Extract unique_internal to a module

Cleanup to make user.rb smaller.
No behavior changes intended.

app/models/concerns/has_unique_internal_users.rb

+# frozen_string_literal: true
+
+module HasUniqueInternalUsers
+  extend ActiveSupport::Concern
+
+  class_methods do
+    private
+
+    def unique_internal(scope, username, email_pattern, &block)
+      scope.first || create_unique_internal(scope, username, email_pattern, &block)
+    end
+
+    def create_unique_internal(scope, username, email_pattern, &creation_block)
+      # Since we only want a single one of these in an instance, we use an
+      # exclusive lease to ensure than this block is never run concurrently.
+      lease_key = "user:unique_internal:#{username}"
+      lease = Gitlab::ExclusiveLease.new(lease_key, timeout: 1.minute.to_i)
+
+      until uuid = lease.try_obtain
+        # Keep trying until we obtain the lease. To prevent hammering Redis too
+        # much we'll wait for a bit between retries.
+        sleep(1)
+      end
+
+      # Recheck if the user is already present. One might have been
+      # added between the time we last checked (first line of this method)
+      # and the time we acquired the lock.
+      existing_user = uncached { scope.first }
+      return existing_user if existing_user.present?
+
+      uniquify = Uniquify.new
+
+      username = uniquify.string(username) { |s| User.find_by_username(s) }
+
+      email = uniquify.string(-> (n) { Kernel.sprintf(email_pattern, n) }) do |s|
+        User.find_by_email(s)
+      end
+
+      user = scope.build(
+        username: username,
+        email: email,
+        &creation_block
+      )
+
+      Users::UpdateService.new(user, user: user).execute(validate: false)
+      user
+    ensure
+      Gitlab::ExclusiveLease.cancel(lease_key, uuid)
+    end
+  end
+end

app/models/user.rb

@@ -21,6 +21,7 @@ class User < ApplicationRecord
   include OptionallySearch
   include FromUnion
   include BatchDestroyDependentAssociations
+  include HasUniqueInternalUsers
   include IgnorableColumns
 
   DEFAULT_NOTIFICATION_LEVEL = :participating
@@ -1793,48 +1794,6 @@ class User < ApplicationRecord
     end
   end
 
-  def self.unique_internal(scope, username, email_pattern, &block)
-    scope.first || create_unique_internal(scope, username, email_pattern, &block)
-  end
-
-  def self.create_unique_internal(scope, username, email_pattern, &creation_block)
-    # Since we only want a single one of these in an instance, we use an
-    # exclusive lease to ensure than this block is never run concurrently.
-    lease_key = "user:unique_internal:#{username}"
-    lease = Gitlab::ExclusiveLease.new(lease_key, timeout: 1.minute.to_i)
-
-    until uuid = lease.try_obtain
-      # Keep trying until we obtain the lease. To prevent hammering Redis too
-      # much we'll wait for a bit between retries.
-      sleep(1)
-    end
-
-    # Recheck if the user is already present. One might have been
-    # added between the time we last checked (first line of this method)
-    # and the time we acquired the lock.
-    existing_user = uncached { scope.first }
-    return existing_user if existing_user.present?
-
-    uniquify = Uniquify.new
-
-    username = uniquify.string(username) { |s| User.find_by_username(s) }
-
-    email = uniquify.string(-> (n) { Kernel.sprintf(email_pattern, n) }) do |s|
-      User.find_by_email(s)
-    end
-
-    user = scope.build(
-      username: username,
-      email: email,
-      &creation_block
-    )
-
-    Users::UpdateService.new(user, user: user).execute(validate: false) # rubocop: disable CodeReuse/ServiceClass
-    user
-  ensure
-    Gitlab::ExclusiveLease.cancel(lease_key, uuid)
-  end
-
   def groups_with_developer_maintainer_project_access
     project_creation_levels = [::Gitlab::Access::DEVELOPER_MAINTAINER_PROJECT_ACCESS]