use root_account association when possible

when our context is an assignment we currently are loading a
rubric_association to identify the root_account

test plan
 - specs should pass

fixes VICE-1280
flag = none

Change-Id: I9d9493da1d80cb8208e999619700f657a8c00bca
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/263328
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Tested-by: Mauricio Ribeiro <mauricio.ribeiro@instructure.com>
Reviewed-by: Mauricio Ribeiro <mauricio.ribeiro@instructure.com>
QA-Review: Mauricio Ribeiro <mauricio.ribeiro@instructure.com>
Product-Review: Mauricio Ribeiro <mauricio.ribeiro@instructure.com>

app/models/message.rb

@@ -370,21 +370,29 @@ class Message < ActiveRecord::Base
   end
 
   # infer a root account associated with the context that the user can log in to
-  def link_root_account
+  def link_root_account(pre_loaded_account: nil)
+    context = pre_loaded_account
     @root_account ||= begin
-      context = self.context
+      context ||= self.context
       if context.is_a?(CommunicationChannel) && @data&.root_account_id
         root_account = Account.where(id: @data.root_account_id).first
         context = root_account if root_account
       end
 
-      context = context.assignment if context.respond_to?(:assignment) && context.assignment
+      # root_account is on lots of objects, use it when we can.
+      context = context.root_account if context.respond_to?(:root_account)
+      # some of these `context =` may not be relevant now that we have
+      # root_account on many classes, but root_account doesn't respond to them
+      # and so it's fast, and there are a lot of ways to generate a message.
+      context = context.assignment.root_account if context.respond_to?(:assignment) && context.assignment
       context = context.rubric_association.context if context.respond_to?(:rubric_association) && context.rubric_association
       context = context.appointment_group.contexts.first if context.respond_to?(:appointment_group) && context.appointment_group
       context = context.master_template.course if context.respond_to?(:master_template) && context.master_template
       context = context.context if context.respond_to?(:context)
       context = context.account if context.respond_to?(:account)
       context = context.root_account if context.respond_to?(:root_account)
+
+      # Going through SisPseudonym.for is important since the account could change
       if context && context.respond_to?(:root_account)
         p = SisPseudonym.for(user, context, type: :implicit, require_sis: false)
         context = p.account if p
@@ -606,9 +614,12 @@ class Message < ActiveRecord::Base
   # path_type - The path to send the message across, e.g, 'email'.
   #
   # Returns nothing.
-  def parse!(path_type=nil)
+  def parse!(path_type=nil, root_account: nil)
     raise StandardError, "Cannot parse without a context" unless self.context
 
+    # set @root_account using our pre_loaded_account, because link_root_account
+    # is called many times.
+    link_root_account(pre_loaded_account: root_account)
     # Get the users timezone but maintain the original timezone in order to set it back at the end
     original_time_zone = Time.zone.name || "UTC"
     user_time_zone     = self.user.try(:time_zone) || root_account_time_zone || original_time_zone

lib/notification_message_creator.rb

@@ -153,7 +153,7 @@ class NotificationMessageCreator
   def build_summary_for(user, policy)
     user.shard.activate do
       message = user.messages.build(message_options_for(user))
-      message.parse!('summary')
+      message.parse!('summary', root_account: @account)
       delayed_message = policy.delayed_messages.build(:notification => @notification,
                                     :frequency => policy.frequency,
                                     # policy.communication_channel should
@@ -179,7 +179,7 @@ class NotificationMessageCreator
     return if @notification.summarizable? && too_many_messages_for?(user) && ['email', 'sms'].include?(channel.path_type)
     message_options = message_options_for(user)
     message = user.messages.build(message_options.merge(communication_channel: channel, to: channel.path))
-    message&.parse!
+    message&.parse!(root_account: @account)
     message.workflow_state = 'bounced' if channel.bouncing?
     message
   end
@@ -205,7 +205,7 @@ class NotificationMessageCreator
     # if a user has never logged in, let's not spam the dashboard for no reason.
     return unless @notification.dashboard? && @notification.show_in_feed? && !user.pre_registered?
     message = user.messages.build(message_options_for(user).merge(:to => 'dashboard'))
-    message.parse!
+    message.parse!(root_account: @account)
     message
   end