LinuxQuestions.org - Non blocking sockets in Perl

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Non blocking sockets in Perl

How to make such a socket?:)
I understood that there are 2 ways:
using IO::Socket
using Fcntl ?
I'm sort of familiar with IO::Socket, and I write simple IRC bots/servers. I thought that
$sock->autoflush(1);
$| = 1;
makes the socket non-blocking, but a friend of mine just laughed and said that I'm wrong :) He said that I better use Fcntl, but it still could be done with IO::Socket... I'm confused.
Let's say according to me, a non-blocking socket allows other parts of the code to be executed in the same time where the socket is being read or wrote. This is how I do with IO::Socket:

Code:

IO::Socket -> create the socket

$sock->autoflush(1);

$| = 1;

while (<$sock>){

if ($sock =~ /some stuff/){

do(some other stuff);

}

}

So in that way I make simple query-response bots, but nothing more than that.
I want to make simple application: a timer bot. Let's say at every 30 seconds, it writes a line to the socked, and uses time() function. I don't know even where from to start. Somebody give me a direction please?

Anyone help?
At least show me a perl forum where I could ask :)

You can use the four argument form of select() to check whether a handle (like a socket) has input waiting. However, IO::Handles (which include IO::Sockets) have the blocking function (for example, $sock->blocking(0)) to turn blocking on and off.

Here's an example:

Code:

print "create_listening_socket()\n";



    # Listen to port

    $socket_errmsg = "";

    $cfg::listen_socket =

                IO::Socket::INET->new(LocalPort => $cfg::params{'RPS_PORT'},

                                      Type      => SOCK_STREAM,

                                      Proto    => 'tcp',

                                      Listen    => SOMAXCONN,

                                      Reuse    => 1,

                                      Blocking  => 0 )

                or $socket_errmsg =

                "Can't make RPS server Listen socket on port ".

                "$cfg::params{'RPS_PORT'}: $@\n";



    # Did we succeed ?

    if( $socket_errmsg )

    {

        send_email($socket_errmsg."\n$0 exiting with error.");

        exit_with_error($socket_errmsg);

    }



in a separate sub, do this:



    # Activate socket

    $read_handles = IO::Select->new();

    $read_handles->add($cfg::listen_socket);

    # Main loop: check reads/accepts, check writes, check ready to process



    # Loop forever, listening for incoming msgs

    while (1)

    {

        # check for new information on the connections we have

        ($new_read_handles) =

                        IO::Select->select($read_handles, undef, undef,

                                            $cfg::params{'LISTEN_WAIT'} );



        # anything to read or accept?

        foreach $client ( @$new_read_handles )

        {

            if( $client == $cfg::listen_socket )

            {

                # accept a new connection

                $new_client = $cfg::listen_socket->accept();

                $read_handles->add($new_client);

            }

            else

            {

                # Msg ready ?

                # read data

                $msg = '';

                $msg = <$client>;



                if( $msg )

                {

#DEBUG

#print "Listen: MSG-IN=$msg\n";



                    # Add to conn recs queue

                    $cfg::send_queue->enqueue($msg);

                }

                else

                {

                    # client has finished/closed

                    $read_handles->remove($client);

                    close $client;

                }

            }

        }

btw; non-blocking socket means socket doesn't wait for a msg if none is incoming ie code doesn't
get stuck waiting. You may or may not want this.
See Perl Cookbook chap 17