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9174716737
This method is a huge footgun in production, since it calls
the Redis KEYS command. From the Redis documentation at
https://redis.io/commands/keys/:
> Warning: consider KEYS as a command that should only be used in
production environments with extreme care. It may ruin performance when
it is executed against large databases. This command is intended for
debugging and special operations, such as changing your keyspace layout.
Don't use KEYS in your regular application code.
Since we were only using `delete_prefixed` in specs (now that we
removed the usage in production in 24ec06ff85)
we can remove this and instead rely on `use_redis_snapshotting` on the
particular tests that need this kind of clearing functionality.
95 lines
2.3 KiB
Ruby
95 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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end
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