87 lines
1.9 KiB
Ruby
87 lines
1.9 KiB
Ruby
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.try(:topic_id)
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# don't leak private categories into the "everything" group
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user = category ? CategoryFeaturedTopic.fake_admin : nil
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options = {
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per_page: SiteSetting.category_featured_topics,
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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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options[:category] = category.id if category
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query = TopicQuery.new(user, options)
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results = query.latest_results.order('RANDOM()')
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.where(closed: false, archived: false)
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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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results.each do |id|
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$redis.rpush(key, id)
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end
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$redis.expire(key, 2.days)
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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 = $redis.multi do
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$redis.lrange(key, 0, count-1)
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$redis.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 = $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 && $redis.llen(key) < BACKFILL_LOW_WATER_MARK
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Scheduler::Defer.later("backfill") do
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backfill(category)
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end
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end
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results
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end
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def self.clear_cache!
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$redis.keys('random_topic_cache*').each{|k| $redis.del k}
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end
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def self.cache_key(category=nil)
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"random_topic_cache_#{category.try(:id)}"
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end
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end
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