package obj;

use 5.010;
use strict;
use threads;
use Thread::Queue qw( );

sub new {
	my ( $class, %args ) = @_;
	my $self = bless( {}, $class );
	say "creating new obj";
	return $self;
}

sub sub1 { say "sub1 starts"; sleep 1 for 1 .. 2; say "sub1 ends" }

sub sub2 {
	my $self = shift;
	$self->{KEY} = 1;
	exists( $self->{KEY} ) ? say "KEY exists" : say "KEY does NOT exist";
	say "sub2 starts";
	sleep 1 for 1 .. 2;
	say "sub2 ends";
}
sub sub3 { say "sub3 starts"; sleep 1 for 1 .. 5; say "sub3 ends" }
sub sub4 { say "sub4 starts"; sleep 1 for 1 .. 5; say "sub4 ends" }
sub sub5 { say "sub5 starts"; sleep 1 for 1 .. 5; say "sub5 ends" }
sub sub6 { say "sub6 starts"; sleep 1 for 1 .. 5; say "sub6 ends" }
sub sub7 { say "sub7 starts"; sleep 1 for 1 .. 2; say "sub7 ends" }
sub sub8 { say "sub8 starts"; sleep 1 for 1 .. 2; say "sub8 ends" }

sub run {
	my $self    = shift;
	my $q       = Thread::Queue->new();
	my $t1      = async { sub1(); $q->enqueue(1); };
	my $t2      = async { sub2($self); $q->enqueue(2); };
	my $pending = 2;
	my @threads;
	for ( ; ; ) {
		my $id = $q->dequeue();
		if ( $id == 1 ) {
			$t1->join();
			push @threads, async { sub3() }, async { sub4() };
			--$pending;
		}
		elsif ( $id == 2 ) {
			$t2->join();
			exists( $self->{KEY} )
			  ? say "KEY exists"
			  : say "KEY does NOT exist";
			push @threads, async { sub5() }, async { sub6() };
			--$pending;
		}

		if ( !$pending ) {
			push @threads, async { sub7() }, async { sub8() };
			last;
		}
	}

	$_->join() for @threads;
}

1;

##</code><code>##

use strict;
use warnings;

use obj;

my $o = obj->new();
$o->run();