The sort function func is passed two elements of the queue.
It should return 0 if they are equal, a negative value if the
first element should be higher in the queue or a positive value
if the first element should be lower in the queue than the second
element.
This function must be called while holding the queue's lock.
Sorts queue using func.
The sort function func is passed two elements of the queue. It should return 0 if they are equal, a negative value if the first element should be higher in the queue or a positive value if the first element should be lower in the queue than the second element.
This function must be called while holding the queue's lock.