NAME
    Net::DNS::Async - Asynchronous DNS helper for high volume applications

SYNOPSIS
            use Net::DNS::Async;

            my $c = new Net::DNS::Async(QueueSize => 20, Retries => 3);

            for (...) {
                    $c->add(\&callback, @query);
            }
            $c->await();

            sub callback {
                    my $response = shift;
                    ...
            }

DESCRIPTION
    Net::DNS::Async is a fire-and-forget asynchronous DNS helper. That is,
    the user application adds DNS questions to the helper, and the callback
    will be called at some point in the future without further intervention
    from the user application. The application need not handle selects,
    timeouts, waiting for a response or any other such issues.

    If the same query is added to the queue more than once, the module may
    combine the queries; that is, it will perform the query only once, and
    will call each callback registered for that query in turn, passing the
    same Net::DNS::Response object to each query. For this reason, you
    should not modify the Net::DNS::Response object in any way lest you
    break things horribly for a subsequent callback.

    This module is similar in principle to POE::Component::Client::DNS, but
    does not require POE.

CONSTRUCTOR
    The class method new(...) constructs a new helper object. All arguments
    are optional. The following parameters are recognised as arguments to
    new():

    QueueSize
        The size of the query queue. If this is exceeded, further calls to
        add() will block until some responses are received or time out.

    Retries
        The number of times to retry a query before giving up.

    Timeout
        The timeout for an individual query.

METHODS
    $c->add($callback, @query)
        Adds a new query for asynchronous handling. The @query arguments are
        those to Net::DNS::Resolver->bgsend(), q.v. This call will block if
        the queue is full. When some pending responses are received or
        timeout events occur, the call will unblock.

        The user callback will be called at some point in the future, with a
        Net::DNS::Packet object representing the response. If the query
        timed out after the specified number of retries, the callback will
        be called with undef.

    $c->await()
        Flushes the queue, that is, waits for and handles all remaining
        responses.

BUGS
    The test suite does not test query timeouts.

SEE ALSO
    Net::DNS, POE::Component::Client::DNS

COPYRIGHT
    Copyright (c) 2005-2006 Shevek. All rights reserved.

    This program is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.