async hooks

[xurc]

Hello.

Is there any way to call to declare an asynchronous handler for "under" or before_dispatch / around_action hooks? Something like

$app->hook(around_action => async sub { await ... });
$route->under(async sub { await ... });

For example, if I need to perform some checks or fill a stash from the database and I want to use async / await in these operations.

How can wait non-blocking calls inside hooks or "under" in such a way that the execution is not transferred to the controller/action until all preliminary async operations have been completed? I also want to be able to cancel dispatch chain in such operations.

Is it possible?

[kraih]

I'm afraid it's not that easy yet. The problem is that async/await are only an optional dependency, so making the router work with it consistently would be very complicated. And backwards compatibility has to be considered as well.

[doojonio]

Is that possible to make it async with continue method in Mojolicious::Controller? Like here https://docs.mojolicious.org/Mojolicious/Guides/Routing#Under. In this case I think we can create Mojo::Promise object and in then callback call continue method

[xurc]

Yes, it works, thanks a lot for the tip.

            my $parent = $route->under(
                sub {
                   #
                   # Some code skipped
                   # 
                    my @promises;
                    for my $filler ( @{$fillers} ) {
                        # 'fill' declared as async
                        push @promises, $c->stashfiller->$filler->fill($c);
                    }

                    Mojo::Promise->all_settled(@promises)->then(
                        sub {
                            my @err;
                            for my $result (@_) {
                                push @err, $result->{value}[0] if $result->{value}[0];
                            }
                            return $c->respond_to( any => { $c->err->build( 409, \@err ) } ) if @err;
                            $c->continue;
                        }
                    )->wait;

                    return undef;
                }
            );