/**
 * Implements hook_cron().
 */
function middlebury_profile_sync_cron() {
  $queueFactory = \Drupal::service('queue');
  $queue = $queueFactory->get('middlebury_profile_update');

  $now = new \DateTime();
  $ttl = new \DateInterval('P1D');
  $cutOff = $now->sub($ttl);

  $storage = \Drupal::service('entity_type.manager')->getStorage('node');
  $query = $storage->getQuery()
    ->condition('type', 'profile')
    ->exists('field_external_id.value')
    ->condition('field_profile_sync', $cutOff->getTimestamp(), '<');
  $nids = $query->execute();
  if (!empty($nids)) {
    foreach ($nids as $nid) {
      $item = new \stdClass();
      $item->nid = $nid;
      $queue->createItem($item);
    }
  }
}

<?php

namespace Drupal\middlebury_profile_sync\Plugin\QueueWorker;

use Drupal\Core\Cache\CacheTagsInvalidatorInterface;
use Drupal\Core\Entity\EntityStorageInterface;
use Drupal\Core\Extension\ModuleHandler;
use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
use Drupal\Core\Queue\QueueWorkerBase;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Provides base functionality for the Profile Queue Workers.
 *
 * @QueueWorker(
 *   id = "middlebury_profile_update",
 *   title = @Translation("Middlebury Profile Update"),
 *   cron = {"time" = 15}
 * )
 */
class ProfileUpdate extends QueueWorkerBase implements ContainerFactoryPluginInterface {

  /**
   * The node storage.
   *
   * @var \Drupal\Core\Entity\EntityStorageInterface
   */
  protected $nodeStorage;

  /**
   * Cache invalidator service.
   *
   * @var \Drupal\Core\Cache\CacheTagsInvalidatorInterface
   */
  protected $cacheInvalidator;

  /**
   * The module handler.
   *
   * @var \Drupal\Core\Extension\ModuleHandler
   */
  protected $moduleHandler;

  /**
   * Creates a new ProfileUpdate object.
   *
   * @param \Drupal\Core\Entity\EntityStorageInterface $node_storage
   *   The node storage.
   * @param \Drupal\Core\Cache\CacheTagsInvalidatorInterface $cache_invalidator
   *   The cache invalidator service for marking cache invalid so that pages
   *   are notified when profiles are updated.
   * @param \Drupal\Core\Extension\ModuleHandler $module_handler
   *   The module handler.
   */
  public function __construct(EntityStorageInterface $node_storage, CacheTagsInvalidatorInterface $cache_invalidator, ModuleHandler $module_handler) {
    $this->nodeStorage = $node_storage;
    $this->cacheInvalidator = $cache_invalidator;
    $this->moduleHandler = $module_handler;
  }

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
    return new static(
      $container->get('entity_type.manager')->getStorage('node'),
      $container->get('cache_tags.invalidator'),
      $container->get('module_handler')
    );
  }

  /**
   * {@inheritdoc}
   */
  public function processItem($data) {
    $node = $this->nodeStorage->load($data->nid);

    $this->cacheInvalidator->invalidateTags(['n:' . $data->nid]);

    if ($node) {
      $changes = [];
      $this->moduleHandler->invokeAll('midd_update_profile_external', [
        $node,
        &$changes,
      ]);
      if (count($changes) > 0) {
        $node->field_profile_sync = strtotime('now');
        $node->isSavedByCron = TRUE;
        return $node->save();
      }
    }
  }

}

/**
 * Implements hook_node_presave().
 */
function middlebury_profile_sync_node_presave($node) {
  if (empty($node->isSavedByCron) && $node->getType() == 'profile' && !empty($node->field_external_id->value)) {
    $changes = [];
    $node->field_profile_sync = strtotime('now');
    \Drupal::moduleHandler()->invokeAll('midd_update_profile_external', [
      $node,
      &$changes,
    ]);
  }
}

/**
 * Implements hook_midd_update_profile_external().
 */
function middlebury_profile_sync_midd_update_profile_external($node, &$changes) {
  $storage = \Drupal::service('entity_type.manager')->getStorage('profile_source');
  $sources = $storage->loadMultiple($storage->getQuery()->execute());
  foreach ($sources as $source) {
    $changed = middlebury_profile_sync_sync_profile($source, $node);
    foreach ($changed as $change) {
      $changes[] = $change;
    }
  }
}

/**
 * Implements hook_midd_update_profile_external().
 */
function middlebury_courselist_midd_update_profile_external($node, &$changes) {
  if ($node->getType() == 'profile' && $node->field_show_courses->value) {
    $changed = \Drupal::service('middlebury_courselist.profile_sync')->syncNode($node);
    foreach ($changed as $change) {
      $changes[] = $change;
    }
  }
}

/**
 * Update a profile.
 *
 * @param \Drupal\middlebury_profile_sync\ProfileInterface $profile
 *   The Profile data.
 * @param \Drupal\node\Entity\Node $node
 *   The profile node.
 */
function middlebury_profile_sync_update_profile(ProfileInterface $profile, Node $node) {
  $changed_fields = [];

  // Email.
  if (empty($node->field_override_email->value) && $profile->hasEmail()) {
    if ($node->field_email->value != $profile->getEmail()) {
      $changed_fields[] = t('email');
    }
    $node->field_email = $profile->getEmail();
  }

  // ... snip ...

  // Job title.
  if (empty($node->field_override_job_title->value) && $profile->hasJobTitle()) {
    if ($node->field_job_title->value != $profile->getJobTitle()) {
      $changed_fields[] = t('job_title');
    }
    $node->field_job_title = $profile->getJobTitle();
  }

  return $changed_fields;
}