(No version information available, might be only in CVS)
SplPriorityQueue::compare — Compare priorities in order to place elements correctly in the heap while sifting up.
Compare priority1 with priority2 .
The priority of the first node being compared.
The priority of the second node being compared.
Result of the comparison, positive integer if priority1 is greater than priority2 , 0 if they are equal, negative integer otherwise.
Informacja: Multiple elements with the same priority will get dequeued in no particular order.