Merge pull request #30550 from tgxworld/fix_memoization_preload

PERF: Partially recover some performance when preloading. 

activerecord/lib/active_record/associations/preloader/association.rb

@@ -50,20 +50,14 @@ def associate_records_to_owner(owner, records)
           end
 
           def owner_keys
-            unless defined?(@owner_keys)
-              @owner_keys = owners.map do |owner|
-                owner[owner_key_name]
-              end
-              @owner_keys.uniq!
-              @owner_keys.compact!
-            end
-            @owner_keys
+            @owner_keys ||= owners_by_key.keys
           end
 
           def owners_by_key
             unless defined?(@owners_by_key)
               @owners_by_key = owners.each_with_object({}) do |owner, h|
-                h[convert_key(owner[owner_key_name])] = owner
+                key = convert_key(owner[owner_key_name])
+                h[key] = owner if key
               end
             end
             @owners_by_key

activerecord/lib/active_record/attribute_methods/primary_key.rb

@@ -17,13 +17,15 @@ def to_key
       # Returns the primary key value.
       def id
         sync_with_transaction_state
-        _read_attribute(self.class.primary_key) if self.class.primary_key
+        primary_key = self.class.primary_key
+        _read_attribute(primary_key) if primary_key
       end
 
       # Sets the primary key value.
       def id=(value)
         sync_with_transaction_state
-        _write_attribute(self.class.primary_key, value) if self.class.primary_key
+        primary_key = self.class.primary_key
+        _write_attribute(primary_key, value) if primary_key
       end
 
       # Queries the primary key value.

activerecord/lib/active_record/attribute_methods/read.rb

@@ -58,8 +58,9 @@ def read_attribute(attr_name, &block)
           attr_name.to_s
         end
 
-        name = self.class.primary_key if name == "id".freeze && self.class.primary_key
-        sync_with_transaction_state if name == self.class.primary_key
+        primary_key = self.class.primary_key
+        name = primary_key if name == "id".freeze && primary_key
+        sync_with_transaction_state if name == primary_key
         _read_attribute(name, &block)
       end
 

activerecord/lib/active_record/attribute_methods/write.rb

@@ -39,8 +39,9 @@ def write_attribute(attr_name, value)
           attr_name.to_s
         end
 
-        name = self.class.primary_key if name == "id".freeze && self.class.primary_key
-        sync_with_transaction_state if name == self.class.primary_key
+        primary_key = self.class.primary_key
+        name = primary_key if name == "id".freeze && primary_key
+        sync_with_transaction_state if name == primary_key
         _write_attribute(name, value)
       end