Hi,
We have a Mojolicious web application which in general works quite nicely.
Recently we had a need to add the capability to get some of the application
data from a remote device.
The remote device might be offline or slow so I wrote a Controller action
to use Mojo::UA in non-blocking mode.
It seems to work fine when the remote device is active, but it generates
spurious error output when the remote device is offline.
For example,
[Wed Jan 10 18:36:31 2018] [debug] GET "/dashboard/hfdata/179"
[Wed Jan 10 18:36:31 2018] [debug] Routing to controller
"Frontend::Controller::Dashboard" and action "hf_proxy"
[Wed Jan 10 18:36:31 2018] [debug] Initiating request for live data from
http://(removed)
[Wed Jan 10 18:36:31 2018] [debug] Request for live data failed;
url=http://(removed)
code=500 msg=Connect timeout
Mojo::Reactor::Poll: Timer failed: Connection already closed at /usr/local/
share/perl/5.22.1/Mojo/UserAgent.pm line 251.
All but the last line are output by my Controller action.
The last line is output by Mojolicious from its internals, writing directly
to STDOUT (or STDERR, I suppose).
Here is my Controller action (invoked via a Mojolicious route), is it doing
something wrong?
(I have obfuscated the remote device's URL in the example above and in the
code below.)
package Frontend::Controller::Dashboard;
use Mojo::Base 'Mojolicious::Controller';
sub hf_proxy {
my $self = shift;
my $user = $self->stash->{user};
my $did = $self->param('did');
my $device = $user->device_by_id($did);
$self->stash(device => $device);
if (!$device) {
# Non-existent device ID, or not owned by this user
$self->app->log->error("No device $did for $user");
return $self->render(status => 404, json => { message => 'Invalid
device ID for this user' } );
}
# Use the Mojolicious UA to query the myWatt board. See the article
# "Blocking vs non-blocking 101" on the Mojolicious WiKi for
explanation.
my $ip = $device->ip;
my $dhash = $device->device_id_hash;
my $url = "http://(removed)";
$self->app->log->debug("Initiating request for live data from $url");
$self->render_later;
$self->ua->get($url => sub {
my ($ua, $tx) = (@_);
if (my $res = $tx->success) {
$self->app->log->debug("Got live data: ".$res->body);
$self->render(data => $res->body, format => 'json');
}
else {
my $error = $tx->error;
my $code = $error->{code} || 500;
my $msg = $error->{message} || 'Connection failed';
$self->app->log->debug("Request for live data failed; url=$url
code=$code msg=$msg");
$self->render(status => $code, json => { message => $msg });
}
});
}
FYI, we are running on Ubuntu 16.4 LTS:
jeremy@devtest:~$ mojo version
CORE
Perl (v5.22.1, linux)
Mojolicious (7.44, Doughnut)
OPTIONAL
EV 4.0+ (n/a)
IO::Socket::Socks 0.64+ (n/a)
IO::Socket::SSL 1.94+ (2.024)
Net::DNS::Native 0.15+ (n/a)
Role::Tiny 2.000001+ (2.000001)
Thanks,
Jeremy Begg
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