Move string similarity algorithm into constant

lib/finish_unfinished_persons.rb

@@ -30,7 +30,7 @@ def self.search_persons(competition_ids = nil)
     unfinished_persons = []
     available_id_spots = {} # to make sure that all of the newcomer IDs that we're creating in one batch are unique among each other
 
-    persons_cache = Person.select(:id, :wca_id, :name, :dob, :countryId).to_a
+    persons_cache = Person.select(:id, :wca_id, :name, :dob, :countryId)
 
     unfinished_person_results.each do |res|
       next if unfinished_persons.length >= MAX_PER_BATCH
@@ -99,14 +99,12 @@ def self.compute_similar_persons(result, persons_cache, n = 5)
                       .take(n)
   end
 
-  def self.string_similarity_algorithm
-    # Original PHP implementation uses PHP stdlib `string_similarity` function, which is custom built
-    # and "kinda like" Jaro-Winkler. I felt that the rewrite warrants a standardised matching algorithm.
-    FuzzyStringMatch::JaroWinkler.create(:native)
-  end
+  # Original PHP implementation uses PHP stdlib `string_similarity` function, which is custom built
+  # and "kinda like" Jaro-Winkler. I felt that the rewrite warrants a standardised matching algorithm.
+  JARO_WINKLER_ALGO = FuzzyStringMatch::JaroWinkler.create(:native)
 
   def self.string_similarity(a, b)
-    self.string_similarity_algorithm.getDistance(a, b)
+    JARO_WINKLER_ALGO.getDistance(a, b)
   end
 
   def self.compute_semi_id(competition_year, person_name, available_per_semi = {})