#! perl -slw
use strict;
use threads;
use Thread::Queue;
use IO::Socket;
use IO::Select;
use constant PACKETLEN => 30;

my $Q = new Thread::Queue;

async {
    my $noBlock = 1;

    my $lsn = IO::Socket::INET->new(
        Proto => 'tcp', LocalPort => 12345,
        Listen => SOMAXCONN, Reuse => 1, TIMEOUT => 3,
    ) or die "Server failed to create listener: $^E";
    binmode $lsn;
    ioctl( $lsn, 0x8004667e, \$noBlock );
    my $sel = IO::Select->new( $lsn );

    my %inbufs;

    while( 1 ) {
        my @ready = $sel->can_read(1);

        for my $ready ( @ready ) {
            if( $ready == $lsn ) {
                my $client = $lsn->accept or next;
                binmode $client;
                ioctl( $client, 0x8004667e, \$noBlock );
                $sel->add( $client );
                $inbufs{ $client } = '';
            }
            else {
                if(
                    read( $ready, $inbufs{ $ready },
                        PACKETLEN - length( $inbufs{ $ready } ),
                        length( $inbufs{ $ready } )
                    ) == 0
                ) {
                    $ready->shutdown( 2 );
                    $sel->remove( $ready );
                    $ready->close;
                    delete $inbufs{ $ready };
                    next;
                }
                length( $inbufs{ $ready } ) == PACKETLEN or next;
                $Q->enqueue( $inbufs{ $ready } );
                $inbufs{ $ready } = '';
            }
        }
    }
}->detach;

my $c = 0;
while( my $packet = $Q->dequeue ) {
    ## Do something with the packet
    printf "\r%u: $packet", ++$c;
}