relay_race.pseudo

function main(argc, argv[]):
  if argc = 4 then
    shared team_count := integer(argv[1])
    shared stage1_delay := integer(argv[1])
    shared stage2_delay := integer(argv[1])
    shared start_barrier := barrier(team_count)
    shared batons := semaphore(0)[team_count]
    shared position := 0
    shared can_access_position := mutex()

    for team := 0 to team_count do
      create_thread(run_stage1, team)
      create_thread(run_stage2, team)
    end for
  else
    print "usage: relay_race team_count stage1_delay stage2_delay"
  end if
end function

function run_stage1(team_number):
  wait(start_barrier)
  delay(stage1_delay)
  signal(batons[team_number])
end function

function run_stage2(team_number):
  wait(batons[team_number])
  delay(stage2_delay)
  lock(can_access_position)
    my_team_position := ++position
    if my_team_position <= 3 then
      print('Place ', my_team_position, ': team ', team_number)
    end if
  unlock(can_access_position)
end function