use warnings;
use strict;

{
my @btime;
sub BEGIN_TIME {
	push @btime, time;
}
sub END_TIME {
	@btime or die "error: END_TIME without BEGIN_TIME";
	my($btime, $etime) = (pop @btime, time);
	warn "elapsed time was ", $etime - $btime, " s\n";
}
END {
	@btime and warn "warning: BEGIN_TIME without END_TIME";
}
}

sub foo {
	sleep 2;
	END_TIME;
	sleep 2;
}

BEGIN_TIME;
sleep 3;
foo();

__END__