Merge pull request #27537 from Le6ow5k1/sti

Cache results of computing model type

1 files changed, 15 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/inheritance.rb b/activerecord/lib/active_record/inheritance.rb
index a1d4f47372..fbdaeaae51 100644
--- a/activerecord/lib/active_record/inheritance.rb
+++ b/activerecord/lib/active_record/inheritance.rb
@@ -130,16 +130,26 @@ module ActiveRecord
         store_full_sti_class ? name : name.demodulize
       end
 
+      def inherited(subclass)
+        subclass.instance_variable_set(:@_type_candidates_cache, Concurrent::Map.new)
+        super
+      end
+
       protected
 
         # Returns the class type of the record using the current module as a prefix. So descendants of
         # MyApp::Business::Account would appear as MyApp::Business::AccountSubclass.
         def compute_type(type_name)
-          if type_name.match(/^::/)
+          if type_name.start_with?("::".freeze)
             # If the type is prefixed with a scope operator then we assume that
             # the type_name is an absolute reference.
             ActiveSupport::Dependencies.constantize(type_name)
           else
+            type_candidate = @_type_candidates_cache[type_name]
+            if type_candidate && type_constant = ActiveSupport::Dependencies.safe_constantize(type_candidate)
+              return type_constant
+            end
+
             # Build a list of candidates to search for
             candidates = []
             name.scan(/::|$/) { candidates.unshift "#{$`}::#{type_name}" }
@@ -147,7 +157,10 @@ module ActiveRecord
 
             candidates.each do |candidate|
               constant = ActiveSupport::Dependencies.safe_constantize(candidate)
-              return constant if candidate == constant.to_s
+              if candidate == constant.to_s
+                @_type_candidates_cache[type_name] = candidate
+                return constant
+              end
             end
 
             raise NameError.new("uninitialized constant #{candidates.first}", candidates.first)