Adapted from http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/PriorityBlockingQueue.html.
Adapted from http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/PriorityBlockingQueue.html. The purpose of this wrapper class is so that FIFO ordering is maintained for elements in the queue having the same priority.
This is a separate class to ensure that state changes are always managed by a single thread.
A collection of stateless MTurk utility functions.