#include <db_cxx.h> int DbTxn::abort();
         The DbTxn::abort() method causes an abnormal termination of the
         transaction. The log is played backward, and any necessary undo
         operations are done through the tx_recover 
         function specified to DbEnv::set_app_dispatch().
          Before DbTxn::abort() returns, any locks held by the transaction
         will have been released.
    
In the case of nested transactions, aborting a parent transaction causes all children (unresolved or not) of the parent transaction to be aborted.
All cursors opened within the transaction must be closed before the transaction is aborted.
         After DbTxn::abort() has been called, regardless of its return, the
         DbTxn  handle may not be
         accessed again.
    
         The DbTxn::abort() 
            
            
                method either returns a non-zero error value or throws an
                exception that encapsulates a non-zero error value on
                failure, and returns 0 on success.