Oops! I had missed that, thanks.
Below is the cycle subroutine with the truncated parts, for anyone kind enough to try to figure this out:

sub cycle {
    my $self = shift;
    my (@new_readable) = $self->{readable_handles}->can_read(.1);
    foreach my $socket (@new_readable) {
        if ($socket == $self->{main_socket}){
            #new connection
            my $new_socket = $socket->accept();
            #Make it non-blocking
            #fcntl($new_socket, F_SETFL(), O_NONBLOCK());
            $self->{players}->{$new_socket} = {
                read => 0,
                message => ''
                 };
            $self->{readable_handles}->add($new_socket);
            print "Added new connection\n";
            #added to list of connections
            #may not have data yet
        } else {
            #check for connection closure
            if (not eof($socket)){
                my $message = '';
                my $read_count;
                #Read from socket
                #First, get size
                #1) Does this always work?
                #2) How can we get rid of the hardcoded sizeof(int)?
                $read_count = sysread($socket, $message, 4);
                if($read_count < 4) {
                    print "Nope, can't guarantee getting message_lengt
+h\n";
                } else {
                    #store length of incoming
                    #Note that we'll have to use pack/unpack to make i
+nt
                    $self->{players}->{$socket}->{read} = unpack("l",$
+message);
                    $self->{players}->{$socket}->{message}="";
                    print "Got incoming length: $message\n";
                    $read_count = sysread($socket, $message, $self->{p
+layers}->{$socket}->{read}); #was missing end of this line
                    if($read_count < $self->{players}->{$socket}->{rea
+d}){
                        print "Only got $read_count of $self->{players
+}->{$socket}->{read}\n"; #was missing end of this line

                    } else {
                        print "Got message: $message\n";
                        $self->{players}->{$socket}->{read}=0;
                    }
                }
            } else {
                #closed socket, remove from list
                $self->{readable_handles}->remove($socket);
                print "Another closed socket\n";
            } #end checking for socket closure
        } #end checking for main/non-main handle
    } #end foreach
}
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