Javadoc
Abstract QueueRefresher class. Scheduler's can extend this and return an
instance of this in the
#getQueueRefresher() method. The
#refreshQueues(List) method of this instance will be invoked by the
QueueManager whenever it gets a request from an administrator to
refresh its own queue-configuration. This method has a documented contract
between the
QueueManager and the
TaskScheduler.
Before calling QueueRefresher, the caller must hold the lock to the
corresponding
TaskScheduler (generally in the
JobTracker).