Limit `update_tracked_fields` to write to database once/hour

app/models/user.rb

@@ -40,6 +40,16 @@ class User < ActiveRecord::Base
   devise :lockable, :recoverable, :rememberable, :trackable,
     :validatable, :omniauthable, :confirmable, :registerable
 
+  # Limit trackable fields to update at most once every hour
+  alias_method :devise_update_tracked_fields!, :update_tracked_fields!
+
+  def update_tracked_fields!(request)
+    lease = Gitlab::ExclusiveLease.new("user_update_tracked_fields:#{id}", timeout: 1.hour.to_i)
+    return unless lease.try_obtain
+
+    devise_update_tracked_fields!(request)
+  end
+
   attr_accessor :force_random_password
 
   # Virtual attribute for authenticating by either username or email

changelogs/unreleased/tc-cache-trackable-attributes.yml

+---
+title: "Limit User's trackable attributes, like `current_sign_in_at`, to update at most once/hour"
+merge_request: 11053
+author:

spec/models/user_spec.rb

@@ -344,6 +344,25 @@ describe User, models: true do
     end
   end
 
+  describe '#update_tracked_fields!', :redis do
+    let(:request) { OpenStruct.new(remote_ip: "127.0.0.1") }
+    let(:user) { create(:user) }
+
+    it 'writes trackable attributes' do
+      expect do
+        user.update_tracked_fields!(request)
+      end.to change { user.reload.current_sign_in_at }
+    end
+
+    it 'does not write trackable attributes when called a second time within the hour' do
+      user.update_tracked_fields!(request)
+
+      expect do
+        user.update_tracked_fields!(request)
+      end.not_to change { user.current_sign_in_at }
+    end
+  end
+
   shared_context 'user keys' do
     let(:user) { create(:user) }
     let!(:key) { create(:key, user: user) }