?(Array) # Redis is in readonly mode
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results = Discourse.redis.lrange(key, 0, count - 1)
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else
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results = results[0]
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end
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results.map!(&:to_i)
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left = count - results.length
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backfilled = false
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if left > 0
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ids = backfill(category)
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backfilled = true
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results += ids[0...count]
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results.uniq!
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results = results[0...count]
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end
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if !backfilled && Discourse.redis.llen(key) < BACKFILL_LOW_WATER_MARK
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Scheduler::Defer.later("backfill") { backfill(category) }
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end
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results
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end
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def self.cache_key(category = nil)
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"random_topic_cache_#{category&.id}"
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end
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def self.clear_cache!
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Discourse.redis.delete_prefixed(cache_key)
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end
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end
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