Hazard Pointer Retire Count

Problem

Count how many retired nodes a hazard-pointer scheme can free.

hazards is a list of per-thread hazard pages (None entries are ignored) and retires is a list of [node_id, page] pairs. A retired node is deferred while any thread holds its page as a hazard, and is freed otherwise.

Return [freed_count, deferred_count].

Hint

Any thread holding the page as a hazard defers reclamation of that node.

Test cases

case 1

in: [[[1,null],[2,null]],[[10,1],[11,1],[12,2],[13,3]]]

expected: [1,3]

case 2

in: [[[null]],[[1,5]]]

expected: [1,0]

case 3

in: [[[7]],[[1,7],[2,7]]]

expected: [0,2]

case 4

in: [[[],[]],[]]

expected: [0,0]

Starter codePython

def hazard_retire_count(hazards, retires):
    # Your code here
    pass

4 test cases · run your code against them in the editor