#!/usr/bin/perl

# http://perlmonks.org/?node_id=1211329

use strict;
use warnings;

if( @ARGV ) # if any argument, it's the server, otherwise the client
            # ( for testing purposes :)
  {
  ### tcp server

  use DBI;
  use IO::Socket::INET;

  ### flush after every write
  $|= 1;

    # creating object interface of IO::Socket::INET modules which internally does
    # socket creation, binding and listening at the specified port address.
    my $socket = new IO::Socket::INET (
      LocalHost=> '127.0.0.1',
      LocalPort=> '5000',
      Proto=> 'tcp',
      Listen=> 5,
      Reuse=> 1
    ) or die "ERROR in Socket creation: $!\n";
    print "I am waiting clients to connect on port 5000.\n";

  ### infinite loop
  while(1) {
    my($client_socket);
    my($peeraddress, $peerport);
    my($row, $data);
    my @processes= ('one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten');


    while($row= shift(@processes)) {
      $client_socket = $socket->accept();
      $peeraddress = $client_socket->peerhost();
      $peerport = $client_socket->peerport();
      print "Sending $row to $peeraddress:$peerport)... ";

      # write to the newly accepted client.
      print $client_socket "$row\n";

      # read from the newly accepted client.
      $data = <$client_socket> // 'nothing';
      chomp($data);
      print "got $data from client.\n";

      $client_socket->close();
    }
    #$socket->close();
  }
  }
else
  {
  ### tcp client
  
  my $max = 2;
  my $active = 0;

  while( 1 )
    {
    while( $active < $max )
      {
      if( my $pid = fork ) # parent
        {
        $active++;
        }
      elsif( defined $pid ) # child
        {
        my($socket, $data);
        $socket= new IO::Socket::INET (
          PeerHost=> '127.0.0.1',
          PeerPort=> '5000',
          Proto=> 'tcp'
        ) or die "ERROR in Socket creation: $!\n";

        $socket->autoflush(1);
        $data= <$socket>;
        chomp($data);
        $socket->close();
        print "($$) Got $data from producer.\n";
        sleep 1;
        exit;
        }
      else
        {
        die "fork failed $!";
        }
      }
    if( $active == $max )
      {
      wait;
      $active--;
      }
    }
  }