public function DatabaseQueue::claimItem in Drupal 10

Same name and namespace in other branches

1. 8 core/lib/Drupal/Core/Queue/DatabaseQueue.php \Drupal\Core\Queue\DatabaseQueue::claimItem()
2. 9 core/lib/Drupal/Core/Queue/DatabaseQueue.php \Drupal\Core\Queue\DatabaseQueue::claimItem()

File

core/lib/Drupal/Core/Queue/DatabaseQueue.php, line 116

Class

DatabaseQueue

Default queue implementation.

Namespace

Drupal\Core\Queue

Code

public function claimItem($lease_time = 30) {

  // Claim an item by updating its expire fields. If claim is not successful
  // another thread may have claimed the item in the meantime. Therefore loop
  // until an item is successfully claimed or we are reasonably sure there
  // are no unclaimed items left.
  while (TRUE) {
    try {
      $item = $this->connection
        ->queryRange('SELECT [data], [created], [item_id] FROM {' . static::TABLE_NAME . '} q WHERE [expire] = 0 AND [name] = :name ORDER BY [created], [item_id] ASC', 0, 1, [
        ':name' => $this->name,
      ])
        ->fetchObject();
    } catch (\Exception $e) {
      $this
        ->catchException($e);
    }

    // If the table does not exist there are no items currently available to
    // claim.
    if (empty($item)) {
      return FALSE;
    }

    // Try to update the item. Only one thread can succeed in UPDATEing the
    // same row. We cannot rely on REQUEST_TIME because items might be
    // claimed by a single consumer which runs longer than 1 second. If we
    // continue to use REQUEST_TIME instead of the current time(), we steal
    // time from the lease, and will tend to reset items before the lease
    // should really expire.
    $update = $this->connection
      ->update(static::TABLE_NAME)
      ->fields([
      'expire' => \Drupal::time()
        ->getCurrentTime() + $lease_time,
    ])
      ->condition('item_id', $item->item_id)
      ->condition('expire', 0);

    // If there are affected rows, this update succeeded.
    if ($update
      ->execute()) {
      $item->data = unserialize($item->data);
      return $item;
    }
  }
}