- * <p>
- * The DeliveryQueue class maintains lists of DeliveryTasks for a single
- * destination (a subscription or another data router node) and assigns
- * delivery threads to try to deliver them. It also maintains a delivery
- * status that causes it to back off on delivery attempts after a failure.
- * <p>
- * If the most recent delivery result was a failure, then no more attempts
- * will be made for a period of time. Initially, and on the first failure
- * following a success, this delay will be DeliveryQueueHelper.getInitFailureTimer() (milliseconds).
- * If, after this delay, additional failures occur, each failure will
- * multiply the delay by DeliveryQueueHelper.getFailureBackoff() up to a
- * maximum delay specified by DeliveryQueueHelper.getMaxFailureTimer().
- * Note that this behavior applies to the delivery queue as a whole and not
- * to individual files in the queue. If multiple files are being
- * delivered and one fails, the delay will be started. If a second
- * delivery fails while the delay was active, it will not change the delay
- * or change the duration of any subsequent delay.
- * If, however, it succeeds, it will cancel the delay.
- * <p>
- * The queue maintains 3 collections of files to deliver: A todo list of
- * files that will be attempted, a working set of files that are being
- * attempted, and a retry set of files that were attempted and failed.
- * Whenever the todo list is empty and needs to be refilled, a scan of the
- * spool directory is made and the file names sorted. Any files in the working set are ignored.
- * If a DeliveryTask for the file is in the retry set, then that delivery
- * task is placed on the todo list. Otherwise, a new DeliveryTask for the
- * file is created and placed on the todo list.
- * If, when a DeliveryTask is about to be removed from the todo list, its
- * age exceeds DeliveryQueueHelper.getExpirationTimer(), then it is instead
- * marked as expired.
- * <p>
- * A delivery queue also maintains a skip flag. This flag is true if the
- * failure timer is active or if no files are found in a directory scan.
+ *
+ * <p>The DeliveryQueue class maintains lists of DeliveryTasks for a single destination (a subscription or another data
+ * router node) and assigns delivery threads to try to deliver them. It also maintains a delivery status that causes it
+ * to back off on delivery attempts after a failure.
+ *
+ * <p>If the most recent delivery result was a failure, then no more attempts will be made for a period of time.
+ * Initially, and on the first failure following a success, this delay will be DeliveryQueueHelper.getInitFailureTimer()
+ * (milliseconds). If, after this delay, additional failures occur, each failure will multiply the delay by
+ * DeliveryQueueHelper.getFailureBackoff() up to a maximum delay specified by DeliveryQueueHelper.getMaxFailureTimer().
+ * Note that this behavior applies to the delivery queue as a whole and not to individual files in the queue. If
+ * multiple files are being delivered and one fails, the delay will be started. If a second delivery fails while the
+ * delay was active, it will not change the delay or change the duration of any subsequent delay. If, however, it
+ * succeeds, it will cancel the delay.
+ *
+ * <p>The queue maintains 3 collections of files to deliver: A to do list of files that will be attempted, a working
+ * set of files that are being attempted, and a retry set of files that were attempted and failed. Whenever the to do
+ * list is empty and needs to be refilled, a scan of the spool directory is made and the file names sorted. Any files
+ * in the working set are ignored. If a DeliveryTask for the file is in the retry set, then that delivery task is placed
+ * on the to do list. Otherwise, a new DeliveryTask for the file is created and placed on the to do list. If, when a
+ * DeliveryTask is about to be removed from the to do list, its age exceeds DeliveryQueueHelper.getExpirationTimer(),
+ * then it is instead marked as expired.
+ *
+ * <p>A delivery queue also maintains a skip flag. This flag is true if the failure timer is active or if no files are
+ * found in a directory scan.