gistfile1.pl

use strict;
use warnings;

use IO::Async::Channel;
use IO::Async::Loop;
use IO::Async::Routine;

my $loop = IO::Async::Loop->new();

{

    package Slave;

    use parent 'IO::Async::Routine';

    sub configure {
        my $self   = shift;
        my %params = @_;

        $self->{controlstream} = IO::Async::Channel->new(
            on_recv => sub {
                my ( $channel, $data ) = @_;
                my $event = delete $data->{event};
                if ( exists $self->{events}->{$event} ) {
                    return $self->{events}->{$event}->($data);
                }
                warn "Unhanlded event << $event >>\n";
            }
        );

        $self->{loop_setup} = delete $params{loop_setup};
        $self->{events}     = delete $params{events};
        $self->{events} //= {};

        $self->SUPER::configure(
            %params,
            channels_in  => [ $self->{controlstream} ],
            channels_out => [],
            code         => sub {
                $self->run();
            },
        );
    }

    sub _add_to_loop {
        my $self = shift;
        if ( exists $self->{loop_setup} ) {
            $self->{loop_setup}->( $self, @_ );
        }
        $self->SUPER::_add_to_loop(@_);
    }

    sub do_event {
        my ( $self, $event, @args ) = @_;
        my $message = {
            event => $event,
            args  => \@args
        };
        $self->{controlstream}->send($message);
    }

    sub on_finish {
        warn "Got exit condition before the exit signal\n";
        $loop->stop();
    }
}

my $slave = Slave->new(
    setup => sub {
        my ( $self, $loop ) = @_;
    },
    events => {
        'hello' => sub { STDERR->say("Got HELLO in slave"); },
        'exit'  => sub { STDERR->say("Got EXIT in slave"); },
    },
);

$loop->add($slave);

$slave->do_event( hello => {} );
$slave->do_event( exit  => {} );

$loop->run();