Is it possible to read headers using Perl HTTP::Async module? - perl

Question

To optimize my Perl application I need to work with async HTTP requests, so I can handle other operations once the HTTP response is finish. So I believe my only option is to work with HTTP::Async module. This works fine for simple requests, but I need to catch cookie header from one response and send it with next one, so I need to read headers. My code is:
...
$async->add($request);
while ($response = $async->wait_for_next_response)
{
threads->yield(); yield();
}
$cookie = $response->header('Set-Cookie');
$cookie =~ s/;.*$//;
$request->header('Cookie' => $cookie);
...
but it's not working, as it ends with an error Can't call method "header" on an undefined value. Obviously $response is undef. How can I catch headers before $response gets undef?

Answer 1

while ($response = $async->wait_for_next_response)
{
threads->yield(); yield();
}
Is guaranteed not to finish until $response is false. The only false value wait_for_next_response will return is undef. You need to either extract the cookie inside the loop, or cache the last good response inside the loop.
Something like
my $last_response;
while ($response = $async->wait_for_next_response)
{
$last_response = $response;
threads->yield(); yield();
}
should work, although I'm not sure you need the loop at all. It's hard to tell without a complete program.