use Scope::Guard qw( );

my %state;

{
   my $backup = freeze(\%state);
   my $sentinel = Scope::Guard->new(sub {
      %state = %{ thaw($backup) };
   });

   $state{a} = ...;
   push @{$state{b}}, ...;
   $state{c}{key} = ...;

   if (success) {
      $sentinel->dismiss();
   }
}