class Batch in Drupal 8

Defines a batch queue handler used by the Batch API.

This implementation:

• Ensures FIFO ordering.
• Allows an item to be repeatedly claimed until it is actually deleted (no notion of lease time or 'expire' date), to allow multipass operations.

Stale items from failed batches are cleaned from the {queue} table on cron using the 'created' date.

Hierarchy

• class \Drupal\Core\Queue\DatabaseQueue implements QueueGarbageCollectionInterface, ReliableQueueInterface uses DependencySerializationTrait
  • class \Drupal\Core\Queue\Batch

Related topics

Queue operations

Queue items to allow later processing.

File

core/lib/Drupal/Core/Queue/Batch.php, line 18

Namespace

Drupal\Core\Queue

class Batch extends DatabaseQueue {

  /**
   * Overrides \Drupal\Core\Queue\DatabaseQueue::claimItem().
   *
   * Unlike \Drupal\Core\Queue\DatabaseQueue::claimItem(), this method provides
   * a default lease time of 0 (no expiration) instead of 30. This allows the
   * item to be claimed repeatedly until it is deleted.
   */
  public function claimItem($lease_time = 0) {
    try {
      $item = $this->connection
        ->queryRange('SELECT data, item_id FROM {queue} q WHERE name = :name ORDER BY item_id ASC', 0, 1, [
        ':name' => $this->name,
      ])
        ->fetchObject();
      if ($item) {
        $item->data = unserialize($item->data);
        return $item;
      }
    } catch (\Exception $e) {
      $this
        ->catchException($e);
    }
    return FALSE;
  }

  /**
   * Retrieves all remaining items in the queue.
   *
   * This is specific to Batch API and is not part of the
   * \Drupal\Core\Queue\QueueInterface.
   *
   * @return array
   *   An array of queue items.
   */
  public function getAllItems() {
    $result = [];
    try {
      $items = $this->connection
        ->query('SELECT data FROM {queue} q WHERE name = :name ORDER BY item_id ASC', [
        ':name' => $this->name,
      ])
        ->fetchAll();
      foreach ($items as $item) {
        $result[] = unserialize($item->data);
      }
    } catch (\Exception $e) {
      $this
        ->catchException($e);
    }
    return $result;
  }

}

Members

Name	Modifiers	Type	Description	Overrides
Batch::claimItem	public	function	Overrides \Drupal\Core\Queue\DatabaseQueue::claimItem(). Overrides DatabaseQueue::claimItem
Batch::getAllItems	public	function	Retrieves all remaining items in the queue.
DatabaseQueue::$connection	protected	property	The database connection.
DatabaseQueue::$name	protected	property	The name of the queue this instance is working with.
DatabaseQueue::catchException	protected	function	Act on an exception when queue might be stale.
DatabaseQueue::createItem	public	function	Adds a queue item and store it directly to the queue. Overrides QueueInterface::createItem
DatabaseQueue::createQueue	public	function	Creates a queue. Overrides QueueInterface::createQueue
DatabaseQueue::deleteItem	public	function	Deletes a finished item from the queue. Overrides QueueInterface::deleteItem
DatabaseQueue::deleteQueue	public	function	Deletes a queue and every item in the queue. Overrides QueueInterface::deleteQueue
DatabaseQueue::doCreateItem	protected	function	Adds a queue item and store it directly to the queue.
DatabaseQueue::ensureTableExists	protected	function	Check if the table exists and create it if not.
DatabaseQueue::garbageCollection	public	function	Cleans queues of garbage. Overrides QueueGarbageCollectionInterface::garbageCollection
DatabaseQueue::numberOfItems	public	function	Retrieves the number of items in the queue. Overrides QueueInterface::numberOfItems
DatabaseQueue::releaseItem	public	function	Releases an item that the worker could not process. Overrides QueueInterface::releaseItem
DatabaseQueue::schemaDefinition	public	function	Defines the schema for the queue table.
DatabaseQueue::TABLE_NAME		constant	The database table name.
DatabaseQueue::__construct	public	function	Constructs a \Drupal\Core\Queue\DatabaseQueue object.
DependencySerializationTrait::$_entityStorages	protected	property	An array of entity type IDs keyed by the property name of their storages.
DependencySerializationTrait::$_serviceIds	protected	property	An array of service IDs keyed by property name used for serialization.
DependencySerializationTrait::__sleep	public	function		1
DependencySerializationTrait::__wakeup	public	function		2