sub do_syslog_server
{
   my $host               = shift;
   my $port               = shift;
   my $sleep_after_accept = shift;
   my $sleep_after_recv   = shift;

   my_log( "Start on host '$host' at " . get_datetime_stamp() . "\n" );
   my_log("  pid=$$\n");
   my_log("  port=$port\n");
   my_log("  sleep_after_accept=$sleep_after_accept\n");
   my_log("  sleep_after_recv=$sleep_after_recv\n");

   # This socket is used to listen for connections.
   my $listener = IO::Socket::INET->new(
      LocalPort => $port,
      Proto     => 'tcp',
      Listen    => 5,
      ReuseAddr => 1,
   ) or die "error: IO::Socket::INET new: $@";

   my $selector = IO::Select->new($listener);

SERVER:
   while ( my @ready = $selector->can_read() )
   {
   CLIENT:
      for my $client (@ready)
      {
         if ( $client == $listener )
         {
            my $new_conn = $listener->accept();
            $selector->add($new_conn);
            my $fh_hex = sprintf '0x%x', $new_conn;

            my $peerhost = $new_conn->peerhost();
            my $peerport = $new_conn->peerport();

            my $peeraddr = $new_conn->peeraddr();
            my $peerhostfull = gethostbyaddr( $peeraddr, AF_INET ) || "Cannot resolve";

            my $fromstr = "from $peerhost:$peerport (host=$peerhostfull)";

            my_log("Accepted new connection $fromstr\n");
            if ($sleep_after_accept)
            {
               my_log("Sleeping for $sleep_after_accept seconds...\n");
               sleep($sleep_after_accept);
            }
         }
         else
         {
            my $cli_cmd_str = recv_tcp_client($client);
            if ( !defined($cli_cmd_str) )
            {
               my $peerhost = $client->peerhost();
               my $peerport = $client->peerport();
               my_log("Client $peerhost:$peerport closed socket\n");
               $selector->remove($client);
               $client->close();
               next CLIENT;
            }
            if ( $cli_cmd_str =~ /^KNOB_SERVER_PLEASE_QUIT\s*$/ )
            {
               my_log("Server quitting on Knob's command\n");
               last SERVER;
            }
            if ($sleep_after_recv)
            {
               my_log("Sleeping for $sleep_after_recv seconds...\n");
               sleep($sleep_after_recv);
            }
         }
      }
   }

   my_log("Closing server\n");
   close($listener) or die "error: close server: $!";
   my_log("End do_syslog_server\n");
}