I am writing a little TCP/IP server to listen for heartbeats from remote machines and raise an alert if one is missed. To keep things simple rather than spawning child processes to handle connections I start a thread that comunicates through a Thread::Queue. Is this safe to do with IO:Socket ? My code follows with a small script to send the heartbeat at the end. Comments on the code also welcome

#!/usr/bin/perl
use strict;
use warnings;
use IO::Socket;
use threads;
use Thread::Queue;

#get the port to bind to or default to 8000
my $port = $ARGV[0] || 8000;

# a hash to record client machines and thread queue for internal comun
+ication
my %clients;
my $queue = Thread::Queue -> new;
my $monitor = threads->create ("monitor", $queue);

#ignore child processes to prevent zombies
$SIG{CHLD} = 'IGNORE';

#create the listen socket
my $listen_socket = IO::Socket::INET->new(LocalPort => $port,
                                          Listen => 10,
                                          Proto => 'tcp',
                                          Reuse => 1);
#make sure we are bound to the port
die "Cant't create a listening socket: $@" unless $listen_socket;

warn "Server ready. Waiting for connections on $port ... \n";

#wait for connections at the accept call
while (my $connection = $listen_socket->accept) {
    # spawn a thread to handle the connection
    my $child = threads->create ("read_data", $queue, $connection);
}

sub read_data {
    # accept data from the socket and put it on the queue
    my ($queue, $socket) = @_;
    while (<$socket>) {
        print "listener got: $_";
        $queue -> enqueue(time." $_");
    }
}

sub monitor {
    my $queue = shift;
    while (1) {
        while ($queue -> pending) {
            my $data = $queue -> dequeue;
            print "monitor got: $data";
            $data =~ /(\d+) Heartbeat from (\S+) next one in (\d+) min
+utes/;
            my $time   = $1;
            my $client = $2;
            my $cycle  = $3;
            if (defined $clients{$client} and $clients{$client} -> [0]
+ eq 'NAK') {
                print "$client sent a beat again\n";
            }
            $clients{$client} = [ 'OK', $time + $cycle * 60 ];
        }
        for my $client (keys %clients) {
            next if $clients{$client}->[0] eq 'NAK';
            next if $clients{$client}->[1] > time;
            print "$client missed a heartbeat, expected at $clients{$c
+lient}->[1], now it is ".time."\n";
            $clients{$client}->[0] = 'NAK';
        }
        sleep 30;
    }
}
[download]

And here is a short script to send heartbeats

#!/usr/bin/perl
use strict;
use warnings;
use IO::Socket;

chomp(my $hostname  = `hostname`);
$hostname =~ s/\..*//;
my $me         = $ARGV[0] || $hostname;
my $cycle_time = $ARGV[1] || 5;
my $port       = $ARGV[2] || 8000;
my $ecg        = 'rtmr';

while (1) {
    print "sending heartbeat\n";
    my $socket = IO::Socket::INET->new(PeerAddr => $ecg,
                                PeerPort => $port,
                                Proto    => "tcp",
                                Type     => SOCK_STREAM)
        or die "Couldn't connect to $ecg:$port : $@\n";

    print "Heartbeat from $me next one in $cycle_time minutes\n";
    print $socket "Heartbeat from $me next one in $cycle_time minutes\
+n";
    close($socket);
    print "zzzzz......\n";
    sleep $cycle_time * 60;
}
[download]

Thanks in advance,
R.

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