Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I have a program that uses AnyEvent and I want to call Finance::MtGox, but do so without blocking the event loop. I tried both LWP::Protocol::AnyEvent::http and calling an internal method in Finance::MtGox to just construct the HTTP::Request and use AnyEvent::HTTP to make the request, but both of these result in a 400 Bad Request. I'm including the code so hopefully somebody can figure out where I'm going wrong. Thanks!

Need to subclass Finance::MtGox so the POST goes to a test server. 

use Data::Dump;

BEGIN {
    package Local::Finance::MtGox;
    use base 'Finance::MtGox';
    sub _build_api_method_uri {
        return URI->new("https://h.wrttn.me/post");
    }
}

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This works as expected, but it's blocking. 
my $mtgox = Local::Finance::MtGox->new({ key => 'key', secret => 'secr
+et' });
$mtgox->{mech}->ssl_opts(verify_hostname => 0);
dd $mtgox->call_auth('getFunds');

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This works and is non-blocking, but it is not very efficient if it is called many times or the parent process is large. 
use AnyEvent;
use AnyEvent::Util 'fork_call';
my $mtgox = Local::Finance::MtGox->new({ key => 'key', secret => 'secr
+et' });
$mtgox->{mech}->ssl_opts(verify_hostname => 0);
my $cv = AE::cv;
fork_call { $mtgox->call_auth('getFunds') } sub { dd @_; $cv->send };
$cv->wait;

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This doesn't work, it returns a 400 Bad Request. 
use Coro;
use LWP::Protocol::AnyEvent::http;
my $mtgox = Local::Finance::MtGox->new({ key => 'key', secret => 'secr
+et' });
my $coro = async {
    say "before";
    $mtgox->call_auth('getFunds');
};
dd $coro->join;

[download]
This also doesn't work and returns a 400 Bad Request. 
use AnyEvent;
use AnyEvent::HTTP::Request;
use AnyEvent::HTTP::Response;

my $mtgox = Local::Finance::MtGox->new({ key => 'key', secret => 'secr
+et' });
my $cv = AE::cv;
my $req = AnyEvent::HTTP::Request->new(
    # Returns an HTTP::Request
    $mtgox->_build_api_method_request(POST => 'getFunds'),
    {
        cb => sub {
            my $res = AnyEvent::HTTP::Response->new(@_)->to_http_messa
+ge;
            dd $res;
            $cv->send;
        }
    }
);
$req->send;

$cv->wait;

[download]

Replies are listed 'Best First'.
Re: Calling LWP/Mech from AnyEvent
by Anonymous Monk on Oct 30, 2012 at 19:11 UTC
    After ruling out the obvious, I used Charles proxy to see the decrypted request each method was making and it looks like AnyEvent::HTTP is probably mangling the request.

    This is what the working request looks like: 

    POST /post HTTP/1.1
TE: deflate,gzip;q=0.3
Connection: TE, close
Accept-Encoding: gzip
Host: h.wrttn.me
User-Agent: WWW-Mechanize/1.72
Content-Type: application/x-www-form-urlencoded
Rest-Key: key
Rest-Sign: eZsAHbbDBmD3/vHe7zg8IDdPJlV8WHBgHiAdd+ZDb8cD9TPHza4liDAYiLM
+52nHLaGF2Jb9hlpoF 72SfxUg1Uw==
Content-Length: 34

pass=&nonce=1351623186546267&name=

    [download]
    And this is the mangled request from AnyEvent::HTTP: 
    POST /post HTTP/1.1
User-agent: Mozilla/5.0 (compatible; U; AnyEvent-HTTP/2.14; +http://so
+ftware.schmorp.de/pkg/AnyEvent)
Connection: close Te
Rest-sign: GvzSzGg5WHPpL4O2bw48Q8lX6O5prasaiysH98FVS9oWYNfcs7pdUtWNpm7
+xGYG8zT3e0/BcPgHP LZWzMTdubg==

    [download]
    I see the same behavior when changing from https to http.
[reply]
[d/l]
[select]
Re: Calling LWP/Mech from AnyEvent
by Anonymous Monk on Nov 04, 2012 at 21:04 UTC
    This is now solved. It turns out LWP::Protocol::http replaces newlines in headers with spaces, and neither AnyEvent::HTTP, nor LWP::Protocol::AnyEvent::http did similar. Though the latter now does so with the latest CPAN update.
[reply]
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