FIX: ensure group's users counters are kept in sync

app/controllers/admin/groups_controller.rb

@@ -66,6 +66,7 @@ class Admin::GroupsController < Admin::AdminController
     group.title = group.automatic ? nil : title
 
     if group.save
+      Group.reset_counters(group.id, :group_users)
       render_serialized(group, BasicGroupSerializer)
     else
       render_json_error group
@@ -101,6 +102,8 @@ class Admin::GroupsController < Admin::AdminController
       group.group_users.where(user_id: user.id).update_all(owner: true)
     end
 
+    Group.reset_counters(group.id, :group_users)
+
     render json: success_json
   end
 
@@ -111,6 +114,8 @@ class Admin::GroupsController < Admin::AdminController
     user = User.find(params[:user_id].to_i)
     group.group_users.where(user_id: user.id).update_all(owner: false)
 
+    Group.reset_counters(group.id, :group_users)
+
     render json: success_json
   end
 

app/jobs/regular/automatic_group_membership.rb

@@ -13,15 +13,17 @@ module Jobs
 
       domains = group.automatic_membership_email_domains.gsub('.', '\.')
 
-      User.where("email ~* '@(#{domains})$' and users.id not in (
+      User.where("email ~* '@(#{domains})$'")
-                    select user_id from group_users where group_users.group_id = ?
+          .where("users.id NOT IN (SELECT user_id FROM group_users WHERE group_users.group_id = ?)", group_id)
-                )", group_id).find_each do |user|
+          .find_each do |user|
         begin
           group.add(user)
         rescue ActiveRecord::RecordNotUnique, PG::UniqueViolation
           # we don't care about this
         end
       end
+
+      Group.reset_counters(group.id, :group_users)
     end
 
   end

app/jobs/scheduled/ensure_db_consistency.rb

@@ -5,7 +5,7 @@ module Jobs
 
     def execute(args)
       UserVisit.ensure_consistency!
-      Group.refresh_automatic_groups!
+      Group.ensure_consistency!
       Notification.ensure_consistency!
       UserAction.ensure_consistency!
       TopicFeaturedUsers.ensure_consistency!

app/models/group.rb

@@ -217,6 +217,17 @@ class Group < ActiveRecord::Base
     group
   end
 
+  def self.ensure_consistency!
+    reset_all_counters
+    refresh_automatic_groups
+  end
+
+  def self.reset_all_counters
+    Group.pluck(:id).each do |group_id|
+      Group.reset_counters(group_id, :group_users)
+    end
+  end
+
   def self.refresh_automatic_groups!(*args)
     if args.length == 0
       args = AUTO_GROUPS.keys