diff -r 07239de796bb -r e756a8c72c3d cms/drupal/includes/batch.queue.inc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/cms/drupal/includes/batch.queue.inc	Fri Sep 08 12:04:06 2017 +0200
@@ -0,0 +1,84 @@
+<?php
+
+/**
+ * @file
+ * Queue handlers used by the Batch API.
+ *
+ * These implementations:
+ * - Ensure FIFO ordering.
+ * - Allow an item to be repeatedly claimed until it is actually deleted (no
+ *   notion of lease time or 'expire' date), to allow multipass operations.
+ */
+
+/**
+ * Defines a batch queue.
+ *
+ * Stale items from failed batches are cleaned from the {queue} table on cron
+ * using the 'created' date.
+ */
+class BatchQueue extends SystemQueue {
+
+  /**
+   * Overrides SystemQueue::claimItem().
+   *
+   * Unlike SystemQueue::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) {
+    $item = db_query_range('SELECT data, item_id FROM {queue} q WHERE name = :name ORDER BY item_id ASC', 0, 1, array(':name' => $this->name))->fetchObject();
+    if ($item) {
+      $item->data = unserialize($item->data);
+      return $item;
+    }
+    return FALSE;
+  }
+
+  /**
+   * Retrieves all remaining items in the queue.
+   *
+   * This is specific to Batch API and is not part of the DrupalQueueInterface.
+   */
+  public function getAllItems() {
+    $result = array();
+    $items = db_query('SELECT data FROM {queue} q WHERE name = :name ORDER BY item_id ASC', array(':name' => $this->name))->fetchAll();
+    foreach ($items as $item) {
+      $result[] = unserialize($item->data);
+    }
+    return $result;
+  }
+}
+
+/**
+ * Defines a batch queue for non-progressive batches.
+ */
+class BatchMemoryQueue extends MemoryQueue {
+
+  /**
+   * Overrides MemoryQueue::claimItem().
+   *
+   * Unlike MemoryQueue::claimItem(), this method provides a default lease
+   * time of 0 (no expiration) instead of 30. This allows the item to be
+   * claimed repeatedly until it is deleted.
+   */
+  public function claimItem($lease_time = 0) {
+    if (!empty($this->queue)) {
+      reset($this->queue);
+      return current($this->queue);
+    }
+    return FALSE;
+  }
+
+  /**
+   * Retrieves all remaining items in the queue.
+   *
+   * This is specific to Batch API and is not part of the DrupalQueueInterface.
+   */
+  public function getAllItems() {
+    $result = array();
+    foreach ($this->queue as $item) {
+      $result[] = $item->data;
+    }
+    return $result;
+  }
+}