Issue #3362297 New Queue Worker to send Email Notifications

Changes:

• New queue recurring_events_registration_email_notifications_queue_worker to send Email Notifications. Queue Worker Class: modules/recurring_events_registration/src/Plugin/QueueWorker/EmailNotificationsQueueWorker.php
• Actions that trigger emails to multiple recipients (registrants) were modified to add items to the queue instead of using recurring_events_registration_send_notification(). Namely, the notifications corresponding to these keys: registration_reminder, series_modification_notification, instance_modification_notification, instance_deletion_notification, series_deletion_notification
• Items can be added to the queue using the new helper function addEmailNotificationToQueue($key, RegistrantInterface $registrant) in the recurring_events_registration.notification_service service
• The new function addEmailNotificationToQueue($key, RegistrantInterface $registrant) also invokes hook_recurring_events_registration_send_notification_alter to let modules determine whether a notification will be added to the queue based on properties of the Registrant
• Actions that trigger just one email notification to one recipient (registrant) continue using recurring_events_registration_send_notification(). Namely: promotion_notification, registration_notification, waitlist_notification

Pending:

• Maybe provide a UI to configure if the system should use Queue Worker or not. People could have a checkbox to decide whether emails for notification types that are sent to multiple recipients should use the queue or send immediately.

modules/recurring_events_registration/modules/recurring_events_reminders/recurring_events_reminders.module

@@ -154,6 +154,7 @@ function recurring_events_reminders_cron() {
       $registration_creation_service->setEventInstance($instance);
 
       $registrants = $registration_creation_service->retrieveRegisteredParties();
+
       if (empty($registrants)) {
         return;
       }
@@ -162,7 +163,8 @@ function recurring_events_reminders_cron() {
 
       // Send an email to all registrants.
       foreach ($registrants as $registrant) {
-        recurring_events_registration_send_notification($key, $registrant);
+        // Add each notification to be sent to the queue.
+        \Drupal::service('recurring_events_registration.notification_service')->addEmailNotificationToQueue($key, $registrant);
       }
     }
   }