IPS::MPS, AnyEvent::HTTPD, AnyEvent::HTTP and DBI

Игрался на perl связкой IPS::MPS, AnyEvent::HTTPD, AnyEvent::HTTP и DBI.
Сделал четыре процесса: главный (управляющий), HTTP сервер, HTTP клиент, DBI клиент.
Хотя блокируемый процесс тут один: DBI, но этого поиграться с межпроцессным взаимодействием в стиле передачи сообщений хватит:

use IPC::MPS::Event;
use AnyEvent::HTTPD;
use AnyEvent::HTTP;
use DBI;

my $port = 9090;

print "Please contact me at: http://127.0.0.1:$port/?q=foo\n";

my $vpid_server = spawn {

  my %url2req; # $url => [$req, ...]

  my $httpd = AnyEvent::HTTPD->new(port => $port);

  $httpd->reg_cb (
    '' => sub {
      my ($httpd, $req) = @_;
      my $q = $req->parm('q');
      if ($q) {
        my $url = "http://www.google.com/search?q=$q";
        snd(0, "req", $url);
        push @{$url2req{$url}}, $req;
      } else {
        $req->respond([404, 'NOT FOUND']);
      }
    },
  );

  receive {
    msg res => sub {
      my ($from, $url, $data, $headers) = @_;
      for my $req (@{$url2req{$url}}) {
        $req->respond([200, 'OK', {'Content-Type' => 'text/html'}, $data]);
      }
      delete $url2req{$url};
    };
  };

};


my $vpid_client = spawn {
  receive {
    msg req => sub {
      my ($from, $url) = @_;
      http_get $url, sub {
        my ($data, $headers) = @_;
        snd($from, "res", $url, $data, $headers);
      };
    };
  }
};


my $vpid_dbi = spawn {

  # CREATE DATABASE nick OWNER nick ENCODING 'UTF8';
  # CREATE TABLE urls (id_url SERIAL, datetime TIMESTAMP DEFAULT now(), url text, PRIMARY KEY (id_url));
  # DROP TABLE urls;
  my $data_sourse = "DBI:Pg:dbname=nick;host=localhost";
  my $dbh = DBI->connect($data_sourse, "nick", "") or die $DBI::errstr;
  my $sth = $dbh->prepare("INSERT INTO urls (url) VALUES (?)") or die $dbh->errstr();

  receive {
    msg res => sub {
      my ($from, $url) = @_;
      $sth->execute($url) or die $dbh->errstr();
    };
  }
};


receive {
  msg req => sub {
    my ($from, $url) = @_;
    snd($vpid_client, "req", $url);
    warn "Q; $url";
  };
  msg res => sub {
    my ($from, $url, $data, $headers) = @_;
    snd($vpid_server, "res", $url, $data, $headers);
    snd($vpid_dbi, "res", $url);
    warn "R; $url";
  };
};

Забавно получается.