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

	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;
		...
	}

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.

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.

$c->add($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.

The test suite does not test query timeouts.

Net::DNS, POE::Component::Client::DNS

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.