Jetpack_Sync_Settings::set_is_sending PHP Method

    static function set_is_sending($is_sending)
    {
        self::$is_sending = $is_sending;
    }

 public function do_sync_for_queue($queue)
 {
     do_action('jetpack_sync_before_send_queue_' . $queue->id);
     if ($queue->size() === 0) {
         return false;
     }
     // now that we're sure we are about to sync, try to
     // ignore user abort so we can avoid getting into a
     // bad state
     if (function_exists('ignore_user_abort')) {
         ignore_user_abort(true);
     }
     $buffer = $queue->checkout_with_memory_limit($this->dequeue_max_bytes, $this->upload_max_rows);
     if (!$buffer) {
         // buffer has no items
         return false;
     }
     if (is_wp_error($buffer)) {
         return $buffer;
     }
     list($items_to_send, $skipped_items_ids, $items) = $this->get_items_to_send($buffer, true);
     /**
      * Fires when data is ready to send to the server.
      * Return false or WP_Error to abort the sync (e.g. if there's an error)
      * The items will be automatically re-sent later
      *
      * @since 4.2.0
      *
      * @param array $data The action buffer
      * @param string $codec The codec name used to encode the data
      * @param double $time The current time
      * @param string $queue The queue used to send ('sync' or 'full_sync')
      */
     Jetpack_Sync_Settings::set_is_sending(true);
     $processed_item_ids = apply_filters('jetpack_sync_send_data', $items_to_send, $this->codec->name(), microtime(true), $queue->id);
     Jetpack_Sync_Settings::set_is_sending(false);
     if (!$processed_item_ids || is_wp_error($processed_item_ids)) {
         $checked_in_item_ids = $queue->checkin($buffer);
         if (is_wp_error($checked_in_item_ids)) {
             error_log('Error checking in buffer: ' . $checked_in_item_ids->get_error_message());
             $queue->force_checkin();
         }
         if (is_wp_error($processed_item_ids)) {
             return $processed_item_ids;
         }
         // returning a WP_Error is a sign to the caller that we should wait a while
         // before syncing again
         return new WP_Error('server_error');
     } else {
         // detect if the last item ID was an error
         $had_wp_error = is_wp_error(end($processed_item_ids));
         if ($had_wp_error) {
             $wp_error = array_pop($processed_item_ids);
         }
         // also checkin any items that were skipped
         if (count($skipped_items_ids) > 0) {
             $processed_item_ids = array_merge($processed_item_ids, $skipped_items_ids);
         }
         $processed_items = array_intersect_key($items, array_flip($processed_item_ids));
         /**
          * Allows us to keep track of all the actions that have been sent.
          * Allows us to calculate the progress of specific actions.
          *
          * @since 4.2.0
          *
          * @param array $processed_actions The actions that we send successfully.
          */
         do_action('jetpack_sync_processed_actions', $processed_items);
         $queue->close($buffer, $processed_item_ids);
         // returning a WP_Error is a sign to the caller that we should wait a while
         // before syncing again
         if ($had_wp_error) {
             return $wp_error;
         }
     }
     return true;
 }