Having issues using AnyEvent::DNS with a call back

[Robin Redeker]

Hi!

On Wed, Jun 16, 2010 at 12:52:00AM -0400, Michael Greb wrote:
> AnyEvent::DNS docs indicate the following should work, however the script exits 0 nearly instantly with no output:
> 
> use AnyEvent::DNS;
> use Data::Dumper;
> my $dns = AnyEvent::DNS->new();
> $dns->resolve( "thegrebs.com", "mx", sub { warn Dumper[@_]} );

You are not running any event loop here. There are only very few operations
with AnyEvent that actually block (and execute a/the event loop). One of them
is the recv() method of a condvar.

> The alternative script below works as expected:
> 
> use AnyEvent::DNS;
> use Data::Dumper;
> my $dns = AnyEvent::DNS->new();
> $dns->resolve( "thegrebs.com", "mx", my $cv = AnyEvent->condvar );
> warn Dumper [$cv->recv];

Yep, here $cv->recv blocks until the domain is resolved and returns the result.

If you need a callback try:

   $dns->resolve( "thegrebs.com", "mx", my $cv = AnyEvent->condvar );
   $cv->cb (sub {
      my ($cv) = @_;
      warn Dumper [$cv->recv]; # inside the callback recv() doesn't block.
   });


Greetings,
   Robin

-- 
Robin Redeker                         | Deliantra, the free code+content MORPG
elmex at ta-sa.org / r.redeker at gmail.com | http://www.deliantra.net
http://www.ta-sa.org/                 |