isPersistentlyCacheable example

/** * Gets entities from the persistent cache backend. * * @param array|null &$ids * If not empty, return entities that match these IDs. IDs that were found * will be removed from the list. * * @return \Drupal\Core\Entity\ContentEntityInterface[] * Array of entities from the persistent cache. */
  protected function getFromPersistentCache(array &$ids = NULL) {
    if (!$this->entityType->isPersistentlyCacheable() || empty($ids)) {
      return [];
    }
    $entities = [];
    // Build the list of cache entries to retrieve.     $cid_map = [];
    foreach ($ids as $id) {
      $cid_map[$id] = $this->buildCacheId($id);
    }
    $cids = array_values($cid_map);
    if ($cache = $this->cacheBackend->getMultiple($cids)) {
      // Get the entities that were found in the cache.