+# this takes in a list of node and user calls (not references) from
+# a config type update for a node and returns
+# the differences as lists of things that have gone away
+# and things that have been added.
+sub calc_config_changes
+{
+ my $self = shift;
+ my %nodes = map {$_ => 1} @{$self->{nodes}};
+ my %users = map {$_ => 1} @{$self->{users}};
+ my $cnodes = shift;
+ my $cusers = shift;
+ my (@dnodes, @dusers, @nnodes, @nusers);
+ push @nnodes, map {my @r = $nodes{$_} ? () : $_; delete $nodes{$_}; @r} @$cnodes;
+ push @dnodes, keys %nodes;
+ push @nusers, map {my @r = $users{$_} ? () : $_; delete $users{$_}; @r} @$cusers;
+ push @dusers, keys %users;
+ return (\@dnodes, \@dusers, \@nnodes, \@nusers);
+}