use strict;
use warnings;

use AnyEvent;
use AnyEvent::Ping;
use Data::Dumper;

# separate the hosts wrt their timer groups
my @todoList1 = map { "192.168.100." . $_ } (1 .. 2);
my @todoList2 = map { "192.168.100." . $_ } (3 .. 4);

# a global hash keyed on IPs, => [0,[]]: no pinging now, =>[1,[]]: ping in progress
# the array ref storing ping history can be a Queue of finite size
my $pingState = { map { $_ => [0,[]] } @todoList1, @todoList2 };

my $cv     = AnyEvent->condvar;
my @timers = (   
    AnyEvent->timer (
        after    => 2,
        interval => 5,
        cb       => sub {
            warn "Timer 1 at " . AnyEvent->now . "\n";
            ping_hosts (1, @todoList1);
        }
    ),      
    AnyEvent->timer (
        after    => 2,
        interval => 7,
        cb       => sub {
            warn "Timer 2 at " . AnyEvent->now . "\n";
            ping_hosts (2, @todoList2);
        }   
    ),  
    AnyEvent->timer (
        after => 20,
        cb    => sub {
            warn "Timer 3 at " . AnyEvent->now . "\n";
            $cv->send;
        }
    ),
);
$cv->recv;

print "DONE.\n".Dumper($pingState);

sub ping_hosts {
    my ($num, @hosts) = @_;

    my $ping_timeout  = 2;     #seconds to wait for response
    my $ping_attempts = 4;     #number of pings to issue,
    my $ping_pktsize  = 32;    #packet size of ping

    my $ping = AnyEvent::Ping->new (packet_size => $ping_pktsize);
    $ping->timeout ($ping_timeout);

    #$cv_ping->begin(sub { shift->send($_[0]) });
    foreach my $host (@hosts) {
        if( $pingState->{$host}->[0] == 1 ){
                print "ping in progress already to host '$host', skipping till the next timer ...\n";
                next
        }
        $pingState->{$host}->[0] = 1; # set the "ping in progress" flag
        $ping->ping (
        #mock_ping( # emulate the ping
            $host,
            $ping_attempts,
            sub {
                print "Pinger $num: $host state:" . Dumper ($_[0]) . "\n";
                # store the ping results in global history and remove the "ping-in-progress" flag
                push @{$pingState->{$host}->[1]}, $_[0];
                $pingState->{$host}->[0] = 0; # ping finished
            },
# mock_ping extra parameters
#	$ping_timeout,
#	50/100 # probability of a failed ping
        );
    }
}

# code below is
# optional for testing without ping'ing
sub	mock_ping {
	my ($host, $attempts, $cb,
	  $timeout, $failure_prob) = @_;

	# no $attempts, just fail or succeed so many % of times
	my $started = AnyEvent->time;
	if( rand()<$failure_prob ){
		# simulate a failed ping with lots of delay
		# so as to coincide with next timer event
		AEsleep($timeout*3);
		$cb->([$host, "$started -> fail -> ".AnyEvent->time]);
		return 0;
	} else {
		# a successful ping safely within the timeout
		AEsleep($timeout/2); # simulate a ping
		$cb->([$host, "$started -> succ -> ".AnyEvent->time]);
		return 1; # success ping
	}
}
# this is the closest I came to emulating spawning a blocking
# ping. Note that using Perl's sleep() is no-go with AnyEvent's timers
# AFAIU, re: "It is usually a mistake to intermix alarm and sleep calls"
# and sadly there is no AE::sleep() AFAIK
sub AEsleep($) { `sleep $_[0]` }