await - defer demo

await_defer.pl

#!/usr/bin/env perl
use strict;
use warnings;
use feature ':5.10';
use AnyEvent;

our $await_info;

sub on_timeout {
    my ($timeout, $code) = @_;
    
    push @{$await_info->{timers}}, AnyEvent->timer(
        after => $timeout / 1000,
        cb    => $code,
    );
}

sub await(&) {
    my $code = shift;
    
    local $await_info = {
        timers   => [],
        to_defer => {},
        done     => AnyEvent->condvar,
    };
    
    $code->();
    
    $await_info->{done}->send if !%{$await_info->{to_defer}};
    $await_info->{done}->recv;
}

sub defer {
    my $to_defer = $await_info->{to_defer};
    my $id = scalar(keys(%$to_defer)) + 1;
    $to_defer->{$id} = 1;
    
    say "  $id defer request";
    
    return sub {
        say "    $id defer done";
        delete $to_defer->{$id};
        $await_info->{done}->send if !%$to_defer;
    };
}


### testing...

say 'starting a 2s wait block';
await { 
    # leave this thing after all timeouts are over
    on_timeout(1000, defer());
    on_timeout(2000, defer());
};
say '2s wait block done';