use strict;
use warnings;
use Time::HiRes 'sleep';
use threads;
use threads::shared;

my $baton:shared = 0;

sub sprinter {
    my ($no_of_threads,$sleep) = @_;
    my $id = threads->self->tid;
    warn ("Thread $id started\n");
    while (1) {
        lock ($baton);
        cond_wait ($baton) until $baton == $id;
        warn ("Thread $id has the baton\n");
        sleep ($sleep);
        $baton = int (rand ($no_of_threads)) until $baton != $id;
        warn ("Thread $id passing the baton to thread $baton\n");
        cond_signal ($baton);
#        cond_broadcast ($baton);
    }
}


my ($no_of_sprinters, $sleep ) = @ARGV;
$no_of_sprinters ||= 3;

my @threads;
push @threads,threads->new (\&sprinter,$no_of_sprinters, $sleep)
    for 1..$no_of_sprinters;

sleep 1;
while(1){
    lock ($baton);
    cond_wait ($baton) until $baton == 0;
    warn ("Thread 0 has the baton\n");
    sleep ($sleep);
    $baton = int (rand ($no_of_sprinters)) until $baton != 0;
    warn ("Thread 0 passing the baton to thread $baton\n");
    cond_signal ($baton);
#    cond_broadcast ($baton);
}