fix(table): refresh the cache after a rollback

rollback did not mark the caches of the rolled-back tables as stale. A
cached read after a write and before the rollback kept the rejected
value. Cached readers then got it for up to 5 seconds after the
rollback. MySQL and PostgreSQL share one handle among tables, so a
rollback through one table also undoes the changes of the others.

rollback now refreshes the cache of every table on its handle.

perl-xCAT/xCAT/Table.pm

@@ -65,7 +65,7 @@ use DBI;
 $DBI::dbi_debug = 9;     # increase the debug output
 
 use strict;
-use Scalar::Util qw/weaken/;
+use Scalar::Util qw/blessed weaken/;
 use xCAT::Utils;
 require xCAT::Schema;
 require xCAT::NodeRange;
@@ -1625,6 +1625,12 @@ sub rollback
         return dbc_call($self, 'rollback', @_);
     }
     $self->{dbh}->rollback;
+
+    #the rollback undoes the changes of every table on this handle, so their caches are invalid
+    #new() registers a table before it opens it, so a table that failed to open stays unblessed
+    foreach my $table (@{ $dbobjsforhandle->{ $self->{dbh} } || [ \$self ] }) {
+        $$table->_refresh_cache() if blessed($$table);
+    }
     if ($self->{intransaction} and not $self->{autocommit} and $self->{realautocommit}) {
 
         #on rollback, if sharing a DB handle for autocommit and non-autocommit, put the handle back to autocommit