Always update counter caches in memory when adding records

Before, calling `size` would only work if it skipped the cache, and
would return a different result from the cache, but only if:

- The association was previously loaded
- Or you called size previously
- But only if the size was 0 when you called it

This ensures that the counter is appropriately updated in memory.

2 files changed, 26 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/associations/has_many_association.rb b/activerecord/lib/active_record/associations/has_many_association.rb
index 2727e23870..477888228d 100644
--- a/activerecord/lib/active_record/associations/has_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_association.rb
@@ -83,6 +83,13 @@ module ActiveRecord
           if has_cached_counter?(reflection)
             counter = cached_counter_attribute_name(reflection)
             owner.class.update_counters(owner.id, counter => difference)
+            update_counter_in_memory(difference, reflection)
+          end
+        end
+
+        def update_counter_in_memory(difference, reflection = reflection())
+          if has_cached_counter?(reflection)
+            counter = cached_counter_attribute_name(reflection)
             owner[counter] += difference
             owner.changed_attributes.delete(counter) # eww
           end
@@ -137,6 +144,25 @@ module ActiveRecord
             false
           end
         end
+
+        def concat_records(records, *)
+          update_counter_if_success(super, records.length)
+        end
+
+        def _create_record(attributes, *)
+          if attributes.is_a?(Array)
+            super
+          else
+            update_counter_if_success(super, 1)
+          end
+        end
+
+        def update_counter_if_success(saved_successfully, difference)
+          if saved_successfully
+            update_counter_in_memory(difference)
+          end
+          saved_successfully
+        end
     end
   end
 end
diff --git a/activerecord/lib/active_record/associations/has_many_through_association.rb b/activerecord/lib/active_record/associations/has_many_through_association.rb
index 175019a72b..00234dc8f4 100644
--- a/activerecord/lib/active_record/associations/has_many_through_association.rb
+++ b/activerecord/lib/active_record/associations/has_many_through_association.rb
@@ -63,7 +63,6 @@ module ActiveRecord
         end
 
         save_through_record(record)
-        update_counter(1)
         record
       end