use Time::HiRes (sleep time);

my $next_time = time();

while (1) {
    next if time() < $next_time;

    $next_time += 60;              # no accumulated lag

    my $price = fetch();
    do_it($price);

    my $took = time()- ($next_time-60); 

    handle_edge_case() if $took > 60;

    sleep 59 - $took;
}