my $cv = AnyEvent->condvar;
my $timer = AnyEvent->timer( after => 10, cb => sub { $cv->croak("Timeout"); };
do_something( 
    on_success => sub{ $cv->send(@_); }, 
    on_error => sub{ $cv->croak(shift); },
);
my $result = $cv->recv();
undef $timer; 
analyze_do_something( $result );