Barry Brevik wrote:
> I am using Active Perl 5.8.8 on Windows.
>
> I am writing an app that opens a TCP socket to a network printer, and
> then prints barcode labels on it. When the app starts up, it tries to
> determine if the specific printer is reachable or not.
>
> If the printer is on the network and online, then the test goes well.
> However, if the printer is not reachable for some reason, there is a
> lengthy timeout before the connect function fails.
>
> I would like to make that timeout much shorter than it is, so I wonder
> if anybody knows how to do that. My sample program is shown below:
>
> use Socket;
> use Warnings;
>
> $printPort = 9100;
> $printHost = '10.18.0.30';
> $printProtocol = (getprotobyname('tcp'))[2];
>
> # The print host can be expressed as either a host name, or an
> # IP address, but it has to end up as a binary IP address.
> if ($printHost =~ /^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/)
> {
> $printHost = pack('C4', split(/\./, $printHost));
> }
> else {$printHost = (gethostbyname($printHost))[4];}
>
> $printHostReadable = join('.', unpack('C4', $printHost));
> print "\n\nConnecting to printer $printHostReadable... ";
>
> if (socket(BARCODE, AF_INET, SOCK_STREAM, $printProtocol))
> {
> if (connect(BARCODE, pack('Sna4x8', AF_INET, $printPort,
> $printHost)))
> {
> print "<< ok >>\n\n";
> close BARCODE;
> }
> else
> {
> print "<< offline >>\n\n";
> }
> }
>
the IO::Socket package has an optional timeout value for connect
(http://perldoc.perl.org/IO/Socket/INET.html). Looking briefly at that
module, it seems to be implemented using select. You can try to do
something like that yourself...or just use the IO::Socket package and be
done with it.
-Mike
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