Express follow_recommendations in terms of account_summaries rather than accounts, integrate filters that are unconditionally used, and materialize the resulting view. This should result in the bulk of the computation being performed only once instead of **once per recommendation language**.
		
			
				
	
	
		
			62 lines
		
	
	
	
		
			1.8 KiB
		
	
	
	
		
			Ruby
		
	
	
	
	
	
			
		
		
	
	
			62 lines
		
	
	
	
		
			1.8 KiB
		
	
	
	
		
			Ruby
		
	
	
	
	
	
# frozen_string_literal: true
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class Scheduler::FollowRecommendationsScheduler
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  include Sidekiq::Worker
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  include Redisable
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  sidekiq_options retry: 0
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  # The maximum number of accounts that can be requested in one page from the
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  # API is 80, and the suggestions API does not allow pagination. This number
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  # leaves some room for accounts being filtered during live access
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  SET_SIZE = 100
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  def perform
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    # Maintaining a materialized view speeds-up subsequent queries significantly
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    AccountSummary.refresh
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    FollowRecommendation.refresh
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    fallback_recommendations = FollowRecommendation.limit(SET_SIZE).index_by(&:account_id)
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    I18n.available_locales.each do |locale|
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      recommendations = begin
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        if AccountSummary.safe.filtered.localized(locale).exists? # We can skip the work if no accounts with that language exist
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          FollowRecommendation.localized(locale).limit(SET_SIZE).index_by(&:account_id)
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        else
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          {}
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        end
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      end
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      # Use language-agnostic results if there are not enough language-specific ones
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      missing = SET_SIZE - recommendations.keys.size
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      if missing.positive?
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        added = 0
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        # Avoid duplicate results
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        fallback_recommendations.each_value do |recommendation|
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          next if recommendations.key?(recommendation.account_id)
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          recommendations[recommendation.account_id] = recommendation
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          added += 1
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          break if added >= missing
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        end
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      end
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      redis.pipelined do
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        redis.del(key(locale))
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        recommendations.each_value do |recommendation|
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          redis.zadd(key(locale), recommendation.rank, recommendation.account_id)
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        end
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      end
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    end
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  end
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  private
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  def key(locale)
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    "follow_recommendations:#{locale}"
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  end
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end
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